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-rw-r--r--third_party/libwebrtc/rtc_base/operations_chain.cc88
1 files changed, 88 insertions, 0 deletions
diff --git a/third_party/libwebrtc/rtc_base/operations_chain.cc b/third_party/libwebrtc/rtc_base/operations_chain.cc
new file mode 100644
index 0000000000..4398bb16c1
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/operations_chain.cc
@@ -0,0 +1,88 @@
+/*
+ * Copyright 2019 The WebRTC Project Authors. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS. All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "rtc_base/operations_chain.h"
+
+#include "api/make_ref_counted.h"
+#include "rtc_base/checks.h"
+
+namespace rtc {
+
+OperationsChain::CallbackHandle::CallbackHandle(
+ scoped_refptr<OperationsChain> operations_chain)
+ : operations_chain_(std::move(operations_chain)) {}
+
+OperationsChain::CallbackHandle::~CallbackHandle() {
+#if RTC_DCHECK_IS_ON
+ RTC_DCHECK(has_run_);
+#endif
+}
+
+void OperationsChain::CallbackHandle::OnOperationComplete() {
+#if RTC_DCHECK_IS_ON
+ RTC_DCHECK(!has_run_);
+ has_run_ = true;
+#endif // RTC_DCHECK_IS_ON
+ operations_chain_->OnOperationComplete();
+ // We have no reason to keep the `operations_chain_` alive through reference
+ // counting anymore.
+ operations_chain_ = nullptr;
+}
+
+// static
+scoped_refptr<OperationsChain> OperationsChain::Create() {
+ // Explicit new, to access private constructor.
+ return rtc::scoped_refptr<OperationsChain>(new OperationsChain());
+}
+
+OperationsChain::OperationsChain() {
+ RTC_DCHECK_RUN_ON(&sequence_checker_);
+}
+
+OperationsChain::~OperationsChain() {
+ // Operations keep the chain alive through reference counting so this should
+ // not be possible. The fact that the chain is empty makes it safe to
+ // destroy the OperationsChain on any sequence.
+ RTC_DCHECK(chained_operations_.empty());
+}
+
+void OperationsChain::SetOnChainEmptyCallback(
+ std::function<void()> on_chain_empty_callback) {
+ RTC_DCHECK_RUN_ON(&sequence_checker_);
+ on_chain_empty_callback_ = std::move(on_chain_empty_callback);
+}
+
+bool OperationsChain::IsEmpty() const {
+ RTC_DCHECK_RUN_ON(&sequence_checker_);
+ return chained_operations_.empty();
+}
+
+std::function<void()> OperationsChain::CreateOperationsChainCallback() {
+ return [handle = rtc::make_ref_counted<CallbackHandle>(
+ rtc::scoped_refptr<OperationsChain>(this))]() {
+ handle->OnOperationComplete();
+ };
+}
+
+void OperationsChain::OnOperationComplete() {
+ RTC_DCHECK_RUN_ON(&sequence_checker_);
+ // The front element is the operation that just completed, remove it.
+ RTC_DCHECK(!chained_operations_.empty());
+ chained_operations_.pop();
+ // If there are any other operations chained, execute the next one. Otherwise,
+ // invoke the "on chain empty" callback if it has been set.
+ if (!chained_operations_.empty()) {
+ chained_operations_.front()->Run();
+ } else if (on_chain_empty_callback_.has_value()) {
+ on_chain_empty_callback_.value()();
+ }
+}
+
+} // namespace rtc