dom/media/UnderrunHandlerLinux.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   4  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include <csignal>
   7 #include <cerrno>
   8 #include <pthread.h>
   9
  10 #include <mozilla/Sprintf.h>
  11 #include <mozilla/Atomics.h>
  12 #include "audio_thread_priority.h"
  13 #include "nsDebug.h"
  14
  15 namespace mozilla {
  16
  17 Atomic<bool, MemoryOrdering::ReleaseAcquire> gRealtimeLimitReached;
  18
  19 void UnderrunHandler(int signum) { gRealtimeLimitReached = true; }
  20
  21 bool SoftRealTimeLimitReached() { return gRealtimeLimitReached; }
  22
  23 void InstallSoftRealTimeLimitHandler() {
  24   struct sigaction action, previous;
  25
  26   action.sa_handler = UnderrunHandler;
  27   sigemptyset(&action.sa_mask);
  28   action.sa_flags = 0;
  29
  30   int rv = sigaction(SIGXCPU, &action, &previous);
  31   if (rv != 0) {
  32     char buf[256];
  33     SprintfLiteral(buf, "sigaction(SIGXCPU, ...): %s", strerror(errno));
  34     NS_WARNING(buf);
  35     return;
  36   }
  37
  38   void* previous_handler = previous.sa_flags == SA_SIGINFO
  39                                ? reinterpret_cast<void*>(previous.sa_sigaction)
  40                                : reinterpret_cast<void*>(previous.sa_handler);
  41
  42   MOZ_ASSERT(previous_handler != UnderrunHandler,
  43              "Only install the SIGXCPU handler once per process.");
  44
  45   if (previous_handler != SIG_DFL && previous_handler != UnderrunHandler) {
  46     NS_WARNING(
  47         "SIGXCPU handler was already set by something else, dropping real-time "
  48         "priority.");
  49     rv = sigaction(SIGXCPU, &previous, nullptr);
  50     if (rv != 0) {
  51       NS_WARNING("Could not restore previous handler for SIGXCPU.");
  52     }
  53     gRealtimeLimitReached = true;
  54     return;
  55   }
  56
  57   gRealtimeLimitReached = false;
  58 }
  59
  60 void DemoteThreadFromRealTime() {
  61   atp_thread_info* info = atp_get_current_thread_info();
  62   if (!info) {
  63     NS_WARNING("Could not get current thread info when demoting thread.");
  64     return;
  65   }
  66   int rv = atp_demote_thread_from_real_time(info);
  67   if (rv) {
  68     NS_WARNING("Could not demote thread from real-time.");
  69     return;
  70   }
  71   rv = atp_free_thread_info(info);
  72   if (rv) {
  73     NS_WARNING("Could not free atp_thread_info struct");
  74   }
  75   gRealtimeLimitReached = false;
  76 }
  77
  78 }  // namespace mozilla