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/*
* Copyright 2020 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/callback_list.h"
#include "rtc_base/checks.h"
namespace webrtc {
namespace callback_list_impl {
CallbackListReceivers::CallbackListReceivers() = default;
CallbackListReceivers::~CallbackListReceivers() {
RTC_CHECK(!send_in_progress_);
}
void CallbackListReceivers::RemoveReceivers(const void* removal_tag) {
RTC_DCHECK(removal_tag);
// We divide the receivers_ vector into three regions: from right to left, the
// "keep" region, the "todo" region, and the "remove" region. The "todo"
// region initially covers the whole vector.
size_t first_todo = 0; // First element of the "todo"
// region.
size_t first_remove = receivers_.size(); // First element of the "remove"
// region.
// Loop until the "todo" region is empty.
while (first_todo != first_remove) {
if (receivers_[first_todo].removal_tag != removal_tag) {
// The first element of the "todo" region should be kept. Move the
// "keep"/"todo" boundary.
++first_todo;
} else if (receivers_[first_remove - 1].removal_tag == removal_tag) {
// The last element of the "todo" region should be removed. Move the
// "todo"/"remove" boundary.
if (send_in_progress_) {
// Tag this receiver for removal, which will be done when `ForEach`
// has completed.
receivers_[first_remove - 1].removal_tag = pending_removal_tag();
}
--first_remove;
} else if (!send_in_progress_) {
// The first element of the "todo" region should be removed, and the last
// element of the "todo" region should be kept. Swap them, and then shrink
// the "todo" region from both ends.
RTC_DCHECK_NE(first_todo, first_remove - 1);
using std::swap;
swap(receivers_[first_todo], receivers_[first_remove - 1]);
RTC_DCHECK_NE(receivers_[first_todo].removal_tag, removal_tag);
++first_todo;
RTC_DCHECK_EQ(receivers_[first_remove - 1].removal_tag, removal_tag);
--first_remove;
}
}
if (!send_in_progress_) {
// Discard the remove region.
receivers_.resize(first_remove);
}
}
void CallbackListReceivers::Foreach(
rtc::FunctionView<void(UntypedFunction&)> fv) {
RTC_CHECK(!send_in_progress_);
bool removals_detected = false;
send_in_progress_ = true;
for (auto& r : receivers_) {
RTC_DCHECK_NE(r.removal_tag, pending_removal_tag());
fv(r.function);
if (r.removal_tag == pending_removal_tag()) {
removals_detected = true;
}
}
send_in_progress_ = false;
if (removals_detected) {
RemoveReceivers(pending_removal_tag());
}
}
template void CallbackListReceivers::AddReceiver(
const void*,
UntypedFunction::TrivialUntypedFunctionArgs<1>);
template void CallbackListReceivers::AddReceiver(
const void*,
UntypedFunction::TrivialUntypedFunctionArgs<2>);
template void CallbackListReceivers::AddReceiver(
const void*,
UntypedFunction::TrivialUntypedFunctionArgs<3>);
template void CallbackListReceivers::AddReceiver(
const void*,
UntypedFunction::TrivialUntypedFunctionArgs<4>);
template void CallbackListReceivers::AddReceiver(
const void*,
UntypedFunction::NontrivialUntypedFunctionArgs);
template void CallbackListReceivers::AddReceiver(
const void*,
UntypedFunction::FunctionPointerUntypedFunctionArgs);
template void CallbackListReceivers::AddReceiver(
UntypedFunction::TrivialUntypedFunctionArgs<1>);
template void CallbackListReceivers::AddReceiver(
UntypedFunction::TrivialUntypedFunctionArgs<2>);
template void CallbackListReceivers::AddReceiver(
UntypedFunction::TrivialUntypedFunctionArgs<3>);
template void CallbackListReceivers::AddReceiver(
UntypedFunction::TrivialUntypedFunctionArgs<4>);
template void CallbackListReceivers::AddReceiver(
UntypedFunction::NontrivialUntypedFunctionArgs);
template void CallbackListReceivers::AddReceiver(
UntypedFunction::FunctionPointerUntypedFunctionArgs);
} // namespace callback_list_impl
} // namespace webrtc
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