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| 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
| 4 | 4 |
| 5 // The cache is stored on disk as a collection of block-files, plus an index | 5 // The cache is stored on disk as a collection of block-files, plus an index |
| 6 // plus a collection of external files. | 6 // plus a collection of external files. |
| 7 // | 7 // |
| 8 // Any data blob bigger than kMaxBlockSize (disk_cache/addr.h) will be stored in | 8 // Any data blob bigger than kMaxBlockSize (disk_cache/addr.h) will be stored in |
| 9 // a separate file named f_xxx where x is a hexadecimal number. Shorter data | 9 // a separate file named f_xxx where x is a hexadecimal number. Shorter data |
| 10 // will be stored as a series of blocks on a block-file. In any case, CacheAddr | 10 // will be stored as a series of blocks on a block-file. In any case, CacheAddr |
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| 38 // time) when the process dies in the middle of an update. There are dedicated | 38 // time) when the process dies in the middle of an update. There are dedicated |
| 39 // backup files for cache bitmaps, used to detect entries out of date. | 39 // backup files for cache bitmaps, used to detect entries out of date. |
| 40 // | 40 // |
| 41 // Although cache files are to be consumed on the same machine that creates | 41 // Although cache files are to be consumed on the same machine that creates |
| 42 // them, if files are to be moved accross machines, little endian storage is | 42 // them, if files are to be moved accross machines, little endian storage is |
| 43 // assumed. | 43 // assumed. |
| 44 | 44 |
| 45 #ifndef NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_V3_H_ | 45 #ifndef NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_V3_H_ |
| 46 #define NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_V3_H_ | 46 #define NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_V3_H_ |
| 47 | 47 |
| 48 #include "base/basictypes.h" | 48 #include <stdint.h> |
| 49 |
| 49 #include "net/disk_cache/blockfile/disk_format_base.h" | 50 #include "net/disk_cache/blockfile/disk_format_base.h" |
| 50 | 51 |
| 51 namespace disk_cache { | 52 namespace disk_cache { |
| 52 | 53 |
| 53 const int kBaseTableLen = 0x400; | 54 const int kBaseTableLen = 0x400; |
| 54 const uint32 kIndexMagicV3 = 0xC103CAC3; | 55 const uint32_t kIndexMagicV3 = 0xC103CAC3; |
| 55 const uint32 kVersion3 = 0x30000; // Version 3.0. | 56 const uint32_t kVersion3 = 0x30000; // Version 3.0. |
| 56 | 57 |
| 57 // Flags for a given cache. | 58 // Flags for a given cache. |
| 58 enum CacheFlags { | 59 enum CacheFlags { |
| 59 SMALL_CACHE = 1 << 0, // See IndexCell. | 60 SMALL_CACHE = 1 << 0, // See IndexCell. |
| 60 CACHE_EVICTION_2 = 1 << 1, // Keep multiple lists for eviction. | 61 CACHE_EVICTION_2 = 1 << 1, // Keep multiple lists for eviction. |
| 61 CACHE_EVICTED = 1 << 2 // Already evicted at least one entry. | 62 CACHE_EVICTED = 1 << 2 // Already evicted at least one entry. |
| 62 }; | 63 }; |
| 63 | 64 |
| 64 // Header for the master index file. | 65 // Header for the master index file. |
| 65 struct IndexHeaderV3 { | 66 struct IndexHeaderV3 { |
| 66 uint32 magic; | 67 uint32_t magic; |
| 67 uint32 version; | 68 uint32_t version; |
| 68 int32 num_entries; // Number of entries currently stored. | 69 int32_t num_entries; // Number of entries currently stored. |
| 69 int32 num_bytes; // Total size of the stored data. | 70 int32_t num_bytes; // Total size of the stored data. |
| 70 int32 last_file; // Last external file created. | 71 int32_t last_file; // Last external file created. |
| 71 int32 reserved1; | 72 int32_t reserved1; |
| 72 CacheAddr stats; // Storage for usage data. | 73 CacheAddr stats; // Storage for usage data. |
| 73 int32 table_len; // Actual size of the table. | 74 int32_t table_len; // Actual size of the table. |
| 74 int32 crash; // Signals a previous crash. | 75 int32_t crash; // Signals a previous crash. |
| 75 int32 experiment; // Id of an ongoing test. | 76 int32_t experiment; // Id of an ongoing test. |
