src: split darwin threading code from the generic posix implementation

src/Makefile.am

@@ -248,7 +248,7 @@ SOURCES_libvlc_darwin = \
 	darwin/dirs.c \
 	posix/filesystem.c \
 	posix/plugin.c \
-	posix/thread.c \
+	darwin/thread.c \
 	posix/timer.c \
 	darwin/specific.c \
 	posix/rand.c \

src/darwin/thread.c

+/*****************************************************************************
+ * thread.c : pthread back-end for LibVLC
+ *****************************************************************************
+ * Copyright (C) 1999-2013 VLC authors and VideoLAN
+ *
+ * Authors: Jean-Marc Dressler <polux@via.ecp.fr>
+ *          Samuel Hocevar <sam@zoy.org>
+ *          Gildas Bazin <gbazin@netcourrier.com>
+ *          Clément Sténac
+ *          Rémi Denis-Courmont
+ *          Felix Paul Kühne <fkuehne # videolan.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <vlc_common.h>
+#include <vlc_atomic.h>
+
+#include "libvlc.h"
+#include <stdarg.h>
+#include <signal.h>
+#include <errno.h>
+#include <time.h>
+#include <assert.h>
+
+#include <sys/types.h>
+#include <unistd.h> /* fsync() */
+#include <pthread.h>
+#include <sched.h>
+
+#include <mach/mach_init.h> /* mach_task_self in semaphores */
+
+#include <execinfo.h>
+
+#include <sys/time.h> /* gettimeofday() */
+
+#define vlc_clock_setup() (void)0
+#warning Monotonic clock not available. Expect timing issues.
+
+static struct timespec mtime_to_ts (mtime_t date)
+{
+    lldiv_t d = lldiv (date, CLOCK_FREQ);
+    struct timespec ts = { d.quot, d.rem * (1000000000 / CLOCK_FREQ) };
+
+    return ts;
+}
+
+/**
+ * Print a backtrace to the standard error for debugging purpose.
+ */
+void vlc_trace (const char *fn, const char *file, unsigned line)
+{
+     fprintf (stderr, "at %s:%u in %s\n", file, line, fn);
+     fflush (stderr); /* needed before switch to low-level I/O */
+#ifdef HAVE_BACKTRACE
+     void *stack[20];
+     int len = backtrace (stack, sizeof (stack) / sizeof (stack[0]));
+     backtrace_symbols_fd (stack, len, 2);
+#endif
+     fsync (2);
+}
+
+static inline unsigned long vlc_threadid (void)
+{
+     union { pthread_t th; unsigned long int i; } v = { };
+     v.th = pthread_self ();
+     return v.i;
+}
+
+#ifndef NDEBUG
+/**
+ * Reports a fatal error from the threading layer, for debugging purposes.
+ */
+static void
+vlc_thread_fatal (const char *action, int error,
+                  const char *function, const char *file, unsigned line)
+{
+    int canc = vlc_savecancel ();
+    fprintf (stderr, "LibVLC fatal error %s (%d) in thread %lu ",
+             action, error, vlc_threadid ());
+    vlc_trace (function, file, line);
+
+    char buf[1000];
+    const char *msg;
+
+    switch (strerror_r (error, buf, sizeof (buf)))
+    {
+        case 0:
+            msg = buf;
+            break;
+        case ERANGE: /* should never happen */
+            msg = "unknown (too big to display)";
+            break;
+        default:
+            msg = "unknown (invalid error number)";
+            break;
+    }
+    fprintf (stderr, " Error message: %s\n", msg);
+    fflush (stderr);
+
+    vlc_restorecancel (canc);
+    abort ();
+}
+
+# define VLC_THREAD_ASSERT( action ) \
+    if (unlikely(val)) \
+        vlc_thread_fatal (action, val, __func__, __FILE__, __LINE__)
+#else
+# define VLC_THREAD_ASSERT( action ) ((void)val)
+#endif
+
+/**
+ * Initializes a fast mutex.
+ */
+void vlc_mutex_init( vlc_mutex_t *p_mutex )
+{
+    pthread_mutexattr_t attr;
+
+    if (unlikely(pthread_mutexattr_init (&attr)))
+        abort();
+#ifdef NDEBUG
+    pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_DEFAULT);
+#else
+    pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_ERRORCHECK);
+#endif
+    if (unlikely(pthread_mutex_init (p_mutex, &attr)))
+        abort();
+    pthread_mutexattr_destroy( &attr );
+}
+
+/**
+ * Initializes a recursive mutex.
