diff options
Diffstat (limited to 'include/leveldb')
| -rw-r--r-- | include/leveldb/c.h | 291 | ||||
| -rw-r--r-- | include/leveldb/cache.h | 99 | ||||
| -rw-r--r-- | include/leveldb/comparator.h | 63 | ||||
| -rw-r--r-- | include/leveldb/db.h | 161 | ||||
| -rw-r--r-- | include/leveldb/env.h | 333 | ||||
| -rw-r--r-- | include/leveldb/filter_policy.h | 70 | ||||
| -rw-r--r-- | include/leveldb/iterator.h | 100 | ||||
| -rw-r--r-- | include/leveldb/options.h | 195 | ||||
| -rw-r--r-- | include/leveldb/slice.h | 109 | ||||
| -rw-r--r-- | include/leveldb/status.h | 106 | ||||
| -rw-r--r-- | include/leveldb/table.h | 85 | ||||
| -rw-r--r-- | include/leveldb/table_builder.h | 92 | ||||
| -rw-r--r-- | include/leveldb/write_batch.h | 64 |
13 files changed, 1768 insertions, 0 deletions
diff --git a/include/leveldb/c.h b/include/leveldb/c.h new file mode 100644 index 0000000000..1fa58866c3 --- /dev/null +++ b/include/leveldb/c.h @@ -0,0 +1,291 @@ +/* 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 + . capturing post-write-snapshot + . 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 unsigned char (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_ + +#ifdef __cplusplus +extern "C" { +#endif + +#include <stdarg.h> +#include <stddef.h> +#include <stdint.h> + +/* 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 */ + +extern leveldb_t* leveldb_open( + const leveldb_options_t* options, + const char* name, + char** errptr); + +extern void leveldb_close(leveldb_t* db); + +extern 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); + +extern void leveldb_delete( + leveldb_t* db, + const leveldb_writeoptions_t* options, + const char* key, size_t keylen, + char** errptr); + +extern 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. */ +extern char* leveldb_get( + leveldb_t* db, + const leveldb_readoptions_t* options, + const char* key, size_t keylen, + size_t* vallen, + char** errptr); + +extern leveldb_iterator_t* leveldb_create_iterator( + leveldb_t* db, + const leveldb_readoptions_t* options); + +extern const leveldb_snapshot_t* leveldb_create_snapshot( + leveldb_t* db); + +extern 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. */ +extern char* leveldb_property_value( + leveldb_t* db, + const char* propname); + +extern 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); + +extern 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 */ + +extern void leveldb_destroy_db( + const leveldb_options_t* options, + const char* name, + char** errptr); + +extern void leveldb_repair_db( + const leveldb_options_t* options, + const char* name, + char** errptr); + +/* Iterator */ + +extern void leveldb_iter_destroy(leveldb_iterator_t*); +extern unsigned char leveldb_iter_valid(const leveldb_iterator_t*); +extern void leveldb_iter_seek_to_first(leveldb_iterator_t*); +extern void leveldb_iter_seek_to_last(leveldb_iterator_t*); +extern void leveldb_iter_seek(leveldb_iterator_t*, const char* k, size_t klen); +extern void leveldb_iter_next(leveldb_iterator_t*); +extern void leveldb_iter_prev(leveldb_iterator_t*); +extern const char* leveldb_iter_key(const leveldb_iterator_t*, size_t* klen); +extern const char* leveldb_iter_value(const leveldb_iterator_t*, size_t* vlen); +extern void leveldb_iter_get_error(const leveldb_iterator_t*, char** errptr); + +/* Write batch */ + +extern leveldb_writebatch_t* leveldb_writebatch_create(); +extern void leveldb_writebatch_destroy(leveldb_writebatch_t*); +extern void leveldb_writebatch_clear(leveldb_writebatch_t*); +extern void leveldb_writebatch_put( + leveldb_writebatch_t*, + const char* key, size_t klen, + const char* val, size_t vlen); +extern void leveldb_writebatch_delete( + leveldb_writebatch_t*, + const char* key, size_t klen); +extern void leveldb_writebatch_iterate( + 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)); + +/* Options */ + +extern leveldb_options_t* leveldb_options_create(); +extern void leveldb_options_destroy(leveldb_options_t*); +extern void leveldb_options_set_comparator( + leveldb_options_t*, + leveldb_comparator_t*); +extern void leveldb_options_set_filter_policy( + leveldb_options_t*, + leveldb_filterpolicy_t*); +extern void leveldb_options_set_create_if_missing( + leveldb_options_t*, unsigned char); +extern void leveldb_options_set_error_if_exists( + leveldb_options_t*, unsigned char); +extern void leveldb_options_set_paranoid_checks( + leveldb_options_t*, unsigned char); +extern void leveldb_options_set_env(leveldb_options_t*, leveldb_env_t*); +extern void leveldb_options_set_info_log(leveldb_options_t*, leveldb_logger_t*); +extern void leveldb_options_set_write_buffer_size(leveldb_options_t*, size_t); +extern void leveldb_options_set_max_open_files(leveldb_options_t*, int); +extern void leveldb_options_set_cache(leveldb_options_t*, leveldb_cache_t*); +extern void leveldb_options_set_block_size(leveldb_options_t*, size_t); +extern void leveldb_options_set_block_restart_interval(leveldb_options_t*, int); + +enum { + leveldb_no_compression = 0, + leveldb_snappy_compression = 1 +}; +extern