feat: added leveldb as a backend for historical data storage

Kit/Supporting Files/Kit.h

@@ -0,0 +1,20 @@
+//
+//  Kit.h
+//  Kit
+//
+//  Created by Serhiy Mytrovtsiy on 05/02/2024
+//  Using Swift 5.0
+//  Running on macOS 14.3
+//
+//  Copyright © 2024 Serhiy Mytrovtsiy. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+//! Project version number for Kit.
+FOUNDATION_EXPORT double KitVersionNumber;
+
+//! Project version string for Kit.
+FOUNDATION_EXPORT const unsigned char KitVersionString[];
+
+#import "lldb.h"

Kit/extensions.swift

@@ -576,6 +576,10 @@ public extension Date {
     func convertToTimeZone(_ timeZone: TimeZone) -> Date {
         return addingTimeInterval(TimeInterval(timeZone.secondsFromGMT(for: self) - TimeZone.current.secondsFromGMT(for: self)))
     }
+    
+    func currentTimeSeconds() -> Int {
+        return Int(self.timeIntervalSince1970)
+    }
 }
 
 public extension TimeZone {

Kit/lldb/LICENSE.txt

@@ -0,0 +1,27 @@
+Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Kit/lldb/include/c.h

@@ -0,0 +1,270 @@
+/* Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+  Use of this source code is governed by a BSD-style license that can be
+  found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+  C bindings for leveldb.  May be useful as a stable ABI that can be
+  used by programs that keep leveldb in a shared library, or for
+  a JNI api.
+
+  Does not support:
+  . getters for the option types
+  . custom comparators that implement key shortening
+  . custom iter, db, env, cache implementations using just the C bindings
+
+  Some conventions:
+
+  (1) We expose just opaque struct pointers and functions to clients.
+  This allows us to change internal representations without having to
+  recompile clients.
+
+  (2) For simplicity, there is no equivalent to the Slice type.  Instead,
+  the caller has to pass the pointer and length as separate
+  arguments.
+
+  (3) Errors are represented by a null-terminated c string.  NULL
+  means no error.  All operations that can raise an error are passed
+  a "char** errptr" as the last argument.  One of the following must
+  be true on entry:
+     *errptr == NULL
+     *errptr points to a malloc()ed null-terminated error message
+       (On Windows, *errptr must have been malloc()-ed by this library.)
+  On success, a leveldb routine leaves *errptr unchanged.
+  On failure, leveldb frees the old value of *errptr and
+  set *errptr to a malloc()ed error message.
+
+  (4) Bools have the type uint8_t (0 == false; rest == true)
+
+  (5) All of the pointer arguments must be non-NULL.
+*/
+
+#ifndef STORAGE_LEVELDB_INCLUDE_C_H_
+#define STORAGE_LEVELDB_INCLUDE_C_H_
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "export.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Exported types */
+
+typedef struct leveldb_t leveldb_t;
+typedef struct leveldb_cache_t leveldb_cache_t;
+typedef struct leveldb_comparator_t leveldb_comparator_t;
+typedef struct leveldb_env_t leveldb_env_t;
+typedef struct leveldb_filelock_t leveldb_filelock_t;
+typedef struct leveldb_filterpolicy_t leveldb_filterpolicy_t;
+typedef struct leveldb_iterator_t leveldb_iterator_t;
+typedef struct leveldb_logger_t leveldb_logger_t;
+typedef struct leveldb_options_t leveldb_options_t;
+typedef struct leveldb_randomfile_t leveldb_randomfile_t;
+typedef struct leveldb_readoptions_t leveldb_readoptions_t;
+typedef struct leveldb_seqfile_t leveldb_seqfile_t;
+typedef struct leveldb_snapshot_t leveldb_snapshot_t;
+typedef struct leveldb_writablefile_t leveldb_writablefile_t;
+typedef struct leveldb_writebatch_t leveldb_writebatch_t;
+typedef struct leveldb_writeoptions_t leveldb_writeoptions_t;
+
+/* DB operations */
+
+LEVELDB_EXPORT leveldb_t* leveldb_open(const leveldb_options_t* options,
+                                       const char* name, char** errptr);
+
+LEVELDB_EXPORT void leveldb_close(leveldb_t* db);
+
+LEVELDB_EXPORT void leveldb_put(leveldb_t* db,
+                                const leveldb_writeoptions_t* options,
+                                const char* key, size_t keylen, const char* val,
+                                size_t vallen, char** errptr);
+
+LEVELDB_EXPORT void leveldb_delete(leveldb_t* db,
+                                   const leveldb_writeoptions_t* options,
+                                   const char* key, size_t keylen,
+                                   char** errptr);
+
+LEVELDB_EXPORT void leveldb_write(leveldb_t* db,
+                                  const leveldb_writeoptions_t* options,
+                                  leveldb_writebatch_t* batch, char** errptr);
+
+/* Returns NULL if not found.  A malloc()ed array otherwise.
+   Stores the length of the array in *vallen. */
+LEVELDB_EXPORT char* leveldb_get(leveldb_t* db,
+                                 const leveldb_readoptions_t* options,
+                                 const char* key, size_t keylen, size_t* vallen,
+                                 char** errptr);
+
+LEVELDB_EXPORT leveldb_iterator_t* leveldb_create_iterator(
+    leveldb_t* db, const leveldb_readoptions_t* options);
+
+LEVELDB_EXPORT const leveldb_snapshot_t* leveldb_create_snapshot(leveldb_t* db);
+
+LEVELDB_EXPORT void leveldb_release_snapshot(
+    leveldb_t* db, const leveldb_snapshot_t* snapshot);
+
+/* Returns NULL if property name is unknown.
+   Else returns a pointer to a malloc()-ed null-terminated value. */
+LEVELDB_EXPORT char* leveldb_property_value(leveldb_t* db,
+                                            const char* propname);
+
+LEVELDB_EXPORT void leveldb_approximate_sizes(
+    leveldb_t* db, int num_ranges, const char* const* range_start_key,
+    const size_t* range_start_key_len, const char* const* range_limit_key,
+    const size_t* range_limit_key_len, uint64_t* sizes);
+
+LEVELDB_EXPORT void leveldb_compact_range(leveldb_t* db, const char* start_key,
+                                          size_t start_key_len,
+                                          const char* limit_key,
+                                          size_t limit_key_len);
+
+/* Management operations */
+
+LEVELDB_EXPORT void leveldb_destroy_db(const leveldb_options_t* options,
+                                       const char* name, char** errptr);
+
+LEVELDB_EXPORT void leveldb_repair_db(const leveldb_options_t* options,
+                                      const char* name, char** errptr);
+
+/* Iterator */
+
+LEVELDB_EXPORT void leveldb_iter_destroy(leveldb_iterator_t*);
+LEVELDB_EXPORT uint8_t leveldb_iter_valid(const leveldb_iterator_t*);
+LEVELDB_EXPORT void leveldb_iter_seek_to_first(leveldb_iterator_t*);
+LEVELDB_EXPORT void leveldb_iter_seek_to_last(leveldb_iterator_t*);
+LEVELDB_EXPORT void leveldb_iter_seek(leveldb_iterator_t*, const char* k,
+                                      size_t klen);
+LEVELDB_EXPORT void leveldb_iter_next(leveldb_iterator_t*);
+LEVELDB_EXPORT void leveldb_iter_prev(leveldb_iterator_t*);
+LEVELDB_EXPORT const char* leveldb_iter_key(const leveldb_iterator_t*,
+                                            size_t* klen);
+LEVELDB_EXPORT const char* leveldb_iter_value(const leveldb_iterator_t*,
+                                              size_t* vlen);
+LEVELDB_EXPORT void leveldb_iter_get_error(const leveldb_iterator_t*,
+                                           char** errptr);
+
+/* Write batch */
+
+LEVELDB_EXPORT leveldb_writebatch_t* leveldb_writebatch_create(void);
+LEVELDB_EXPORT void leveldb_writebatch_destroy(leveldb_writebatch_t*);
+LEVELDB_EXPORT void leveldb_writebatch_clear(leveldb_writebatch_t*);
+LEVELDB_EXPORT void leveldb_writebatch_put(leveldb_writebatch_t*,
+                                           const char* key, size_t klen,
+                                           const char* val, size_t vlen);
+LEVELDB_EXPORT void leveldb_writebatch_delete(leveldb_writebatch_t*,
+                                              const char* key, size_t klen);
+LEVELDB_EXPORT void leveldb_writebatch_iterate(
+    const leveldb_writebatch_t*, void* state,
+    void (*put)(void*, const char* k, size_t klen, const char* v, size_t vlen),
+    void (*deleted)(void*, const char* k, size_t klen));
+LEVELDB_EXPORT void leveldb_writebatch_append(
+    leveldb_writebatch_t* destination, const leveldb_writebatch_t* source);
+
+/* Options */
+
+LEVELDB_EXPORT leveldb_options_t* leveldb_options_create(void);
+LEVELDB_EXPORT void leveldb_options_destroy(leveldb_options_t*);
+LEVELDB_EXPORT void leveldb_options_set_comparator(leveldb_options_t*,
+                                                   leveldb_comparator_t*);
+LEVELDB_EXPORT void leveldb_options_set_filter_policy(leveldb_options_t*,
+                                                      leveldb_filterpolicy_t*);
+LEVELDB_EXPORT void leveldb_options_set_create_if_missing(leveldb_options_t*,
+                                                          uint8_t);
+LEVELDB_EXPORT void leveldb_options_set_error_if_exists(leveldb_options_t*,
+                                                        uint8_t);
+LEVELDB_EXPORT void leveldb_options_set_paranoid_checks(leveldb_options_t*,
+                                                        uint8_t);
+LEVELDB_EXPORT void leveldb_options_set_env(leveldb_options_t*, leveldb_env_t*);
+LEVELDB_EXPORT void leveldb_options_set_info_log(leveldb_options_t*,
+                                                 leveldb_logger_t*);
+LEVELDB_EXPORT void leveldb_options_set_write_buffer_size(leveldb_options_t*,
+                                                          size_t);
+LEVELDB_EXPORT void leveldb_options_set_max_open_files(leveldb_options_t*, int);
+LEVELDB_EXPORT void leveldb_options_set_cache(leveldb_options_t*,
+                                              leveldb_cache_t*);
+LEVELDB_EXPORT void leveldb_options_set_block_size(leveldb_options_t*, size_t);
+LEVELDB_EXPORT void leveldb_options_set_block_restart_interval(
+    leveldb_options_t*, int);
+LEVELDB_EXPORT void leveldb_options_set_max_file_size(leveldb_options_t*,
+                                                      size_t);
+
+enum { leveldb_no_compression = 0, leveldb_snappy_compression = 1 };
+LEVELDB_EXPORT void leveldb_options_set_compression(leveldb_options_t*, int);
+
+/* Comparator */
+
+LEVELDB_EXPORT leveldb_comparator_t* leveldb_comparator_create(
+    void* state, void (*destructor)(void*),
+    int (*compare)(void*, const char* a, size_t alen, const char* b,
+                   size_t blen),
+    const char* (*name)(void*));
+LEVELDB_EXPORT void leveldb_comparator_destroy(leveldb_comparator_t*);
+
+/* Filter policy */
+
+LEVELDB_EXPORT leveldb_filterpolicy_t* leveldb_filterpolicy_create(
+    void* state, void (*destructor)(void*),
+    char* (*create_filter)(void*, const char* const* key_array,
+                           const size_t* key_length_array, int num_keys,
+                           size_t* filter_length),
+    uint8_t (*key_may_match)(void*, const char* key, size_t length,
+                             const char* filter, size_t filter_length),
+    const char* (*name)(void*));
+LEVELDB_EXPORT void leveldb_filterpolicy_destroy(leveldb_filterpolicy_t*);
+
+LEVELDB_EXPORT leveldb_filterpolicy_t* leveldb_filterpolicy_create_bloom(
+    int bits_per_key);
+
+/* Read options */
+
+LEVELDB_EXPORT leveldb_readoptions_t* leveldb_readoptions_create(void);
+LEVELDB_EXPORT void leveldb_readoptions_destroy(leveldb_readoptions_t*);
+LEVELDB_EXPORT void leveldb_readoptions_set_verify_checksums(
+    leveldb_readoptions_t*, uint8_t);
+LEVELDB_EXPORT void leveldb_readoptions_set_fill_cache(leveldb_readoptions_t*,
+                                                       uint8_t);
+LEVELDB_EXPORT void leveldb_readoptions_set_snapshot(leveldb_readoptions_t*,
+                                                     const leveldb_snapshot_t*);
+
+/* Write options */
+
+LEVELDB_EXPORT leveldb_writeoptions_t* leveldb_writeoptions_create(void);
+LEVELDB_EXPORT void leveldb_writeoptions_destroy(leveldb_writeoptions_t*);
+LEVELDB_EXPORT void leveldb_writeoptions_set_sync(leveldb_writeoptions_t*,
+                                                  uint8_t);
+
+/* Cache */
+
+LEVELDB_EXPORT leveldb_cache_t* leveldb_cache_create_lru(size_t capacity);
+LEVELDB_EXPORT void leveldb_cache_destroy(leveldb_cache_t* cache);
+
+/* Env */
+
+LEVELDB_EXPORT leveldb_env_t* leveldb_create_default_env(void);
+LEVELDB_EXPORT void leveldb_env_destroy(leveldb_env_t*);
+
+/* If not NULL, the returned buffer must be released using leveldb_free(). */
+LEVELDB_EXPORT char* leveldb_env_get_test_directory(leveldb_env_t*);
+
+/* Utility */
+
+/* Calls free(ptr).
+   REQUIRES: ptr was malloc()-ed and returned by one of the routines
+   in this file.  Note that in certain cases (typically on Windows), you
+   may need to call this routine instead of free(ptr) to dispose of
+   malloc()-ed memory returned by this library. */
+LEVELDB_EXPORT void leveldb_free(void* ptr);
+
+/* Return the major version number for this release. */
+LEVELDB_EXPORT int leveldb_major_version(void);
+
+/* Return the minor version number for this release. */
+LEVELDB_EXPORT int leveldb_minor_version(void);
+
+#ifdef __cplusplus
+} /* end extern "C" */
+#endif
+
+#endif /* STORAGE_LEVELDB_INCLUDE_C_H_ */

