Added small description and pthread_mutex_trylock wrapper

1 files changed, 69 insertions, 6 deletions

diff --git a/tools/debug_mutex.h b/tools/debug_mutex.h
index dc25ec7e..38bb12ce 100644
--- a/tools/debug_mutex.h
+++ b/tools/debug_mutex.h
@@ -4,7 +4,7 @@
  * See the main source file 'xineliboutput.c' for copyright information and
  * how to reach the author.
  *
- * $Id: debug_mutex.h,v 1.1 2006-12-19 17:21:50 phintuka Exp $
+ * $Id: debug_mutex.h,v 1.2 2006-12-21 08:07:24 phintuka Exp $
  *
  */
 
@@ -15,20 +15,44 @@
 #  error pthread.h must be included before debug_mutex.h
 #endif
 
+/*
+ * Override pthread_mutex_ calls:
+ *
+ * Change type of each mutex to PTHREAD_MUTEX_ERRORCHECK_NP
+ *
+ * Store line number of last succeed pthread_mutex_lock call 
+ * for each initialized mutex
+ *
+ * Check every pthread_mutex_ call for errors and log all errors
+ *
+ * To help detecting deadlocks and minimize logging:
+ * - Try locking first in pthread_mutex_lock
+ * - If pthread_mutex_trylock fails, log a message and retry.
+ * - When trylock failed, log another message when lock is acquired.
+ *
+ *
+ * NOTE: debugging itself is not thread-safe and may indicate wrong line numbers !
+ *
+ */
+
+#define MAX_DBG_MUTEX 64
 static struct {
   pthread_mutex_t *lock;
   int line;
-} dbgdata[64] = {{NULL,0}};
+} dbgdata[MAX_DBG_MUTEX+1] = {{NULL,0}};
 
 static void dbg_setdata(pthread_mutex_t *mutex, int line)
 {
   int i;
-  for(i=0; i<32; i++)
+  for(i=0; i<MAX_DBG_MUTEX; i++)
     if(dbgdata[i].lock == mutex) {
       dbgdata[i].line = line;
       return;
     }
-    else if(!dbgdata[i].lock) {
+
+  LOGMSG("********** dbg_setdata: new entry (0x%x at %d)", (unsigned long int)mutex, line);
+  for(i=0; i<MAX_DBG_MUTEX; i++)
+    if(!dbgdata[i].lock) {
       dbgdata[i].lock = mutex;
       dbgdata[i].line = line;
       return;
@@ -40,7 +64,7 @@ static void dbg_setdata(pthread_mutex_t *mutex, int line)
 static int dbg_getdata(pthread_mutex_t *mutex, int line)
 {
   int i;
-  for(i=0; i<32; i++)
+  for(i=0; i<MAX_DBG_MUTEX; i++)
     if(dbgdata[i].lock == mutex)
       return dbgdata[i].line;
 
@@ -48,10 +72,24 @@ static int dbg_getdata(pthread_mutex_t *mutex, int line)
   return -1;
 }
 
+static void dbg_deldata(pthread_mutex_t *mutex, int line)
+{
+  int i;
+  for(i=0; i<MAX_DBG_MUTEX; i++)
+    if(dbgdata[i].lock == mutex) {
+      dbgdata[i].lock = NULL;
+      return;
+    }
+
+  LOGMSG("********** dbg_deldata: NO ENTRY ! (%d)", line);
+  return;
+}
+
 static int dbg_init(pthread_mutex_t *mutex, pthread_mutexattr_t *pattr, int line)
 {
   int r;
 
+  errno = 0;
   if(!pattr) {
     pthread_mutexattr_t attr;
     pthread_mutexattr_init(&attr);
@@ -74,11 +112,13 @@ static int dbg_free(pthread_mutex_t *mutex, int line)
 {
   int r;
 
+  errno = 0;
   r = pthread_mutex_destroy(mutex);
 
   if(r) 
     LOGERR("********** dbg_free: pthread_mutex_destroy FAILED at %d ; last lock at %d", 
 	   line, dbg_getdata(mutex, line));
+  dbg_deldata(mutex, line);
 
   return r;
 }
@@ -89,6 +129,7 @@ static int dbg_lock(pthread_mutex_t *mutex, int line)
   /*struct timespec abs_timeout;*/
 
   /* try lock first to reduce logging */
+  errno = 0;
   r = pthread_mutex_trylock(mutex);
   if(!r) {
     dbg_setdata(mutex,line);
@@ -96,12 +137,13 @@ static int dbg_lock(pthread_mutex_t *mutex, int line)
   }
 
   /* try failed - we're going to wait, so log at wait start and end to detect deadlocks */
-  LOGMSG("********** dbg_lock: pthread_mutex_trylock failed at %d (locked at %d)", 
+  LOGERR("********** dbg_lock: pthread_mutex_trylock failed at %d (locked at %d)", 
 	 line, dbg_getdata(mutex, line));
 
   /*  int pthread_mutex_timedlock(pthread_mutex_t *restrict mutex,
       const struct timespec *restrict abs_timeout); */
 
+  errno = 0;
   r = pthread_mutex_lock(mutex);
 
   if(r) 
@@ -113,10 +155,30 @@ static int dbg_lock(pthread_mutex_t *mutex, int line)
  return r;
 }
 
+static int dbg_trylock(pthread_mutex_t *mutex, int line)
+{
+  int r;
+  /*struct timespec abs_timeout;*/
+
+  /* try lock first to reduce logging */
+  errno = 0;
+  r = pthread_mutex_trylock(mutex);
+  if(!r) {
+    dbg_setdata(mutex,line);
+    return r;
+  }
+
+  LOGERR("********** dbg_trylock: pthread_mutex_trylock failed at %d (locked at %d)", 
+	 line, dbg_getdata(mutex, line));
+  
+  return r;
+}
+
 static int dbg_unlock(pthread_mutex_t *mutex, int line)
 {
   int r;
 
+  errno = 0;
   r = pthread_mutex_unlock(mutex);
 
   if(r) 
@@ -129,6 +191,7 @@ static int dbg_unlock(pthread_mutex_t *mutex, int line)
 /* override pthread_ functions with own ones */
 #define pthread_mutex_init(l,a)  dbg_init(l, a, __LINE__)
 #define pthread_mutex_lock(l)    dbg_lock(l, __LINE__)
+#define pthread_mutex_trylock(l) dbg_trylock(l, __LINE__)
 #define pthread_mutex_unlock(l)  dbg_unlock(l, __LINE__)
 #define pthread_mutex_destroy(l) dbg_free(l, __LINE__)