void leveldb_options_set_compression(leveldb_options_t*, int); + +/* Comparator */ + +extern 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*)); +extern void leveldb_comparator_destroy(leveldb_comparator_t*); + +/* Filter policy */ + +extern 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), + unsigned char (*key_may_match)( + void*, + const char* key, size_t length, + const char* filter, size_t filter_length), + const char* (*name)(void*)); +extern void leveldb_filterpolicy_destroy(leveldb_filterpolicy_t*); + +extern leveldb_filterpolicy_t* leveldb_filterpolicy_create_bloom( + int bits_per_key); + +/* Read options */ + +extern leveldb_readoptions_t* leveldb_readoptions_create(); +extern void leveldb_readoptions_destroy(leveldb_readoptions_t*); +extern void leveldb_readoptions_set_verify_checksums( + leveldb_readoptions_t*, + unsigned char); +extern void leveldb_readoptions_set_fill_cache( + leveldb_readoptions_t*, unsigned char); +extern void leveldb_readoptions_set_snapshot( + leveldb_readoptions_t*, + const leveldb_snapshot_t*); + +/* Write options */ + +extern leveldb_writeoptions_t* leveldb_writeoptions_create(); +extern void leveldb_writeoptions_destroy(leveldb_writeoptions_t*); +extern void leveldb_writeoptions_set_sync( + leveldb_writeoptions_t*, unsigned char); + +/* Cache */ + +extern leveldb_cache_t* leveldb_cache_create_lru(size_t capacity); +extern void leveldb_cache_destroy(leveldb_cache_t* cache); + +/* Env */ + +extern leveldb_env_t* leveldb_create_default_env(); +extern void leveldb_env_destroy(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. */ +extern void leveldb_free(void* ptr); + +/* Return the major version number for this release. */ +extern int leveldb_major_version(); + +/* Return the minor version number for this release. */ +extern int leveldb_minor_version(); + +#ifdef __cplusplus +} /* end extern "C" */ +#endif + +#endif /* STORAGE_LEVELDB_INCLUDE_C_H_ */ diff --git a/include/leveldb/cache.h b/include/leveldb/cache.h new file mode 100644 index 0000000000..5e3b47637d --- /dev/null +++ b/include/leveldb/cache.h @@ -0,0 +1,99 @@ +// 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 <stdint.h> +#include "leveldb/slice.h" + +namespace leveldb { + +class Cache; + +// Create a new cache with a fixed size capacity. This implementation +// of Cache uses a least-recently-used eviction policy. +extern Cache* NewLRUCache(size_t capacity); + +class Cache { + public: + Cache() { } + + // 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 NULL. + // + // 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; + + private: + void LRU_Remove(Handle* e); + void LRU_Append(Handle* e); + void Unref(Handle* e); + + struct Rep; + Rep* rep_; + + // No copying allowed + Cache(const Cache&); + void operator=(const Cache&); +}; + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_UTIL_CACHE_H_ diff --git a/include/leveldb/comparator.h b/include/leveldb/comparator.h new file mode 100644 index 0000000000..556b984c76 --- /dev/null +++ b/include/leveldb/comparator.h @@ -0,0 +1,63 @@ +// 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> + +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 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. +extern const Comparator* BytewiseComparator(); + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_COMPARATOR_H_ diff --git a/include/leveldb/db.h b/include/leveldb/db.h new file mode 100644 index 0000000000..29d3674479 --- /dev/null +++ b/include/leveldb/db.h @@ -0,0 +1,161 @@ +// 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 <stdint.h> +#include <stdio.h> +#include "leveldb/iterator.h" +#include "leveldb/options.h" + +namespace leveldb { + +// Update Makefile if you change these +static const int kMajorVersion = 1; +static const int kMinorVersion = 9; + +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 Snapshot { + protected: + virtual ~Snapshot(); +}; + +// A range of keys +struct Range { + Slice start; // Included in the range + Slice limit; // Not included in the range + + Range() { } + Range(const Slice& s, const Slice& l) : start(s), limit(l) { } +}; + +// 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 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 NULL 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() { } + 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. + 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==NULL is treated as a key before all keys in the database. + // end==NULL is treated as a key after all keys in the database. + // Therefore the following call will compact the entire database: + // db->CompactRange(NULL, NULL); + virtual void CompactRange(const Slice* begin, const Slice* end) = 0; + + private: + // No copying allowed + DB(const DB&); + void operator=(const DB&); +}; + +// Destroy the contents of the specified database. +// Be very careful using this method. +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. +Status RepairDB(const std::string& dbname, const Options& options); + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_DB_H_ diff --git a/include/leveldb/env.h b/include/leveldb/env.h new file mode 100644 index 0000000000..fa32289f58 --- /dev/null +++ b/include/leveldb/env.h @@ -0,0 +1,333 @@ +// 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 <string> +#include <vector> +#include <stdint.h> +#include "leveldb/status.h" + +namespace leveldb { + +class FileLock; +class Logger; +class RandomAccessFile; +class SequentialFile; +class Slice; +class WritableFile; + +class Env { + public: + Env() { } + 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 a brand new sequentially-readable file with the specified name. + // On success, stores a pointer to the new file in *result and returns OK. + // On failure stores NULL in *result and returns non-OK. If the file does + // not exist, returns a non-OK status. + // + // The returned file will only be accessed by one thread at a time. + virtual Status NewSequentialFile(const std::string& fname, + SequentialFile** result) = 0; + + // Create a brand new random access read-only file with the + // specified name. On success, stores a pointer to the new file in + // *result and returns OK. On failure stores NULL in *result and + // returns non-OK. If the file does not exist, returns a non-OK + // status. + // + // 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 NULL 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; + + // 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. + virtual Status DeleteFile(const std::string& fname) = 0; + + // Create the specified directory. + virtual Status CreateDir(const std::string& dirname) = 0; + + // Delete the specified directory. + virtual Status DeleteDir(const std::string& dirname) = 0; + + // 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 NULL 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 many 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 perscribed number of micro-seconds. + virtual void SleepForMicroseconds(int micros) = 0; + + private: + // No copying allowed + Env(const Env&); + void operator=(const Env&); +}; + +// A file abstraction for reading sequentially through a file +class SequentialFile { + public: + SequentialFile() { } + 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; + + private: + // No copying allowed + SequentialFile(const SequentialFile&); + void operator=(const SequentialFile&); +}; + +// A file abstraction for randomly reading the contents of a file. +class RandomAccessFile { + public: + RandomAccessFile() { } + 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; + + private: + // No copying allowed + RandomAccessFile(const RandomAccessFile&); + void operator=(const RandomAccessFile&); +}; + +// A file abstraction for sequential writing. The implementation +// must provide buffering since callers may append small fragments +// at a time to the file. +class WritableFile { + public: + WritableFile() { } + virtual ~WritableFile(); + + virtual Status Append(const Slice& data) = 0; + virtual Status Close() = 0; + virtual Status Flush() = 0; + virtual Status Sync() = 0; + + private: + // No copying allowed + WritableFile(const WritableFile&); + void operator=(const WritableFile&); +}; + +// An interface for writing log messages. +class Logger { + public: + Logger() { } + virtual ~Logger(); + + // Write an entry to the log file with the specified format. + virtual void Logv(const char* format, va_list ap) = 0; + + private: + // No copying allowed + Logger(const Logger&); + void operator=(const Logger&); +}; + + +// Identifies a locked file. +class FileLock { + public: + FileLock() { } + virtual ~FileLock(); + private: + // No copying allowed + FileLock(const FileLock&); + void operator=(const FileLock&); +}; + +// Log the specified data to *info_log if info_log is non-NULL. +extern 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. +extern Status WriteStringToFile(Env* env, const Slice& data, + const std::string& fname); + +// A utility routine: read contents of named file into *data +extern 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 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) { + return target_->NewSequentialFile(f, r); + } + Status NewRandomAccessFile(const std::string& f, RandomAccessFile** r) { + return target_->NewRandomAccessFile(f, r); + } + Status NewWritableFile(const std::string& f, WritableFile** r) { + return target_->NewWritableFile(f, r); + } + bool FileExists(const std::string& f) { return target_->FileExists(f); } + Status GetChildren(const std::string& dir, std::vector<std::string>* r) { + return target_->GetChildren(dir, r); + } + Status DeleteFile(const std::string& f) { return target_->DeleteFile(f); } + Status CreateDir(const std::string& d) { return target_->CreateDir(d); } + Status DeleteDir(const std::string& d) { return target_->DeleteDir(d); } + Status GetFileSize(const std::string& f, uint64_t* s) { + return target_->GetFileSize(f, s); + } + Status RenameFile(const std::string& s, const std::string& t) { + return target_->RenameFile(s, t); + } + Status