Kit/lldb/include/cache.h

@@ -0,0 +1,103 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+//
+// A Cache is an interface that maps keys to values.  It has internal
+// synchronization and may be safely accessed concurrently from
+// multiple threads.  It may automatically evict entries to make room
+// for new entries.  Values have a specified charge against the cache
+// capacity.  For example, a cache where the values are variable
+// length strings, may use the length of the string as the charge for
+// the string.
+//
+// A builtin cache implementation with a least-recently-used eviction
+// policy is provided.  Clients may use their own implementations if
+// they want something more sophisticated (like scan-resistance, a
+// custom eviction policy, variable cache sizing, etc.)
+
+#ifndef STORAGE_LEVELDB_INCLUDE_CACHE_H_
+#define STORAGE_LEVELDB_INCLUDE_CACHE_H_
+
+#include <cstdint>
+
+#include "export.h"
+#include "slice.h"
+
+namespace leveldb {
+
+class LEVELDB_EXPORT Cache;
+
+// Create a new cache with a fixed size capacity.  This implementation
+// of Cache uses a least-recently-used eviction policy.
+LEVELDB_EXPORT Cache* NewLRUCache(size_t capacity);
+
+class LEVELDB_EXPORT Cache {
+ public:
+  Cache() = default;
+
+  Cache(const Cache&) = delete;
+  Cache& operator=(const Cache&) = delete;
+
+  // Destroys all existing entries by calling the "deleter"
+  // function that was passed to the constructor.
+  virtual ~Cache();
+
+  // Opaque handle to an entry stored in the cache.
+  struct Handle {};
+
+  // Insert a mapping from key->value into the cache and assign it
+  // the specified charge against the total cache capacity.
+  //
+  // Returns a handle that corresponds to the mapping.  The caller
+  // must call this->Release(handle) when the returned mapping is no
+  // longer needed.
+  //
+  // When the inserted entry is no longer needed, the key and
+  // value will be passed to "deleter".
+  virtual Handle* Insert(const Slice& key, void* value, size_t charge,
+                         void (*deleter)(const Slice& key, void* value)) = 0;
+
+  // If the cache has no mapping for "key", returns nullptr.
+  //
+  // Else return a handle that corresponds to the mapping.  The caller
+  // must call this->Release(handle) when the returned mapping is no
+  // longer needed.
+  virtual Handle* Lookup(const Slice& key) = 0;
+
+  // Release a mapping returned by a previous Lookup().
+  // REQUIRES: handle must not have been released yet.
+  // REQUIRES: handle must have been returned by a method on *this.
+  virtual void Release(Handle* handle) = 0;
+
+  // Return the value encapsulated in a handle returned by a
+  // successful Lookup().
+  // REQUIRES: handle must not have been released yet.
+  // REQUIRES: handle must have been returned by a method on *this.
+  virtual void* Value(Handle* handle) = 0;
+
+  // If the cache contains entry for key, erase it.  Note that the
+  // underlying entry will be kept around until all existing handles
+  // to it have been released.
+  virtual void Erase(const Slice& key) = 0;
+
+  // Return a new numeric id.  May be used by multiple clients who are
+  // sharing the same cache to partition the key space.  Typically the
+  // client will allocate a new id at startup and prepend the id to
+  // its cache keys.
+  virtual uint64_t NewId() = 0;
+
+  // Remove all cache entries that are not actively in use.  Memory-constrained
+  // applications may wish to call this method to reduce memory usage.
+  // Default implementation of Prune() does nothing.  Subclasses are strongly
+  // encouraged to override the default implementation.  A future release of
+  // leveldb may change Prune() to a pure abstract method.
+  virtual void Prune() {}
+
+  // Return an estimate of the combined charges of all elements stored in the
+  // cache.
+  virtual size_t TotalCharge() const = 0;
+};
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_CACHE_H_

Kit/lldb/include/comparator.h

@@ -0,0 +1,64 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_COMPARATOR_H_
+#define STORAGE_LEVELDB_INCLUDE_COMPARATOR_H_
+
+#include <string>
+
+#include "export.h"
+
+namespace leveldb {
+
+class Slice;
+
+// A Comparator object provides a total order across slices that are
+// used as keys in an sstable or a database.  A Comparator implementation
+// must be thread-safe since leveldb may invoke its methods concurrently
+// from multiple threads.
+class LEVELDB_EXPORT Comparator {
+ public:
+  virtual ~Comparator();
+
+  // Three-way comparison.  Returns value:
+  //   < 0 iff "a" < "b",
+  //   == 0 iff "a" == "b",
+  //   > 0 iff "a" > "b"
+  virtual int Compare(const Slice& a, const Slice& b) const = 0;
+
+  // The name of the comparator.  Used to check for comparator
+  // mismatches (i.e., a DB created with one comparator is
+  // accessed using a different comparator.
+  //
+  // The client of this package should switch to a new name whenever
+  // the comparator implementation changes in a way that will cause
+  // the relative ordering of any two keys to change.
+  //
+  // Names starting with "leveldb." are reserved and should not be used
+  // by any clients of this package.
+  virtual const char* Name() const = 0;
+
+  // Advanced functions: these are used to reduce the space requirements
+  // for internal data structures like index blocks.
+
+  // If *start < limit, changes *start to a short string in [start,limit).
+  // Simple comparator implementations may return with *start unchanged,
+  // i.e., an implementation of this method that does nothing is correct.
+  virtual void FindShortestSeparator(std::string* start,
+                                     const Slice& limit) const = 0;
+
+  // Changes *key to a short string >= *key.
+  // Simple comparator implementations may return with *key unchanged,
+  // i.e., an implementation of this method that does nothing is correct.
+  virtual void FindShortSuccessor(std::string* key) const = 0;
+};
+
+// Return a builtin comparator that uses lexicographic byte-wise
+// ordering.  The result remains the property of this module and
+// must not be deleted.
+LEVELDB_EXPORT const Comparator* BytewiseComparator();
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_COMPARATOR_H_

