Disk cache: Extend the internal buffering performed by each entry...

net/disk_cache/backend_impl.h

 // Copyright (c) 2006-2010 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_
 #pragma once
 
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   // 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_;
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   // Performs basic checks on the index file. Returns false on failure.
   bool CheckIndex();
 
   // Part of the selt 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.
   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.
   net::CacheType cache_type_;
   int uma_report_;  // Controls transmision 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.
 
   Stats stats_;  // Usage statistcs.
   base::RepeatingTimer<BackendImpl> timer_;  // Usage timer.
   base::WaitableEvent done_;  // Signals the end of background work.
   scoped_refptr<TraceObject> trace_object_;  // Inits internal tracing.
   ScopedRunnableMethodFactory<BackendImpl> factory_;
   base::WeakPtrFactory<BackendImpl> ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BackendImpl);
 };
 
 // Returns the prefered max cache size given the available disk space.
 int PreferedCacheSize(int64 available);
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_BACKEND_IMPL_H_