| 76 int32 max_bytes; // Total maximum size of the stored data. | 77 int32_t max_bytes; // Total maximum size of the stored data. |
| 77 uint32 flags; | 78 uint32_t flags; |
| 78 int32 used_cells; | 79 int32_t used_cells; |
| 79 int32 max_bucket; | 80 int32_t max_bucket; |
| 80 uint64 create_time; // Creation time for this set of files. | 81 uint64_t create_time; // Creation time for this set of files. |
| 81 uint64 base_time; // Current base for timestamps. | 82 uint64_t base_time; // Current base for timestamps. |
| 82 uint64 old_time; // Previous time used for timestamps. | 83 uint64_t old_time; // Previous time used for timestamps. |
| 83 int32 max_block_file; | 84 int32_t max_block_file; |
| 84 int32 num_no_use_entries; | 85 int32_t num_no_use_entries; |
| 85 int32 num_low_use_entries; | 86 int32_t num_low_use_entries; |
| 86 int32 num_high_use_entries; | 87 int32_t num_high_use_entries; |
| 87 int32 reserved; | 88 int32_t reserved; |
| 88 int32 num_evicted_entries; | 89 int32_t num_evicted_entries; |
| 89 int32 pad[6]; | 90 int32_t pad[6]; |
| 90 }; | 91 }; |
| 91 | 92 |
| 92 const int kBaseBitmapBytes = 3968; | 93 const int kBaseBitmapBytes = 3968; |
| 93 // The IndexBitmap is directly saved to a file named index. The file grows in | 94 // The IndexBitmap is directly saved to a file named index. The file grows in |
| 94 // page increments (4096 bytes), but all bits don't have to be in use at any | 95 // page increments (4096 bytes), but all bits don't have to be in use at any |
| 95 // given time. The required file size can be computed from header.table_len. | 96 // given time. The required file size can be computed from header.table_len. |
| 96 struct IndexBitmap { | 97 struct IndexBitmap { |
| 97 IndexHeaderV3 header; | 98 IndexHeaderV3 header; |
| 98 uint32 bitmap[kBaseBitmapBytes / 4]; // First page of the bitmap. | 99 uint32_t bitmap[kBaseBitmapBytes / 4]; // First page of the bitmap. |
| 99 }; | 100 }; |
| 100 static_assert(sizeof(IndexBitmap) == 4096, "bad IndexHeader"); | 101 static_assert(sizeof(IndexBitmap) == 4096, "bad IndexHeader"); |
| 101 | 102 |
| 102 // Possible states for a given entry. | 103 // Possible states for a given entry. |
| 103 enum EntryState { | 104 enum EntryState { |
| 104 ENTRY_FREE = 0, // Available slot. | 105 ENTRY_FREE = 0, // Available slot. |
| 105 ENTRY_NEW, // The entry is being created. | 106 ENTRY_NEW, // The entry is being created. |
| 106 ENTRY_OPEN, // The entry is being accessed. | 107 ENTRY_OPEN, // The entry is being accessed. |
| 107 ENTRY_MODIFIED, // The entry is being modified. | 108 ENTRY_MODIFIED, // The entry is being modified. |
| 108 ENTRY_DELETED, // The entry is being deleted. | 109 ENTRY_DELETED, // The entry is being deleted. |
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| 173 // | 174 // |
| 174 // For example, a small table may store something like 0x1234 as the location | 175 // For example, a small table may store something like 0x1234 as the location |
| 175 // field. That means it stores the entry number 0x1234. If that record belongs | 176 // field. That means it stores the entry number 0x1234. If that record belongs |
| 176 // to a deleted entry, the regular cache address may look something like | 177 // to a deleted entry, the regular cache address may look something like |
| 177 // BLOCK_EVICTED + 1 block + file number 6 + entry number 0x1234 | 178 // BLOCK_EVICTED + 1 block + file number 6 + entry number 0x1234 |
| 178 // so Addr = 0xf0061234 | 179 // so Addr = 0xf0061234 |
| 179 // | 180 // |
| 180 // If that same Addr is stored on a large table, the location field would be | 181 // If that same Addr is stored on a large table, the location field would be |
| 181 // 0x61234 | 182 // 0x61234 |
| 182 | 183 |
| 183 uint64 first_part; | 184 uint64_t first_part; |
| 184 uint8 last_part; | 185 uint8_t last_part; |
| 185 }; | 186 }; |
| 186 static_assert(sizeof(IndexCell) == 9, "bad IndexCell"); | 187 static_assert(sizeof(IndexCell) == 9, "bad IndexCell"); |
| 187 | 188 |
| 188 const int kCellsPerBucket = 4; | 189 const int kCellsPerBucket = 4; |
