New blobstoragecontext for use in the main browser process, not plugged in yet.

webkit/blob/blob_storage_context.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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 WEBKIT_BLOB_BLOB_STORAGE_CONTROLLER_H_
-#define WEBKIT_BLOB_BLOB_STORAGE_CONTROLLER_H_
+#ifndef WEBKIT_BLOB_BLOB_STORAGE_CONTEXT_H_
+#define WEBKIT_BLOB_BLOB_STORAGE_CONTEXT_H_
 
 #include <map>
+#include <set>
 #include <string>
+#include <utility>
 
+#include "base/gtest_prod_util.h"
 #include "base/hash_tables.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/process.h"
+#include "base/shared_memory.h"
+#include "base/supports_user_data.h"
 #include "webkit/blob/blob_data.h"
 #include "webkit/storage/webkit_storage_export.h"
 
 class GURL;
 
 namespace base {
 class FilePath;
+class SequencedTaskRunner;
 class Time;
 }
 
 namespace webkit_blob {
 
-// This class handles the logistics of blob Storage within the browser process.
-class WEBKIT_STORAGE_EXPORT BlobStorageController {
+class BlobDataHandle;
+class BlobStorageHost;
+class BlobStorageContext;
+
+// A scoper object for use in chrome's main browser process, ensures
+// the underlying BlobData and its uuid remain in BlobStorageContext's
+// collection for the duration. This object has delete semantics and
+// maybe deleted on any thread.
+class WEBKIT_STORAGE_EXPORT BlobDataHandle
+    : public base::SupportsUserData::Data {
  public:
-  BlobStorageController();
-  ~BlobStorageController();
-
-  void StartBuildingBlob(const GURL& url);
-  void AppendBlobDataItem(const GURL& url, const BlobData::Item& data_item);
-  void FinishBuildingBlob(const GURL& url, const std::string& content_type);
-  void AddFinishedBlob(const GURL& url, const BlobData* blob_data);
-  void CloneBlob(const GURL& url, const GURL& src_url);
-  void RemoveBlob(const GURL& url);
-  BlobData* GetBlobDataFromUrl(const GURL& url);
+  virtual ~BlobDataHandle();  // Maybe be deleted on any thread.
+  BlobData* data() const;  // May only be accessed on the IO thread.
 
  private:
-  friend class ViewBlobInternalsJob;
+  friend class BlobStorageContext;
+  BlobDataHandle(BlobData* blob_data, BlobStorageContext* context,
+                 base::SequencedTaskRunner* task_runner);
 
-  typedef base::hash_map<std::string, scoped_refptr<BlobData> > BlobMap;
-  typedef std::map<BlobData*, int> BlobDataUsageMap;
+  static void DeleteHelper(
+      base::WeakPtr<BlobStorageContext> context,
+      BlobData* blob_data);
+
+  BlobData* blob_data_;  // Intentionally a raw ptr to a non-thread-safe ref.

[ericu, 2013/04/24 23:54:43]

Why?

[ericu, 2013/04/26 22:17:37]

This is still worth a more-helpful comment, though.

[michaeln, 2013/04/29 18:32:48]

I added that greater explanation comment in the .cc file in the vicinity of
where blob_data_ is used.

+  base::WeakPtr<BlobStorageContext> context_;
+  scoped_refptr<base::SequencedTaskRunner> io_task_runner_;
+};
+
+// This class handles the logistics of blob storage for a single child process.
+// There is one instance per child process. When the child process
+// terminates all blob references attibutable to that process go away upon
+// destruction of the instance. The class is single threaded and should
+// only be used on the IO thread.
+class WEBKIT_STORAGE_EXPORT BlobStorageHost {
+ public:
+  explicit BlobStorageHost(BlobStorageContext* context);
+  ~BlobStorageHost();
+
+  // Methods to support the IPC message protocol.
+  // A false return indicates a problem with the inputs
+  // like a non-existent or pre-existent uuid or url.
+  bool StartBuildingBlob(const std::string& uuid);
+  bool AppendBlobDataItem(const std::string& uuid,
+                          const BlobData::Item& data_item);
+  bool CancelBuildingBlob(const std::string& uuid);

[ericu, 2013/04/24 23:54:43]

What would you think about WARN_UNUSED_RETURN on these?

[michaeln, 2013/04/29 18:32:48]

Done.