+ * \warning This is strongly discouraged. Please use normal mutexes.
+ */
+void vlc_mutex_init_recursive( vlc_mutex_t *p_mutex )
+{
+    pthread_mutexattr_t attr;
+
+    if (unlikely(pthread_mutexattr_init (&attr)))
+        abort();
+    pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE);
+    if (unlikely(pthread_mutex_init (p_mutex, &attr)))
+        abort();
+    pthread_mutexattr_destroy( &attr );
+}
+
+
+/**
+ * Destroys a mutex. The mutex must not be locked.
+ *
+ * @param p_mutex mutex to destroy
+ * @return always succeeds
+ */
+void vlc_mutex_destroy (vlc_mutex_t *p_mutex)
+{
+    int val = pthread_mutex_destroy( p_mutex );
+    VLC_THREAD_ASSERT ("destroying mutex");
+}
+
+#ifndef NDEBUG
+# ifdef HAVE_VALGRIND_VALGRIND_H
+#  include <valgrind/valgrind.h>
+# else
+#  define RUNNING_ON_VALGRIND (0)
+# endif
+
+/**
+ * Asserts that a mutex is locked by the calling thread.
+ */
+void vlc_assert_locked (vlc_mutex_t *p_mutex)
+{
+    if (RUNNING_ON_VALGRIND > 0)
+        return;
+    assert (pthread_mutex_lock (p_mutex) == EDEADLK);
+}
+#endif
+
+/**
+ * Acquires a mutex. If needed, waits for any other thread to release it.
+ * Beware of deadlocks when locking multiple mutexes at the same time,
+ * or when using mutexes from callbacks.
+ * This function is not a cancellation-point.
+ *
+ * @param p_mutex mutex initialized with vlc_mutex_init() or
+ *                vlc_mutex_init_recursive()
+ */
+void vlc_mutex_lock (vlc_mutex_t *p_mutex)
+{
+    int val = pthread_mutex_lock( p_mutex );
+    VLC_THREAD_ASSERT ("locking mutex");
+}
+
+/**
+ * Acquires a mutex if and only if it is not currently held by another thread.
+ * This function never sleeps and can be used in delay-critical code paths.
+ * This function is not a cancellation-point.
+ *
+ * <b>Beware</b>: If this function fails, then the mutex is held... by another
+ * thread. The calling thread must deal with the error appropriately. That
+ * typically implies postponing the operations that would have required the
+ * mutex. If the thread cannot defer those operations, then it must use
+ * vlc_mutex_lock(). If in doubt, use vlc_mutex_lock() instead.
+ *
+ * @param p_mutex mutex initialized with vlc_mutex_init() or
+ *                vlc_mutex_init_recursive()
+ * @return 0 if the mutex could be acquired, an error code otherwise.
+ */
+int vlc_mutex_trylock (vlc_mutex_t *p_mutex)
+{
+    int val = pthread_mutex_trylock( p_mutex );
+
+    if (val != EBUSY)
+        VLC_THREAD_ASSERT ("locking mutex");
+    return val;
+}
+
+/**
+ * Releases a mutex (or crashes if the mutex is not locked by the caller).
+ * @param p_mutex mutex locked with vlc_mutex_lock().
+ */
+void vlc_mutex_unlock (vlc_mutex_t *p_mutex)
+{
+    int val = pthread_mutex_unlock( p_mutex );
+    VLC_THREAD_ASSERT ("unlocking mutex");
+}
+
+/**
+ * Initializes a condition variable.
+ */
+void vlc_cond_init (vlc_cond_t *p_condvar)
+{
+    pthread_condattr_t attr;
+
+    if (unlikely(pthread_condattr_init (&attr)))
+        abort ();
+
+    if (unlikely(pthread_cond_init (p_condvar, &attr)))
+        abort ();
+    pthread_condattr_destroy (&attr);
+}
+
+/**
+ * Initializes a condition variable.
+ * Contrary to vlc_cond_init(), the wall clock will be used as a reference for
+ * the vlc_cond_timedwait() time-out parameter.
