storage/browser/blob/shareable_file_reference.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef STORAGE_BROWSER_BLOB_SHAREABLE_FILE_REFERENCE_H_
   6 #define STORAGE_BROWSER_BLOB_SHAREABLE_FILE_REFERENCE_H_
   7
   8 #include <vector>
   9
  10 #include "storage/browser/blob/scoped_file.h"
  11 #include "storage/browser/storage_browser_export.h"
  12
  13 namespace storage {
  14
  15 // ShareableFileReference allows consumers to share FileReference for the
  16 // same path if it already exists in its internal map.
  17 // This class is non-thread-safe and all methods must be called on a single
  18 // thread.
  19 class STORAGE_EXPORT ShareableFileReference
  20     : public base::RefCounted<ShareableFileReference> {
  21  public:
  22   typedef ScopedFile::ScopeOutCallback FinalReleaseCallback;
  23
  24   enum FinalReleasePolicy {
  25     DELETE_ON_FINAL_RELEASE = ScopedFile::DELETE_ON_SCOPE_OUT,
  26     DONT_DELETE_ON_FINAL_RELEASE = ScopedFile::DONT_DELETE_ON_SCOPE_OUT,
  27   };
  28
  29   // Returns a ShareableFileReference for the given path, if no reference
  30   // for this path exists returns NULL.
  31   static scoped_refptr<ShareableFileReference> Get(const base::FilePath& path);
  32
  33   // Returns a ShareableFileReference for the given path, creating a new
  34   // reference if none yet exists. If there's a pre-existing reference for
  35   // the path, the policy parameter of this method is ignored.
  36   static scoped_refptr<ShareableFileReference> GetOrCreate(
  37       const base::FilePath& path,
  38       FinalReleasePolicy policy,
  39       base::TaskRunner* file_task_runner);
  40
  41   // Returns a ShareableFileReference for the given path of the |scoped_file|,
  42   // creating a new reference if none yet exists. The ownership of |scoped_file|
  43   // is passed to this reference.
  44   // If there's a pre-existing reference for the path, the scope out policy
  45   // and scope-out-callbacks of the given |scoped_file| is ignored.
  46   // If the given scoped_file has an empty path (e.g. maybe already
  47   // released) this returns NULL reference.
  48   //
  49   // TODO(kinuko): Make sure if this behavior is ok, we could alternatively
  50   // merge callbacks to the existing one.
  51   static scoped_refptr<ShareableFileReference> GetOrCreate(
  52       ScopedFile scoped_file);
  53
  54   // The full file path.
  55   const base::FilePath& path() const { return scoped_file_.path(); }
  56
  57   // The |callback| is fired when the final reference of this instance
  58   // is released. If release policy is DELETE_ON_FINAL_RELEASE the
  59   // callback task(s) is/are posted before the deletion is scheduled.
  60   void AddFinalReleaseCallback(const FinalReleaseCallback& callback);
  61
  62  private:
  63   friend class base::RefCounted<ShareableFileReference>;
  64
  65   ShareableFileReference(ScopedFile scoped_file);
  66   ~ShareableFileReference();
  67
  68   ScopedFile scoped_file_;
  69
  70   DISALLOW_COPY_AND_ASSIGN(ShareableFileReference);
  71 };
  72
  73 }  // namespace storage
  74
  75 #endif  // STORAGE_BROWSER_BLOB_SHAREABLE_FILE_REFERENCE_H_