// Copyright (c) 2012 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.
// See net/disk_cache/disk_cache.h for the public interface of the cache.
#ifndef NET_DISK_CACHE_BLOCKFILE_BACKEND_IMPL_V3_H_
#define NET_DISK_CACHE_BLOCKFILE_BACKEND_IMPL_V3_H_
#include "base/containers/hash_tables.h"
#include "base/files/file_path.h"
#include "base/timer/timer.h"
#include "net/disk_cache/blockfile/block_bitmaps_v3.h"
#include "net/disk_cache/blockfile/block_files.h"
#include "net/disk_cache/blockfile/eviction_v3.h"
#include "net/disk_cache/blockfile/index_table_v3.h"
#include "net/disk_cache/blockfile/stats.h"
#include "net/disk_cache/blockfile/stress_support.h"
#include "net/disk_cache/blockfile/trace.h"
#include "net/disk_cache/disk_cache.h"
namespace net {
class NetLog;
} // namespace net
namespace disk_cache {
class EntryImplV3;
// This class implements the Backend interface. An object of this
// class handles the operations of the cache for a particular profile.
class NET_EXPORT_PRIVATE BackendImplV3 : public Backend {
public:
enum BackendFlags {
MAX_SIZE = 1 << 1, // A maximum size was provided.
UNIT_TEST_MODE = 1 << 2, // We are modifying the behavior for testing.
UPGRADE_MODE = 1 << 3, // This is the upgrade tool (dump).
EVICTION_V2 = 1 << 4, // Use of new eviction was specified.
BASIC_UNIT_TEST = 1 << 5, // Identifies almost all unit tests.
NO_LOAD_PROTECTION = 1 << 6, // Don't act conservatively under load.
NO_BUFFERING = 1 << 7, // Disable extended IO buffering.
NO_CLEAN_ON_EXIT = 1 << 8 // Avoid saving data at exit time.
};
BackendImplV3(const base::FilePath& path,
base::MessageLoopProxy* cache_thread,
net::NetLog* net_log);
virtual ~BackendImplV3();
// Performs general initialization for this current instance of the cache.
int Init(const CompletionCallback& callback);
// Same behavior as OpenNextEntry but walks the list from back to front.
int OpenPrevEntry(void** iter, Entry** prev_entry,
const CompletionCallback& callback);
// Sets the maximum size for the total amount of data stored by this instance.
bool SetMaxSize(int max_bytes);
// Sets the cache type for this backend.
void SetType(net::CacheType type);
// Creates a new storage block of size block_count.
bool CreateBlock(FileType block_type, int block_count,
Addr* block_address);
// Updates the ranking information for an entry.
void UpdateRank(EntryImplV3* entry, bool modified);
// Permanently deletes an entry, but still keeps track of it.
void InternalDoomEntry(EntryImplV3* entry);
// This method must be called when an entry is released for the last time, so
// the entry should not be used anymore. |address| is the cache address of the
// entry.
void OnEntryDestroyBegin(Addr address);
// This method must be called after all resources for an entry have been
// released.
void OnEntryDestroyEnd();
// If the |address| corresponds to an open entry, returns a pointer to that
// entry, otherwise returns NULL. Note that this method does not increase the
// ref counter for the entry.
EntryImplV3* GetOpenEntry(Addr address) const;
// Returns the id being used on this run of the cache.
int32 GetCurrentEntryId() const;
// Returns the maximum size for a file to reside on the cache.
int MaxFileSize() const;
// A user data block is being created, extended or truncated.
void ModifyStorageSize(int32 old_size, int32 new_size);
// Logs requests that are denied due to being too big.
void TooMuchStorageRequested(int32 size);
// Returns true if a temporary buffer is allowed to be extended.
bool IsAllocAllowed(int current_size, int new_size);
// Tracks the release of |size| bytes by an entry buffer.
void BufferDeleted(int size);
// Only intended for testing the two previous methods.
int GetTotalBuffersSize() const {
return buffer_bytes_;
}
// Returns true if this instance seems to be under heavy load.
bool IsLoaded() const;
// Returns the full histogram name, for the given base |name| and the current
// cache type. The name will be "DiskCache3.name_type".
std::string HistogramName(const char* name) const;
net::CacheType cache_type() const {
return cache_type_;
}
bool read_only() const {
return read_only_;
}
// Returns a weak pointer to this object.
base::WeakPtr<BackendImplV3> GetWeakPtr();
// Returns true if we should send histograms for this user again. The caller
// must call this function only once per run (because it returns always the
// same thing on a given run).
bool ShouldReportAgain();
// Reports some data when we filled up the cache.
void FirstEviction();
// Called when an interesting event should be logged (counted).
void OnEvent(Stats::Counters an_event);
// Keeps track of payload access (doesn't include metadata).
void OnRead(int bytes);
void OnWrite(int bytes);
// Timer callback to calculate usage statistics and perform backups.
void OnTimerTick();
// Sets internal parameters to enable unit testing mode.
void SetUnitTestMode();
// Sets internal parameters to enable upgrade mode (for internal tools).