Kit/lldb/include/db.h

@@ -0,0 +1,167 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_DB_H_
+#define STORAGE_LEVELDB_INCLUDE_DB_H_
+
+#include <cstdint>
+#include <cstdio>
+
+#include "export.h"
+#include "iterator.h"
+#include "options.h"
+
+namespace leveldb {
+
+// Update CMakeLists.txt if you change these
+static const int kMajorVersion = 1;
+static const int kMinorVersion = 23;
+
+struct Options;
+struct ReadOptions;
+struct WriteOptions;
+class WriteBatch;
+
+// Abstract handle to particular state of a DB.
+// A Snapshot is an immutable object and can therefore be safely
+// accessed from multiple threads without any external synchronization.
+class LEVELDB_EXPORT Snapshot {
+ protected:
+  virtual ~Snapshot();
+};
+
+// A range of keys
+struct LEVELDB_EXPORT Range {
+  Range() = default;
+  Range(const Slice& s, const Slice& l) : start(s), limit(l) {}
+
+  Slice start;  // Included in the range
+  Slice limit;  // Not included in the range
+};
+
+// A DB is a persistent ordered map from keys to values.
+// A DB is safe for concurrent access from multiple threads without
+// any external synchronization.
+class LEVELDB_EXPORT DB {
+ public:
+  // Open the database with the specified "name".
+  // Stores a pointer to a heap-allocated database in *dbptr and returns
+  // OK on success.
+  // Stores nullptr in *dbptr and returns a non-OK status on error.
+  // Caller should delete *dbptr when it is no longer needed.
+  static Status Open(const Options& options, const std::string& name,
+                     DB** dbptr);
+
+  DB() = default;
+
+  DB(const DB&) = delete;
+  DB& operator=(const DB&) = delete;
+
+  virtual ~DB();
+
+  // Set the database entry for "key" to "value".  Returns OK on success,
+  // and a non-OK status on error.
+  // Note: consider setting options.sync = true.
+  virtual Status Put(const WriteOptions& options, const Slice& key,
+                     const Slice& value) = 0;
+
+  // Remove the database entry (if any) for "key".  Returns OK on
+  // success, and a non-OK status on error.  It is not an error if "key"
+  // did not exist in the database.
+  // Note: consider setting options.sync = true.
+  virtual Status Delete(const WriteOptions& options, const Slice& key) = 0;
+
+  // Apply the specified updates to the database.
+  // Returns OK on success, non-OK on failure.
+  // Note: consider setting options.sync = true.
+  virtual Status Write(const WriteOptions& options, WriteBatch* updates) = 0;
+
+  // If the database contains an entry for "key" store the
+  // corresponding value in *value and return OK.
+  //
+  // If there is no entry for "key" leave *value unchanged and return
+  // a status for which Status::IsNotFound() returns true.
+  //
+  // May return some other Status on an error.
+  virtual Status Get(const ReadOptions& options, const Slice& key,
+                     std::string* value) = 0;
+
+  // Return a heap-allocated iterator over the contents of the database.
+  // The result of NewIterator() is initially invalid (caller must
+  // call one of the Seek methods on the iterator before using it).
+  //
+  // Caller should delete the iterator when it is no longer needed.
+  // The returned iterator should be deleted before this db is deleted.
+  virtual Iterator* NewIterator(const ReadOptions& options) = 0;
+
+  // Return a handle to the current DB state.  Iterators created with
+  // this handle will all observe a stable snapshot of the current DB
+  // state.  The caller must call ReleaseSnapshot(result) when the
+  // snapshot is no longer needed.
+  virtual const Snapshot* GetSnapshot() = 0;
+
+  // Release a previously acquired snapshot.  The caller must not
+  // use "snapshot" after this call.
+  virtual void ReleaseSnapshot(const Snapshot* snapshot) = 0;
+
+  // DB implementations can export properties about their state
+  // via this method.  If "property" is a valid property understood by this
+  // DB implementation, fills "*value" with its current value and returns
+  // true.  Otherwise returns false.
+  //
+  //
+  // Valid property names include:
+  //
+  //  "leveldb.num-files-at-level<N>" - return the number of files at level <N>,
+  //     where <N> is an ASCII representation of a level number (e.g. "0").
+  //  "leveldb.stats" - returns a multi-line string that describes statistics
+  //     about the internal operation of the DB.
+  //  "leveldb.sstables" - returns a multi-line string that describes all
+  //     of the sstables that make up the db contents.
+  //  "leveldb.approximate-memory-usage" - returns the approximate number of
+  //     bytes of memory in use by the DB.
+  virtual bool GetProperty(const Slice& property, std::string* value) = 0;
+
+  // For each i in [0,n-1], store in "sizes[i]", the approximate
+  // file system space used by keys in "[range[i].start .. range[i].limit)".
+  //
+  // Note that the returned sizes measure file system space usage, so
+  // if the user data compresses by a factor of ten, the returned
+  // sizes will be one-tenth the size of the corresponding user data size.
+  //
+  // The results may not include the sizes of recently written data.
+  virtual void GetApproximateSizes(const Range* range, int n,
+                                   uint64_t* sizes) = 0;
+
+  // Compact the underlying storage for the key range [*begin,*end].
+  // In particular, deleted and overwritten versions are discarded,
+  // and the data is rearranged to reduce the cost of operations
+  // needed to access the data.  This operation should typically only
+  // be invoked by users who understand the underlying implementation.
+  //
+  // begin==nullptr is treated as a key before all keys in the database.
+  // end==nullptr is treated as a key after all keys in the database.
+  // Therefore the following call will compact the entire database:
+  //    db->CompactRange(nullptr, nullptr);
+  virtual void CompactRange(const Slice* begin, const Slice* end) = 0;
+};
+
+// Destroy the contents of the specified database.
+// Be very careful using this method.
+//
+// Note: For backwards compatibility, if DestroyDB is unable to list the
+// database files, Status::OK() will still be returned masking this failure.
+LEVELDB_EXPORT Status DestroyDB(const std::string& name,
+                                const Options& options);
+
+// If a DB cannot be opened, you may attempt to call this method to
+// resurrect as much of the contents of the database as possible.
+// Some data may be lost, so be careful when calling this function
+// on a database that contains important information.
+LEVELDB_EXPORT Status RepairDB(const std::string& dbname,
+                               const Options& options);
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_DB_H_

Kit/lldb/include/dumpfile.h

@@ -0,0 +1,28 @@
+// Copyright (c) 2014 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_DUMPFILE_H_
+#define STORAGE_LEVELDB_INCLUDE_DUMPFILE_H_
+
+#include <string>
+
+#include "env.h"
+#include "export.h"
+#include "status.h"
+
+namespace leveldb {
+
+// Dump the contents of the file named by fname in text format to
+// *dst.  Makes a sequence of dst->Append() calls; each call is passed
+// the newline-terminated text corresponding to a single item found
+// in the file.
+//
+// Returns a non-OK result if fname does not name a leveldb storage
+// file, or if the file cannot be read.
+LEVELDB_EXPORT Status DumpFile(Env* env, const std::string& fname,
+                               WritableFile* dst);
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_DUMPFILE_H_

