Raise the number of nested readers limit 2^16 and 2^32 on 32 and 64-bits arch.

[urcu.git] / urcu.c

diff --git a/urcu.c b/urcu.c
index 232a57bb718fbf12be651cebd6a808b01976c924..5514b278e4322b0f600a6d3427eab700057dc573 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -19,10 +19,10 @@
 
 pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
 
-/* Global quiescent period parity */
-int urcu_qparity;
+/* Global grace period counter */
+int urcu_gp_ctr;
 
-int __thread urcu_active_readers[2];
+int __thread urcu_active_readers;
 
 /* Thread IDs of registered readers */
 #define INIT_NUM_THREADS 4
@@ -32,11 +32,16 @@ struct reader_data {
        int *urcu_active_readers;
 };
 
+#ifdef DEBUG_YIELD
+unsigned int yield_active;
+unsigned int __thread rand_yield;
+#endif
+
 static struct reader_data *reader_data;
 static int num_readers, alloc_readers;
 static int sig_done;
 
-void rcu_write_lock(void)
+void internal_urcu_lock(void)
 {
        int ret;
        ret = pthread_mutex_lock(&urcu_mutex);
@@ -46,7 +51,7 @@ void rcu_write_lock(void)
        }
 }
 
-void rcu_write_unlock(void)
+void internal_urcu_unlock(void)
 {
        int ret;
 
@@ -60,11 +65,9 @@ void rcu_write_unlock(void)
 /*
  * called with urcu_mutex held.
  */
-static int switch_next_urcu_qparity(void)
+static void switch_next_urcu_qparity(void)
 {
-       int old_parity = urcu_qparity;
-       urcu_qparity = 1 - old_parity;
-       return old_parity;
+       urcu_gp_ctr ^= RCU_GP_CTR_BIT;
 }
 
 static void force_mb_all_threads(void)
@@ -76,20 +79,27 @@ static void force_mb_all_threads(void)
         */
        if (!reader_data)
                return;
+       debug_yield_write();
        sig_done = 0;
+       debug_yield_write();
        mb();   /* write sig_done before sending the signals */
-       for (index = reader_data; index < reader_data + num_readers; index++)
+       debug_yield_write();
+       for (index = reader_data; index < reader_data + num_readers; index++) {
                pthread_kill(index->tid, SIGURCU);
+               debug_yield_write();
+       }
        /*
         * Wait for sighandler (and thus mb()) to execute on every thread.
         * BUSY-LOOP.
         */
        while (sig_done < num_readers)
                barrier();
+       debug_yield_write();
        mb();   /* read sig_done before ending the barrier */
+       debug_yield_write();
 }
 
-void wait_for_quiescent_state(int parity)
+void wait_for_quiescent_state(void)
 {
        struct reader_data *index;
 
@@ -101,7 +111,7 @@ void wait_for_quiescent_state(int parity)
                /*
                 * BUSY-LOOP.
                 */
-               while (index->urcu_active_readers[parity] != 0)
+               while (rcu_old_gp_ongoing(index->urcu_active_readers))
                        barrier();
        }
        /*
@@ -113,41 +123,32 @@ void wait_for_quiescent_state(int parity)
        force_mb_all_threads();
 }
 
-/*
- * Return old pointer, OK to free, no more reference exist.
- * Called under rcu_write_lock.
- */
-void *urcu_publish_content(void **ptr, void *new)
+static void switch_qparity(void)
 {
-       int ret, prev_parity;
-       void *oldptr;
-
-       /*
-        * We can publish the new pointer before we change the current qparity.
-        * Readers seeing the new pointer while being in the previous qparity
-        * window will make us wait until the end of the quiescent state before
-        * we release the unrelated memory area. However, given we hold the
-        * urcu_mutex, we are making sure that no further garbage collection can
-        * occur until we release the mutex, therefore we guarantee that this
-        * given reader will have completed its execution using the new pointer
-        * when the next quiescent state window will be over.
-        */
-       oldptr = *ptr;
-       *ptr = new;
-       /* All threads should read qparity before ptr */
+       /* All threads should read qparity before accessing data structure. */
        /* Write ptr before changing the qparity */
        force_mb_all_threads();
-       prev_parity = switch_next_urcu_qparity();
+       debug_yield_write();
+       switch_next_urcu_qparity();
+       debug_yield_write();
 
        /*
         * Wait for previous parity to be empty of readers.
         */
-       wait_for_quiescent_state(prev_parity);
-       /*
-        * Deleting old data is ok !
-        */
-       
-       return oldptr;
+       wait_for_quiescent_state();
+}
+
+void synchronize_rcu(void)
+{
+       debug_yield_write();
+       internal_urcu_lock();
+       debug_yield_write();
+       switch_qparity();
+       debug_yield_write();
+       switch_qparity();
+       debug_yield_write();
+       internal_urcu_unlock();
+       debug_yield_write();
 }
 
 void urcu_add_reader(pthread_t id)
@@ -171,7 +172,7 @@ void urcu_add_reader(pthread_t id)
        }
        reader_data[num_readers].tid = id;
        /* reference to the TLS of _this_ reader thread. */
-       reader_data[num_readers].urcu_active_readers = urcu_active_readers;
+       reader_data[num_readers].urcu_active_readers = &urcu_active_readers;
        num_readers++;
 }
 
@@ -185,7 +186,7 @@ void urcu_remove_reader(pthread_t id)
 
        assert(reader_data != NULL);
        for (index = reader_data; index < reader_data + num_readers; index++) {
-               if (index->tid == id) {
+               if (pthread_equal(index->tid, id)) {
                        memcpy(index, &reader_data[num_readers - 1],
                                sizeof(struct reader_data));
                        reader_data[num_readers - 1].tid = 0;
@@ -200,17 +201,16 @@ void urcu_remove_reader(pthread_t id)
 
 void urcu_register_thread(void)
 {
-       rcu_write_lock();
+       internal_urcu_lock();
        urcu_add_reader(pthread_self());
-       rcu_write_unlock();
+       internal_urcu_unlock();
 }
 
 void urcu_unregister_thread(void)
 {
-       pthread_t self = pthread_self();
-       rcu_write_lock();
+       internal_urcu_lock();
        urcu_remove_reader(pthread_self());
-       rcu_write_unlock();
+       internal_urcu_unlock();
 }
 
 void sigurcu_handler(int signo, siginfo_t *siginfo, void *context)