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 <stdint.h>
11  
12  #include <string>
13  
14  #include "db/dbformat.h"
15  #include "leveldb/cache.h"
16  #include "leveldb/table.h"
17  #include "port/port.h"
18  
19  namespace leveldb {
20  
21  class Env;
22  
23  class TableCache {
24   public:
25    TableCache(const std::string& dbname, const Options& options, int entries);
26    ~TableCache();
27  
28    // Return an iterator for the specified file number (the corresponding
29    // file length must be exactly "file_size" bytes).  If "tableptr" is
30    // non-null, also sets "*tableptr" to point to the Table object
31    // underlying the returned iterator, or to nullptr if no Table object
32    // underlies the returned iterator.  The returned "*tableptr" object is owned
33    // by the cache and should not be deleted, and is valid for as long as the
34    // returned iterator is live.
35    Iterator* NewIterator(const ReadOptions& options, uint64_t file_number,
36                          uint64_t file_size, Table** tableptr = nullptr);
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, uint64_t file_number,
41               uint64_t file_size, const Slice& k, void* arg,
42               void (*handle_result)(void*, const Slice&, const Slice&));
43  
44    // Evict any entry for the specified file number
45    void Evict(uint64_t file_number);
46  
47   private:
48    Status FindTable(uint64_t file_number, uint64_t file_size, Cache::Handle**);
49  
50    Env* const env_;
51    const std::string dbname_;
52    const Options& options_;
53    Cache* cache_;
54  };
55  
56  }  // namespace leveldb
57  
58  #endif  // STORAGE_LEVELDB_DB_TABLE_CACHE_H_