Kit/lldb/include/env.h

@@ -0,0 +1,417 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+//
+// An Env is an interface used by the leveldb implementation to access
+// operating system functionality like the filesystem etc.  Callers
+// may wish to provide a custom Env object when opening a database to
+// get fine gain control; e.g., to rate limit file system operations.
+//
+// All Env implementations are safe for concurrent access from
+// multiple threads without any external synchronization.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_ENV_H_
+#define STORAGE_LEVELDB_INCLUDE_ENV_H_
+
+#include <cstdarg>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include "export.h"
+#include "status.h"
+
+// This workaround can be removed when leveldb::Env::DeleteFile is removed.
+#if defined(_WIN32)
+// On Windows, the method name DeleteFile (below) introduces the risk of
+// triggering undefined behavior by exposing the compiler to different
+// declarations of the Env class in different translation units.
+//
+// This is because <windows.h>, a fairly popular header file for Windows
+// applications, defines a DeleteFile macro. So, files that include the Windows
+// header before this header will contain an altered Env declaration.
+//
+// This workaround ensures that the compiler sees the same Env declaration,
+// independently of whether <windows.h> was included.
+#if defined(DeleteFile)
+#undef DeleteFile
+#define LEVELDB_DELETEFILE_UNDEFINED
+#endif  // defined(DeleteFile)
+#endif  // defined(_WIN32)
+
+namespace leveldb {
+
+class FileLock;
+class Logger;
+class RandomAccessFile;
+class SequentialFile;
+class Slice;
+class WritableFile;
+
+class LEVELDB_EXPORT Env {
+ public:
+  Env();
+
+  Env(const Env&) = delete;
+  Env& operator=(const Env&) = delete;
+
+  virtual ~Env();
+
+  // Return a default environment suitable for the current operating
+  // system.  Sophisticated users may wish to provide their own Env
+  // implementation instead of relying on this default environment.
+  //
+  // The result of Default() belongs to leveldb and must never be deleted.
+  static Env* Default();
+
+  // Create an object that sequentially reads the file with the specified name.
+  // On success, stores a pointer to the new file in *result and returns OK.
+  // On failure stores nullptr in *result and returns non-OK.  If the file does
+  // not exist, returns a non-OK status.  Implementations should return a
+  // NotFound status when the file does not exist.
+  //
+  // The returned file will only be accessed by one thread at a time.
+  virtual Status NewSequentialFile(const std::string& fname,
+                                   SequentialFile** result) = 0;
+
+  // Create an object supporting random-access reads from the file with the
+  // specified name.  On success, stores a pointer to the new file in
+  // *result and returns OK.  On failure stores nullptr in *result and
+  // returns non-OK.  If the file does not exist, returns a non-OK
+  // status.  Implementations should return a NotFound status when the file does
+  // not exist.
+  //
+  // The returned file may be concurrently accessed by multiple threads.
+  virtual Status NewRandomAccessFile(const std::string& fname,
+                                     RandomAccessFile** result) = 0;
+
+  // Create an object that writes to a new file with the specified
+  // name.  Deletes any existing file with the same name and creates a
+  // new file.  On success, stores a pointer to the new file in
+  // *result and returns OK.  On failure stores nullptr in *result and
+  // returns non-OK.
+  //
+  // The returned file will only be accessed by one thread at a time.
+  virtual Status NewWritableFile(const std::string& fname,
+                                 WritableFile** result) = 0;
+
+  // Create an object that either appends to an existing file, or
+  // writes to a new file (if the file does not exist to begin with).
+  // On success, stores a pointer to the new file in *result and
+  // returns OK.  On failure stores nullptr in *result and returns
+  // non-OK.
+  //
+  // The returned file will only be accessed by one thread at a time.
+  //
+  // May return an IsNotSupportedError error if this Env does
+  // not allow appending to an existing file.  Users of Env (including
+  // the leveldb implementation) must be prepared to deal with
+  // an Env that does not support appending.
+  virtual Status NewAppendableFile(const std::string& fname,
+                                   WritableFile** result);
+
+  // Returns true iff the named file exists.
+  virtual bool FileExists(const std::string& fname) = 0;
+
+  // Store in *result the names of the children of the specified directory.
+  // The names are relative to "dir".
+  // Original contents of *results are dropped.
+  virtual Status GetChildren(const std::string& dir,
+                             std::vector<std::string>* result) = 0;
+  // Delete the named file.
+  //
+  // The default implementation calls DeleteFile, to support legacy Env
+  // implementations. Updated Env implementations must override RemoveFile and
+  // ignore the existence of DeleteFile. Updated code calling into the Env API
+  // must call RemoveFile instead of DeleteFile.
+  //
+  // A future release will remove DeleteDir and the default implementation of
+  // RemoveDir.
+  virtual Status RemoveFile(const std::string& fname);
+
+  // DEPRECATED: Modern Env implementations should override RemoveFile instead.
+  //
+  // The default implementation calls RemoveFile, to support legacy Env user
+  // code that calls this method on modern Env implementations. Modern Env user
+  // code should call RemoveFile.
+  //
+  // A future release will remove this method.
+  virtual Status DeleteFile(const std::string& fname);
+
+  // Create the specified directory.
+  virtual Status CreateDir(const std::string& dirname) = 0;
+
+  // Delete the specified directory.
+  //
+  // The default implementation calls DeleteDir, to support legacy Env
+  // implementations. Updated Env implementations must override RemoveDir and
+  // ignore the existence of DeleteDir. Modern code calling into the Env API
+  // must call RemoveDir instead of DeleteDir.
+  //
+  // A future release will remove DeleteDir and the default implementation of
+  // RemoveDir.
+  virtual Status RemoveDir(const std::string& dirname);
+
+  // DEPRECATED: Modern Env implementations should override RemoveDir instead.
+  //
+  // The default implementation calls RemoveDir, to support legacy Env user
+  // code that calls this method on modern Env implementations. Modern Env user
+  // code should call RemoveDir.
+  //
+  // A future release will remove this method.
+  virtual Status DeleteDir(const std::string& dirname);
+
+  // Store the size of fname in *file_size.
+  virtual Status GetFileSize(const std::string& fname, uint64_t* file_size) = 0;
+
+  // Rename file src to target.
+  virtual Status RenameFile(const std::string& src,
+                            const std::string& target) = 0;
+
+  // Lock the specified file.  Used to prevent concurrent access to
+  // the same db by multiple processes.  On failure, stores nullptr in
+  // *lock and returns non-OK.
+  //
+  // On success, stores a pointer to the object that represents the
+  // acquired lock in *lock and returns OK.  The caller should call
+  // UnlockFile(*lock) to release the lock.  If the process exits,
+  // the lock will be automatically released.
+  //
+  // If somebody else already holds the lock, finishes immediately
+  // with a failure.  I.e., this call does not wait for existing locks
+  // to go away.
+  //
+  // May create the named file if it does not already exist.
+  virtual Status LockFile(const std::string& fname, FileLock** lock) = 0;
+
+  // Release the lock acquired by a previous successful call to LockFile.
+  // REQUIRES: lock was returned by a successful LockFile() call
+  // REQUIRES: lock has not already been unlocked.
+  virtual Status UnlockFile(FileLock* lock) = 0;
+
+  // Arrange to run "(*function)(arg)" once in a background thread.
+  //
+  // "function" may run in an unspecified thread.  Multiple functions
+  // added to the same Env may run concurrently in different threads.
+  // I.e., the caller may not assume that background work items are
+  // serialized.
+  virtual void Schedule(void (*function)(void* arg), void* arg) = 0;
+
+  // Start a new thread, invoking "function(arg)" within the new thread.
+  // When "function(arg)" returns, the thread will be destroyed.
+  virtual void StartThread(void (*function)(void* arg), void* arg) = 0;
+
+  // *path is set to a temporary directory that can be used for testing. It may
+  // or may not have just been created. The directory may or may not differ
+  // between runs of the same process, but subsequent calls will return the
+  // same directory.
+  virtual Status GetTestDirectory(std::string* path) = 0;
+
+  // Create and return a log file for storing informational messages.
+  virtual Status NewLogger(const std::string& fname, Logger** result) = 0;
+
+  // Returns the number of micro-seconds since some fixed point in time. Only
+  // useful for computing deltas of time.
+  virtual uint64_t NowMicros() = 0;
+
+  // Sleep/delay the thread for the prescribed number of micro-seconds.
+  virtual void SleepForMicroseconds(int micros) = 0;
+};
+
+// A file abstraction for reading sequentially through a file
+class LEVELDB_EXPORT SequentialFile {
+ public:
+  SequentialFile() = default;
+
+  SequentialFile(const SequentialFile&) = delete;
+  SequentialFile& operator=(const SequentialFile&) = delete;
+
+  virtual ~SequentialFile();
+
+  // Read up to "n" bytes from the file.  "scratch[0..n-1]" may be
+  // written by this routine.  Sets "*result" to the data that was
+  // read (including if fewer than "n" bytes were successfully read).
+  // May set "*result" to point at data in "scratch[0..n-1]", so
+  // "scratch[0..n-1]" must be live when "*result" is used.
+  // If an error was encountered, returns a non-OK status.
+  //
+  // REQUIRES: External synchronization
+  virtual Status Read(size_t n, Slice* result, char* scratch) = 0;
+
+  // Skip "n" bytes from the file. This is guaranteed to be no
+  // slower that reading the same data, but may be faster.
+  //
+  // If end of file is reached, skipping will stop at the end of the
+  // file, and Skip will return OK.
+  //
+  // REQUIRES: External synchronization
+  virtual Status Skip(uint64_t n) = 0;
+};
+
+// A file abstraction for randomly reading the contents of a file.
+class LEVELDB_EXPORT RandomAccessFile {
+ public:
+  RandomAccessFile() = default;
+
+  RandomAccessFile(const RandomAccessFile&) = delete;
+  RandomAccessFile& operator=(const RandomAccessFile&) = delete;
+
+  virtual ~RandomAccessFile();
+
+  // Read up to "n" bytes from the file starting at "offset".
+  // "scratch[0..n-1]" may be written by this routine.  Sets "*result"
+  // to the data that was read (including if fewer than "n" bytes were
+  // successfully read).  May set "*result" to point at data in
+  // "scratch[0..n-1]", so "scratch[0..n-1]" must be live when
+  // "*result" is used.  If an error was encountered, returns a non-OK
+  // status.
+  //
+  // Safe for concurrent use by multiple threads.
+  virtual Status Read(uint64_t offset, size_t n, Slice* result,
+                      char* scratch) const = 0;
+};
+
+// A file abstraction for sequential writing.  The implementation
+// must provide buffering since callers may append small fragments
+// at a time to the file.
+class LEVELDB_EXPORT WritableFile {
+ public:
+  WritableFile() = default;
+
+  WritableFile(const WritableFile&) = delete;
+  WritableFile& operator=(const WritableFile&) = delete;
+
+  virtual ~WritableFile();
+
+  virtual Status Append(const Slice& data) = 0;
+  virtual Status Close() = 0;
+  virtual Status Flush() = 0;
+  virtual Status Sync() = 0;
+};
+
+// An interface for writing log messages.
+class LEVELDB_EXPORT Logger {
+ public:
+  Logger() = default;
+
+  Logger(const Logger&) = delete;
+  Logger& operator=(const Logger&) = delete;
+
+  virtual ~Logger();
+
+  // Write an entry to the log file with the specified format.
+  virtual void Logv(const char* format, std::va_list ap) = 0;
+};
+
+// Identifies a locked file.
+class LEVELDB_EXPORT FileLock {
+ public:
+  FileLock() = default;
+
+  FileLock(const FileLock&) = delete;
+  FileLock& operator=(const FileLock&) = delete;
+
+  virtual ~FileLock();
+};
+
+// Log the specified data to *info_log if info_log is non-null.
+void Log(Logger* info_log, const char* format, ...)
+#if defined(__GNUC__) || defined(__clang__)
+    __attribute__((__format__(__printf__, 2, 3)))
+#endif
+    ;
+
+// A utility routine: write "data" to the named file.
+LEVELDB_EXPORT Status WriteStringToFile(Env* env, const Slice& data,
+                                        const std::string& fname);
+
+// A utility routine: read contents of named file into *data
+LEVELDB_EXPORT Status ReadFileToString(Env* env, const std::string& fname,
+                                       std::string* data);
+
+// An implementation of Env that forwards all calls to another Env.
+// May be useful to clients who wish to override just part of the
+// functionality of another Env.
+class LEVELDB_EXPORT EnvWrapper : public Env {
+ public:
+  // Initialize an EnvWrapper that delegates all calls to *t.
+  explicit EnvWrapper(Env* t) : target_(t) {}
+  virtual ~EnvWrapper();
+
+  // Return the target to which this Env forwards all calls.
+  Env* target() const { return target_; }
+
+  // The following text is boilerplate that forwards all methods to target().
+  Status NewSequentialFile(const std::string& f, SequentialFile** r) override {
+    return target_->NewSequentialFile(f, r);
+  }
+  Status NewRandomAccessFile(const std::string& f,
+                             RandomAccessFile** r) override {
+    return target_->NewRandomAccessFile(f, r);
+  }
+  Status NewWritableFile(const std::string& f, WritableFile** r) override {
+    return target_->NewWritableFile(f, r);
+  }
+  Status NewAppendableFile(const std::string& f, WritableFile** r) override {
+    return target_->NewAppendableFile(f, r);
+  }
+  bool FileExists(const std::string& f) override {
+    return target_->FileExists(f);
+  }
+  Status GetChildren(const std::string& dir,
+                     std::vector<std::string>* r) override {
+    return target_->GetChildren(dir, r);
+  }
+  Status RemoveFile(const std::string& f) override {
+    return target_->RemoveFile(f);
+  }
+  Status CreateDir(const std::string& d) override {
+    return target_->CreateDir(d);
+  }
+  Status RemoveDir(const std::string& d) override {
+    return target_->RemoveDir(d);
+  }
+  Status GetFileSize(const std::string& f, uint64_t* s) override {
+    return target_->GetFileSize(f, s);
+  }
+  Status RenameFile(const std::string& s, const std::string& t) override {
+    return target_->RenameFile(s, t);
+  }
+  Status LockFile(const std::string& f, FileLock** l) override {
+    return target_->LockFile(f, l);
+  }
+  Status UnlockFile(FileLock* l) override { return target_->UnlockFile(l); }
+  void Schedule(void (*f)(void*), void* a) override {
+    return target_->Schedule(f, a);
+  }
+  void StartThread(void (*f)(void*), void* a) override {
+    return target_->StartThread(f, a);
+  }
+  Status GetTestDirectory(std::string* path) override {
+    return target_->GetTestDirectory(path);
+  }
+  Status NewLogger(const std::string& fname, Logger** result) override {
+    return target_->NewLogger(fname, result);
+  }
+  uint64_t NowMicros() override { return target_->NowMicros(); }
+  void SleepForMicroseconds(int micros) override {
+    target_->SleepForMicroseconds(micros);
+  }
+
+ private:
+  Env* target_;
+};
+
+}  // namespace leveldb
+
+// This workaround can be removed when leveldb::Env::DeleteFile is removed.
+// Redefine DeleteFile if it was undefined earlier.
+#if defined(_WIN32) && defined(LEVELDB_DELETEFILE_UNDEFINED)
+#if defined(UNICODE)
+#define DeleteFile DeleteFileW
+#else
+#define DeleteFile DeleteFileA
+#endif  // defined(UNICODE)
+#endif  // defined(_WIN32) && defined(LEVELDB_DELETEFILE_UNDEFINED)
+
+#endif  // STORAGE_LEVELDB_INCLUDE_ENV_H_

