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