1 files changed, 78 insertions, 0 deletions
diff --git a/dom/media/UnderrunHandlerLinux.cpp b/dom/media/UnderrunHandlerLinux.cpp
new file mode 100644
index 0000000000..05646fbeb8
--- /dev/null
+++ b/dom/media/UnderrunHandlerLinux.cpp
@@ -0,0 +1,78 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <csignal>
+#include <cerrno>
+#include <pthread.h>
+
+#include <mozilla/Sprintf.h>
+#include <mozilla/Atomics.h>
+#include "audio_thread_priority.h"
+#include "nsDebug.h"
+
+namespace mozilla {
+
+Atomic<bool, MemoryOrdering::ReleaseAcquire> gRealtimeLimitReached;
+
+void UnderrunHandler(int signum) { gRealtimeLimitReached = true; }
+
+bool SoftRealTimeLimitReached() { return gRealtimeLimitReached; }
+
+void InstallSoftRealTimeLimitHandler() {
+  struct sigaction action, previous;
+
+  action.sa_handler = UnderrunHandler;
+  sigemptyset(&action.sa_mask);
+  action.sa_flags = 0;
+
+  int rv = sigaction(SIGXCPU, &action, &previous);
+  if (rv != 0) {
+    char buf[256];
+    SprintfLiteral(buf, "sigaction(SIGXCPU, ...): %s", strerror(errno));
+    NS_WARNING(buf);
+    return;
+  }
+
+  void* previous_handler = previous.sa_flags == SA_SIGINFO
+                               ? reinterpret_cast<void*>(previous.sa_sigaction)
+                               : reinterpret_cast<void*>(previous.sa_handler);
+
+  MOZ_ASSERT(previous_handler != UnderrunHandler,
+             "Only install the SIGXCPU handler once per process.");
+
+  if (previous_handler != SIG_DFL && previous_handler != UnderrunHandler) {
+    NS_WARNING(
+        "SIGXCPU handler was already set by something else, dropping real-time "
+        "priority.");
+    rv = sigaction(SIGXCPU, &previous, nullptr);
+    if (rv != 0) {
+      NS_WARNING("Could not restore previous handler for SIGXCPU.");
+    }
+    gRealtimeLimitReached = true;
+    return;
+  }
+
+  gRealtimeLimitReached = false;
+}
+
+void DemoteThreadFromRealTime() {
+  atp_thread_info* info = atp_get_current_thread_info();
+  if (!info) {
+    NS_WARNING("Could not get current thread info when demoting thread.");
+    return;
+  }
+  int rv = atp_demote_thread_from_real_time(info);
+  if (rv) {
+    NS_WARNING("Could not demote thread from real-time.");
+    return;
+  }
+  rv = atp_free_thread_info(info);
+  if (rv) {
+    NS_WARNING("Could not free atp_thread_info struct");
+  }
+  gRealtimeLimitReached = false;
+}
+
+}  // namespace mozilla