1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
|
/*
* Copyright (C) 2025 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "RealtimeAudioThread.h"
#include <wtf/MonotonicTime.h>
namespace WebCore {
static constexpr uint8_t s_maximumConcurrentRealtimeThreads { 3 };
Ref<Thread> createMaybeRealtimeAudioThread(ASCIILiteral threadName, Function<void()>&& entryPoint, Seconds rawRenderingQuantumDuration)
{
// Create a thread with Realtime scheduling, so that this thread does not become deprioritized
// during heavy loads. Realtime threads have a runtime cost, so ensure no more than three realtime
// audio threads can be created simultaneously.
// FIXME: Coalesce these threads to allow a single realtime thread to service every audio instance.
bool shouldCreateRealtimeThread = [] {
Locker threadLocker { Thread::allThreadsLock() };
uint8_t numberOfRealtimeThreads = 0;
for (RefPtr thread : Thread::allThreads()) {
if (thread && thread->isRealtime())
++numberOfRealtimeThreads;
}
return numberOfRealtimeThreads < s_maximumConcurrentRealtimeThreads;
}();
auto schedulingPolicy = shouldCreateRealtimeThread ? Thread::SchedulingPolicy::Realtime : Thread::SchedulingPolicy::Other;
auto thread = Thread::create(threadName, WTFMove(entryPoint), ThreadType::Audio, Thread::QOS::UserInteractive, schedulingPolicy);
#if HAVE(THREAD_TIME_CONSTRAINTS)
if (shouldCreateRealtimeThread) {
// Add thread time constraints to allow the system to ensure contiguous scheduling for this thread
auto renderingQuantumDuration = MonotonicTime::fromRawSeconds(rawRenderingQuantumDuration.seconds());
auto renderingTimeConstraint = MonotonicTime::fromRawSeconds(rawRenderingQuantumDuration.seconds() * 2);
thread->setThreadTimeConstraints(renderingQuantumDuration, renderingQuantumDuration, renderingTimeConstraint, true);
}
#else
UNUSED_PARAM(rawRenderingQuantumDuration);
#endif
// Roughly match the priority of the Audio IO thread in the GPU process.
thread->changePriority(60);
return thread;
}
}
|
