// 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_IMPL_H_
#define NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_IMPL_H_
#include <queue>
#include <string>
#include "base/files/file_path.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/threading/thread_checker.h"
#include "net/base/cache_type.h"
#include "net/base/net_export.h"
#include "net/base/net_log.h"
#include "net/disk_cache/disk_cache.h"
#include "net/disk_cache/simple/simple_entry_format.h"
#include "net/disk_cache/simple/simple_entry_operation.h"
namespace base {
class TaskRunner;
}
namespace net {
class GrowableIOBuffer;
class IOBuffer;
}
namespace disk_cache {
class SimpleBackendImpl;
class SimpleSynchronousEntry;
class SimpleEntryStat;
struct SimpleEntryCreationResults;
// SimpleEntryImpl is the IO thread interface to an entry in the very simple
// disk cache. It proxies for the SimpleSynchronousEntry, which performs IO
// on the worker thread.
class NET_EXPORT_PRIVATE SimpleEntryImpl : public Entry,
public base::RefCounted<SimpleEntryImpl>,
public base::SupportsWeakPtr<SimpleEntryImpl> {
friend class base::RefCounted<SimpleEntryImpl>;
public:
enum OperationsMode {
NON_OPTIMISTIC_OPERATIONS,
OPTIMISTIC_OPERATIONS,
};
SimpleEntryImpl(net::CacheType cache_type,
const base::FilePath& path,
uint64 entry_hash,
OperationsMode operations_mode,
SimpleBackendImpl* backend,
net::NetLog* net_log);
// Adds another reader/writer to this entry, if possible, returning |this| to
// |entry|.
int OpenEntry(Entry** entry, const CompletionCallback& callback);
// Creates this entry, if possible. Returns |this| to |entry|.
int CreateEntry(Entry** entry, const CompletionCallback& callback);
// Identical to Backend::Doom() except that it accepts a CompletionCallback.
int DoomEntry(const CompletionCallback& callback);
const std::string& key() const { return key_; }
uint64 entry_hash() const { return entry_hash_; }
void SetKey(const std::string& key);
// From Entry:
virtual void Doom() OVERRIDE;
virtual void Close() OVERRIDE;
virtual std::string GetKey() const OVERRIDE;
virtual base::Time GetLastUsed() const OVERRIDE;
virtual base::Time GetLastModified() const OVERRIDE;
virtual int32 GetDataSize(int index) const OVERRIDE;
virtual int ReadData(int stream_index,
int offset,
net::IOBuffer* buf,
int buf_len,
const CompletionCallback& callback) OVERRIDE;
virtual int WriteData(int stream_index,
int offset,
net::IOBuffer* buf,
int buf_len,
const CompletionCallback& callback,
bool truncate) OVERRIDE;
virtual int ReadSparseData(int64 offset,
net::IOBuffer* buf,
int buf_len,
const CompletionCallback& callback) OVERRIDE;
virtual int WriteSparseData(int64 offset,
net::IOBuffer* buf,
int buf_len,
const CompletionCallback& callback) OVERRIDE;
virtual int GetAvailableRange(int64 offset,
int len,
int64* start,
const CompletionCallback& callback) OVERRIDE;
virtual bool CouldBeSparse() const OVERRIDE;
virtual void CancelSparseIO() OVERRIDE;
virtual int ReadyForSparseIO(const CompletionCallback& callback) OVERRIDE;
private:
class ScopedOperationRunner;
friend class ScopedOperationRunner;
enum State {
// The state immediately after construction, but before |synchronous_entry_|
// has been assigned. This is the state at construction, and is the only
// legal state to destruct an entry in.
STATE_UNINITIALIZED,
// This entry is available for regular IO.
STATE_READY,
// IO is currently in flight, operations must wait for completion before
// launching.
STATE_IO_PENDING,
// A failure occurred in the current or previous operation. All operations
// after that must fail, until we receive a Close().
