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// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stdint.h>
#include <algorithm>
#include <map>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "base/feature_list.h"
#include "base/files/file.h"
#include "base/files/file_path.h"
#include "base/gtest_prod_util.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/scoped_refptr.h"
#include "base/strings/string_piece_forward.h"
#include "base/time/time.h"
#include "net/base/cache_type.h"
#include "net/base/net_errors.h"
#include "net/base/net_export.h"
#include "net/disk_cache/simple/simple_entry_format.h"
#include "net/disk_cache/simple/simple_file_tracker.h"
#include "net/disk_cache/simple/simple_histogram_enums.h"
namespace net {
class GrowableIOBuffer;
class IOBuffer;
FORWARD_DECLARE_TEST(DiskCacheBackendTest, SimpleCacheEnumerationLongKeys);
namespace disk_cache {
class BackendFileOperations;
class UnboundBackendFileOperations;
NET_EXPORT_PRIVATE extern const char kSimpleCacheFullPrefetchBytesParam[];
NET_EXPORT_PRIVATE extern const char
// Returns how large a file would get prefetched on reading the entry.
// If the experiment is disabled, returns 0.
NET_EXPORT_PRIVATE int GetSimpleCachePrefetchSize();
class SimpleSynchronousEntry;
struct RangeResult;
// This class handles the passing of data about the entry between
// SimpleEntryImplementation and SimpleSynchronousEntry and the computation of
// file offsets based on the data size for all streams.
class NET_EXPORT_PRIVATE SimpleEntryStat {
SimpleEntryStat(base::Time last_used,
base::Time last_modified,
const int32_t data_size[],
const int32_t sparse_data_size);
int GetOffsetInFile(size_t key_length, int offset, int stream_index) const;
int GetEOFOffsetInFile(size_t key_length, int stream_index) const;
int GetLastEOFOffsetInFile(size_t key_length, int file_index) const;
int64_t GetFileSize(size_t key_length, int file_index) const;
base::Time last_used() const { return last_used_; }
base::Time last_modified() const { return last_modified_; }
void set_last_used(base::Time last_used) { last_used_ = last_used; }
void set_last_modified(base::Time last_modified) {
last_modified_ = last_modified;
int32_t data_size(int stream_index) const { return data_size_[stream_index]; }
void set_data_size(int stream_index, int data_size) {
data_size_[stream_index] = data_size;
int32_t sparse_data_size() const { return sparse_data_size_; }
void set_sparse_data_size(int32_t sparse_data_size) {
sparse_data_size_ = sparse_data_size;
base::Time last_used_;
base::Time last_modified_;
int32_t data_size_[kSimpleEntryStreamCount];
int32_t sparse_data_size_;
struct SimpleStreamPrefetchData {
scoped_refptr<net::GrowableIOBuffer> data;
uint32_t stream_crc32;
struct SimpleEntryCreationResults {
explicit SimpleEntryCreationResults(SimpleEntryStat entry_stat);
raw_ptr<SimpleSynchronousEntry> sync_entry;
// This is set when `sync_entry` is null.
std::unique_ptr<UnboundBackendFileOperations> unbound_file_operations;
// Expectation is that [0] will always be filled in, but [1] might not be.
SimpleStreamPrefetchData stream_prefetch_data[2];
SimpleEntryStat entry_stat;
int32_t computed_trailer_prefetch_size = -1;
int result = net::OK;
bool created = false;
struct SimpleEntryCloseResults {
int32_t estimated_trailer_prefetch_size = -1;
// Worker thread interface to the very simple cache. This interface is not
// thread safe, and callers must ensure that it is only ever accessed from
// a single thread between synchronization points.
class SimpleSynchronousEntry {
struct CRCRecord {
CRCRecord(int index_p, bool has_crc32_p, uint32_t data_crc32_p);
int index;
bool has_crc32;
uint32_t data_crc32;
struct ReadRequest {
// Also sets request_update_crc to false.
