github.com/cellofellow/gopkg@v0.0.0-20140722061823-eec0544a62ad/database/leveldb.chai2010/src/table_cache.h (about)

     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_