STATE_FAILURE,
};
// Used in histograms, please only add entries at the end.
enum CheckCrcResult {
CRC_CHECK_NEVER_READ_TO_END = 0,
CRC_CHECK_NOT_DONE = 1,
CRC_CHECK_DONE = 2,
CRC_CHECK_NEVER_READ_AT_ALL = 3,
CRC_CHECK_MAX = 4,
};
virtual ~SimpleEntryImpl();
// Must be used to invoke a client-provided completion callback for an
// operation initiated through the backend (e.g. create, open) so that clients
// don't get notified after they deleted the backend (which they would not
// expect).
void PostClientCallback(const CompletionCallback& callback, int result);
// Sets entry to STATE_UNINITIALIZED.
void MakeUninitialized();
// Return this entry to a user of the API in |out_entry|. Increments the user
// count.
void ReturnEntryToCaller(Entry** out_entry);
// Ensures that |this| is no longer referenced by our |backend_|, this
// guarantees that this entry cannot have OpenEntry/CreateEntry called again.
void RemoveSelfFromBackend();
// An error occured, and the SimpleSynchronousEntry should have Doomed
// us at this point. We need to remove |this| from the Backend and the
// index.
void MarkAsDoomed();
// Runs the next operation in the queue, if any and if there is no other
// operation running at the moment.
// WARNING: May delete |this|, as an operation in the queue can contain
// the last reference.
void RunNextOperationIfNeeded();
void OpenEntryInternal(bool have_index,
const CompletionCallback& callback,
Entry** out_entry);
void CreateEntryInternal(bool have_index,
const CompletionCallback& callback,
Entry** out_entry);
void CloseInternal();
void ReadDataInternal(int index,
int offset,
net::IOBuffer* buf,
int buf_len,
const CompletionCallback& callback);
void WriteDataInternal(int index,
int offset,
net::IOBuffer* buf,
int buf_len,
const CompletionCallback& callback,
bool truncate);
void ReadSparseDataInternal(int64 sparse_offset,
net::IOBuffer* buf,
int buf_len,
const CompletionCallback& callback);
void WriteSparseDataInternal(int64 sparse_offset,
net::IOBuffer* buf,
int buf_len,
const CompletionCallback& callback);
void GetAvailableRangeInternal(int64 sparse_offset,
int len,
int64* out_start,
const CompletionCallback& callback);
void DoomEntryInternal(const CompletionCallback& callback);
// Called after a SimpleSynchronousEntry has completed CreateEntry() or
// OpenEntry(). If |in_sync_entry| is non-NULL, creation is successful and we
// can return |this| SimpleEntryImpl to |*out_entry|. Runs
// |completion_callback|.
void CreationOperationComplete(
const CompletionCallback& completion_callback,
const base::TimeTicks& start_time,
scoped_ptr<SimpleEntryCreationResults> in_results,
Entry** out_entry,
net::NetLog::EventType end_event_type);
// Called after we've closed and written the EOF record to our entry. Until
// this point it hasn't been safe to OpenEntry() the same entry, but from this
// point it is.
void CloseOperationComplete();
// Internal utility method used by other completion methods. Calls
// |completion_callback| after updating state and dooming on errors.
void EntryOperationComplete(const CompletionCallback& completion_callback,
const SimpleEntryStat& entry_stat,
scoped_ptr<int> result);
// Called after an asynchronous read. Updates |crc32s_| if possible.
void ReadOperationComplete(int stream_index,
int offset,
const CompletionCallback& completion_callback,
scoped_ptr<uint32> read_crc32,
scoped_ptr<SimpleEntryStat> entry_stat,
scoped_ptr<int> result);
// Called after an asynchronous write completes.
void WriteOperationComplete(int stream_index,
const CompletionCallback& completion_callback,
scoped_ptr<SimpleEntryStat> entry_stat,
scoped_ptr<int> result);
void ReadSparseOperationComplete(
const CompletionCallback& completion_callback,
scoped_ptr<base::Time> last_used,
scoped_ptr<int> result);
void WriteSparseOperationComplete(
const CompletionCallback& completion_callback,
scoped_ptr<SimpleEntryStat> entry_stat,
scoped_ptr<int> result);
void GetAvailableRangeOperationComplete(
const CompletionCallback& completion_callback,
scoped_ptr<int> result);
// Called after an asynchronous doom completes.
void DoomOperationComplete(const CompletionCallback& callback,
State state_to_restore,
int result);
// Called after validating the checksums on an entry. Passes through the
// original result if successful, propogates the error if the checksum does
// not validate.