ReadRequest(int index_p, int offset_p, int buf_len_p);
int index;
int offset;
int buf_len;
// Partial CRC of data immediately preceeding this read. Only relevant if
// request_update_crc is set.
uint32_t previous_crc32;
bool request_update_crc = false;
bool request_verify_crc; // only relevant if request_update_crc is set
struct ReadResult {
ReadResult() = default;
int result;
uint32_t updated_crc32; // only relevant if crc_updated set
bool crc_updated = false;
struct WriteRequest {
WriteRequest(int index_p,
int offset_p,
int buf_len_p,
uint32_t previous_crc32_p,
bool truncate_p,
bool doomed_p,
bool request_update_crc_p);
int index;
int offset;
int buf_len;
uint32_t previous_crc32;
bool truncate;
bool doomed;
bool request_update_crc;
struct WriteResult {
WriteResult() = default;
int result;
uint32_t updated_crc32; // only relevant if crc_updated set
bool crc_updated = false;
struct SparseRequest {
SparseRequest(int64_t sparse_offset_p, int buf_len_p);
int64_t sparse_offset;
int buf_len;
NET_EXPORT_PRIVATE SimpleSynchronousEntry(
net::CacheType cache_type,
const base::FilePath& path,
const std::string& key,
uint64_t entry_hash,
SimpleFileTracker* simple_file_tracker,
std::unique_ptr<UnboundBackendFileOperations> file_operations,
int32_t stream_0_size);
// Like Entry, the SimpleSynchronousEntry self releases when Close() is
// called, but sometimes temporary ones are kept in unique_ptr.
NET_EXPORT_PRIVATE ~SimpleSynchronousEntry();
// Opens a disk cache entry on disk. The |key| parameter is optional, if empty
// the operation may be slower. The |entry_hash| parameter is required.
static void OpenEntry(
net::CacheType cache_type,
const base::FilePath& path,
const std::string& key,
uint64_t entry_hash,
SimpleFileTracker* file_tracker,
std::unique_ptr<UnboundBackendFileOperations> file_operations,
int32_t trailer_prefetch_size,
SimpleEntryCreationResults* out_results);
static void CreateEntry(
net::CacheType cache_type,
const base::FilePath& path,
const std::string& key,
uint64_t entry_hash,
SimpleFileTracker* file_tracker,
std::unique_ptr<UnboundBackendFileOperations> file_operations,
SimpleEntryCreationResults* out_results);
static void OpenOrCreateEntry(
net::CacheType cache_type,
const base::FilePath& path,
const std::string& key,
uint64_t entry_hash,
OpenEntryIndexEnum index_state,
bool optimistic_create,
SimpleFileTracker* file_tracker,
std::unique_ptr<UnboundBackendFileOperations> file_operations,
int32_t trailer_prefetch_size,
SimpleEntryCreationResults* out_results);
// Renames the entry on the file system, making it no longer possible to open
// it again, but allowing operations to continue to be executed through that
// instance. The renamed file will be removed once the entry is closed.
// Returns a net error code.
int Doom();
// Deletes an entry from the file system. This variant should only be used
// if there is no actual open instance around, as it doesn't account for
// possibility of it having been renamed to a non-standard name.
static int DeleteEntryFiles(
const base::FilePath& path,
net::CacheType cache_type,
uint64_t entry_hash,
std::unique_ptr<UnboundBackendFileOperations> unbound_file_operations);
// Like |DeleteEntryFiles()| above, except that it truncates the entry files
// rather than deleting them. Used when dooming entries after the backend has
// shutdown. See implementation of |SimpleEntryImpl::DoomEntryInternal()| for
// more.
static int TruncateEntryFiles(
const base::FilePath& path,
uint64_t entry_hash,
std::unique_ptr<UnboundBackendFileOperations> file_operations);
// Like |DeleteEntryFiles()| above. Deletes all entries corresponding to the
// |key_hashes|. Succeeds only when all entries are deleted. Returns a net
// error code.
static int DeleteEntrySetFiles(
const std::vector<uint64_t>* key_hashes,
const base::FilePath& path,
std::unique_ptr<UnboundBackendFileOperations> unbound_file_operations);
// N.B. ReadData(), WriteData(), CheckEOFRecord(), ReadSparseData(),
// WriteSparseData() and Close() may block on IO.
// All of these methods will put the //net return value into |*out_result|.
void ReadData(const ReadRequest& in_entry_op,
SimpleEntryStat* entry_stat,
net::IOBuffer* out_buf,
ReadResult* out_result);
void WriteData(const WriteRequest& in_entry_op,
net::IOBuffer* in_buf,
SimpleEntryStat* out_entry_stat,
WriteResult* out_write_result);
int CheckEOFRecord(BackendFileOperations* file_operations,
base::File* file,
int stream_index,
const SimpleEntryStat& entry_stat,
uint32_t expected_crc32);
void ReadSparseData(const SparseRequest& in_entry_op,
net::IOBuffer* out_buf,
base::Time* out_last_used,
int* out_result);
void WriteSparseData(const SparseRequest& in_entry_op,
net::IOBuffer* in_buf,
uint64_t max_sparse_data_size,
SimpleEntryStat* out_entry_stat,
int* out_result);
void GetAvailableRange(const SparseRequest& in_entry_op,
RangeResult* out_result);
// Close all streams, and add write EOF records to streams indicated by the
// CRCRecord entries in |crc32s_to_write|.
