lock: Improve performance of DEBUG_THREADS.

Add a volatile flag to lock tracking structures so we only need to use
the global lock when first initializing tracking.

Additionally add support for DEBUG_THREADS_LOOSE_ABI.  This is used by
astobj2.c to eliminate storage for tracking fields when DEBUG_THREADS is
not defined.

Change-Id: Iabd650908901843e9fff47ef1c539f0e1b8cb13b

diff --git a/include/asterisk/astobj2.h b/include/asterisk/astobj2.h
index 74f8f61f9985345d68aa8aa0919c6b97a328053e..03752015c3f2fa16e53674add55783c3fea3bd79 100644 (file)
--- a/include/asterisk/astobj2.h
+++ b/include/asterisk/astobj2.h
@@ -634,6 +634,9 @@ int __ao2_trylock(void *a, enum ao2_lock_req lock_how, const char *file, const c
  * lock address, this allows you to correlate against
  * object address, to match objects to reported locks.
  *
+ * \warning AO2 lock objects do not include tracking fields when
+ * DEBUG_THREADS is not enabled.
+ *
  * \since 1.6.1
  */
 void *ao2_object_get_lockaddr(void *obj);

diff --git a/include/asterisk/lock.h b/include/asterisk/lock.h
index 652ca136eaece13ab89776455638ea824f0ca917..5b596d2894b45e5d2ddc468e0a5f52c9b0d981a2 100644 (file)
--- a/include/asterisk/lock.h
+++ b/include/asterisk/lock.h
@@ -92,11 +92,11 @@
 #define AST_LOCK_TRACK_INIT_VALUE { { NULL }, { 0 }, 0, { NULL }, { 0 }, PTHREAD_MUTEX_INIT_VALUE }
 #endif
 
-#define AST_MUTEX_INIT_VALUE { PTHREAD_MUTEX_INIT_VALUE, NULL, 1 }
-#define AST_MUTEX_INIT_VALUE_NOTRACKING { PTHREAD_MUTEX_INIT_VALUE, NULL, 0 }
+#define AST_MUTEX_INIT_VALUE { PTHREAD_MUTEX_INIT_VALUE, NULL, {1, 0} }
+#define AST_MUTEX_INIT_VALUE_NOTRACKING { PTHREAD_MUTEX_INIT_VALUE, NULL, {0, 0} }
 
-#define AST_RWLOCK_INIT_VALUE { __AST_RWLOCK_INIT_VALUE, NULL, 1 }
-#define AST_RWLOCK_INIT_VALUE_NOTRACKING { __AST_RWLOCK_INIT_VALUE, NULL, 0 }
+#define AST_RWLOCK_INIT_VALUE { __AST_RWLOCK_INIT_VALUE, NULL, {1, 0} }
+#define AST_RWLOCK_INIT_VALUE_NOTRACKING { __AST_RWLOCK_INIT_VALUE, NULL, {0, 0} }
 
 #define AST_MAX_REENTRANCY 10
 
@@ -120,6 +120,13 @@ struct ast_lock_track {
        pthread_mutex_t reentr_mutex;
 };
 
+struct ast_lock_track_flags {
+       /*! non-zero if lock tracking is enabled */
+       unsigned int tracking:1;
+       /*! non-zero if track is setup */
+       volatile unsigned int setup:1;
+};
+
 /*! \brief Structure for mutex and tracking information.
  *
  * We have tracking information in this structure regardless of DEBUG_THREADS being enabled.
@@ -127,9 +134,18 @@ struct ast_lock_track {
  */
 struct ast_mutex_info {
        pthread_mutex_t mutex;
-       /*! Track which thread holds this mutex */
+#if !defined(DEBUG_THREADS) && !defined(DEBUG_THREADS_LOOSE_ABI)
+       /*!
+        * These fields are renamed to ensure they are never used when
+        * DEBUG_THREADS is not defined.
+        */
+       struct ast_lock_track *_track;
+       struct ast_lock_track_flags _flags;
+#elif defined(DEBUG_THREADS)
+       /*! Track which thread holds this mutex. */
        struct ast_lock_track *track;
-       unsigned int tracking:1;
+       struct ast_lock_track_flags flags;
+#endif
 };
 