| 189 struct IndexBucket { | 190 struct IndexBucket { |
| 190 IndexCell cells[kCellsPerBucket]; | 191 IndexCell cells[kCellsPerBucket]; |
| 191 int32 next; | 192 int32_t next; |
| 192 uint32 hash; // The high order byte is reserved (should be zero). | 193 uint32_t hash; // The high order byte is reserved (should be zero). |
| 193 }; | 194 }; |
| 194 static_assert(sizeof(IndexBucket) == 44, "bad IndexBucket"); | 195 static_assert(sizeof(IndexBucket) == 44, "bad IndexBucket"); |
| 195 const int kBytesPerCell = 44 / kCellsPerBucket; | 196 const int kBytesPerCell = 44 / kCellsPerBucket; |
| 196 | 197 |
| 197 // The main cache index. Backed by a file named index_tb1. | 198 // The main cache index. Backed by a file named index_tb1. |
| 198 // The extra table (index_tb2) has a similar format, but different size. | 199 // The extra table (index_tb2) has a similar format, but different size. |
| 199 struct Index { | 200 struct Index { |
| 200 // Default size. Actual size controlled by header.table_len. | 201 // Default size. Actual size controlled by header.table_len. |
| 201 IndexBucket table[kBaseTableLen / kCellsPerBucket]; | 202 IndexBucket table[kBaseTableLen / kCellsPerBucket]; |
| 202 }; | 203 }; |
| 203 #pragma pack(pop) | 204 #pragma pack(pop) |
| 204 | 205 |
| 205 // Flags that can be applied to an entry. | 206 // Flags that can be applied to an entry. |
| 206 enum EntryFlags { | 207 enum EntryFlags { |
| 207 PARENT_ENTRY = 1, // This entry has children (sparse) entries. | 208 PARENT_ENTRY = 1, // This entry has children (sparse) entries. |
| 208 CHILD_ENTRY = 1 << 1 // Child entry that stores sparse data. | 209 CHILD_ENTRY = 1 << 1 // Child entry that stores sparse data. |
| 209 }; | 210 }; |
| 210 | 211 |
| 211 struct EntryRecord { | 212 struct EntryRecord { |
| 212 uint32 hash; | 213 uint32_t hash; |
| 213 uint32 pad1; | 214 uint32_t pad1; |
| 214 uint8 reuse_count; | 215 uint8_t reuse_count; |
| 215 uint8 refetch_count; | 216 uint8_t refetch_count; |
| 216 int8 state; // Current EntryState. | 217 int8_t state; // Current EntryState. |
| 217 uint8 flags; // Any combination of EntryFlags. | 218 uint8_t flags; // Any combination of EntryFlags. |
| 218 int32 key_len; | 219 int32_t key_len; |
| 219 int32 data_size[4]; // We can store up to 4 data streams for each | 220 int32_t data_size[4]; // We can store up to 4 data streams for each |
| 220 CacheAddr data_addr[4]; // entry. | 221 CacheAddr data_addr[4]; // entry. |
| 221 uint32 data_hash[4]; | 222 uint32_t data_hash[4]; |
| 222 uint64 creation_time; | 223 uint64_t creation_time; |
| 223 uint64 last_modified_time; | 224 uint64_t last_modified_time; |
| 224 uint64 last_access_time; | 225 uint64_t last_access_time; |
| 225 int32 pad[3]; | 226 int32_t pad[3]; |
| 226 uint32 self_hash; | 227 uint32_t self_hash; |
| 227 }; | 228 }; |
| 228 static_assert(sizeof(EntryRecord) == 104, "bad EntryRecord"); | 229 static_assert(sizeof(EntryRecord) == 104, "bad EntryRecord"); |
| 229 | 230 |
| 230 struct ShortEntryRecord { | 231 struct ShortEntryRecord { |
| 231 uint32 hash; | 232 uint32_t hash; |
| 232 uint32 pad1; | 233 uint32_t pad1; |
| 233 uint8 reuse_count; | 234 uint8_t reuse_count; |
| 234 uint8 refetch_count; | 235 uint8_t refetch_count; |
| 235 int8 state; // Current EntryState. | 236 int8_t state; // Current EntryState. |
| 236 uint8 flags; | 237 uint8_t flags; |
| 237 int32 key_len; | 238 int32_t key_len; |
| 238 uint64 last_access_time; | 239 uint64_t last_access_time; |
| 239 uint32 long_hash[5]; | 240 uint32_t long_hash[5]; |
| 240 uint32 self_hash; | 241 uint32_t self_hash; |
| 241 }; | 242 }; |
| 242 static_assert(sizeof(ShortEntryRecord) == 48, "bad ShortEntryRecord"); | 243 static_assert(sizeof(ShortEntryRecord) == 48, "bad ShortEntryRecord"); |
| 243 | 244 |
| 244 } // namespace disk_cache | 245 } // namespace disk_cache |
| 245 | 246 |
| 246 #endif // NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_V3_H_ | 247 #endif // NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_V3_H_ |
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