src/leveldb/db/table_cache.h

   1 // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file. See the AUTHORS file for names of contributors.
   4 //
   5 // Thread-safe (provides internal synchronization)
   6
   7 #ifndef STORAGE_LEVELDB_DB_TABLE_CACHE_H_
   8 #define STORAGE_LEVELDB_DB_TABLE_CACHE_H_
   9
  10 #include <string>
  11 #include <stdint.h>
  12 #include "db/dbformat.h"
  13 #include "leveldb/cache.h"
  14 #include "leveldb/table.h"
  15 #include "port/port.h"
  16
  17 namespace leveldb {
  18
  19 class Env;
  20
  21 class TableCache {
  22  public:
  23   TableCache(const std::string& dbname, const Options* options, int entries);
  24   ~TableCache();
  25
  26   // Return an iterator for the specified file number (the corresponding
  27   // file length must be exactly "file_size" bytes).  If "tableptr" is
  28   // non-NULL, also sets "*tableptr" to point to the Table object
  29   // underlying the returned iterator, or NULL if no Table object underlies
  30   // the returned iterator.  The returned "*tableptr" object is owned by
  31   // the cache and should not be deleted, and is valid for as long as the
  32   // returned iterator is live.
  33   Iterator* NewIterator(const ReadOptions& options,
  34                         uint64_t file_number,
  35                         uint64_t file_size,
  36                         Table** tableptr = NULL);
  37
  38   // If a seek to internal key "k" in specified file finds an entry,
  39   // call (*handle_result)(arg, found_key, found_value).
  40   Status Get(const ReadOptions& options,
  41              uint64_t file_number,
  42              uint64_t file_size,
  43              const Slice& k,
  44              void* arg,
  45              void (*handle_result)(void*, const Slice&, const Slice&));
  46
  47   // Evict any entry for the specified file number
  48   void Evict(uint64_t file_number);
  49
  50  private:
  51   Env* const env_;
  52   const std::string dbname_;
  53   const Options* options_;
  54   Cache* cache_;
  55
  56   Status FindTable(uint64_t file_number, uint64_t file_size, Cache::Handle**);
  57 };
  58
  59 }  // namespace leveldb
  60
  61 #endif  // STORAGE_LEVELDB_DB_TABLE_CACHE_H_