Kit/lldb/include/export.h

@@ -0,0 +1,33 @@
+// Copyright (c) 2017 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_EXPORT_H_
+#define STORAGE_LEVELDB_INCLUDE_EXPORT_H_
+
+#if !defined(LEVELDB_EXPORT)
+
+#if defined(LEVELDB_SHARED_LIBRARY)
+#if defined(_WIN32)
+
+#if defined(LEVELDB_COMPILE_LIBRARY)
+#define LEVELDB_EXPORT __declspec(dllexport)
+#else
+#define LEVELDB_EXPORT __declspec(dllimport)
+#endif  // defined(LEVELDB_COMPILE_LIBRARY)
+
+#else  // defined(_WIN32)
+#if defined(LEVELDB_COMPILE_LIBRARY)
+#define LEVELDB_EXPORT __attribute__((visibility("default")))
+#else
+#define LEVELDB_EXPORT
+#endif
+#endif  // defined(_WIN32)
+
+#else  // defined(LEVELDB_SHARED_LIBRARY)
+#define LEVELDB_EXPORT
+#endif
+
+#endif  // !defined(LEVELDB_EXPORT)
+
+#endif  // STORAGE_LEVELDB_INCLUDE_EXPORT_H_

Kit/lldb/include/filter_policy.h

@@ -0,0 +1,72 @@
+// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+//
+// A database can be configured with a custom FilterPolicy object.
+// This object is responsible for creating a small filter from a set
+// of keys.  These filters are stored in leveldb and are consulted
+// automatically by leveldb to decide whether or not to read some
+// information from disk. In many cases, a filter can cut down the
+// number of disk seeks form a handful to a single disk seek per
+// DB::Get() call.
+//
+// Most people will want to use the builtin bloom filter support (see
+// NewBloomFilterPolicy() below).
+
+#ifndef STORAGE_LEVELDB_INCLUDE_FILTER_POLICY_H_
+#define STORAGE_LEVELDB_INCLUDE_FILTER_POLICY_H_
+
+#include <string>
+
+#include "export.h"
+
+namespace leveldb {
+
+class Slice;
+
+class LEVELDB_EXPORT FilterPolicy {
+ public:
+  virtual ~FilterPolicy();
+
+  // Return the name of this policy.  Note that if the filter encoding
+  // changes in an incompatible way, the name returned by this method
+  // must be changed.  Otherwise, old incompatible filters may be
+  // passed to methods of this type.
+  virtual const char* Name() const = 0;
+
+  // keys[0,n-1] contains a list of keys (potentially with duplicates)
+  // that are ordered according to the user supplied comparator.
+  // Append a filter that summarizes keys[0,n-1] to *dst.
+  //
+  // Warning: do not change the initial contents of *dst.  Instead,
+  // append the newly constructed filter to *dst.
+  virtual void CreateFilter(const Slice* keys, int n,
+                            std::string* dst) const = 0;
+
+  // "filter" contains the data appended by a preceding call to
+  // CreateFilter() on this class.  This method must return true if
+  // the key was in the list of keys passed to CreateFilter().
+  // This method may return true or false if the key was not on the
+  // list, but it should aim to return false with a high probability.
+  virtual bool KeyMayMatch(const Slice& key, const Slice& filter) const = 0;
+};
+
+// Return a new filter policy that uses a bloom filter with approximately
+// the specified number of bits per key.  A good value for bits_per_key
+// is 10, which yields a filter with ~ 1% false positive rate.
+//
+// Callers must delete the result after any database that is using the
+// result has been closed.
+//
+// Note: if you are using a custom comparator that ignores some parts
+// of the keys being compared, you must not use NewBloomFilterPolicy()
+// and must provide your own FilterPolicy that also ignores the
+// corresponding parts of the keys.  For example, if the comparator
+// ignores trailing spaces, it would be incorrect to use a
+// FilterPolicy (like NewBloomFilterPolicy) that does not ignore
+// trailing spaces in keys.
+LEVELDB_EXPORT const FilterPolicy* NewBloomFilterPolicy(int bits_per_key);
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_FILTER_POLICY_H_

Kit/lldb/include/iterator.h

@@ -0,0 +1,112 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+//
+// An iterator yields a sequence of key/value pairs from a source.
+// The following class defines the interface.  Multiple implementations
+// are provided by this library.  In particular, iterators are provided
+// to access the contents of a Table or a DB.
+//
+// Multiple threads can invoke const methods on an Iterator without
+// external synchronization, but if any of the threads may call a
+// non-const method, all threads accessing the same Iterator must use
+// external synchronization.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_ITERATOR_H_
+#define STORAGE_LEVELDB_INCLUDE_ITERATOR_H_
+
+#include "export.h"
+#include "slice.h"
+#include "status.h"
+
+namespace leveldb {
+
+class LEVELDB_EXPORT Iterator {
+ public:
+  Iterator();
+
+  Iterator(const Iterator&) = delete;
+  Iterator& operator=(const Iterator&) = delete;
+
+  virtual ~Iterator();
+
+  // An iterator is either positioned at a key/value pair, or
+  // not valid.  This method returns true iff the iterator is valid.
+  virtual bool Valid() const = 0;
+
+  // Position at the first key in the source.  The iterator is Valid()
+  // after this call iff the source is not empty.
+  virtual void SeekToFirst() = 0;
+
+  // Position at the last key in the source.  The iterator is
+  // Valid() after this call iff the source is not empty.
+  virtual void SeekToLast() = 0;
+
+  // Position at the first key in the source that is at or past target.
+  // The iterator is Valid() after this call iff the source contains
+  // an entry that comes at or past target.
+  virtual void Seek(const Slice& target) = 0;
+
+  // Moves to the next entry in the source.  After this call, Valid() is
+  // true iff the iterator was not positioned at the last entry in the source.
+  // REQUIRES: Valid()
+  virtual void Next() = 0;
+
+  // Moves to the previous entry in the source.  After this call, Valid() is
+  // true iff the iterator was not positioned at the first entry in source.
+  // REQUIRES: Valid()
+  virtual void Prev() = 0;
+
+  // Return the key for the current entry.  The underlying storage for
+  // the returned slice is valid only until the next modification of
+  // the iterator.
+  // REQUIRES: Valid()
+  virtual Slice key() const = 0;
+
+  // Return the value for the current entry.  The underlying storage for
+  // the returned slice is valid only until the next modification of
+  // the iterator.
+  // REQUIRES: Valid()
+  virtual Slice value() const = 0;
+
+  // If an error has occurred, return it.  Else return an ok status.
+  virtual Status status() const = 0;
+
+  // Clients are allowed to register function/arg1/arg2 triples that
+  // will be invoked when this iterator is destroyed.
+  //
+  // Note that unlike all of the preceding methods, this method is
+  // not abstract and therefore clients should not override it.
+  using CleanupFunction = void (*)(void* arg1, void* arg2);
+  void RegisterCleanup(CleanupFunction function, void* arg1, void* arg2);
+
+ private:
+  // Cleanup functions are stored in a single-linked list.
+  // The list's head node is inlined in the iterator.
+  struct CleanupNode {
+    // True if the node is not used. Only head nodes might be unused.
+    bool IsEmpty() const { return function == nullptr; }
+    // Invokes the cleanup function.
+    void Run() {
+      assert(function != nullptr);
+      (*function)(arg1, arg2);
+    }
+
+    // The head node is used if the function pointer is not null.
+    CleanupFunction function;
+    void* arg1;
+    void* arg2;
+    CleanupNode* next;
+  };
+  CleanupNode cleanup_head_;
+};
+
+// Return an empty iterator (yields nothing).
+LEVELDB_EXPORT Iterator* NewEmptyIterator();
+
+// Return an empty iterator with the specified status.
+LEVELDB_EXPORT Iterator* NewErrorIterator(const Status& status);
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_ITERATOR_H_