 /*! \brief Structure for rwlock and tracking information.
@@ -139,9 +155,18 @@ struct ast_mutex_info {
  */
 struct ast_rwlock_info {
        pthread_rwlock_t lock;
+#if !defined(DEBUG_THREADS) && !defined(DEBUG_THREADS_LOOSE_ABI)
+       /*!
+        * These fields are renamed to ensure they are never used when
+        * DEBUG_THREADS is not defined.
+        */
+       struct ast_lock_track *_track;
+       struct ast_lock_track_flags _flags;
+#elif defined(DEBUG_THREADS)
        /*! Track which thread holds this lock */
        struct ast_lock_track *track;
-       unsigned int tracking:1;
+       struct ast_lock_track_flags flags;
+#endif
 };
 
 typedef struct ast_mutex_info ast_mutex_t;

diff --git a/main/astobj2.c b/main/astobj2.c
index 825c3c8e61446aa3bbefaccc74e2e1cc3ad98dd4..95c922721634dc92a9e72d03278deee07a046087 100644 (file)
--- a/main/astobj2.c
+++ b/main/astobj2.c
@@ -25,6 +25,10 @@
        <support_level>core</support_level>
  ***/
 
+/* This reduces the size of lock structures within astobj2 objects when
+ * DEBUG_THREADS is not defined. */
+#define DEBUG_THREADS_LOOSE_ABI
+
 #include "asterisk.h"
 
 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

diff --git a/main/lock.c b/main/lock.c
index c196c56afde0cd110473476f0c330984848ecb58..23dff4f7375f40ed33c7a0ac7a6fc47010d39868 100644 (file)
--- a/main/lock.c
+++ b/main/lock.c
@@ -65,21 +65,16 @@ static void __dump_backtrace(struct ast_bt *bt, int canlog)
 #ifdef DEBUG_THREADS
 AST_MUTEX_DEFINE_STATIC(reentrancy_lock);
 
-static inline struct ast_lock_track *ast_get_reentrancy(struct ast_lock_track **plt)
+static inline struct ast_lock_track *ast_get_reentrancy(struct ast_lock_track **plt,
+       struct ast_lock_track_flags *flags, int no_setup)
 {
        pthread_mutexattr_t reentr_attr;
        struct ast_lock_track *lt;
 
-       /* It's a bit painful to lock a global mutex for every access to the
-        * reentrancy structure, but it's necessary to ensure that we don't
-        * double-allocate the structure or double-initialize the reentr_mutex.
-        *
-        * If you'd like to replace this with a double-checked lock, be sure to
-        * properly volatile-ize everything to avoid optimizer bugs.
-        *
-        * We also have to use the underlying pthread calls for manipulating
-        * the mutex, because this is called from the Asterisk mutex code.
-        */
+       if (!flags->tracking || flags->setup) {
+               return *plt;
+       }
+
        pthread_mutex_lock(&reentrancy_lock.mutex);
 
        if (*plt) {
@@ -87,6 +82,11 @@ static inline struct ast_lock_track *ast_get_reentrancy(struct ast_lock_track **
                return *plt;
        }
 
+       if (no_setup) {
+               pthread_mutex_unlock(&reentrancy_lock.mutex);
+               return NULL;
+       }
+
        lt = *plt = ast_std_calloc(1, sizeof(*lt));
        if (!lt) {
                fprintf(stderr, "%s: Failed to allocate lock tracking\n", __func__);
@@ -103,6 +103,7 @@ static inline struct ast_lock_track *ast_get_reentrancy(struct ast_lock_track **
        pthread_mutex_init(&lt->reentr_mutex, &reentr_attr);
        pthread_mutexattr_destroy(&reentr_attr);
 
