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Diffstat (limited to 'chromium/net/disk_cache/disk_format.h')
| -rw-r--r-- | chromium/net/disk_cache/disk_format.h | 153 |
1 files changed, 0 insertions, 153 deletions
diff --git a/chromium/net/disk_cache/disk_format.h b/chromium/net/disk_cache/disk_format.h deleted file mode 100644 index 5d7597ab17d..00000000000 --- a/chromium/net/disk_cache/disk_format.h +++ /dev/null @@ -1,153 +0,0 @@ -// Copyright (c) 2011 The Chromium Authors. All rights reserved. -// Use of this source code is governed by a BSD-style license that can be -// found in the LICENSE file. - -// The cache is stored on disk as a collection of block-files, plus an index -// file plus a collection of external files. -// -// Any data blob bigger than kMaxBlockSize (disk_cache/addr.h) will be stored in -// a separate file named f_xxx where x is a hexadecimal number. Shorter data -// will be stored as a series of blocks on a block-file. In any case, CacheAddr -// represents the address of the data inside the cache. -// -// The index file is just a simple hash table that maps a particular entry to -// a CacheAddr value. Linking for a given hash bucket is handled internally -// by the cache entry. -// -// The last element of the cache is the block-file. A block file is a file -// designed to store blocks of data of a given size. For more details see -// disk_cache/disk_format_base.h -// -// A new cache is initialized with four block files (named data_0 through -// data_3), each one dedicated to store blocks of a given size. The number at -// the end of the file name is the block file number (in decimal). -// -// There are two "special" types of blocks: an entry and a rankings node. An -// entry keeps track of all the information related to the same cache entry, -// such as the key, hash value, data pointers etc. A rankings node keeps track -// of the information that is updated frequently for a given entry, such as its -// location on the LRU lists, last access time etc. -// -// The files that store internal information for the cache (blocks and index) -// are at least partially memory mapped. They have a location that is signaled -// every time the internal structures are modified, so it is possible to detect -// (most of the time) when the process dies in the middle of an update. -// -// In order to prevent dirty data to be used as valid (after a crash), every -// cache entry has a dirty identifier. Each running instance of the cache keeps -// a separate identifier (maintained on the "this_id" header field) that is used -// to mark every entry that is created or modified. When the entry is closed, -// and all the data can be trusted, the dirty flag is cleared from the entry. -// When the cache encounters an entry whose identifier is different than the one -// being currently used, it means that the entry was not properly closed on a -// previous run, so it is discarded. - -#ifndef NET_DISK_CACHE_DISK_FORMAT_H_ -#define NET_DISK_CACHE_DISK_FORMAT_H_ - -#include "base/basictypes.h" -#include "net/base/net_export.h" -#include "net/disk_cache/disk_format_base.h" - -namespace disk_cache { - -const int kIndexTablesize = 0x10000; -const uint32 kIndexMagic = 0xC103CAC3; -const uint32 kCurrentVersion = 0x20000; // Version 2.0. - -struct LruData { - int32 pad1[2]; - int32 filled; // Flag to tell when we filled the cache. - int32 sizes[5]; - CacheAddr heads[5]; - CacheAddr tails[5]; - CacheAddr transaction; // In-flight operation target. - int32 operation; // Actual in-flight operation. - int32 operation_list; // In-flight operation list. - int32 pad2[7]; -}; - -// Header for the master index file. -struct NET_EXPORT_PRIVATE IndexHeader { - IndexHeader(); - - uint32 magic; - uint32 version; - int32 num_entries; // Number of entries currently stored. - int32 num_bytes; // Total size of the stored data. - int32 last_file; // Last external file created. - int32 this_id; // Id for all entries being changed (dirty flag). - CacheAddr stats; // Storage for usage data. - int32 table_len; // Actual size of the table (0 == kIndexTablesize). - int32 crash; // Signals a previous crash. - int32 experiment; // Id of an ongoing test. - uint64 create_time; // Creation time for this set of files. - int32 pad[52]; - LruData lru; // Eviction control data. -}; - -// The structure of the whole index file. -struct Index { - IndexHeader header; - CacheAddr table[kIndexTablesize]; // Default size. Actual size controlled - // by header.table_len. -}; - -// Main structure for an entry on the backing storage. If the key is longer than -// what can be stored on this structure, it will be extended on consecutive -// blocks (adding 256 bytes each time), up to 4 blocks (1024 - 32 - 1 chars). -// After that point, the whole key will be stored as a data block or external -// file. -struct EntryStore { - uint32 hash; // Full hash of the key. - CacheAddr next; // Next entry with the same hash or bucket. - CacheAddr rankings_node; // Rankings node for this entry. - int32 reuse_count; // How often is this entry used. - int32 refetch_count; // How often is this fetched from the net. - int32 state; // Current state. - uint64 creation_time; - int32 key_len; - CacheAddr long_key; // Optional address of a long key. - int32 data_size[4]; // We can store up to 4 data streams for each - CacheAddr data_addr[4]; // entry. - uint32 flags; // Any combination of EntryFlags. - int32 pad[4]; - uint32 self_hash; // The hash of EntryStore up to this point. - char key[256 - 24 * 4]; // null terminated -}; - -COMPILE_ASSERT(sizeof(EntryStore) == 256, bad_EntyStore); -const int kMaxInternalKeyLength = 4 * sizeof(EntryStore) - - offsetof(EntryStore, key) - 1; - -// Possible states for a given entry. -enum EntryState { - ENTRY_NORMAL = 0, - ENTRY_EVICTED, // The entry was recently evicted from the cache. - ENTRY_DOOMED // The entry was doomed. -}; - -// Flags that can be applied to an entry. -enum EntryFlags { - PARENT_ENTRY = 1, // This entry has children (sparse) entries. - CHILD_ENTRY = 1 << 1 // Child entry that stores sparse data. -}; - -#pragma pack(push, 4) -// Rankings information for a given entry. -struct RankingsNode { - uint64 last_used; // LRU info. - uint64 last_modified; // LRU info. - CacheAddr next; // LRU list. - CacheAddr prev; // LRU list. - CacheAddr contents; // Address of the EntryStore. - int32 dirty; // The entry is being modifyied. - uint32 self_hash; // RankingsNode's hash. -}; -#pragma pack(pop) - -COMPILE_ASSERT(sizeof(RankingsNode) == 36, bad_RankingsNode); - -} // namespace disk_cache - -#endif // NET_DISK_CACHE_DISK_FORMAT_H_ |