void Close(const SimpleEntryStat& entry_stat,
std::unique_ptr<std::vector<CRCRecord>> crc32s_to_write,
net::GrowableIOBuffer* stream_0_data,
SimpleEntryCloseResults* out_results);
const base::FilePath& path() const { return path_; }
std::string key() const { return key_; }
const SimpleFileTracker::EntryFileKey& entry_file_key() const {
return entry_file_key_;
NET_EXPORT_PRIVATE base::FilePath GetFilenameForSubfile(
SimpleFileTracker::SubFile sub_file) const;
int32_t computed_trailer_prefetch_size() const {
return computed_trailer_prefetch_size_;
friend class SimpleFileTrackerTest;
class PrefetchData;
class ScopedFileOperationsBinding;
enum FileRequired {
struct SparseRange {
int64_t offset;
int64_t length;
uint32_t data_crc32;
int64_t file_offset;
bool operator<(const SparseRange& other) const {
return offset < other.offset;
// When opening an entry without knowing the key, the header must be read
// without knowing the size of the key. This is how much to read initially, to
// make it likely the entire key is read.
static const size_t kInitialHeaderRead = 64 * 1024;
// Tries to open one of the cache entry files. Succeeds if the open succeeds
// or if the file was not found and is allowed to be omitted if the
// corresponding stream is empty.
bool MaybeOpenFile(BackendFileOperations* file_operations,
int file_index,
base::File::Error* out_error);
// Creates one of the cache entry files if necessary. If the file is allowed
// to be omitted if the corresponding stream is empty, and if |file_required|
// is FILE_NOT_REQUIRED, then the file is not created; otherwise, it is.
bool MaybeCreateFile(BackendFileOperations* file_operations,
int file_index,
FileRequired file_required,
base::File::Error* out_error);
bool OpenFiles(BackendFileOperations* file_operations,
SimpleEntryStat* out_entry_stat);
bool CreateFiles(BackendFileOperations* file_operations,
SimpleEntryStat* out_entry_stat);
void CloseFile(BackendFileOperations* file_operations, int index);
void CloseFiles();
// Read the header and key at the beginning of the file, and validate that
// they are correct. If this entry was opened with a key, the key is checked
// for a match. If not, then the |key_| member is set based on the value in
// this header. Records histograms if any check is failed.
bool CheckHeaderAndKey(base::File* file, int file_index);
// Returns a net error, i.e. net::OK on success.
int InitializeForOpen(BackendFileOperations* file_operations,
SimpleEntryStat* out_entry_stat,
SimpleStreamPrefetchData stream_prefetch_data[2]);
// Writes the header and key to a newly-created stream file. |index| is the
// index of the stream. Returns true on success; returns false and failure.
bool InitializeCreatedFile(BackendFileOperations* file_operations, int index);
// Returns a net error, including net::OK on success and net::FILE_EXISTS
// when the entry already exists.
int InitializeForCreate(BackendFileOperations* file_operations,
SimpleEntryStat* out_entry_stat);
// Allocates and fills a buffer with stream 0 data in |stream_0_data|, then
// checks its crc32. May also optionally read in |stream_1_data| and its
// crc, but might decide not to.
int ReadAndValidateStream0AndMaybe1(
BackendFileOperations* file_operations,
int file_size,
SimpleEntryStat* out_entry_stat,
SimpleStreamPrefetchData stream_prefetch_data[2]);
// Reads the EOF record located at |file_offset| in file |file_index|,
// with |file_0_prefetch| potentially having prefetched file 0 content.
// Puts the result into |*eof_record| and sanity-checks it.
// Returns net status, and records any failures to UMA.
int GetEOFRecordData(base::File* file,
PrefetchData* prefetch_data,
int file_index,
int file_offset,
SimpleFileEOF* eof_record);
// Reads either from |file_0_prefetch| or |file|.
// Range-checks all the in-memory reads.
bool ReadFromFileOrPrefetched(base::File* file,
PrefetchData* prefetch_data,
int file_index,
int offset,
int size,
char* dest);
// Extracts out the payload of stream |stream_index|, reading either from
// |file_0_prefetch|, if available, or |file|. |entry_stat| will be used to
// determine file layout, though |extra_size| additional bytes will be read
// past the stream payload end.
