Index: net/disk_cache/blockfile/disk_format_base.h |
diff --git a/net/disk_cache/blockfile/disk_format_base.h b/net/disk_cache/blockfile/disk_format_base.h |
deleted file mode 100644 |
index 1c49a48e737f7f5ee93cf75dc612f2010db89f1a..0000000000000000000000000000000000000000 |
--- a/net/disk_cache/blockfile/disk_format_base.h |
+++ /dev/null |
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-// 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. |
- |
-// For a general description of the files used by the cache see file_format.h. |
-// |
-// A block file is a file designed to store blocks of data of a given size. It |
-// is able to store data that spans from one to four consecutive "blocks", and |
-// it grows as needed to store up to approximately 65000 blocks. It has a fixed |
-// size header used for book keeping such as tracking free of blocks on the |
-// file. For example, a block-file for 1KB blocks will grow from 8KB when |
-// totally empty to about 64MB when completely full. At that point, data blocks |
-// of 1KB will be stored on a second block file that will store the next set of |
-// 65000 blocks. The first file contains the number of the second file, and the |
-// second file contains the number of a third file, created when the second file |
-// reaches its limit. It is important to remember that no matter how long the |
-// chain of files is, any given block can be located directly by its address, |
-// which contains the file number and starting block inside the file. |
- |
-#ifndef NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_BASE_H_ |
-#define NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_BASE_H_ |
- |
-#include "base/basictypes.h" |
-#include "net/base/net_export.h" |
- |
-namespace disk_cache { |
- |
-typedef uint32 CacheAddr; |
- |
-const uint32 kBlockVersion2 = 0x20000; // Version 2.0. |
-const uint32 kBlockCurrentVersion = 0x30000; // Version 3.0. |
- |
-const uint32 kBlockMagic = 0xC104CAC3; |
-const int kBlockHeaderSize = 8192; // Two pages: almost 64k entries |
-const int kMaxBlocks = (kBlockHeaderSize - 80) * 8; |
-const int kNumExtraBlocks = 1024; // How fast files grow. |
- |
-// Bitmap to track used blocks on a block-file. |
-typedef uint32 AllocBitmap[kMaxBlocks / 32]; |
- |
-// A block-file is the file used to store information in blocks (could be |
-// EntryStore blocks, RankingsNode blocks or user-data blocks). |
-// We store entries that can expand for up to 4 consecutive blocks, and keep |
-// counters of the number of blocks available for each type of entry. For |
-// instance, an entry of 3 blocks is an entry of type 3. We also keep track of |
-// where did we find the last entry of that type (to avoid searching the bitmap |
-// from the beginning every time). |
-// This Structure is the header of a block-file: |
-struct BlockFileHeader { |
- uint32 magic; |
- uint32 version; |
- int16 this_file; // Index of this file. |
- int16 next_file; // Next file when this one is full. |
- int32 entry_size; // Size of the blocks of this file. |
- int32 num_entries; // Number of stored entries. |
- int32 max_entries; // Current maximum number of entries. |
- int32 empty[4]; // Counters of empty entries for each type. |
- int32 hints[4]; // Last used position for each entry type. |
- volatile int32 updating; // Keep track of updates to the header. |
- int32 user[5]; |
- AllocBitmap allocation_map; |
-}; |
- |
-static_assert(sizeof(BlockFileHeader) == kBlockHeaderSize, "bad header"); |
- |
-// Sparse data support: |
-// We keep a two level hierarchy to enable sparse data for an entry: the first |
-// level consists of using separate "child" entries to store ranges of 1 MB, |
-// and the second level stores blocks of 1 KB inside each child entry. |
-// |
-// Whenever we need to access a particular sparse offset, we first locate the |
-// child entry that stores that offset, so we discard the 20 least significant |
-// bits of the offset, and end up with the child id. For instance, the child id |
-// to store the first megabyte is 0, and the child that should store offset |
-// 0x410000 has an id of 4. |
-// |
-// The child entry is stored the same way as any other entry, so it also has a |
-// name (key). The key includes a signature to be able to identify children |
-// created for different generations of the same resource. In other words, given |
-// that a given sparse entry can have a large number of child entries, and the |
-// resource can be invalidated and replaced with a new version at any time, it |
-// is important to be sure that a given child actually belongs to certain entry. |
-// |
-// The full name of a child entry is composed with a prefix ("Range_"), and two |
-// hexadecimal 64-bit numbers at the end, separated by semicolons. The first |
-// number is the signature of the parent key, and the second number is the child |
-// id as described previously. The signature itself is also stored internally by |
-// the child and the parent entries. For example, a sparse entry with a key of |
-// "sparse entry name", and a signature of 0x052AF76, may have a child entry |
-// named "Range_sparse entry name:052af76:4", which stores data in the range |
-// 0x400000 to 0x4FFFFF. |
-// |
-// Each child entry keeps track of all the 1 KB blocks that have been written |
-// to the entry, but being a regular entry, it will happily return zeros for any |
-// read that spans data not written before. The actual sparse data is stored in |
-// one of the data streams of the child entry (at index 1), while the control |
-// information is stored in another stream (at index 2), both by parents and |
-// the children. |
- |
-// This structure contains the control information for parent and child entries. |
-// It is stored at offset 0 of the data stream with index 2. |
-// It is possible to write to a child entry in a way that causes the last block |
-// to be only partialy filled. In that case, last_block and last_block_len will |
-// keep track of that block. |
-struct SparseHeader { |
- int64 signature; // The parent and children signature. |
- uint32 magic; // Structure identifier (equal to kIndexMagic). |
- int32 parent_key_len; // Key length for the parent entry. |
- int32 last_block; // Index of the last written block. |
- int32 last_block_len; // Lenght of the last written block. |
- int32 dummy[10]; |
-}; |
- |
-// The SparseHeader will be followed by a bitmap, as described by this |
-// structure. |
-struct SparseData { |
- SparseHeader header; |
- uint32 bitmap[32]; // Bitmap representation of known children (if this |
- // is a parent entry), or used blocks (for child |
- // entries. The size is fixed for child entries but |
- // not for parents; it can be as small as 4 bytes |
- // and as large as 8 KB. |
-}; |
- |
-// The number of blocks stored by a child entry. |
-const int kNumSparseBits = 1024; |
-static_assert(sizeof(SparseData) == sizeof(SparseHeader) + kNumSparseBits / 8, |
- "invalid SparseData bitmap"); |
- |
-} // namespace disk_cache |
- |
-#endif // NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_BASE_H_ |