Bug 1290625 - Make libcubeb mutex recurse again, to avoid deadlock when getting microphone. r=achronop

MozReview-Commit-ID: AvYa8ylsdOf

--HG--
extra : rebase_source : 51d340d1607c78002fda6c665932fb966c66a298

media/libcubeb/src/cubeb_utils_unix.h

@@ -0,0 +1,81 @@
+/*
+ * Copyright © 2016 Mozilla Foundation
+ *
+ * This program is made available under an ISC-style license.  See the
+ * accompanying file LICENSE for details.
+ */
+
+#if !defined(CUBEB_UTILS_UNIX)
+#define CUBEB_UTILS_UNIX
+
+#include <pthread.h>
+#include <errno.h>
+#include <stdio.h>
+
+/* This wraps a critical section to track the owner in debug mode. */
+class owned_critical_section
+{
+public:
+  owned_critical_section()
+  {
+    pthread_mutexattr_t attr;
+    pthread_mutexattr_init(&attr);
+    pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+
+#ifdef DEBUG
+    int r =
+#endif
+    pthread_mutex_init(&mutex, &attr);
+#ifdef DEBUG
+    assert(r == 0);
+#endif
+
+    pthread_mutexattr_destroy(&attr);
+  }
+
+  ~owned_critical_section()
+  {
+#ifdef DEBUG
+    int r =
+#endif
+    pthread_mutex_destroy(&mutex);
+#ifdef DEBUG
+    assert(r == 0);
+#endif
+  }
+
+  void enter()
+  {
+#ifdef DEBUG
+    int r =
+#endif
+    pthread_mutex_lock(&mutex);
+#ifdef DEBUG
+    assert(r == 0 && "Deadlock");
+#endif
+  }
+
+  void leave()
+  {
+#ifdef DEBUG
+    int r =
+#endif
+    pthread_mutex_unlock(&mutex);
+#ifdef DEBUG
+    assert(r == 0 && "Unlocking unlocked mutex");
+#endif
+  }
+
+  void assert_current_thread_owns()
+  {
+#ifdef DEBUG
+    int r = pthread_mutex_lock(&mutex);
+    assert(r == EDEADLK);
+#endif
+  }
+
+private:
+  pthread_mutex_t mutex;
+};
+
+#endif /* CUBEB_UTILS_UNIX */