+  bool FinishBuildingBlob(const std::string& uuid, const std::string& type);
+  bool IncrementBlobRefCount(const std::string& uuid);
+  bool DecrementBlobRefCount(const std::string& uuid);
+  bool RegisterPublicBlobURL(const GURL& blob_url, const std::string& uuid);
+  bool RevokePublicBlobURL(const GURL& blob_url);
+
+ private:
+  typedef std::map<std::string, int> BlobReferenceMap;
+
+  bool IsInUse(const std::string& uuid);
+  bool HasUseCountOfOne(const std::string& uuid);
+  bool IsUrlRegistered(const GURL& blob_url);
+
+  // Collection of blob ids and a count of how many usages
+  // of that id are attributable to this consumer.
+  BlobReferenceMap blobs_inuse_map_;
+
+  // The set of public blob urls coined by this consumer.
+  std::set<GURL> public_blob_urls_;
+
+  base::WeakPtr<BlobStorageContext> context_;
+};
+
+// This class handles the logistics of blob Storage within the browser process,
+// and maintains a mapping from blob uuid to the data. The class is single
+// threaded and should  only be used on the IO thread.
+// In chromium, there is one instance per profile.
+class WEBKIT_STORAGE_EXPORT BlobStorageContext
+    : public base::SupportsWeakPtr<BlobStorageContext> {
+ public:
+  BlobStorageContext();
+  ~BlobStorageContext();
+
+  scoped_ptr<BlobDataHandle> GetBlobDataFromUUID(const std::string& uuid);
+  scoped_ptr<BlobDataHandle> GetBlobDataFromPublicURL(const GURL& url);
+
+  // Useful for coining blobs from within the browser process. If the
+  // blob cannot be added due to memory consumption, returns NULL.
+  scoped_ptr<BlobDataHandle> AddFinishedBlob(const BlobData* blob_data);
+
+ private:
+  friend class BlobDataHandle;
+  friend class BlobStorageHost;
+
+  enum EntryFlags {
+    BEING_BUILT = 1 << 0,
+    EXCEEDED_MEMORY = 1 << 1,
+  };
+
+  struct BlobMapEntry {
+    int refcount;
+    int flags;
+    scoped_refptr<BlobData> data;
+
+    BlobMapEntry() : refcount(0), flags(0) {}
+    BlobMapEntry(int refcount, int flags, BlobData* data)
+        : refcount(refcount), flags(flags), data(data) {}
+  };
+
+  typedef std::map<std::string, BlobMapEntry>
+      BlobMap;
+  typedef std::map<GURL, std::string> BlobURLMap;
+
+  void StartBuildingBlob(const std::string& uuid);
+  void AppendBlobDataItem(const std::string& uuid,
+                          const BlobData::Item& data_item);
+  void FinishBuildingBlob(const std::string& uuid, const std::string& type);
+  void CancelBuildingBlob(const std::string& uuid);
+  void IncrementBlobRefCount(const std::string& uuid);
+  void DecrementBlobRefCount(const std::string& uuid);
+  void RegisterPublicBlobURL(const GURL& url, const std::string& uuid);
+  void RevokePublicBlobURL(const GURL& url);
 
   void AppendStorageItems(BlobData* target_blob_data,
                           BlobData* src_blob_data,
                           uint64 offset,
                           uint64 length);
   void AppendFileItem(BlobData* target_blob_data,
-                      const base::FilePath& file_path, uint64 offset,
-                      uint64 length,
+                      const base::FilePath& file_path,
+                      uint64 offset, uint64 length,
                       const base::Time& expected_modification_time);
   void AppendFileSystemFileItem(
       BlobData* target_blob_data,
       const GURL& url, uint64 offset, uint64 length,
       const base::Time& expected_modification_time);
 
-  bool RemoveFromMapHelper(BlobMap* map, const GURL& url);
-
-  void IncrementBlobDataUsage(BlobData* blob_data);
-  // Returns true if no longer in use.
-  bool DecrementBlobDataUsage(BlobData* blob_data);
+  bool IsInUse(const std::string& uuid);
+  bool HasUseCountOfOne(const std::string& uuid);
+  bool IsUrlRegistered(const GURL& blob_url);
 
   BlobMap blob_map_;
-  BlobMap unfinalized_blob_map_;
+  BlobURLMap public_blob_urls_;
 
   // Used to keep track of how much memory is being utitlized for blob data,
   // we count only the items of TYPE_DATA which are held in memory and not
   // items of TYPE_FILE.
   int64 memory_usage_;
 
-  // Multiple urls can refer to the same blob data, this map keeps track of
-  // how many urls refer to a BlobData.
-  BlobDataUsageMap blob_data_usage_count_;
-
-  DISALLOW_COPY_AND_ASSIGN(BlobStorageController);
+  DISALLOW_COPY_AND_ASSIGN(BlobStorageContext);
 };
 
 }  // namespace webkit_blob
 
-#endif  // WEBKIT_BLOB_BLOB_STORAGE_CONTROLLER_H_
+#endif  // WEBKIT_BLOB_BLOB_STORAGE_CONTEXT_H_