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- // Copyright (c) 2013 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.
- #ifndef NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_FORMAT_H_
- #define NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_FORMAT_H_
- #include <stdint.h>
- #include "net/base/net_export.h"
- namespace disk_cache {
- const uint64_t kSimpleInitialMagicNumber = UINT64_C(0xfcfb6d1ba7725c30);
- const uint64_t kSimpleFinalMagicNumber = UINT64_C(0xf4fa6f45970d41d8);
- const uint64_t kSimpleSparseRangeMagicNumber = UINT64_C(0xeb97bf016553676b);
- // A file containing stream 0 and stream 1 in the Simple cache consists of:
- // - a SimpleFileHeader.
- // - the key.
- // - the data from stream 1.
- // - a SimpleFileEOF record for stream 1.
- // - the data from stream 0.
- // - (optionally) the SHA256 of the key.
- // - a SimpleFileEOF record for stream 0.
- //
- // Because stream 0 data (typically HTTP headers) is on the critical path of
- // requests, on open, the cache reads the end of the record and does not
- // read the SimpleFileHeader. If the key can be validated with a SHA256, then
- // the stream 0 data can be returned to the caller without reading the
- // SimpleFileHeader. If the key SHA256 is not present, then the cache must
- // read the SimpleFileHeader to confirm key equality.
- // A file containing stream 2 in the Simple cache consists of:
- // - a SimpleFileHeader.
- // - the key.
- // - the data.
- // - at the end, a SimpleFileEOF record.
- // This is the number of files we can use for representing normal/dense streams.
- static const int kSimpleEntryNormalFileCount = 2;
- static const int kSimpleEntryStreamCount = 3;
- // Total # of files name we can potentially use; this includes both normal
- // API and sparse streams.
- static const int kSimpleEntryTotalFileCount = kSimpleEntryNormalFileCount + 1;
- // Note that stream 0/stream 1 files rely on the footer to verify the entry,
- // so if the format changes, it's insufficient to change the version here;
- // likely the EOF magic should be updated as well.
- struct NET_EXPORT_PRIVATE SimpleFileHeader {
- SimpleFileHeader();
- uint64_t initial_magic_number;
- uint32_t version;
- uint32_t key_length;
- uint32_t key_hash;
- };
- struct NET_EXPORT_PRIVATE SimpleFileEOF {
- enum Flags {
- FLAG_HAS_CRC32 = (1U << 0),
- FLAG_HAS_KEY_SHA256 = (1U << 1), // Preceding the record if present.
- };
- SimpleFileEOF();
- uint64_t final_magic_number;
- uint32_t flags;
- uint32_t data_crc32;
- // |stream_size| is only used in the EOF record for stream 0.
- uint32_t stream_size;
- };
- struct SimpleFileSparseRangeHeader {
- SimpleFileSparseRangeHeader();
- uint64_t sparse_range_magic_number;
- int64_t offset;
- int64_t length;
- uint32_t data_crc32;
- };
- } // namespace disk_cache
- #endif // NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_FORMAT_H_
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