QUIC - use size_t for kMaxInitialRoundTripTimeUs.
[chromium-blink-merge.git] / media / base / callback_holder.h
blob2ea5edbeb19d01fad02e2c6e060c043545174d69
1 // Copyright 2013 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.
5 #ifndef MEDIA_BASE_CALLBACK_HOLDER_H_
6 #define MEDIA_BASE_CALLBACK_HOLDER_H_
8 #include "base/bind.h"
9 #include "base/callback.h"
10 #include "base/callback_helpers.h"
11 #include "media/base/bind_to_loop.h"
13 namespace media {
15 // A helper class that can hold a callback from being fired.
16 template <typename CB> class CallbackHolder {
17 public:
18 CallbackHolder() : hold_(false) {}
20 ~CallbackHolder() {
21 // Make sure all callbacks are satisfied!
22 DCHECK(!hold_);
23 DCHECK(original_cb_.is_null());
24 DCHECK(held_cb_.is_null());
27 // Sets the callback to be potentially held.
28 void SetCallback(const CB& cb) {
29 DCHECK(original_cb_.is_null());
30 DCHECK(held_cb_.is_null());
31 original_cb_ = cb;
34 bool IsNull() const {
35 return original_cb_.is_null() && held_cb_.is_null();
38 // Holds the callback when Run() is called.
39 void HoldCallback() { hold_ = true; }
41 // Runs or holds the callback as specified by |hold_|.
42 // This method has overloaded versions to support different types of CB.
43 void RunOrHold() {
44 DCHECK(held_cb_.is_null());
45 if (hold_)
46 held_cb_ = base::ResetAndReturn(&original_cb_);
47 else
48 base::ResetAndReturn(&original_cb_).Run();
51 template <typename A1> void RunOrHold(A1 a1) {
52 DCHECK(held_cb_.is_null());
53 if (hold_) {
54 held_cb_ = base::Bind(base::ResetAndReturn(&original_cb_),
55 internal::TrampolineForward(a1));
56 } else {
57 base::ResetAndReturn(&original_cb_).Run(a1);
61 template <typename A1, typename A2> void RunOrHold(A1 a1, A2 a2) {
62 DCHECK(held_cb_.is_null());
63 if (hold_) {
64 held_cb_ = base::Bind(base::ResetAndReturn(&original_cb_),
65 internal::TrampolineForward(a1),
66 internal::TrampolineForward(a2));
67 } else {
68 base::ResetAndReturn(&original_cb_).Run(a1, a2);
72 // Releases and runs the held callback.
73 void RunHeldCallback() {
74 DCHECK(hold_);
75 DCHECK(!held_cb_.is_null());
76 hold_ = false;
77 base::ResetAndReturn(&held_cb_).Run();
80 private:
81 bool hold_;
82 CB original_cb_;
83 base::Closure held_cb_;
86 } // namespace media
88 #endif // MEDIA_BASE_CALLBACK_HOLDER_H_