+ */
+void vlc_cond_init_daytime (vlc_cond_t *p_condvar)
+{
+    if (unlikely(pthread_cond_init (p_condvar, NULL)))
+        abort ();
+}
+
+/**
+ * Destroys a condition variable. No threads shall be waiting or signaling the
+ * condition.
+ * @param p_condvar condition variable to destroy
+ */
+void vlc_cond_destroy (vlc_cond_t *p_condvar)
+{
+    int val = pthread_cond_destroy( p_condvar );
+
+    /* due to a faulty pthread implementation within Darwin 11 and
+     * later condition variables cannot be destroyed without
+     * terminating the application immediately.
+     * This Darwin kernel issue is still present in version 13
+     * and might not be resolved prior to Darwin 15.
+     * radar://12496249
+     *
+     * To work-around this, we are just leaking the condition variable
+     * which is acceptable due to VLC's low number of created variables
+     * and its usually limited runtime.
+     * Ideally, we should implement a re-useable pool.
+     */
+    if (val != 0) {
+        #ifndef NDEBUG
+        printf("pthread_cond_destroy returned %i\n", val);
+        #endif
+
+        if (val == EBUSY)
+            return;
+    }
+
+    VLC_THREAD_ASSERT ("destroying condition");
+}
+
+/**
+ * Wakes up one thread waiting on a condition variable, if any.
+ * @param p_condvar condition variable
+ */
+void vlc_cond_signal (vlc_cond_t *p_condvar)
+{
+    int val = pthread_cond_signal( p_condvar );
+    VLC_THREAD_ASSERT ("signaling condition variable");
+}
+
+/**
+ * Wakes up all threads (if any) waiting on a condition variable.
+ * @param p_cond condition variable
+ */
+void vlc_cond_broadcast (vlc_cond_t *p_condvar)
+{
+    pthread_cond_broadcast (p_condvar);
+}
+
+/**
+ * Waits for a condition variable. The calling thread will be suspended until
+ * another thread calls vlc_cond_signal() or vlc_cond_broadcast() on the same
+ * condition variable, the thread is cancelled with vlc_cancel(), or the
+ * system causes a "spurious" unsolicited wake-up.
+ *
+ * A mutex is needed to wait on a condition variable. It must <b>not</b> be
+ * a recursive mutex. Although it is possible to use the same mutex for
+ * multiple condition, it is not valid to use different mutexes for the same
+ * condition variable at the same time from different threads.
+ *
+ * In case of thread cancellation, the mutex is always locked before
+ * cancellation proceeds.
+ *
+ * The canonical way to use a condition variable to wait for event foobar is:
+ @code
+   vlc_mutex_lock (&lock);
+   mutex_cleanup_push (&lock); // release the mutex in case of cancellation
+
+   while (!foobar)
+       vlc_cond_wait (&wait, &lock);
+
+   --- foobar is now true, do something about it here --
+
+   vlc_cleanup_run (); // release the mutex
+  @endcode
+ *
+ * @param p_condvar condition variable to wait on
+ * @param p_mutex mutex which is unlocked while waiting,
+ *                then locked again when waking up.
+ * @param deadline <b>absolute</b> timeout
+ */
+void vlc_cond_wait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex)
+{
+    int val = pthread_cond_wait( p_condvar, p_mutex );
+    VLC_THREAD_ASSERT ("waiting on condition");
+}
+
+/**
+ * Waits for a condition variable up to a certain date.
+ * This works like vlc_cond_wait(), except for the additional time-out.
+ *
+ * If the variable was initialized with vlc_cond_init(), the timeout has the
+ * same arbitrary origin as mdate(). If the variable was initialized with
+ * vlc_cond_init_daytime(), the timeout is expressed from the Unix epoch.
+ *
+ * @param p_condvar condition variable to wait on
+ * @param p_mutex mutex which is unlocked while waiting,
+ *                then locked again when waking up.
+ * @param deadline <b>absolute</b> timeout
+ *
+ * @return 0 if the condition was signaled, an error code in case of timeout.
+ */
+int vlc_cond_timedwait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex,
+                        mtime_t deadline)
+{
+    struct timespec ts = mtime_to_ts (deadline);
+    int val = pthread_cond_timedwait (p_condvar, p_mutex, &ts);
+    if (val != ETIMEDOUT)
+        VLC_THREAD_ASSERT ("timed-waiting on condition");
+    return val;
+}
+
+/**
+ * Initializes a semaphore.
