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- // 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_MEMORY_MEM_BACKEND_IMPL_H_
- #define NET_DISK_CACHE_MEMORY_MEM_BACKEND_IMPL_H_
- #include <stdint.h>
- #include <string>
- #include <unordered_map>
- #include "base/callback_forward.h"
- #include "base/compiler_specific.h"
- #include "base/containers/linked_list.h"
- #include "base/memory/memory_pressure_listener.h"
- #include "base/memory/raw_ptr.h"
- #include "base/memory/weak_ptr.h"
- #include "base/strings/string_split.h"
- #include "base/time/time.h"
- #include "net/base/net_export.h"
- #include "net/disk_cache/disk_cache.h"
- #include "net/disk_cache/memory/mem_entry_impl.h"
- namespace base {
- class Clock;
- }
- namespace net {
- class NetLog;
- } // namespace net
- namespace disk_cache {
- // This class implements the Backend interface. An object of this class handles
- // the operations of the cache without writing to disk.
- class NET_EXPORT_PRIVATE MemBackendImpl final : public Backend {
- public:
- explicit MemBackendImpl(net::NetLog* net_log);
- MemBackendImpl(const MemBackendImpl&) = delete;
- MemBackendImpl& operator=(const MemBackendImpl&) = delete;
- ~MemBackendImpl() override;
- // Returns an instance of a Backend implemented only in memory. The returned
- // object should be deleted when not needed anymore. max_bytes is the maximum
- // size the cache can grow to. If zero is passed in as max_bytes, the cache
- // will determine the value to use based on the available memory. The returned
- // pointer can be NULL if a fatal error is found.
- static std::unique_ptr<MemBackendImpl> CreateBackend(int64_t max_bytes,
- net::NetLog* net_log);
- // Performs general initialization for this current instance of the cache.
- bool Init();
- // Sets the maximum size for the total amount of data stored by this instance.
- bool SetMaxSize(int64_t max_bytes);
- // Returns the maximum size for a file to reside on the cache.
- int64_t MaxFileSize() const override;
- // These next methods (before the implementation of the Backend interface) are
- // called by MemEntryImpl to update the state of the backend during the entry
- // lifecycle.
- // Signals that new entry has been created, and should be placed in
- // |lru_list_| so that it is eligable for eviction.
- void OnEntryInserted(MemEntryImpl* entry);
- // Signals that an entry has been updated, and thus should be moved to the end
- // of |lru_list_|.
- void OnEntryUpdated(MemEntryImpl* entry);
- // Signals that an entry has been doomed, and so it should be removed from the
- // list of active entries as appropriate, as well as removed from the
- // |lru_list_|.
- void OnEntryDoomed(MemEntryImpl* entry);
- // Adjust the current size of this backend by |delta|. This is used to
- // determine if eviction is necessary and when eviction is finished.
- void ModifyStorageSize(int32_t delta);
- // Returns true if the cache's size is greater than the maximum allowed
- // size.
- bool HasExceededStorageSize() const;
- // Sets a callback to be posted after we are destroyed. Should be called at
- // most once.
- void SetPostCleanupCallback(base::OnceClosure cb);
- static base::Time Now(const base::WeakPtr<MemBackendImpl>& self);
- void SetClockForTesting(base::Clock* clock); // doesn't take ownership.
- // Backend interface.
- 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;
- int64_t CalculateSizeOfEntriesBetween(
- base::Time initial_time,
- base::Time end_time,
- Int64CompletionOnceCallback callback) override;
- std::unique_ptr<Iterator> CreateIterator() override;
- void GetStats(base::StringPairs* stats) override {}
- void OnExternalCacheHit(const std::string& key) override;
- private:
- class MemIterator;
- friend class MemIterator;
- using EntryMap = std::unordered_map<std::string, MemEntryImpl*>;
- // Deletes entries from the cache until the current size is below the limit.
- void EvictIfNeeded();
- // Deletes entries until the current size is below |goal|.
- void EvictTill(int target_size);
- // Called when we get low on memory.
- void OnMemoryPressure(
- base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
- raw_ptr<base::Clock> custom_clock_for_testing_ = nullptr; // usually nullptr.
- EntryMap entries_;
- // Stored in increasing order of last use time, from least recently used to
- // most recently used.
- base::LinkedList<MemEntryImpl> lru_list_;
- int32_t max_size_ = 0; // Maximum data size for this instance.
- int32_t current_size_ = 0;
- raw_ptr<net::NetLog> net_log_;
- base::OnceClosure post_cleanup_callback_;
- base::MemoryPressureListener memory_pressure_listener_;
- base::WeakPtrFactory<MemBackendImpl> weak_factory_{this};
- };
- } // namespace disk_cache
- #endif // NET_DISK_CACHE_MEMORY_MEM_BACKEND_IMPL_H_
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