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Diffstat (limited to 'chromium/net/disk_cache/v3/disk_format_v3.h')
| -rw-r--r-- | chromium/net/disk_cache/v3/disk_format_v3.h | 190 |
1 files changed, 0 insertions, 190 deletions
diff --git a/chromium/net/disk_cache/v3/disk_format_v3.h b/chromium/net/disk_cache/v3/disk_format_v3.h deleted file mode 100644 index 56163770cfa..00000000000 --- a/chromium/net/disk_cache/v3/disk_format_v3.h +++ /dev/null @@ -1,190 +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 -// 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 is actually a collection of four files that store a hash table with -// allocation bitmaps and backup data. Hash collisions are handled directly by -// the table, which from some point of view behaves like a 4-way associative -// cache with overflow buckets (so not really open addressing). -// -// Basically the hash table is a collection of buckets. The first part of the -// table has a fixed number of buckets and it is directly addressed by the hash, -// while the second part of the table (stored on a second file) has a variable -// number of buckets. Each bucket stores up to four cells (each cell represents -// a possibl entry). The index bitmap tracks the state of individual cells. -// -// 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 a set of block files (named data_0 through -// data_6), each one dedicated to store blocks of a given size or function. The -// number at the end of the file name is the block file number (in decimal). -// -// There are three "special" types of blocks: normal entries, evicted entries -// and control data for external files. -// -// The files that store internal information for the cache (blocks and index) -// are 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. There are dedicated -// backup files for cache bitmaps, used to detect entries out of date. - -#ifndef NET_DISK_CACHE_V3_DISK_FORMAT_V3_H_ -#define NET_DISK_CACHE_V3_DISK_FORMAT_V3_H_ - -#include "base/basictypes.h" -#include "net/disk_cache/disk_format_base.h" - -namespace disk_cache { - -const int kBaseTableLen = 0x10000; -const uint32 kIndexMagicV3 = 0xC103CAC3; -const uint32 kVersion3 = 0x30000; // Version 3.0. - -// Flags for a given cache. -enum CacheFlags { - CACHE_EVICTION_2 = 1, // Keep multiple lists for eviction. - CACHE_EVICTED = 1 << 1 // Already evicted at least one entry. -}; - -// Header for the master index file. -struct IndexHeaderV3 { - 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 reserved1; - CacheAddr stats; // Storage for usage data. - int32 table_len; // Actual size of the table. - int32 crash; // Signals a previous crash. - int32 experiment; // Id of an ongoing test. - int32 max_bytes; // Total maximum size of the stored data. - uint32 flags; - int32 used_cells; - int32 max_bucket; - uint64 create_time; // Creation time for this set of files. - uint64 base_time; // Current base for timestamps. - uint64 old_time; // Previous time used for timestamps. - int32 max_block_file; - int32 num_no_use_entries; - int32 num_low_use_entries; - int32 num_high_use_entries; - int32 reserved; - int32 num_evicted_entries; - int32 pad[6]; -}; - -const int kBaseBitmapBytes = 3968; -// The IndexBitmap is directly saved to a file named index. The file grows in -// page increments (4096 bytes), but all bits don't have to be in use at any -// given time. The required file size can be computed from header.table_len. -struct IndexBitmap { - IndexHeaderV3 header; - uint32 bitmap[kBaseBitmapBytes / 4]; // First page of the bitmap. -}; -COMPILE_ASSERT(sizeof(IndexBitmap) == 4096, bad_IndexHeader); - -// Possible states for a given entry. -enum EntryState { - ENTRY_FREE = 0, // Available slot. - ENTRY_NEW, // The entry is being created. - ENTRY_OPEN, // The entry is being accessed. - ENTRY_MODIFIED, // The entry is being modified. - ENTRY_DELETED, // The entry is being deleted. - ENTRY_FIXING, // Inconsistent state. The entry is being verified. - ENTRY_USED // The slot is in use (entry is present). -}; -COMPILE_ASSERT(ENTRY_USED <= 7, state_uses_3_bits); - -enum EntryGroup { - ENTRY_NO_USE = 0, // The entry has not been reused. - ENTRY_LOW_USE, // The entry has low reuse. - ENTRY_HIGH_USE, // The entry has high reuse. - ENTRY_RESERVED, // Reserved for future use. - ENTRY_EVICTED // The entry was deleted. -}; -COMPILE_ASSERT(ENTRY_USED <= 7, group_uses_3_bits); - -#pragma pack(push, 1) -struct IndexCell { - void Clear() { memset(this, 0, sizeof(*this)); } - - uint64 address : 22; - uint64 hash : 18; - uint64 timestamp : 20; - uint64 reuse : 4; - uint8 state : 3; - uint8 group : 3; - uint8 sum : 2; -}; -COMPILE_ASSERT(sizeof(IndexCell) == 9, bad_IndexCell); - -struct IndexBucket { - IndexCell cells[4]; - int32 next; - uint32 hash : 24; // The last byte is only defined for buckets of - uint32 reserved : 8; // the extra table. -}; -COMPILE_ASSERT(sizeof(IndexBucket) == 44, bad_IndexBucket); -const int kBytesPerCell = 44 / 4; - -// The main cache index. Backed by a file named index_tb1. -// The extra table (index_tb2) has a similar format, but different size. -struct Index { - // Default size. Actual size controlled by header.table_len. - IndexBucket table[kBaseTableLen / 4]; -}; -#pragma pack(pop) - -// 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. -}; - -struct EntryRecord { - uint32 hash; - uint32 pad1; - uint8 reuse_count; - uint8 refetch_count; - int8 state; // Current EntryState. - uint8 flags; // Any combination of EntryFlags. - int32 key_len; - int32 data_size[4]; // We can store up to 4 data streams for each - CacheAddr data_addr[4]; // entry. - uint32 data_hash[4]; - uint64 creation_time; - uint64 last_modified_time; - uint64 last_access_time; - int32 pad[3]; - uint32 self_hash; -}; -COMPILE_ASSERT(sizeof(EntryRecord) == 104, bad_EntryRecord); - -struct ShortEntryRecord { - uint32 hash; - uint32 pad1; - uint8 reuse_count; - uint8 refetch_count; - int8 state; // Current EntryState. - uint8 flags; - int32 key_len; - uint64 last_access_time; - uint32 long_hash[5]; - uint32 self_hash; -}; -COMPILE_ASSERT(sizeof(ShortEntryRecord) == 48, bad_ShortEntryRecord); - -} // namespace disk_cache - -#endif // NET_DISK_CACHE_V3_DISK_FORMAT_V3_H_ |