Reorganize net/disk_cache into backend specific directories.

net/disk_cache/backend_impl.h

-// 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_BACKEND_IMPL_H_
-#define NET_DISK_CACHE_BACKEND_IMPL_H_
-
-#include "base/containers/hash_tables.h"
-#include "base/files/file_path.h"
-#include "base/timer/timer.h"
-#include "net/disk_cache/block_files.h"
-#include "net/disk_cache/disk_cache.h"
-#include "net/disk_cache/eviction.h"
-#include "net/disk_cache/in_flight_backend_io.h"
-#include "net/disk_cache/rankings.h"
-#include "net/disk_cache/stats.h"
-#include "net/disk_cache/stress_support.h"
-#include "net/disk_cache/trace.h"
-
-namespace net {
-class NetLog;
-}  // namespace net
-
-namespace disk_cache {
-
-struct Index;
-
-enum BackendFlags {
-  kNone = 0,
-  kMask = 1,                    // A mask (for the index table) was specified.
-  kMaxSize = 1 << 1,            // A maximum size was provided.
-  kUnitTestMode = 1 << 2,       // We are modifying the behavior for testing.
-  kUpgradeMode = 1 << 3,        // This is the upgrade tool (dump).
-  kNewEviction = 1 << 4,        // Use of new eviction was specified.
-  kNoRandom = 1 << 5,           // Don't add randomness to the behavior.
-  kNoLoadProtection = 1 << 6,   // Don't act conservatively under load.
-  kNoBuffering = 1 << 7         // Disable extended IO buffering.
-};
-
-// 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 BackendImpl : public Backend {
-  friend class Eviction;
- public:
-  BackendImpl(const base::FilePath& path, base::MessageLoopProxy* cache_thread,
-              net::NetLog* net_log);
-  // mask can be used to limit the usable size of the hash table, for testing.
-  BackendImpl(const base::FilePath& path, uint32 mask,
-              base::MessageLoopProxy* cache_thread, net::NetLog* net_log);
-  virtual ~BackendImpl();
-
-  // Performs general initialization for this current instance of the cache.
-  int Init(const CompletionCallback& callback);
-
-  // Performs the actual initialization and final cleanup on destruction.
-  int SyncInit();
-  void CleanupCache();
-
-  // Same behavior as OpenNextEntry but walks the list from back to front.
-  int OpenPrevEntry(void** iter, Entry** prev_entry,
-                    const CompletionCallback& callback);
-
-  // Synchronous implementation of the asynchronous interface.
-  int SyncOpenEntry(const std::string& key, Entry** entry);
-  int SyncCreateEntry(const std::string& key, Entry** entry);
-  int SyncDoomEntry(const std::string& key);
-  int SyncDoomAllEntries();
-  int SyncDoomEntriesBetween(base::Time initial_time,
-                             base::Time end_time);
-  int SyncDoomEntriesSince(base::Time initial_time);
-  int SyncOpenNextEntry(void** iter, Entry** next_entry);
-  int SyncOpenPrevEntry(void** iter, Entry** prev_entry);
-  void SyncEndEnumeration(void* iter);
-  void SyncOnExternalCacheHit(const std::string& key);
-
-  // Open or create an entry for the given |key| or |iter|.
-  EntryImpl* OpenEntryImpl(const std::string& key);
-  EntryImpl* CreateEntryImpl(const std::string& key);
-  EntryImpl* OpenNextEntryImpl(void** iter);
-  EntryImpl* OpenPrevEntryImpl(void** iter);
-
-  // 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);
-
-  // Returns the full name for an external storage file.
-  base::FilePath GetFileName(Addr address) const;
-
-  // Returns the actual file used to store a given (non-external) address.
-  MappedFile* File(Addr address);
-
-  // Returns a weak pointer to the background queue.
-  base::WeakPtr<InFlightBackendIO> GetBackgroundQueue();
-
-  // Creates an external storage file.
-  bool CreateExternalFile(Addr* address);
-
-  // Creates a new storage block of size block_count.
-  bool CreateBlock(FileType block_type, int block_count,
-                   Addr* block_address);
-
-  // Deletes a given storage block. deep set to true can be used to zero-fill
-  // the related storage in addition of releasing the related block.
-  void DeleteBlock(Addr block_address, bool deep);
-
-  // Retrieves a pointer to the LRU-related data.
-  LruData* GetLruData();
-
-  // Updates the ranking information for an entry.
-  void UpdateRank(EntryImpl* entry, bool modified);
-
-  // A node was recovered from a crash, it may not be on the index, so this
-  // method checks it and takes the appropriate action.
-  void RecoveredEntry(CacheRankingsBlock* rankings);
-
-  // Permanently deletes an entry, but still keeps track of it.
-  void InternalDoomEntry(EntryImpl* entry);
-
-#if defined(NET_BUILD_STRESS_CACHE)
-  // Returns the address of the entry linked to the entry at a given |address|.
-  CacheAddr GetNextAddr(Addr address);
-
-  // Verifies that |entry| is not currently reachable through the index.
-  void NotLinked(EntryImpl* entry);
-#endif
-
-  // Removes all references to this entry.
-  void RemoveEntry(EntryImpl* 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 data stored by the provided |rankings| points 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.