void SetUpgradeMode();
// Sets the eviction algorithm to version 2.
void SetNewEviction();
// Sets an explicit set of BackendFlags.
void SetFlags(uint32 flags);
// Sends a dummy operation through the operation queue, for unit tests.
int FlushQueueForTest(const CompletionCallback& callback);
// Trims an entry (all if |empty| is true) from the list of deleted
// entries. This method should be called directly on the cache thread.
void TrimForTest(bool empty);
// Trims an entry (all if |empty| is true) from the list of deleted
// entries. This method should be called directly on the cache thread.
void TrimDeletedListForTest(bool empty);
// Performs a simple self-check, and returns the number of dirty items
// or an error code (negative value).
int SelfCheck();
// Backend implementation.
virtual net::CacheType GetCacheType() const OVERRIDE;
virtual int32 GetEntryCount() const OVERRIDE;
virtual int OpenEntry(const std::string& key, Entry** entry,
const CompletionCallback& callback) OVERRIDE;
virtual int CreateEntry(const std::string& key, Entry** entry,
const CompletionCallback& callback) OVERRIDE;
virtual int DoomEntry(const std::string& key,
const CompletionCallback& callback) OVERRIDE;
virtual int DoomAllEntries(const CompletionCallback& callback) OVERRIDE;
virtual int DoomEntriesBetween(base::Time initial_time,
base::Time end_time,
const CompletionCallback& callback) OVERRIDE;
virtual int DoomEntriesSince(base::Time initial_time,
const CompletionCallback& callback) OVERRIDE;
virtual int OpenNextEntry(void** iter, Entry** next_entry,
const CompletionCallback& callback) OVERRIDE;
virtual void EndEnumeration(void** iter) OVERRIDE;
virtual void GetStats(StatsItems* stats) OVERRIDE;
virtual void OnExternalCacheHit(const std::string& key) OVERRIDE;
private:
friend class EvictionV3;
typedef base::hash_map<CacheAddr, EntryImplV3*> EntriesMap;
class Worker;
void AdjustMaxCacheSize();
bool InitStats(void* stats_data);
void StoreStats();
// Deletes the cache and starts again.
void RestartCache(bool failure);
void PrepareForRestart();
// Performs final cleanup.
void CleanupCache();
// Creates a new entry object. Returns zero on success, or a disk_cache error
// on failure.
int NewEntry(Addr address, EntryImplV3** entry);
// Opens the next or previous entry on a cache iteration.
int OpenFollowingEntry(bool forward, void** iter, Entry** next_entry,
const CompletionCallback& callback);
// Handles the used storage count.
void AddStorageSize(int32 bytes);
void SubstractStorageSize(int32 bytes);
// Update the number of referenced cache entries.
void IncreaseNumRefs();
void DecreaseNumRefs();
void IncreaseNumEntries();
void DecreaseNumEntries();
// Dumps current cache statistics to the log.
void LogStats();
// Send UMA stats.
void ReportStats();
// Reports an uncommon, recoverable error.
void ReportError(int error);
// Performs basic checks on the index file. Returns false on failure.
bool CheckIndex();
// Part of the self test. Returns the number or dirty entries, or an error.
int CheckAllEntries();
// Part of the self test. Returns false if the entry is corrupt.
bool CheckEntry(EntryImplV3* cache_entry);
// Returns the maximum total memory for the memory buffers.
int MaxBuffersSize();
IndexTable index_;
base::FilePath path_; // Path to the folder used as backing storage.
BlockBitmaps block_files_;
int32 max_size_; // Maximum data size for this instance.
EvictionV3 eviction_; // Handler of the eviction algorithm.
EntriesMap open_entries_;
int num_refs_; // Number of referenced cache entries.
int max_refs_; // Max number of referenced cache entries.
int entry_count_; // Number of entries accessed lately.
int byte_count_; // Number of bytes read/written lately.
int buffer_bytes_; // Total size of the temporary entries' buffers.
int up_ticks_; // The number of timer ticks received (OnTimerTick).
net::CacheType cache_type_;
int uma_report_; // Controls transmission of UMA data.
uint32 user_flags_; // Flags set by the user.
bool init_; // controls the initialization of the system.
bool restarted_;
bool read_only_; // Prevents updates of the rankings data (used by tools).
bool disabled_;
bool lru_eviction_; // What eviction algorithm should be used.
bool first_timer_; // True if the timer has not been called.
bool user_load_; // True if we see a high load coming from the caller.
net::NetLog* net_log_;
Stats stats_; // Usage statistics.
scoped_ptr<base::RepeatingTimer<BackendImplV3> > timer_; // Usage timer.
scoped_refptr<TraceObject> trace_object_; // Initializes internal tracing.
base::WeakPtrFactory<BackendImplV3> ptr_factory_;
DISALLOW_COPY_AND_ASSIGN(BackendImplV3);
};
} // namespace disk_cache
#endif // NET_DISK_CACHE_BLOCKFILE_BACKEND_IMPL_V3_H_