128 lines
4.1 KiB
C++
128 lines
4.1 KiB
C++
// Copyright 2018 Google Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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#include "packager/media/chunking/sync_point_queue.h"
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#include "packager/media/base/media_handler.h"
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#include <algorithm>
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#include <limits>
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namespace shaka {
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namespace media {
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SyncPointQueue::SyncPointQueue(const AdCueGeneratorParams& params)
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: sync_condition_(&lock_) {
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for (const Cuepoint& point : params.cue_points) {
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std::shared_ptr<CueEvent> event = std::make_shared<CueEvent>();
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event->time_in_seconds = point.start_time_in_seconds;
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unpromoted_[point.start_time_in_seconds] = std::move(event);
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}
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}
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void SyncPointQueue::AddThread() {
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base::AutoLock auto_lock(lock_);
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thread_count_++;
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}
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void SyncPointQueue::Cancel() {
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{
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base::AutoLock auto_lock(lock_);
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cancelled_ = true;
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}
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sync_condition_.Broadcast();
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}
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double SyncPointQueue::GetHint(double time_in_seconds) {
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base::AutoLock auto_lock(lock_);
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auto iter = promoted_.upper_bound(time_in_seconds);
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if (iter != promoted_.end())
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return iter->first;
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iter = unpromoted_.upper_bound(time_in_seconds);
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if (iter != unpromoted_.end())
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return iter->first;
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// Use MAX DOUBLE as the fall back so that we can force all streams to run
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// out all their samples even when there are no cues.
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return std::numeric_limits<double>::max();
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}
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std::shared_ptr<const CueEvent> SyncPointQueue::GetNext(
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double hint_in_seconds) {
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base::AutoLock auto_lock(lock_);
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while (!cancelled_) {
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// Find the promoted cue that would line up with our hint, which is the
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// first cue that is not less than |hint_in_seconds|.
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auto iter = promoted_.lower_bound(hint_in_seconds);
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if (iter != promoted_.end()) {
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return iter->second;
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}
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// Promote |hint_in_seconds| if everyone is waiting.
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if (waiting_thread_count_ + 1 == thread_count_) {
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std::shared_ptr<const CueEvent> cue = PromoteAtNoLocking(hint_in_seconds);
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CHECK(cue);
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return cue;
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}
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waiting_thread_count_++;
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// This blocks until either a cue is promoted or all threads are blocked
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// (in which case, the unpromoted cue at the hint will be self-promoted
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// and returned - see section above). Spurious signal events are possible
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// with most condition variable implementations, so if it returns, we go
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// back and check if a cue is actually promoted or not.
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sync_condition_.Wait();
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waiting_thread_count_--;
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}
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return nullptr;
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}
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std::shared_ptr<const CueEvent> SyncPointQueue::PromoteAt(
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double time_in_seconds) {
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base::AutoLock auto_lock(lock_);
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return PromoteAtNoLocking(time_in_seconds);
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}
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std::shared_ptr<const CueEvent> SyncPointQueue::PromoteAtNoLocking(
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double time_in_seconds) {
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lock_.AssertAcquired();
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// It is possible that |time_in_seconds| has been promoted.
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auto iter = promoted_.find(time_in_seconds);
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if (iter != promoted_.end())
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return iter->second;
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// Find the unpromoted cue that would work for the given time, which is the
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// first cue that is not greater than |time_in_seconds|.
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// So find the the first cue that is greater than |time_in_seconds| first and
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// then get the previous one.
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iter = unpromoted_.upper_bound(time_in_seconds);
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// The first cue in |unpromoted_| should not be greater than
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// |time_in_seconds|. It could happen only if it has been promoted at a
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// different timestamp, which can only be the result of unaligned GOPs.
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if (iter == unpromoted_.begin())
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return nullptr;
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auto prev_iter = std::prev(iter);
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DCHECK(prev_iter != unpromoted_.end());
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std::shared_ptr<CueEvent> cue = prev_iter->second;
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cue->time_in_seconds = time_in_seconds;
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promoted_[time_in_seconds] = cue;
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// Remove all unpromoted cues up to the cue that was just promoted.
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// User may provide multiple cue points at the same or similar timestamps. The
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// extra unused cues are simply ignored.
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unpromoted_.erase(unpromoted_.begin(), iter);
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// Wake up other threads that may be waiting.
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sync_condition_.Broadcast();
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return std::move(cue);
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}
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} // namespace media
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} // namespace shaka
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