-  EntryImpl* GetOpenEntry(CacheRankingsBlock* rankings) 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 experiment,
-  // and the current cache type. The name will be "DiskCache.t.name_e" where n
-  // is the cache type and e the provided |experiment|.
-  std::string HistogramName(const char* name, int experiment) 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<BackendImpl> 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();
-
-  // Reports a critical error (and disables the cache).
-  void CriticalError(int error);
-
-  // Reports an uncommon, recoverable error.
-  void ReportError(int error);
-
-  // 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.
-  void OnStatsTimer();
-
-  // Handles the pending asynchronous IO count.
-  void IncrementIoCount();
-  void DecrementIoCount();
-
-  // 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);
-
-  // Clears the counter of references to test handling of corruptions.
-  void ClearRefCountForTest();
-
-  // Sends a dummy operation through the operation queue, for unit tests.
-  int FlushQueueForTest(const CompletionCallback& callback);
-
-  // Runs the provided task on the cache thread. The task will be automatically
-  // deleted after it runs.
-  int RunTaskForTest(const base::Closure& task,
-                     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);
-
-  // Only intended for testing
-  base::RepeatingTimer<BackendImpl>* GetTimerForTest();
-
-  // Performs a simple self-check, and returns the number of dirty items
-  // or an error code (negative value).
-  int SelfCheck();
-
-  // Ensures the index is flushed to disk (a no-op on platforms with mmap).
-  void FlushIndex();
-
-  // 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:
-  typedef base::hash_map<CacheAddr, EntryImpl*> EntriesMap;
-
-  // Creates a new backing file for the cache index.
-  bool CreateBackingStore(disk_cache::File* file);
-  bool InitBackingStore(bool* file_created);
-  void AdjustMaxCacheSize(int table_len);
-
-  bool InitStats();
-  void StoreStats();
-
-  // Deletes the cache and starts again.
-  void RestartCache(bool failure);
-  void PrepareForRestart();
-
-  // Creates a new entry object. Returns zero on success, or a disk_cache error
-  // on failure.
-  int NewEntry(Addr address, EntryImpl** entry);
-
-  // Returns a given entry from the cache. The entry to match is determined by
-  // key and hash, and the returned entry may be the matched one or it's parent
-  // on the list of entries with the same hash (or bucket). To look for a parent
-  // of a given entry, |entry_addr| should be grabbed from that entry, so that
-  // if it doesn't match the entry on the index, we know that it was replaced
-  // with a new entry; in this case |*match_error| will be set to true and the
-  // return value will be NULL.
-  EntryImpl* MatchEntry(const std::string& key, uint32 hash, bool find_parent,
-                        Addr entry_addr, bool* match_error);
-
-  // Opens the next or previous entry on a cache iteration.
-  EntryImpl* OpenFollowingEntry(bool forward, void** iter);
-
-  // Opens the next or previous entry on a single list. If successful,
-  // |from_entry| will be updated to point to the new entry, otherwise it will
-  // be set to NULL; in other words, it is used as an explicit iterator.
-  bool OpenFollowingEntryFromList(bool forward, Rankings::List list,
-                                  CacheRankingsBlock** from_entry,
-                                  EntryImpl** next_entry);
-
-  // Returns the entry that is pointed by |next|, from the given |list|.
-  EntryImpl* GetEnumeratedEntry(CacheRankingsBlock* next, Rankings::List list);
-
-  // Re-opens an entry that was previously deleted.
-  EntryImpl* ResurrectEntry(EntryImpl* deleted_entry);
-
-  void DestroyInvalidEntry(EntryImpl* entry);
-
-  // 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();
-
-  // Upgrades the index file to version 2.1.
-  void UpgradeTo2_1();
-
-  // 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(EntryImpl* cache_entry);
-
-  // Returns the maximum total memory for the memory buffers.
-  int MaxBuffersSize();
-
-  InFlightBackendIO background_queue_;  // The controller of pending operations.
-  scoped_refptr<MappedFile> index_;  // The main cache index.
-  base::FilePath path_;  // Path to the folder used as backing storage.
-  Index* data_;  // Pointer to the index data.
-  BlockFiles block_files_;  // Set of files used to store all data.
-  Rankings rankings_;  // Rankings to be able to trim the cache.
-  uint32 mask_;  // Binary mask to map a hash to the hash table.
-  int32 max_size_;  // Maximum data size for this instance.
-  Eviction eviction_;  // Handler of the eviction algorithm.
-  EntriesMap open_entries_;  // Map of open entries.
-  int num_refs_;  // Number of referenced cache entries.
-  int max_refs_;  // Max number of referenced cache entries.
-  int num_pending_io_;  // Number of pending IO operations.
-  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 (OnStatsTimer).
-  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 unit_test_;
-  bool read_only_;  // Prevents updates of the rankings data (used by tools).
-  bool disabled_;
-  bool new_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<BackendImpl> > timer_;  // Usage timer.
-  base::WaitableEvent done_;  // Signals the end of background work.
-  scoped_refptr<TraceObject> trace_object_;  // Initializes internal tracing.
-  base::WeakPtrFactory<BackendImpl> ptr_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(BackendImpl);
-};
-
-}  // namespace disk_cache
-
-#endif  // NET_DISK_CACHE_BACKEND_IMPL_H_