// |*stream_data| will be pointed to a fresh buffer with the results,
// and |*out_crc32| will get the checksum, which will be verified against
// |eof_record|.
int PreReadStreamPayload(base::File* file,
PrefetchData* prefetch_data,
int stream_index,
int extra_size,
const SimpleEntryStat& entry_stat,
const SimpleFileEOF& eof_record,
SimpleStreamPrefetchData* out);
// Opens the sparse data file and scans it if it exists.
bool OpenSparseFileIfExists(BackendFileOperations* file_operations,
int32_t* out_sparse_data_size);
// Creates and initializes the sparse data file.
bool CreateSparseFile(BackendFileOperations* file_operations);
// Closes the sparse data file.
void CloseSparseFile(BackendFileOperations* file_operations);
// Writes the header to the (newly-created) sparse file.
bool InitializeSparseFile(base::File* file);
// Removes all but the header of the sparse file.
bool TruncateSparseFile(base::File* sparse_file);
// Scans the existing ranges in the sparse file. Populates |sparse_ranges_|
// and sets |*out_sparse_data_size| to the total size of all the ranges (not
// including headers).
bool ScanSparseFile(base::File* sparse_file, int32_t* out_sparse_data_size);
// Reads from a single sparse range. If asked to read the entire range, also
// verifies the CRC32.
bool ReadSparseRange(base::File* sparse_file,
const SparseRange* range,
int offset,
int len,
char* buf);
// Writes to a single (existing) sparse range. If asked to write the entire
// range, also updates the CRC32; otherwise, invalidates it.
bool WriteSparseRange(base::File* sparse_file,
SparseRange* range,
int offset,
int len,
const char* buf);
// Appends a new sparse range to the sparse data file.
bool AppendSparseRange(base::File* sparse_file,
int64_t offset,
int len,
const char* buf);
static int DeleteEntryFilesInternal(const base::FilePath& path,
net::CacheType cache_type,
uint64_t entry_hash,
BackendFileOperations* file_operations);
static bool DeleteFileForEntryHash(const base::FilePath& path,
uint64_t entry_hash,
int file_index,
BackendFileOperations* file_operations);
static bool DeleteFilesForEntryHash(const base::FilePath& path,
uint64_t entry_hash,
BackendFileOperations* file_operations);
static bool TruncateFilesForEntryHash(const base::FilePath& path,
uint64_t entry_hash,
BackendFileOperations* file_operations);
int DoomInternal(BackendFileOperations* file_operations);
base::FilePath GetFilenameFromFileIndex(int file_index) const;
bool sparse_file_open() const { return sparse_file_open_; }
const net::CacheType cache_type_;
const base::FilePath path_;
SimpleFileTracker::EntryFileKey entry_file_key_;
std::string key_;
bool have_open_files_ = false;
bool initialized_ = false;
// Normally false. This is set to true when an entry is opened without
// checking the file headers. Any subsequent read will perform the check
// before completing.
bool header_and_key_check_needed_[kSimpleEntryNormalFileCount] = {
raw_ptr<SimpleFileTracker> file_tracker_;
// An interface to allow file operations. This is in an "unbound" state
// because each operation can run on different sequence from each other.
// Each operation can convert this to a BackendFileOperations with calling
// Bind(), relying on that at most one operation runs at a time.
std::unique_ptr<UnboundBackendFileOperations> unbound_file_operations_;
// The number of trailing bytes in file 0 that we believe should be
// prefetched in order to read the EOF record and stream 0. This is
// a hint from the index and may not be exactly right. -1 if we
// don't have a hinted value.
int32_t trailer_prefetch_size_;
// The exact number of trailing bytes that were needed to read the
// EOF record and stream 0 when the entry was actually opened. This
// may be different from the trailer_prefetch_size_ hint and is
// propagated back to the index in order to optimize the next open.
int32_t computed_trailer_prefetch_size_ = -1;
// True if the corresponding stream is empty and therefore no on-disk file
// was created to store it.
bool empty_file_omitted_[kSimpleEntryNormalFileCount];
typedef std::map<int64_t, SparseRange> SparseRangeOffsetMap;
typedef SparseRangeOffsetMap::iterator SparseRangeIterator;
SparseRangeOffsetMap sparse_ranges_;
bool sparse_file_open_ = false;
// Offset of the end of the sparse file (where the next sparse range will be
// written).
int64_t sparse_tail_offset_;
} // namespace disk_cache