tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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UnderrunHandlerLinux.cpp (2323B)

      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 <mozilla/Atomics.h>
      7 #include <mozilla/Sprintf.h>
      8 #include <pthread.h>
      9 
     10 #include <cerrno>
     11 #include <csignal>
     12 
     13 #include "audio_thread_priority.h"
     14 #include "nsDebug.h"
     15 
     16 namespace mozilla {
     17 
     18 Atomic<bool, MemoryOrdering::ReleaseAcquire> gRealtimeLimitReached;
     19 
     20 void UnderrunHandler(int signum) { gRealtimeLimitReached = true; }
     21 
     22 bool SoftRealTimeLimitReached() { return gRealtimeLimitReached; }
     23 
     24 void InstallSoftRealTimeLimitHandler() {
     25  struct sigaction action, previous;
     26 
     27  action.sa_handler = UnderrunHandler;
     28  sigemptyset(&action.sa_mask);
     29  action.sa_flags = 0;
     30 
     31  int rv = sigaction(SIGXCPU, &action, &previous);
     32  if (rv != 0) {
     33    char buf[256];
     34    SprintfLiteral(buf, "sigaction(SIGXCPU, ...): %s", strerror(errno));
     35    NS_WARNING(buf);
     36    return;
     37  }
     38 
     39  void* previous_handler = previous.sa_flags == SA_SIGINFO
     40                               ? reinterpret_cast<void*>(previous.sa_sigaction)
     41                               : reinterpret_cast<void*>(previous.sa_handler);
     42 
     43  MOZ_ASSERT(previous_handler != UnderrunHandler,
     44             "Only install the SIGXCPU handler once per process.");
     45 
     46  if (previous_handler != SIG_DFL && previous_handler != UnderrunHandler) {
     47    NS_WARNING(
     48        "SIGXCPU handler was already set by something else, dropping real-time "
     49        "priority.");
     50    rv = sigaction(SIGXCPU, &previous, nullptr);
     51    if (rv != 0) {
     52      NS_WARNING("Could not restore previous handler for SIGXCPU.");
     53    }
     54    gRealtimeLimitReached = true;
     55    return;
     56  }
     57 
     58  gRealtimeLimitReached = false;
     59 }
     60 
     61 void DemoteThreadFromRealTime() {
     62  atp_thread_info* info = atp_get_current_thread_info();
     63  if (!info) {
     64    NS_WARNING("Could not get current thread info when demoting thread.");
     65    return;
     66  }
     67  int rv = atp_demote_thread_from_real_time(info);
     68  if (rv) {
     69    NS_WARNING("Could not demote thread from real-time.");
     70    return;
     71  }
     72  rv = atp_free_thread_info(info);
     73  if (rv) {
     74    NS_WARNING("Could not free atp_thread_info struct");
     75  }
     76  gRealtimeLimitReached = false;
     77 }
     78 
     79 }  // namespace mozilla