blob: db2a43fed28afd01f24cdde8887e2abfcdded80e [file] [log] [blame]
// 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.
#include <stdint.h>
#include <unordered_map>
#include "base/files/file_path.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/timer/timer.h"
#include "net/base/net_export.h"
#include "net/disk_cache/blockfile/block_files.h"
#include "net/disk_cache/blockfile/eviction.h"
#include "net/disk_cache/blockfile/in_flight_backend_io.h"
#include "net/disk_cache/blockfile/rankings.h"
#include "net/disk_cache/blockfile/stats.h"
#include "net/disk_cache/blockfile/stress_support.h"
#include "net/disk_cache/disk_cache.h"
namespace base {
class SingleThreadTaskRunner;
} // namespace base
namespace net {
class NetLog;
} // namespace net
namespace disk_cache {
class BackendCleanupTracker;
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;
BackendImpl(const base::FilePath& path,
scoped_refptr<BackendCleanupTracker> cleanup_tracker,
const scoped_refptr<base::SingleThreadTaskRunner>& cache_thread,
net::CacheType cache_type,
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_t mask,
const scoped_refptr<base::SingleThreadTaskRunner>& cache_thread,
net::CacheType cache_type,
net::NetLog* net_log);
~BackendImpl() override;
// Performs general initialization for this current instance of the cache.
net::Error Init(CompletionOnceCallback callback);
// Performs the actual initialization and final cleanup on destruction.
int SyncInit();
void CleanupCache();
// Synchronous implementation of the asynchronous interface.
int SyncOpenEntry(const std::string& key, scoped_refptr<EntryImpl>* entry);
int SyncCreateEntry(const std::string& key, scoped_refptr<EntryImpl>* entry);
int SyncDoomEntry(const std::string& key);
int SyncDoomAllEntries();
int SyncDoomEntriesBetween(base::Time initial_time,
base::Time end_time);
int SyncCalculateSizeOfAllEntries();
int SyncDoomEntriesSince(base::Time initial_time);
int SyncOpenNextEntry(Rankings::Iterator* iterator,
scoped_refptr<EntryImpl>* next_entry);
void SyncEndEnumeration(std::unique_ptr<Rankings::Iterator> iterator);
void SyncOnExternalCacheHit(const std::string& key);
// Called at end of any backend operation on the background thread.
void OnSyncBackendOpComplete();
// Open or create an entry for the given |key| or |iter|.
scoped_refptr<EntryImpl> OpenEntryImpl(const std::string& key);
scoped_refptr<EntryImpl> CreateEntryImpl(const std::string& key);
scoped_refptr<EntryImpl> OpenNextEntryImpl(Rankings::Iterator* iter);
// Sets the maximum size for the total amount of data stored by this instance.
bool SetMaxSize(int64_t max_bytes);
// 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);
// 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);
// 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_t GetCurrentEntryId() const;
// Returns the maximum size for a file to reside on the cache.
int64_t MaxFileSize() const override;
// A user data block is being created, extended or truncated.
void ModifyStorageSize(int32_t old_size, int32_t new_size);
// Logs requests that are denied due to being too big.
void TooMuchStorageRequested(int32_t 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;
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_t 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(CompletionOnceCallback callback);
// Runs the provided task on the cache thread. The task will be automatically
// deleted after it runs.
int RunTaskForTest(base::OnceClosure task, CompletionOnceCallback 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* 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();
// Ensures that the private cache thread completes work.
static void FlushForTesting();
// Backend implementation.
int32_t GetEntryCount() const override;
EntryResult OpenOrCreateEntry(const std::string& key,
net::RequestPriority request_priority,
EntryResultCallback callback) override;
EntryResult OpenEntry(const std::string& key,
net::RequestPriority request_priority,
EntryResultCallback callback) override;
EntryResult CreateEntry(const std::string& key,
net::RequestPriority request_priority,
EntryResultCallback callback) override;
net::Error DoomEntry(const std::string& key,
net::RequestPriority priority,
CompletionOnceCallback callback) override;
net::Error DoomAllEntries(CompletionOnceCallback callback) override;
net::Error DoomEntriesBetween(base::Time initial_time,
base::Time end_time,
CompletionOnceCallback callback) override;
net::Error DoomEntriesSince(base::Time initial_time,
CompletionOnceCallback callback) override;
int64_t CalculateSizeOfAllEntries(
Int64CompletionOnceCallback callback) override;
// NOTE: The blockfile Backend::Iterator::OpenNextEntry method does not modify
// the last_used field of the entry, and therefore it does not impact the
// eviction ranking of the entry. However, an enumeration will go through all
// entries on the cache only if the cache is not modified while the
// enumeration is taking place. Significantly altering the entry pointed by
// the iterator (for example, deleting the entry) will invalidate the
// iterator. Performing operations on an entry that modify the entry may
// result in loops in the iteration, skipped entries or similar.
std::unique_ptr<Iterator> CreateIterator() override;
void GetStats(StatsItems* stats) override;
void OnExternalCacheHit(const std::string& key) override;
size_t DumpMemoryStats(
base::trace_event::ProcessMemoryDump* pmd,
const std::string& parent_absolute_name) const override;
using EntriesMap = std::unordered_map<CacheAddr, EntryImpl*>;
class IteratorImpl;
// 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, scoped_refptr<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.
scoped_refptr<EntryImpl> MatchEntry(const std::string& key,
uint32_t hash,
bool find_parent,
Addr entry_addr,
bool* match_error);
// 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(Rankings::List list,
CacheRankingsBlock** from_entry,
scoped_refptr<EntryImpl>* next_entry);
// Returns the entry that is pointed by |next|, from the given |list|.
scoped_refptr<EntryImpl> GetEnumeratedEntry(CacheRankingsBlock* next,
Rankings::List list);
// Re-opens an entry that was previously deleted.
scoped_refptr<EntryImpl> ResurrectEntry(
scoped_refptr<EntryImpl> deleted_entry);
void DestroyInvalidEntry(EntryImpl* entry);
// Handles the used storage count.
void AddStorageSize(int32_t bytes);
void SubstractStorageSize(int32_t 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();
// We want this destroyed after every other field.
scoped_refptr<BackendCleanupTracker> cleanup_tracker_;
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_t mask_ = 0; // Binary mask to map a hash to the hash table.
int32_t max_size_ = 0; // 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_ = 0; // The number of timer ticks received (OnStatsTimer).
int uma_report_ = 0; // Controls transmission of UMA data.
uint32_t user_flags_; // Flags set by the user.
bool init_ = false; // controls the initialization of the system.
bool restarted_ = false;
bool unit_test_ = false;
bool read_only_ =
false; // Prevents updates of the rankings data (used by tools).
bool disabled_ = false;
bool new_eviction_ = false; // What eviction algorithm should be used.
bool first_timer_ = true; // True if the timer has not been called.
bool user_load_ =
false; // True if we see a high load coming from the caller.
// True if we should consider doing eviction at end of current operation.
bool consider_evicting_at_op_end_ = false;
net::NetLog* net_log_;
Stats stats_; // Usage statistics.
std::unique_ptr<base::RepeatingTimer> timer_; // Usage timer.
base::WeakPtrFactory<BackendImpl> ptr_factory_{this};
} // namespace disk_cache