| Index: net/disk_cache/disk_format.h
|
| diff --git a/net/disk_cache/disk_format.h b/net/disk_cache/disk_format.h
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| deleted file mode 100644
|
| index 5d7597ab17d5c4c6e78c999b9ba02fd33cfb04f7..0000000000000000000000000000000000000000
|
| --- a/net/disk_cache/disk_format.h
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| +++ /dev/null
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| @@ -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
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| -// 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
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| -// 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
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| -// 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
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| -// to mark every entry that is created or modified. When the entry is closed,
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| -// and all the data can be trusted, the dirty flag is cleared from the entry.
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| -// 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.
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| -
|
| -#ifndef NET_DISK_CACHE_DISK_FORMAT_H_
|
| -#define NET_DISK_CACHE_DISK_FORMAT_H_
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| -
|
| -#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];
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| - int32 filled; // Flag to tell when we filled the cache.
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| - int32 sizes[5];
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| - CacheAddr heads[5];
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| - CacheAddr tails[5];
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| - CacheAddr transaction; // In-flight operation target.
|
| - int32 operation; // Actual in-flight operation.
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| - int32 operation_list; // In-flight operation list.
|
| - int32 pad2[7];
|
| -};
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| -
|
| -// Header for the master index file.
|
| -struct NET_EXPORT_PRIVATE IndexHeader {
|
| - IndexHeader();
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| -
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| - uint32 magic;
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| - uint32 version;
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| - int32 num_entries; // Number of entries currently stored.
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| - int32 num_bytes; // Total size of the stored data.
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| - int32 last_file; // Last external file created.
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| - int32 this_id; // Id for all entries being changed (dirty flag).
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| - CacheAddr stats; // Storage for usage data.
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| - int32 table_len; // Actual size of the table (0 == kIndexTablesize).
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| - int32 crash; // Signals a previous crash.
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| - int32 experiment; // Id of an ongoing test.
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| - uint64 create_time; // Creation time for this set of files.
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| - int32 pad[52];
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| - LruData lru; // Eviction control data.
|
| -};
|
| -
|
| -// The structure of the whole index file.
|
| -struct Index {
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| - IndexHeader header;
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| - 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
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| -// blocks (adding 256 bytes each time), up to 4 blocks (1024 - 32 - 1 chars).
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| -// After that point, the whole key will be stored as a data block or external
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| -// file.
|
| -struct EntryStore {
|
| - uint32 hash; // Full hash of the key.
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| - CacheAddr next; // Next entry with the same hash or bucket.
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| - CacheAddr rankings_node; // Rankings node for this entry.
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| - int32 reuse_count; // How often is this entry used.
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| - int32 refetch_count; // How often is this fetched from the net.
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| - int32 state; // Current state.
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| - uint64 creation_time;
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| - int32 key_len;
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| - CacheAddr long_key; // Optional address of a long key.
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| - int32 data_size[4]; // We can store up to 4 data streams for each
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| - CacheAddr data_addr[4]; // entry.
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| - uint32 flags; // Any combination of EntryFlags.
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| - int32 pad[4];
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| - uint32 self_hash; // The hash of EntryStore up to this point.
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| - 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,
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| - ENTRY_EVICTED, // The entry was recently evicted from the cache.
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| - 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.
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| - uint64 last_modified; // LRU info.
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| - CacheAddr next; // LRU list.
|
| - CacheAddr prev; // LRU list.
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| - CacheAddr contents; // Address of the EntryStore.
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| - 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_
|
|
|