+       flags->setup = 1;
        pthread_mutex_unlock(&reentrancy_lock.mutex);
        return lt;
 }
@@ -141,7 +142,8 @@ int __ast_pthread_mutex_init(int tracking, const char *filename, int lineno, con
 #endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
 
        t->track = NULL;
-       t->tracking = tracking;
+       t->flags.tracking = tracking;
+       t->flags.setup = 0;
 #endif /* DEBUG_THREADS */
 
        pthread_mutexattr_init(&attr);
@@ -158,8 +160,8 @@ int __ast_pthread_mutex_destroy(const char *filename, int lineno, const char *fu
        int res;
 
 #ifdef DEBUG_THREADS
-       struct ast_lock_track *lt = t->track;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 1);
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 
 #if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
        if ((t->mutex) == ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
@@ -236,16 +238,12 @@ int __ast_pthread_mutex_lock(const char *filename, int lineno, const char *func,
        int res;
 
 #ifdef DEBUG_THREADS
-       struct ast_lock_track *lt = NULL;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 #ifdef HAVE_BKTR
        struct ast_bt *bt = NULL;
 #endif
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
        if (lt) {
 #ifdef HAVE_BKTR
                struct ast_bt tmp;
@@ -360,16 +358,12 @@ int __ast_pthread_mutex_trylock(const char *filename, int lineno, const char *fu
        int res;
 
 #ifdef DEBUG_THREADS
-       struct ast_lock_track *lt = NULL;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 #ifdef HAVE_BKTR
        struct ast_bt *bt = NULL;
 #endif
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
        if (lt) {
 #ifdef HAVE_BKTR
                struct ast_bt tmp;
@@ -425,7 +419,7 @@ int __ast_pthread_mutex_unlock(const char *filename, int lineno, const char *fun
 
 #ifdef DEBUG_THREADS
        struct ast_lock_track *lt = NULL;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 #ifdef HAVE_BKTR
        struct ast_bt *bt = NULL;
 #endif
@@ -439,10 +433,7 @@ int __ast_pthread_mutex_unlock(const char *filename, int lineno, const char *fun
        }
 #endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
+       lt = ast_get_reentrancy(&t->track, &t->flags, 0);
        if (lt) {
                ast_reentrancy_lock(lt);
                if (lt->reentrancy && (lt->thread_id[ROFFSET] != pthread_self())) {
@@ -554,7 +545,7 @@ int __ast_cond_wait(const char *filename, int lineno, const char *func,
 #ifdef DEBUG_THREADS
        struct ast_lock_track *lt = NULL;
        struct ast_lock_track lt_orig;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 
 #if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
        if ((t->mutex) == ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
@@ -565,10 +556,7 @@ int __ast_cond_wait(const char *filename, int lineno, const char *func,
        }
 #endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
+       lt = ast_get_reentrancy(&t->track, &t->flags, 0);
        if (lt) {
                ast_reentrancy_lock(lt);
                if (lt->reentrancy && (lt->thread_id[ROFFSET] != pthread_self())) {
@@ -622,7 +610,7 @@ int __ast_cond_timedwait(const char *filename, int lineno, const char *func,
 #ifdef DEBUG_THREADS
        struct ast_lock_track *lt = NULL;
        struct ast_lock_track lt_orig;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 
 #if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
        if ((t->mutex) == ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
@@ -633,10 +621,7 @@ int __ast_cond_timedwait(const char *filename, int lineno, const char *func,
        }
 #endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
+       lt = ast_get_reentrancy(&t->track, &t->flags, 0);
        if (lt) {
                ast_reentrancy_lock(lt);
                if (lt->reentrancy && (lt->thread_id[ROFFSET] != pthread_self())) {
@@ -699,7 +684,8 @@ int __ast_rwlock_init(int tracking, const char *filename, int lineno, const char
 #endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
 
        t->track = NULL;
-       t->tracking = tracking;
+       t->flags.tracking = tracking;
+       t->flags.setup = 0;
 #endif /* DEBUG_THREADS */
 
        pthread_rwlockattr_init(&attr);
@@ -717,8 +703,8 @@ int __ast_rwlock_destroy(const char *filename, int lineno, const char *func, con
        int res;
 