+ */
+void vlc_sem_init (vlc_sem_t *sem, unsigned value)
+{
+    if (unlikely(semaphore_create(mach_task_self(), sem, SYNC_POLICY_FIFO, value) != KERN_SUCCESS))
+        abort ();
+}
+
+/**
+ * Destroys a semaphore.
+ */
+void vlc_sem_destroy (vlc_sem_t *sem)
+{
+    int val;
+
+    if (likely(semaphore_destroy(mach_task_self(), *sem) == KERN_SUCCESS))
+        return;
+
+    val = EINVAL;
+
+    VLC_THREAD_ASSERT ("destroying semaphore");
+}
+
+/**
+ * Increments the value of a semaphore.
+ * @return 0 on success, EOVERFLOW in case of integer overflow
+ */
+int vlc_sem_post (vlc_sem_t *sem)
+{
+    int val;
+
+    if (likely(semaphore_signal(*sem) == KERN_SUCCESS))
+        return 0;
+
+    val = EINVAL;
+
+    if (unlikely(val != EOVERFLOW))
+        VLC_THREAD_ASSERT ("unlocking semaphore");
+    return val;
+}
+
+/**
+ * Atomically wait for the semaphore to become non-zero (if needed),
+ * then decrements it.
+ */
+void vlc_sem_wait (vlc_sem_t *sem)
+{
+    int val;
+
+    if (likely(semaphore_wait(*sem) == KERN_SUCCESS))
+        return;
+
+    val = EINVAL;
+
+    VLC_THREAD_ASSERT ("locking semaphore");
+}
+
+/**
+ * Initializes a read/write lock.
+ */
+void vlc_rwlock_init (vlc_rwlock_t *lock)
+{
+    if (unlikely(pthread_rwlock_init (lock, NULL)))
+        abort ();
+}
+
+/**
+ * Destroys an initialized unused read/write lock.
+ */
+void vlc_rwlock_destroy (vlc_rwlock_t *lock)
+{
+    int val = pthread_rwlock_destroy (lock);
+    VLC_THREAD_ASSERT ("destroying R/W lock");
+}
+
+/**
+ * Acquires a read/write lock for reading. Recursion is allowed.
+ * @note This function may be a point of cancellation.
+ */
+void vlc_rwlock_rdlock (vlc_rwlock_t *lock)
+{
+    int val = pthread_rwlock_rdlock (lock);
+    VLC_THREAD_ASSERT ("acquiring R/W lock for reading");
+}
+
+/**
+ * Acquires a read/write lock for writing. Recursion is not allowed.
+ * @note This function may be a point of cancellation.
+ */
+void vlc_rwlock_wrlock (vlc_rwlock_t *lock)
+{
+    int val = pthread_rwlock_wrlock (lock);
+    VLC_THREAD_ASSERT ("acquiring R/W lock for writing");
+}
+
+/**
+ * Releases a read/write lock.
+ */
+void vlc_rwlock_unlock (vlc_rwlock_t *lock)
+{
+    int val = pthread_rwlock_unlock (lock);
+    VLC_THREAD_ASSERT ("releasing R/W lock");
+}
+
+/**
+ * Allocates a thread-specific variable.
+ * @param key where to store the thread-specific variable handle
+ * @param destr a destruction callback. It is called whenever a thread exits
+ * and the thread-specific variable has a non-NULL value.
+ * @return 0 on success, a system error code otherwise. This function can
+ * actually fail because there is a fixed limit on the number of
+ * thread-specific variable in a process on most systems.
+ */
+int vlc_threadvar_create (vlc_threadvar_t *key, void (*destr) (void *))
+{
+    return pthread_key_create (key, destr);
+}
+
+void vlc_threadvar_delete (vlc_threadvar_t *p_tls)
+{
+    pthread_key_delete (*p_tls);
+}
+
+/**
+ * Sets a thread-specific variable.
+ * @param key thread-local variable key (created with vlc_threadvar_create())
+ * @param value new value for the variable for the calling thread
+ * @return 0 on success, a system error code otherwise.