Kit/lldb/include/options.h

@@ -0,0 +1,190 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_OPTIONS_H_
+#define STORAGE_LEVELDB_INCLUDE_OPTIONS_H_
+
+#include <cstddef>
+
+#include "export.h"
+
+namespace leveldb {
+
+class Cache;
+class Comparator;
+class Env;
+class FilterPolicy;
+class Logger;
+class Snapshot;
+
+// DB contents are stored in a set of blocks, each of which holds a
+// sequence of key,value pairs.  Each block may be compressed before
+// being stored in a file.  The following enum describes which
+// compression method (if any) is used to compress a block.
+enum CompressionType {
+  // NOTE: do not change the values of existing entries, as these are
+  // part of the persistent format on disk.
+  kNoCompression = 0x0,
+  kSnappyCompression = 0x1,
+  kZstdCompression = 0x2,
+};
+
+// Options to control the behavior of a database (passed to DB::Open)
+struct LEVELDB_EXPORT Options {
+  // Create an Options object with default values for all fields.
+  Options();
+
+  // -------------------
+  // Parameters that affect behavior
+
+  // Comparator used to define the order of keys in the table.
+  // Default: a comparator that uses lexicographic byte-wise ordering
+  //
+  // REQUIRES: The client must ensure that the comparator supplied
+  // here has the same name and orders keys *exactly* the same as the
+  // comparator provided to previous open calls on the same DB.
+  const Comparator* comparator;
+
+  // If true, the database will be created if it is missing.
+  bool create_if_missing = false;
+
+  // If true, an error is raised if the database already exists.
+  bool error_if_exists = false;
+
+  // If true, the implementation will do aggressive checking of the
+  // data it is processing and will stop early if it detects any
+  // errors.  This may have unforeseen ramifications: for example, a
+  // corruption of one DB entry may cause a large number of entries to
+  // become unreadable or for the entire DB to become unopenable.
+  bool paranoid_checks = false;
+
+  // Use the specified object to interact with the environment,
+  // e.g. to read/write files, schedule background work, etc.
+  // Default: Env::Default()
+  Env* env;
+
+  // Any internal progress/error information generated by the db will
+  // be written to info_log if it is non-null, or to a file stored
+  // in the same directory as the DB contents if info_log is null.
+  Logger* info_log = nullptr;
+
+  // -------------------
+  // Parameters that affect performance
+
+  // Amount of data to build up in memory (backed by an unsorted log
+  // on disk) before converting to a sorted on-disk file.
+  //
+  // Larger values increase performance, especially during bulk loads.
+  // Up to two write buffers may be held in memory at the same time,
+  // so you may wish to adjust this parameter to control memory usage.
+  // Also, a larger write buffer will result in a longer recovery time
+  // the next time the database is opened.
+  size_t write_buffer_size = 4 * 1024 * 1024;
+
+  // Number of open files that can be used by the DB.  You may need to
+  // increase this if your database has a large working set (budget
+  // one open file per 2MB of working set).
+  int max_open_files = 1000;
+
+  // Control over blocks (user data is stored in a set of blocks, and
+  // a block is the unit of reading from disk).
+
+  // If non-null, use the specified cache for blocks.
+  // If null, leveldb will automatically create and use an 8MB internal cache.
+  Cache* block_cache = nullptr;
+
+  // Approximate size of user data packed per block.  Note that the
+  // block size specified here corresponds to uncompressed data.  The
+  // actual size of the unit read from disk may be smaller if
+  // compression is enabled.  This parameter can be changed dynamically.
+  size_t block_size = 4 * 1024;
+
+  // Number of keys between restart points for delta encoding of keys.
+  // This parameter can be changed dynamically.  Most clients should
+  // leave this parameter alone.
+  int block_restart_interval = 16;
+
+  // Leveldb will write up to this amount of bytes to a file before
+  // switching to a new one.
+  // Most clients should leave this parameter alone.  However if your
+  // filesystem is more efficient with larger files, you could
+  // consider increasing the value.  The downside will be longer
+  // compactions and hence longer latency/performance hiccups.
+  // Another reason to increase this parameter might be when you are
+  // initially populating a large database.
+  size_t max_file_size = 2 * 1024 * 1024;
+
+  // Compress blocks using the specified compression algorithm.  This
+  // parameter can be changed dynamically.
+  //
+  // Default: kSnappyCompression, which gives lightweight but fast
+  // compression.
+  //
+  // Typical speeds of kSnappyCompression on an Intel(R) Core(TM)2 2.4GHz:
+  //    ~200-500MB/s compression
+  //    ~400-800MB/s decompression
+  // Note that these speeds are significantly faster than most
+  // persistent storage speeds, and therefore it is typically never
+  // worth switching to kNoCompression.  Even if the input data is
+  // incompressible, the kSnappyCompression implementation will
+  // efficiently detect that and will switch to uncompressed mode.
+  CompressionType compression = kSnappyCompression;
+
+  // Compression level for zstd.
+  // Currently only the range [-5,22] is supported. Default is 1.
+  int zstd_compression_level = 1;
+
+  // EXPERIMENTAL: If true, append to existing MANIFEST and log files
+  // when a database is opened.  This can significantly speed up open.
+  //
+  // Default: currently false, but may become true later.
+  bool reuse_logs = false;
+
+  // If non-null, use the specified filter policy to reduce disk reads.
+  // Many applications will benefit from passing the result of
+  // NewBloomFilterPolicy() here.
+  const FilterPolicy* filter_policy = nullptr;
+};
+
+// Options that control read operations
+struct LEVELDB_EXPORT ReadOptions {
+  // If true, all data read from underlying storage will be
+  // verified against corresponding checksums.
+  bool verify_checksums = false;
+
+  // Should the data read for this iteration be cached in memory?
+  // Callers may wish to set this field to false for bulk scans.
+  bool fill_cache = true;
+
+  // If "snapshot" is non-null, read as of the supplied snapshot
+  // (which must belong to the DB that is being read and which must
+  // not have been released).  If "snapshot" is null, use an implicit
+  // snapshot of the state at the beginning of this read operation.
+  const Snapshot* snapshot = nullptr;
+};
+
+// Options that control write operations
+struct LEVELDB_EXPORT WriteOptions {
+  WriteOptions() = default;
+
+  // If true, the write will be flushed from the operating system
+  // buffer cache (by calling WritableFile::Sync()) before the write
+  // is considered complete.  If this flag is true, writes will be
+  // slower.
+  //
+  // If this flag is false, and the machine crashes, some recent
+  // writes may be lost.  Note that if it is just the process that
+  // crashes (i.e., the machine does not reboot), no writes will be
+  // lost even if sync==false.
+  //
+  // In other words, a DB write with sync==false has similar
+  // crash semantics as the "write()" system call.  A DB write
+  // with sync==true has similar crash semantics to a "write()"
+  // system call followed by "fsync()".
+  bool sync = false;
+};
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_OPTIONS_H_

Kit/lldb/include/slice.h

@@ -0,0 +1,114 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+//
+// Slice is a simple structure containing a pointer into some external
+// storage and a size.  The user of a Slice must ensure that the slice
+// is not used after the corresponding external storage has been
+// deallocated.
+//
+// Multiple threads can invoke const methods on a Slice without
+// external synchronization, but if any of the threads may call a
+// non-const method, all threads accessing the same Slice must use
+// external synchronization.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_SLICE_H_
+#define STORAGE_LEVELDB_INCLUDE_SLICE_H_
+
+#include <cassert>
+#include <cstddef>
+#include <cstring>
+#include <string>
+
+#include "export.h"
+
+namespace leveldb {
+
+class LEVELDB_EXPORT Slice {
+ public:
+  // Create an empty slice.
+  Slice() : data_(""), size_(0) {}
+
+  // Create a slice that refers to d[0,n-1].
+  Slice(const char* d, size_t n) : data_(d), size_(n) {}
+
+  // Create a slice that refers to the contents of "s"
+  Slice(const std::string& s) : data_(s.data()), size_(s.size()) {}
+
+  // Create a slice that refers to s[0,strlen(s)-1]
+  Slice(const char* s) : data_(s), size_(strlen(s)) {}
+
+  // Intentionally copyable.
+  Slice(const Slice&) = default;
+  Slice& operator=(const Slice&) = default;
+
+  // Return a pointer to the beginning of the referenced data
+  const char* data() const { return data_; }
+
+  // Return the length (in bytes) of the referenced data
+  size_t size() const { return size_; }
+
+  // Return true iff the length of the referenced data is zero
+  bool empty() const { return size_ == 0; }
+
+  // Return the ith byte in the referenced data.
+  // REQUIRES: n < size()
+  char operator[](size_t n) const {
+    assert(n < size());
+    return data_[n];
+  }
+
+  // Change this slice to refer to an empty array
+  void clear() {
+    data_ = "";
+    size_ = 0;
+  }
+
+  // Drop the first "n" bytes from this slice.
+  void remove_prefix(size_t n) {
+    assert(n <= size());
+    data_ += n;
+    size_ -= n;
+  }
+
+  // Return a string that contains the copy of the referenced data.
+  std::string ToString() const { return std::string(data_, size_); }
+
+  // Three-way comparison.  Returns value:
+  //   <  0 iff "*this" <  "b",
+  //   == 0 iff "*this" == "b",
+  //   >  0 iff "*this" >  "b"
+  int compare(const Slice& b) const;
+
+  // Return true iff "x" is a prefix of "*this"
+  bool starts_with(const Slice& x) const {
+    return ((size_ >= x.size_) && (memcmp(data_, x.data_, x.size_) == 0));
+  }
+
+ private:
+  const char* data_;
+  size_t size_;
+};
+
+inline bool operator==(const Slice& x, const Slice& y) {
+  return ((x.size() == y.size()) &&
+          (memcmp(x.data(), y.data(), x.size()) == 0));
+}
+
+inline bool operator!=(const Slice& x, const Slice& y) { return !(x == y); }
+
+inline int Slice::compare(const Slice& b) const {
+  const size_t min_len = (size_ < b.size_) ? size_ : b.size_;
+  int r = memcmp(data_, b.data_, min_len);
+  if (r == 0) {
+    if (size_ < b.size_)
+      r = -1;
+    else if (size_ > b.size_)
+      r = +1;
+  }
+  return r;
+}
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_SLICE_H_