 #ifdef DEBUG_THREADS
-       struct ast_lock_track *lt = t->track;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 1);
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 
 #if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
        if (t->lock == ((pthread_rwlock_t) __AST_RWLOCK_INIT_VALUE)) {
@@ -765,7 +751,7 @@ int __ast_rwlock_unlock(const char *filename, int line, const char *func, ast_rw
 
 #ifdef DEBUG_THREADS
        struct ast_lock_track *lt = NULL;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 #ifdef HAVE_BKTR
        struct ast_bt *bt = NULL;
 #endif
@@ -780,10 +766,7 @@ int __ast_rwlock_unlock(const char *filename, int line, const char *func, ast_rw
        }
 #endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
+       lt = ast_get_reentrancy(&t->track, &t->flags, 0);
        if (lt) {
                ast_reentrancy_lock(lt);
                if (lt->reentrancy) {
@@ -844,16 +827,12 @@ int __ast_rwlock_rdlock(const char *filename, int line, const char *func, ast_rw
        int res;
 
 #ifdef DEBUG_THREADS
-       struct ast_lock_track *lt = NULL;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 #ifdef HAVE_BKTR
        struct ast_bt *bt = NULL;
 #endif
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
        if (lt) {
 #ifdef HAVE_BKTR
                struct ast_bt tmp;
@@ -953,16 +932,12 @@ int __ast_rwlock_wrlock(const char *filename, int line, const char *func, ast_rw
        int res;
 
 #ifdef DEBUG_THREADS
-       struct ast_lock_track *lt = NULL;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 #ifdef HAVE_BKTR
        struct ast_bt *bt = NULL;
 #endif
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
        if (lt) {
 #ifdef HAVE_BKTR
                struct ast_bt tmp;
@@ -1062,16 +1037,12 @@ int __ast_rwlock_timedrdlock(const char *filename, int line, const char *func, a
        int res;
 
 #ifdef DEBUG_THREADS
-       struct ast_lock_track *lt = NULL;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 #ifdef HAVE_BKTR
        struct ast_bt *bt = NULL;
 #endif
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
        if (lt) {
 #ifdef HAVE_BKTR
                struct ast_bt tmp;
@@ -1155,16 +1126,12 @@ int __ast_rwlock_timedwrlock(const char *filename, int line, const char *func, a
        int res;
 
 #ifdef DEBUG_THREADS
-       struct ast_lock_track *lt = NULL;
-       int canlog = t->tracking && strcmp(filename, "logger.c");
+       struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+       int canlog = t->flags.tracking && strcmp(filename, "logger.c");
 #ifdef HAVE_BKTR
        struct ast_bt *bt = NULL;
 #endif
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
        if (lt) {
 #ifdef HAVE_BKTR
                struct ast_bt tmp;
@@ -1247,15 +1214,11 @@ int __ast_rwlock_tryrdlock(const char *filename, int line, const char *func, ast
        int res;
 
 #ifdef DEBUG_THREADS
-       struct ast_lock_track *lt = NULL;
+       struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
 #ifdef HAVE_BKTR
        struct ast_bt *bt = NULL;
 #endif
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
        if (lt) {
 #ifdef HAVE_BKTR
                struct ast_bt tmp;
@@ -1306,15 +1269,11 @@ int __ast_rwlock_trywrlock(const char *filename, int line, const char *func, ast
        int res;
 
 #ifdef DEBUG_THREADS
-       struct ast_lock_track *lt = NULL;
+       struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
 #ifdef HAVE_BKTR
        struct ast_bt *bt = NULL;
 #endif
 
-       if (t->tracking) {
-               lt = ast_get_reentrancy(&t->track);
-       }
-
        if (lt) {
 #ifdef HAVE_BKTR
                struct ast_bt tmp;