void ChecksumOperationComplete(
int stream_index,
int orig_result,
const CompletionCallback& completion_callback,
scoped_ptr<int> result);
// Called after completion of asynchronous IO and receiving file metadata for
// the entry in |entry_stat|. Updates the metadata in the entry and in the
// index to make them available on next IO operations.
void UpdateDataFromEntryStat(const SimpleEntryStat& entry_stat);
int64 GetDiskUsage() const;
// Used to report histograms.
void RecordReadIsParallelizable(const SimpleEntryOperation& operation) const;
void RecordWriteDependencyType(const SimpleEntryOperation& operation) const;
// Reads from the stream 0 data kept in memory.
int ReadStream0Data(net::IOBuffer* buf, int offset, int buf_len);
// Copies data from |buf| to the internal in-memory buffer for stream 0. If
// |truncate| is set to true, the target buffer will be truncated at |offset|
// + |buf_len| before being written.
int SetStream0Data(net::IOBuffer* buf,
int offset, int buf_len,
bool truncate);
// Updates |crc32s_| and |crc32s_end_offset_| for a write of the data in
// |buffer| on |stream_index|, starting at |offset| and of length |length|.
void AdvanceCrc(net::IOBuffer* buffer,
int offset,
int length,
int stream_index);
// All nonstatic SimpleEntryImpl methods should always be called on the IO
// thread, in all cases. |io_thread_checker_| documents and enforces this.
base::ThreadChecker io_thread_checker_;
const base::WeakPtr<SimpleBackendImpl> backend_;
const net::CacheType cache_type_;
const scoped_refptr<base::TaskRunner> worker_pool_;
const base::FilePath path_;
const uint64 entry_hash_;
const bool use_optimistic_operations_;
std::string key_;
// |last_used_|, |last_modified_| and |data_size_| are copied from the
// synchronous entry at the completion of each item of asynchronous IO.
// TODO(clamy): Unify last_used_ with data in the index.
base::Time last_used_;
base::Time last_modified_;
int32 data_size_[kSimpleEntryStreamCount];
int32 sparse_data_size_;
// Number of times this object has been returned from Backend::OpenEntry() and
// Backend::CreateEntry() without subsequent Entry::Close() calls. Used to
// notify the backend when this entry not used by any callers.
int open_count_;
bool doomed_;
State state_;
// When possible, we compute a crc32, for the data in each entry as we read or
// write. For each stream, |crc32s_[index]| is the crc32 of that stream from
// [0 .. |crc32s_end_offset_|). If |crc32s_end_offset_[index] == 0| then the
// value of |crc32s_[index]| is undefined.
int32 crc32s_end_offset_[kSimpleEntryStreamCount];
uint32 crc32s_[kSimpleEntryStreamCount];
// If |have_written_[index]| is true, we have written to the file that
// contains stream |index|.
bool have_written_[kSimpleEntryStreamCount];
// Reflects how much CRC checking has been done with the entry. This state is
// reported on closing each entry stream.
CheckCrcResult crc_check_state_[kSimpleEntryStreamCount];
// The |synchronous_entry_| is the worker thread object that performs IO on
// entries. It's owned by this SimpleEntryImpl whenever |executing_operation_|
// is false (i.e. when an operation is not pending on the worker pool). When
// an operation is being executed no one owns the synchronous entry. Therefore
// SimpleEntryImpl should not be deleted while an operation is running as that
// would leak the SimpleSynchronousEntry.
SimpleSynchronousEntry* synchronous_entry_;
std::queue<SimpleEntryOperation> pending_operations_;
net::BoundNetLog net_log_;
scoped_ptr<SimpleEntryOperation> executing_operation_;
// Unlike other streams, stream 0 data is read from the disk when the entry is
// opened, and then kept in memory. All read/write operations on stream 0
// affect the |stream_0_data_| buffer. When the entry is closed,
// |stream_0_data_| is written to the disk.
// Stream 0 is kept in memory because it is stored in the same file as stream
// 1 on disk, to reduce the number of file descriptors and save disk space.
// This strategy allows stream 1 to change size easily. Since stream 0 is only
// used to write HTTP headers, the memory consumption of keeping it in memory
// is acceptable.
scoped_refptr<net::GrowableIOBuffer> stream_0_data_;
};
} // namespace disk_cache
#endif // NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_IMPL_H_