hphp/runtime/base/apc-file-storage.h

   1 /*
   2    +----------------------------------------------------------------------+
   3    | HipHop for PHP                                                       |
   4    +----------------------------------------------------------------------+
   5    | Copyright (c) 2010-present Facebook, Inc. (http://www.facebook.com)  |
   6    +----------------------------------------------------------------------+
   7    | This source file is subject to version 3.01 of the PHP license,      |
   8    | that is bundled with this package in the file LICENSE, and is        |
   9    | available through the world-wide-web at the following url:           |
  10    | http://www.php.net/license/3_01.txt                                  |
  11    | If you did not receive a copy of the PHP license and are unable to   |
  12    | obtain it through the world-wide-web, please send a note to          |
  13    | license@php.net so we can mail you a copy immediately.               |
  14    +----------------------------------------------------------------------+
  15 */
  16
  17 #ifndef incl_HPHP_APC_FILE_STORAGE_H_
  18 #define incl_HPHP_APC_FILE_STORAGE_H_
  19
  20 #include <atomic>
  21 #include <string>
  22 #include <mutex>
  23 #include <vector>
  24
  25 #include "hphp/util/hash.h"
  26
  27 namespace HPHP {
  28
  29 //////////////////////////////////////////////////////////////////////
  30
  31 /*
  32  * To save memory, hhvm puts portions of primed APC data in a file-backed mmap
  33  * that we can madvise away after an initial warmup period.
  34  */
  35 struct APCFileStorage {
  36   enum class StorageState {
  37     Invalid,
  38     Open,
  39     Sealed,
  40     Full
  41   };
  42
  43   APCFileStorage() = default;
  44   APCFileStorage(const APCFileStorage&) = delete;
  45   APCFileStorage& operator=(const APCFileStorage&) = delete;
  46
  47   void enable(const std::string& prefix, size_t chunkSize);
  48   char *put(const char *data, uint32_t len);
  49   void seal();
  50   void adviseOut();
  51   bool hashCheck();
  52   void cleanup();
  53   StorageState getState() { return m_state; }
  54
  55 private:
  56   bool addFile();
  57
  58 private:
  59   // [32-bit chunk index]:[32-bit offset]
  60   std::atomic_uint_fast64_t m_current{0};
  61   size_t m_chunkSize{0};
  62   StorageState m_state{StorageState::Invalid};
  63   std::vector<char*> m_chunks;
  64   std::vector<std::string> m_fileNames;
  65   std::vector<int> m_fds;
  66   std::string m_prefix;
  67
  68   // This lock is needed when manipulating chunks.
  69   std::mutex m_lock;
  70   static constexpr strhash_t TombHash = 0xdeadbeef;
  71   static constexpr uint32_t PaddingSize = sizeof(strhash_t) + // hash
  72                                           sizeof(int32_t) + // len
  73                                           sizeof(char); // '\0'
  74 };
  75
  76 extern APCFileStorage s_apc_file_storage;
  77
  78 //////////////////////////////////////////////////////////////////////
  79
  80 }
  81
  82 #endif