Kit/lldb/include/status.h

@@ -0,0 +1,122 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+//
+// A Status encapsulates the result of an operation.  It may indicate success,
+// or it may indicate an error with an associated error message.
+//
+// Multiple threads can invoke const methods on a Status without
+// external synchronization, but if any of the threads may call a
+// non-const method, all threads accessing the same Status must use
+// external synchronization.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_STATUS_H_
+#define STORAGE_LEVELDB_INCLUDE_STATUS_H_
+
+#include <algorithm>
+#include <string>
+
+#include "export.h"
+#include "slice.h"
+
+namespace leveldb {
+
+class LEVELDB_EXPORT Status {
+ public:
+  // Create a success status.
+  Status() noexcept : state_(nullptr) {}
+  ~Status() { delete[] state_; }
+
+  Status(const Status& rhs);
+  Status& operator=(const Status& rhs);
+
+  Status(Status&& rhs) noexcept : state_(rhs.state_) { rhs.state_ = nullptr; }
+  Status& operator=(Status&& rhs) noexcept;
+
+  // Return a success status.
+  static Status OK() { return Status(); }
+
+  // Return error status of an appropriate type.
+  static Status NotFound(const Slice& msg, const Slice& msg2 = Slice()) {
+    return Status(kNotFound, msg, msg2);
+  }
+  static Status Corruption(const Slice& msg, const Slice& msg2 = Slice()) {
+    return Status(kCorruption, msg, msg2);
+  }
+  static Status NotSupported(const Slice& msg, const Slice& msg2 = Slice()) {
+    return Status(kNotSupported, msg, msg2);
+  }
+  static Status InvalidArgument(const Slice& msg, const Slice& msg2 = Slice()) {
+    return Status(kInvalidArgument, msg, msg2);
+  }
+  static Status IOError(const Slice& msg, const Slice& msg2 = Slice()) {
+    return Status(kIOError, msg, msg2);
+  }
+
+  // Returns true iff the status indicates success.
+  bool ok() const { return (state_ == nullptr); }
+
+  // Returns true iff the status indicates a NotFound error.
+  bool IsNotFound() const { return code() == kNotFound; }
+
+  // Returns true iff the status indicates a Corruption error.
+  bool IsCorruption() const { return code() == kCorruption; }
+
+  // Returns true iff the status indicates an IOError.
+  bool IsIOError() const { return code() == kIOError; }
+
+  // Returns true iff the status indicates a NotSupportedError.
+  bool IsNotSupportedError() const { return code() == kNotSupported; }
+
+  // Returns true iff the status indicates an InvalidArgument.
+  bool IsInvalidArgument() const { return code() == kInvalidArgument; }
+
+  // Return a string representation of this status suitable for printing.
+  // Returns the string "OK" for success.
+  std::string ToString() const;
+
+ private:
+  enum Code {
+    kOk = 0,
+    kNotFound = 1,
+    kCorruption = 2,
+    kNotSupported = 3,
+    kInvalidArgument = 4,
+    kIOError = 5
+  };
+
+  Code code() const {
+    return (state_ == nullptr) ? kOk : static_cast<Code>(state_[4]);
+  }
+
+  Status(Code code, const Slice& msg, const Slice& msg2);
+  static const char* CopyState(const char* s);
+
+  // OK status has a null state_.  Otherwise, state_ is a new[] array
+  // of the following form:
+  //    state_[0..3] == length of message
+  //    state_[4]    == code
+  //    state_[5..]  == message
+  const char* state_;
+};
+
+inline Status::Status(const Status& rhs) {
+  state_ = (rhs.state_ == nullptr) ? nullptr : CopyState(rhs.state_);
+}
+inline Status& Status::operator=(const Status& rhs) {
+  // The following condition catches both aliasing (when this == &rhs),
+  // and the common case where both rhs and *this are ok.
+  if (state_ != rhs.state_) {
+    delete[] state_;
+    state_ = (rhs.state_ == nullptr) ? nullptr : CopyState(rhs.state_);
+  }
+  return *this;
+}
+inline Status& Status::operator=(Status&& rhs) noexcept {
+  std::swap(state_, rhs.state_);
+  return *this;
+}
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_STATUS_H_

Kit/lldb/include/table.h

@@ -0,0 +1,84 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_TABLE_H_
+#define STORAGE_LEVELDB_INCLUDE_TABLE_H_
+
+#include <cstdint>
+
+#include "export.h"
+#include "iterator.h"
+
+namespace leveldb {
+
+class Block;
+class BlockHandle;
+class Footer;
+struct Options;
+class RandomAccessFile;
+struct ReadOptions;
+class TableCache;
+
+// A Table is a sorted map from strings to strings.  Tables are
+// immutable and persistent.  A Table may be safely accessed from
+// multiple threads without external synchronization.
+class LEVELDB_EXPORT Table {
+ public:
+  // Attempt to open the table that is stored in bytes [0..file_size)
+  // of "file", and read the metadata entries necessary to allow
+  // retrieving data from the table.
+  //
+  // If successful, returns ok and sets "*table" to the newly opened
+  // table.  The client should delete "*table" when no longer needed.
+  // If there was an error while initializing the table, sets "*table"
+  // to nullptr and returns a non-ok status.  Does not take ownership of
+  // "*source", but the client must ensure that "source" remains live
+  // for the duration of the returned table's lifetime.
+  //
+  // *file must remain live while this Table is in use.
+  static Status Open(const Options& options, RandomAccessFile* file,
+                     uint64_t file_size, Table** table);
+
+  Table(const Table&) = delete;
+  Table& operator=(const Table&) = delete;
+
+  ~Table();
+
+  // Returns a new iterator over the table contents.
+  // The result of NewIterator() is initially invalid (caller must
+  // call one of the Seek methods on the iterator before using it).
+  Iterator* NewIterator(const ReadOptions&) const;
+
+  // Given a key, return an approximate byte offset in the file where
+  // the data for that key begins (or would begin if the key were
+  // present in the file).  The returned value is in terms of file
+  // bytes, and so includes effects like compression of the underlying data.
+  // E.g., the approximate offset of the last key in the table will
+  // be close to the file length.
+  uint64_t ApproximateOffsetOf(const Slice& key) const;
+
+ private:
+  friend class TableCache;
+  struct Rep;
+
+  static Iterator* BlockReader(void*, const ReadOptions&, const Slice&);
+
+  explicit Table(Rep* rep) : rep_(rep) {}
+
+  // Calls (*handle_result)(arg, ...) with the entry found after a call
+  // to Seek(key).  May not make such a call if filter policy says
+  // that key is not present.
+  Status InternalGet(const ReadOptions&, const Slice& key, void* arg,
+                     void (*handle_result)(void* arg, const Slice& k,
+                                           const Slice& v));
+
+  void ReadMeta(const Footer& footer);
+  void ReadFilter(const Slice& filter_handle_value);
+
+  Rep* const rep_;
+};
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_TABLE_H_

Kit/lldb/include/table_builder.h

@@ -0,0 +1,93 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+//
+// TableBuilder provides the interface used to build a Table
+// (an immutable and sorted map from keys to values).
+//
+// Multiple threads can invoke const methods on a TableBuilder without
+// external synchronization, but if any of the threads may call a
+// non-const method, all threads accessing the same TableBuilder must use
+// external synchronization.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_
+#define STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_
+
+#include <cstdint>
+
+#include "export.h"
+#include "options.h"
+#include "status.h"
+
+namespace leveldb {
+
+class BlockBuilder;
+class BlockHandle;
+class WritableFile;
+
+class LEVELDB_EXPORT TableBuilder {
+ public:
+  // Create a builder that will store the contents of the table it is
+  // building in *file.  Does not close the file.  It is up to the
+  // caller to close the file after calling Finish().
+  TableBuilder(const Options& options, WritableFile* file);
+
+  TableBuilder(const TableBuilder&) = delete;
+  TableBuilder& operator=(const TableBuilder&) = delete;
+
+  // REQUIRES: Either Finish() or Abandon() has been called.
+  ~TableBuilder();
+
+  // Change the options used by this builder.  Note: only some of the
+  // option fields can be changed after construction.  If a field is
+  // not allowed to change dynamically and its value in the structure
+  // passed to the constructor is different from its value in the
+  // structure passed to this method, this method will return an error
+  // without changing any fields.
+  Status ChangeOptions(const Options& options);
+
+  // Add key,value to the table being constructed.
+  // REQUIRES: key is after any previously added key according to comparator.
+  // REQUIRES: Finish(), Abandon() have not been called
+  void Add(const Slice& key, const Slice& value);
+
+  // Advanced operation: flush any buffered key/value pairs to file.
+  // Can be used to ensure that two adjacent entries never live in
+  // the same data block.  Most clients should not need to use this method.
+  // REQUIRES: Finish(), Abandon() have not been called
+  void Flush();
+
+  // Return non-ok iff some error has been detected.
+  Status status() const;
+
+  // Finish building the table.  Stops using the file passed to the
+  // constructor after this function returns.
+  // REQUIRES: Finish(), Abandon() have not been called
+  Status Finish();
+
+  // Indicate that the contents of this builder should be abandoned.  Stops
+  // using the file passed to the constructor after this function returns.
+  // If the caller is not going to call Finish(), it must call Abandon()
+  // before destroying this builder.
+  // REQUIRES: Finish(), Abandon() have not been called
+  void Abandon();
+
+  // Number of calls to Add() so far.
+  uint64_t NumEntries() const;
+
+  // Size of the file generated so far.  If invoked after a successful
+  // Finish() call, returns the size of the final generated file.
+  uint64_t FileSize() const;
+
+ private:
+  bool ok() const { return status().ok(); }
+  void WriteBlock(BlockBuilder* block, BlockHandle* handle);
+  void WriteRawBlock(const Slice& data, CompressionType, BlockHandle* handle);
+
+  struct Rep;
+  Rep* rep_;
+};
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_

Kit/lldb/include/write_batch.h

@@ -0,0 +1,83 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+//
+// WriteBatch holds a collection of updates to apply atomically to a DB.
+//
+// The updates are applied in the order in which they are added
+// to the WriteBatch.  For example, the value of "key" will be "v3"
+// after the following batch is written:
+//
+//    batch.Put("key", "v1");
+//    batch.Delete("key");
+//    batch.Put("key", "v2");
+//    batch.Put("key", "v3");
+//
+// Multiple threads can invoke const methods on a WriteBatch without
+// external synchronization, but if any of the threads may call a
+// non-const method, all threads accessing the same WriteBatch must use
+// external synchronization.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_
+#define STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_
+
+#include <string>
+
+#include "export.h"
+#include "status.h"
+
+namespace leveldb {
+
+class Slice;
+
+class LEVELDB_EXPORT WriteBatch {
+ public:
+  class LEVELDB_EXPORT Handler {
+   public:
+    virtual ~Handler();
+    virtual void Put(const Slice& key, const Slice& value) = 0;
+    virtual void Delete(const Slice& key) = 0;
+  };
+
+  WriteBatch();
+
+  // Intentionally copyable.
+  WriteBatch(const WriteBatch&) = default;
+  WriteBatch& operator=(const WriteBatch&) = default;
+
+  ~WriteBatch();
+
+  // Store the mapping "key->value" in the database.
+  void Put(const Slice& key, const Slice& value);
+
+  // If the database contains a mapping for "key", erase it.  Else do nothing.
+  void Delete(const Slice& key);
+
+  // Clear all updates buffered in this batch.
+  void Clear();
+
+  // The size of the database changes caused by this batch.
+  //
+  // This number is tied to implementation details, and may change across
+  // releases. It is intended for LevelDB usage metrics.
+  size_t ApproximateSize() const;
+
+  // Copies the operations in "source" to this batch.
+  //
+  // This runs in O(source size) time. However, the constant factor is better
+  // than calling Iterate() over the source batch with a Handler that replicates
+  // the operations into this batch.
+  void Append(const WriteBatch& source);
+
+  // Support for iterating over the contents of a batch.
+  Status Iterate(Handler* handler) const;
+
+ private:
+  friend class WriteBatchInternal;
+
+  std::string rep_;  // See comment in write_batch.cc for the format of rep_
+};
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_