LockFile(const std::string& f, FileLock** l) { + return target_->LockFile(f, l); + } + Status UnlockFile(FileLock* l) { return target_->UnlockFile(l); } + void Schedule(void (*f)(void*), void* a) { + return target_->Schedule(f, a); + } + void StartThread(void (*f)(void*), void* a) { + return target_->StartThread(f, a); + } + virtual Status GetTestDirectory(std::string* path) { + return target_->GetTestDirectory(path); + } + virtual Status NewLogger(const std::string& fname, Logger** result) { + return target_->NewLogger(fname, result); + } + uint64_t NowMicros() { + return target_->NowMicros(); + } + void SleepForMicroseconds(int micros) { + target_->SleepForMicroseconds(micros); + } + private: + Env* target_; +}; + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_ENV_H_ diff --git a/include/leveldb/filter_policy.h b/include/leveldb/filter_policy.h new file mode 100644 index 0000000000..1fba08001f --- /dev/null +++ b/include/leveldb/filter_policy.h @@ -0,0 +1,70 @@ +// 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> + +namespace leveldb { + +class Slice; + +class 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. +extern const FilterPolicy* NewBloomFilterPolicy(int bits_per_key); + +} + +#endif // STORAGE_LEVELDB_INCLUDE_FILTER_POLICY_H_ diff --git a/include/leveldb/iterator.h b/include/leveldb/iterator.h new file mode 100644 index 0000000000..ad543eb46c --- /dev/null +++ b/include/leveldb/iterator.h @@ -0,0 +1,100 @@ +// 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 "leveldb/slice.h" +#include "leveldb/status.h" + +namespace leveldb { + +class Iterator { + public: + Iterator(); + 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 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: !AtEnd() && !AtStart() + 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. + typedef void (*CleanupFunction)(void* arg1, void* arg2); + void RegisterCleanup(CleanupFunction function, void* arg1, void* arg2); + + private: + struct Cleanup { + CleanupFunction function; + void* arg1; + void* arg2; + Cleanup* next; + }; + Cleanup cleanup_; + + // No copying allowed + Iterator(const Iterator&); + void operator=(const Iterator&); +}; + +// Return an empty iterator (yields nothing). +extern Iterator* NewEmptyIterator(); + +// Return an empty iterator with the specified status. +extern Iterator* NewErrorIterator(const Status& status); + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_ITERATOR_H_ diff --git a/include/leveldb/options.h b/include/leveldb/options.h new file mode 100644 index 0000000000..fdda718d30 --- /dev/null +++ b/include/leveldb/options.h @@ -0,0 +1,195 @@ +// 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 <stddef.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 +}; + +// Options to control the behavior of a database (passed to DB::Open) +struct 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. + // Default: false + bool create_if_missing; + + // If true, an error is raised if the database already exists. + // Default: false + bool error_if_exists; + + // 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. + // Default: false + bool paranoid_checks; + + // 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. + // Default: NULL + Logger* info_log; + + // ------------------- + // 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. + // + // Default: 4MB + size_t write_buffer_size; + + // 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). + // + // Default: 1000 + int max_open_files; + + // 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. + // Default: NULL + Cache* block_cache; + + // 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. + // + // Default: 4K + size_t block_size; + + // Number of keys between restart points for delta encoding of keys. + // This parameter can be changed dynamically. Most clients should + // leave this parameter alone. + // + // Default: 16 + int block_restart_interval; + + // 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; + + // If non-NULL, use the specified filter policy to reduce disk reads. + // Many applications will benefit from passing the result of + // NewBloomFilterPolicy() here. + // + // Default: NULL + const FilterPolicy* filter_policy; + + // Create an Options object with default values for all fields. + Options(); +}; + +// Options that control read operations +struct ReadOptions { + // If true, all data read from underlying storage will be + // verified against corresponding checksums. + // Default: false + bool verify_checksums; + + // Should the data read for this iteration be cached in memory? + // Callers may wish to set this field to false for bulk scans. + // Default: true + bool fill_cache; + + // 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 impliicit + // snapshot of the state at the beginning of this read operation. + // Default: NULL + const Snapshot* snapshot; + + ReadOptions() + : verify_checksums(false), + fill_cache(true), + snapshot(NULL) { + } +}; + +// Options that control write operations +struct WriteOptions { + // 