+ */
+int vlc_threadvar_set (vlc_threadvar_t key, void *value)
+{
+    return pthread_setspecific (key, value);
+}
+
+/**
+ * Gets the value of a thread-local variable for the calling thread.
+ * This function cannot fail.
+ * @return the value associated with the given variable for the calling
+ * or NULL if there is no value.
+ */
+void *vlc_threadvar_get (vlc_threadvar_t key)
+{
+    return pthread_getspecific (key);
+}
+
+static bool rt_priorities = false;
+static int rt_offset;
+
+void vlc_threads_setup (libvlc_int_t *p_libvlc)
+{
+    static vlc_mutex_t lock = VLC_STATIC_MUTEX;
+    static bool initialized = false;
+
+    vlc_mutex_lock (&lock);
+    /* Initializes real-time priorities before any thread is created,
+     * just once per process. */
+    if (!initialized)
+    {
+        rt_offset = var_InheritInteger (p_libvlc, "rt-offset");
+        rt_priorities = true;
+        initialized = true;
+    }
+    vlc_mutex_unlock (&lock);
+}
+
+
+static int vlc_clone_attr (vlc_thread_t *th, pthread_attr_t *attr,
+                           void *(*entry) (void *), void *data, int priority)
+{
+    int ret;
+
+    /* Block the signals that signals interface plugin handles.
+     * If the LibVLC caller wants to handle some signals by itself, it should
+     * block these before whenever invoking LibVLC. And it must obviously not
+     * start the VLC signals interface plugin.
+     *
+     * LibVLC will normally ignore any interruption caused by an asynchronous
+     * signal during a system call. But there may well be some buggy cases
+     * where it fails to handle EINTR (bug reports welcome). Some underlying
+     * libraries might also not handle EINTR properly.
+     */
+    sigset_t oldset;
+    {
+        sigset_t set;
+        sigemptyset (&set);
+        sigdelset (&set, SIGHUP);
+        sigaddset (&set, SIGINT);
+        sigaddset (&set, SIGQUIT);
+        sigaddset (&set, SIGTERM);
+
+        sigaddset (&set, SIGPIPE); /* We don't want this one, really! */
+        pthread_sigmask (SIG_BLOCK, &set, &oldset);
+    }
+
+    (void) priority;
+
+    /* The thread stack size.
+     * The lower the value, the less address space per thread, the highest
+     * maximum simultaneous threads per process. Too low values will cause
+     * stack overflows and weird crashes. Set with caution. Also keep in mind
+     * that 64-bits platforms consume more stack than 32-bits one.
+     *
+     * Thanks to on-demand paging, thread stack size only affects address space
+     * consumption. In terms of memory, threads only use what they need
+     * (rounded up to the page boundary).
+     *
+     * For example, on Linux i386, the default is 2 mega-bytes, which supports
+     * about 320 threads per processes. */
+#define VLC_STACKSIZE (128 * sizeof (void *) * 1024)
+
+#ifdef VLC_STACKSIZE
+    ret = pthread_attr_setstacksize (attr, VLC_STACKSIZE);
+    assert (ret == 0); /* fails iif VLC_STACKSIZE is invalid */
+#endif
+
+    ret = pthread_create (th, attr, entry, data);
+    pthread_sigmask (SIG_SETMASK, &oldset, NULL);
+    pthread_attr_destroy (attr);
+    return ret;
+}
+
+/**
+ * Creates and starts new thread.
+ *
+ * The thread must be <i>joined</i> with vlc_join() to reclaim resources
+ * when it is not needed anymore.
+ *
+ * @param th [OUT] pointer to write the handle of the created thread to
+ *                 (mandatory, must be non-NULL)
+ * @param entry entry point for the thread
+ * @param data data parameter given to the entry point
+ * @param priority thread priority value
+ * @return 0 on success, a standard error code on error.
+ */
+int vlc_clone (vlc_thread_t *th, void *(*entry) (void *), void *data,
+               int priority)
+{
+    pthread_attr_t attr;
+
+    pthread_attr_init (&attr);
+    return vlc_clone_attr (th, &attr, entry, data, priority);
+}
+
+/**
+ * Waits for a thread to complete (if needed), then destroys it.
+ * This is a cancellation point; in case of cancellation, the join does _not_
+ * occur.
+ * @warning