Kit/lldb/lldb.h

@@ -0,0 +1,30 @@
+//
+//  lldb.h
+//  Kit
+//
+//  Created by Serhiy Mytrovtsiy on 03/02/2024
+//  Using Swift 5.0
+//  Running on macOS 14.3
+//
+//  Copyright © 2024 Serhiy Mytrovtsiy. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+@interface LLDB:NSObject
+-(instancetype)init:(NSString *) path;
+
+-(NSArray *)keys:(NSString *)key;
+
+-(bool)insert:(NSString *)key value:(NSString *)value;
+
+-(NSString *)findOne:(NSString *)key;
+-(NSString *)findLast:(NSString *)prefix;
+-(NSArray *)findMany:(NSString *)prefix;
+
+-(bool)deleteOne:(NSString *)key;
+-(bool)deleteMany:(NSArray*)keys;
+
+-(void)close;
+
+@end

Kit/lldb/lldb.m

@@ -0,0 +1,145 @@
+//
+//  lldb.m
+//  Kit
+//
+//  Created by Serhiy Mytrovtsiy on 03/02/2024
+//  Using Swift 5.0
+//  Running on macOS 14.3
+//
+//  Copyright © 2024 Serhiy Mytrovtsiy. All rights reserved.
+//
+
+#import "lldb.h"
+
+#include <iostream>
+#include <sstream>
+#include <string>
+
+#import <db.h>
+#import <write_batch.h>
+
+using namespace std;
+
+@implementation LLDB {
+    leveldb::DB *db;
+}
+
+- (instancetype) init:(NSString *) name {
+    self = [super init];
+    if (self) {
+        [self createDB:name];
+    }
+    return self;
+}
+
+-(void)createDB:(NSString *) path {
+    leveldb::Options options;
+    options.create_if_missing = true;
+    leveldb::Status status = leveldb::DB::Open(options, [path UTF8String], &self->db);
+    if (false == status.ok()) {
+        NSLog(@"ERROR: Unable to open/create database.");
+        std::cout << status.ToString();
+    }
+}
+
+-(NSArray *)keys:(NSString *)key {
+    leveldb::ReadOptions readOptions;
+    leveldb::Iterator *it = db->NewIterator(readOptions);
+    leveldb::Slice slice = leveldb::Slice(key.UTF8String);
+    NSMutableArray *array = [[NSMutableArray alloc] init];
+    
+    for (it->Seek(slice); it->Valid() && it->key().starts_with(slice); it->Next()) {
+        NSString *value = [[NSString alloc] initWithCString:it->key().ToString().c_str() encoding: NSUTF8StringEncoding];
+        [array addObject:value];
+    }
+    delete it;
+    
+    return array;
+}
+
+-(bool)insert:(NSString *)key value:(NSString *)value {
+    ostringstream keyStream;
+    keyStream << key.UTF8String;
+    
+    ostringstream valueStream;
+    valueStream << value.UTF8String;
+    
+    leveldb::WriteOptions writeOptions;
+    leveldb::Status s = self->db->Put(writeOptions, keyStream.str(), valueStream.str());
+    
+    return s.ok();
+}
+
+-(NSString *)findOne:(NSString *)key {
+    ostringstream keyStream;
+    keyStream << key.UTF8String;
+    
+    leveldb::ReadOptions readOptions;
+    string value;
+    leveldb::Status s = self->db->Get(readOptions, keyStream.str(), &value);
+    
+    NSString *nsstr = [[NSString alloc] initWithUTF8String:value.c_str()];
+    
+    return [nsstr stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
+}
+
+-(NSString *)findLast:(NSString *)prefix {
+    leveldb::ReadOptions readOptions;
+    leveldb::Iterator *it = db->NewIterator(readOptions);
+    leveldb::Slice slice = leveldb::Slice(prefix.UTF8String);
+    NSString *value;
+    
+    it->SeekToLast();
+    
+    for (it->SeekToLast(); it->Valid() && it->key().starts_with(slice);) {
+        value = [[NSString alloc] initWithCString:it->value().ToString().c_str() encoding:[NSString defaultCStringEncoding]];
+        break;
+    }
+    delete it;
+    
+    return value;
+}
+
+-(NSArray *)findMany:(NSString *)prefix {
+    leveldb::ReadOptions readOptions;
+    leveldb::Iterator *it = db->NewIterator(readOptions);
+    leveldb::Slice slice = leveldb::Slice(prefix.UTF8String);
+    NSMutableArray *array = [[NSMutableArray alloc] init];
+    
+    for (it->Seek(slice); it->Valid() && it->key().starts_with(slice); it->Next()) {
+        NSString *value = [[NSString alloc] initWithCString:it->value().ToString().c_str() encoding:[NSString defaultCStringEncoding]];
+        [array addObject:value];
+    }
+    delete it;
+    
+    return array;
+}
+
+-(bool)deleteOne:(NSString *)key {
+    ostringstream keySream;
+    keySream << key.UTF8String;
+    
+    leveldb::WriteOptions writeOptions;
+    leveldb::Status s = self->db->Delete(writeOptions, keySream.str());
+    
+    return s.ok();
+}
+
+-(bool)deleteMany:(NSArray*)keys {
+    leveldb::WriteBatch batch;
+    
+    for (int i=0; i <[keys count]; i++) {
+        NSString *key = [keys objectAtIndex:i];
+        leveldb::Slice slice = leveldb::Slice(key.UTF8String);
+        batch.Delete(slice);
+    }
+    
+    leveldb::Status s = self->db->Write(leveldb::WriteOptions(), &batch);
+    return s.ok();
+}
+
+-(void)close {
+    delete self->db;
+}
+
+@end

Kit/plugins/DB.swift

@@ -0,0 +1,97 @@
+//
+//  DB.swift
+//  Kit
+//
+//  Created by Serhiy Mytrovtsiy on 03/02/2024
+//  Using Swift 5.0
+//  Running on macOS 14.3
+//
+//  Copyright © 2024 Serhiy Mytrovtsiy. All rights reserved.
+//
+
+import Foundation
+
+public class DB {
+    public static let shared = DB()
+    
+    private var lldb: LLDB? = nil
+    private let queue = DispatchQueue(label: "eu.exelban.db")
+    private let ttl: Int = 60*60
+    
+    public var keys: [String] = []
+    
+    private var _values: [String: Codable] = [:]
+    public var values: [String: Codable] {
+        get { self.queue.sync { self._values } }
+        set { self.queue.sync { self._values = newValue } }
+    }
+    
+    init() {
+        var dbPath: URL
+        
+        let fileManager = FileManager.default
+        let appSupportURL = fileManager.urls(for: .applicationSupportDirectory, in: .userDomainMask).first!
+        let folder = appSupportURL.appendingPathComponent("Stats")
+        do {
+            try fileManager.createDirectory(at: folder, withIntermediateDirectories: true, attributes: nil)
+            dbPath = folder.appendingPathComponent("lldb")
+        } catch {
+            dbPath = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent("Stats").appendingPathComponent("lldb")
+        }
+        
+        self.lldb = LLDB(dbPath.path)
+    }
+    
+    deinit {
+        self.lldb?.close()
+    }
+    
+    public func setup<T: Codable>(_ type: T.Type, _ key: String) {
+        self.keys.append(key)
+        self.clean(key)
+        
+        if let raw = self.lldb?.findOne(key), let value = try? JSONDecoder().decode(type, from: Data(raw.utf8)) {
+            self.values[key] = value
+        }
+    }
+    
+    public func insert(key: String, value: Codable, ts: Bool = true) {
+        self.values[key] = value
+        guard let blobData = try? JSONEncoder().encode(value) else { return }
+        self.lldb?.insert(key, value: String(decoding: blobData, as: UTF8.self))
+        if ts {
+            self.lldb?.insert("\(key)@\(Date().currentTimeSeconds())", value: String(decoding: blobData, as: UTF8.self))
+        }
+    }
+    
+    public func findOne<T: Decodable>(_ dynamicType: T.Type, key: String) -> T? {
+        return self.values[key] as? T
+    }
+    
+    public func findMany<T: Decodable>(_ type: T.Type, key: String) -> [T] {
+        guard let values = self.lldb?.findMany(key) as? [String] else { return [] }
+        
+        var list: [T] = []
+        values.forEach({ value in
+            if let value = try? JSONDecoder().decode(type, from: Data(value.utf8)) {
+                list.append(value)
+            }
+        })
+        
+        return list
+    }
+    
+    private func clean(_ key: String) {
+        guard let keys = self.lldb?.keys(key) as? [String] else { return }
+        let maxLiveTS = Date().currentTimeSeconds() - self.ttl
+        var toDeleteKeys: [String] = []
+        
+        keys.forEach { (key: String) in
+            if let ts = key.split(separator: "@").last, let ts = Int(ts), ts < maxLiveTS {
+                toDeleteKeys.append(key)
+            }
+        }
+        
+        self.lldb?.deleteMany(toDeleteKeys)
+    }
+}

Kit/scripts/uninstall.sh

@@ -3,3 +3,4 @@
 sudo launchctl unload /Library/LaunchDaemons/eu.exelban.Stats.SMC.Helper.plist
 sudo rm /Library/LaunchDaemons/eu.exelban.Stats.SMC.Helper.plist
 sudo rm /Library/PrivilegedHelperTools/eu.exelban.Stats.SMC.Helper
+sudo rm $HOME/Library/Application Support/Stats