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()". + // + // Default: false + bool sync; + + WriteOptions() + : sync(false) { + } +}; + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_OPTIONS_H_ diff --git a/include/leveldb/slice.h b/include/leveldb/slice.h new file mode 100644 index 0000000000..74ea8fa49a --- /dev/null +++ b/include/leveldb/slice.h @@ -0,0 +1,109 @@ +// 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 <assert.h> +#include <stddef.h> +#include <string.h> +#include <string> + +namespace leveldb { + +class 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)) { } + + // 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_; + + // Intentionally copyable +}; + +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 int 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_ diff --git a/include/leveldb/status.h b/include/leveldb/status.h new file mode 100644 index 0000000000..11dbd4b47e --- /dev/null +++ b/include/leveldb/status.h @@ -0,0 +1,106 @@ +// 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 <string> +#include "leveldb/slice.h" + +namespace leveldb { + +class Status { + public: + // Create a success status. + Status() : state_(NULL) { } + ~Status() { delete[] state_; } + + // Copy the specified status. + Status(const Status& s); + void operator=(const Status& s); + + // 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_ == NULL); } + + // 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; } + + // Return a string representation of this status suitable for printing. + // Returns the string "OK" for success. + std::string ToString() const; + + private: + // 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_; + + enum Code { + kOk = 0, + kNotFound = 1, + kCorruption = 2, + kNotSupported = 3, + kInvalidArgument = 4, + kIOError = 5 + }; + + Code code() const { + return (state_ == NULL) ? kOk : static_cast<Code>(state_[4]); + } + + Status(Code code, const Slice& msg, const Slice& msg2); + static const char* CopyState(const char* s); +}; + +inline Status::Status(const Status& s) { + state_ = (s.state_ == NULL) ? NULL : CopyState(s.state_); +} +inline void Status::operator=(const Status& s) { + // The following condition catches both aliasing (when this == &s), + // and the common case where both s and *this are ok. + if (state_ != s.state_) { + delete[] state_; + state_ = (s.state_ == NULL) ? NULL : CopyState(s.state_); + } +} + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_STATUS_H_ diff --git a/include/leveldb/table.h b/include/leveldb/table.h new file mode 100644 index 0000000000..a9746c3f5e --- /dev/null +++ b/include/leveldb/table.h @@ -0,0 +1,85 @@ +// 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 <stdint.h> +#include "leveldb/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 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 NULL 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(); + + // 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: + struct Rep; + Rep* rep_; + + explicit Table(Rep* rep) { rep_ = rep; } + static Iterator* BlockReader(void*, const ReadOptions&, const Slice&); + + // 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. + friend class TableCache; + 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); + + // No copying allowed + Table(const Table&); + void operator=(const Table&); +}; + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_TABLE_H_ diff --git a/include/leveldb/table_builder.h b/include/leveldb/table_builder.h new file mode 100644 index 0000000000..5fd1dc71f1 --- /dev/null +++ b/include/leveldb/table_builder.h @@ -0,0 +1,92 @@ +// 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 <stdint.h> +#include "leveldb/options.h" +#include "leveldb/status.h" + +namespace leveldb { + +class BlockBuilder; +class BlockHandle; +class WritableFile; + +class 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); + + // 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_; + + // No copying allowed + TableBuilder(const TableBuilder&); + void operator=(const TableBuilder&); +}; + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_ diff --git a/include/leveldb/write_batch.h b/include/leveldb/write_batch.h new file mode 100644 index 0000000000..ee9aab68e0 --- /dev/null +++ b/include/leveldb/write_batch.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. +// +// 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 "leveldb/status.h" + +namespace leveldb { + +class Slice; + +class WriteBatch { + public: + WriteBatch(); + ~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(); + + // Support for iterating over the contents of a batch. + class Handler { + public: + virtual ~Handler(); + virtual void Put(const Slice& key, const Slice& value) = 0; + virtual void Delete(const Slice& key) = 0; + }; + Status Iterate(Handler* handler) const; + + private: + friend class WriteBatchInternal; + + std::string rep_; // See comment in write_batch.cc for the format of rep_ + + // Intentionally copyable +}; + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_ |