Track entries pending Doom in SimpleCache backend.

net/disk_cache/simple/simple_backend_impl.h

 // Copyright (c) 2013 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.
 
 #ifndef NET_DISK_CACHE_SIMPLE_SIMPLE_BACKEND_IMPL_H_
 #define NET_DISK_CACHE_SIMPLE_SIMPLE_BACKEND_IMPL_H_
 
 #include <string>
 #include <utility>
 #include <vector>
 
+#include "base/callback_forward.h"
 #include "base/compiler_specific.h"
 #include "base/containers/hash_tables.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/task_runner.h"
 #include "base/time/time.h"
 #include "net/base/cache_type.h"
 #include "net/disk_cache/disk_cache.h"
@@ skipping 35 matching lines @@
   // Sets the maximum size for the total amount of data stored by this instance.
   bool SetMaxSize(int max_bytes);
 
   // Returns the maximum file size permitted in this backend.
   int GetMaxFileSize() const;
 
   // Removes |entry| from the |active_entries_| set, forcing future Open/Create
   // operations to construct a new object.
   void OnDeactivated(const SimpleEntryImpl* entry);
 
+  // The entry for |entry_hash| is being doomed; the backend will not attempt
+  // run new operations for this |entry_hash| until the Doom is completed.
+  void OnDoomStart(uint64 entry_hash);
+
+  // The entry for |entry_hash| has been successfully doomed, we can now allow
+  // operations on this entry, and we can run any operations enqueued while the
+  // doom completed.
+  void OnDoomComplete(uint64 entry_hash);
+
   // Backend:
   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;
@@ skipping 34 matching lines @@
                          int result);
 
   // Try to create the directory if it doesn't exist. This must run on the IO
   // thread.
   static DiskStatResult InitCacheStructureOnDisk(const base::FilePath& path,
                                                  uint64 suggested_max_size);
 
   // Searches |active_entries_| for the entry corresponding to |key|. If found,
   // returns the found entry. Otherwise, creates a new entry and returns that.
   scoped_refptr<SimpleEntryImpl> CreateOrFindActiveEntry(
+      uint64 entry_hash,
       const std::string& key);
 
   // Given a hash, will try to open the corresponding Entry. If we have an Entry
   // corresponding to |hash| in the map of active entries, opens it. Otherwise,
   // a new empty Entry will be created, opened and filled with information from
   // the disk.
   int OpenEntryFromHash(uint64 hash,
                         Entry** entry,
                         const CompletionCallback& callback);
 
@@ skipping 32 matching lines @@
                                  int error_code);
 
   const base::FilePath path_;
   scoped_ptr<SimpleIndex> index_;
   const scoped_refptr<base::SingleThreadTaskRunner> cache_thread_;
   scoped_refptr<base::TaskRunner> worker_pool_;
 
   int orig_max_size_;
   const SimpleEntryImpl::OperationsMode entry_operations_mode_;
 
-  // TODO(gavinp): Store the entry_hash in SimpleEntryImpl, and index this map
-  // by hash. This will save memory, and make IndexReadyForDoom easier.
   EntryMap active_entries_;
 
+  // The set of all entries which are currently being doomed. To avoid races,
+  // these entries cannot have Doom/Create/Open operations run until the doom
+  // is complete. The base::Closure map target is used to store deferred
+  // operations to be run at the completion of the Doom.
+  base::hash_map<uint64, base::Closure> entries_pending_doom_;
+
   net::NetLog* const net_log_;
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_BACKEND_IMPL_H_