xpcom/io/InputStreamLengthHelper.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_InputStreamLengthHelper_h
   8 #define mozilla_InputStreamLengthHelper_h
   9
  10 #include <functional>
  11
  12 #include "nsISupportsImpl.h"
  13 #include "nsIInputStreamLength.h"
  14 #include "nsThreadUtils.h"
  15
  16 class nsIInputStream;
  17
  18 namespace mozilla {
  19
  20 // This class helps to retrieve the stream's length.
  21
  22 class InputStreamLengthHelper final : public Runnable,
  23                                       public nsIInputStreamLengthCallback {
  24  public:
  25   NS_DECL_ISUPPORTS_INHERITED
  26
  27   // This is one of the 2 entry points of this class. It returns false if the
  28   // length cannot be taken synchronously.
  29   static bool GetSyncLength(nsIInputStream* aStream, int64_t* aLength);
  30
  31   // This is one of the 2 entry points of this class. The callback is executed
  32   // asynchronously when the length is known.
  33   static void GetAsyncLength(
  34       nsIInputStream* aStream,
  35       const std::function<void(int64_t aLength)>& aCallback);
  36
  37  private:
  38   NS_DECL_NSIINPUTSTREAMLENGTHCALLBACK
  39
  40   InputStreamLengthHelper(
  41       nsIInputStream* aStream,
  42       const std::function<void(int64_t aLength)>& aCallback);
  43
  44   ~InputStreamLengthHelper();
  45
  46   NS_IMETHOD
  47   Run() override;
  48
  49   void ExecCallback(int64_t aLength);
  50
  51   nsCOMPtr<nsIInputStream> mStream;
  52   std::function<void(int64_t aLength)> mCallback;
  53 };
  54
  55 }  // namespace mozilla
  56
  57 #endif  // mozilla_InputStreamLengthHelper_h