Fix: syscall event rule: emission sites not compared in is_equal

[lttng-tools.git] / src / common / waiter.cpp

diff --git a/src/common/waiter.cpp b/src/common/waiter.cpp
index d185e299720617e64e7514d114e33cea4a0eb386..8d2ba4d696ec228a5f886bc79ef10fa29f34c36e 100644 (file)
--- a/src/common/waiter.cpp
+++ b/src/common/waiter.cpp
@@ -14,10 +14,9 @@
 #include <urcu/futex.h>
 #include <urcu/uatomic.h>
 
-/*
- * Number of busy-loop attempts before waiting on futex.
- */
-#define WAIT_ATTEMPTS 1000
+namespace {
+/* Number of busy-loop attempts before waiting on futex. */
+constexpr auto wait_attempt_count = 1000;
 
 enum waiter_state {
        /* WAITER_WAITING is compared directly (futex compares it). */
@@ -27,36 +26,39 @@ enum waiter_state {
        WAITER_RUNNING = (1 << 1),
        WAITER_TEARDOWN = (1 << 2),
 };
+} /* namespace */
 
-void lttng_waiter_init(struct lttng_waiter *waiter)
+lttng::synchro::waiter::waiter()
 {
-       cds_wfs_node_init(&waiter->wait_queue_node);
-       uatomic_set(&waiter->state, WAITER_WAITING);
+       arm();
+}
+
+void lttng::synchro::waiter::arm() noexcept
+{
+       cds_wfs_node_init(&_wait_queue_node);
+       uatomic_set(&_state, WAITER_WAITING);
        cmm_smp_mb();
 }
 
 /*
- * User must init "waiter" before passing its memory to waker thread.
+ * User must arm "waiter" before passing its memory to waker thread.
  */
-void lttng_waiter_wait(struct lttng_waiter *waiter)
+void lttng::synchro::waiter::wait()
 {
-       unsigned int i;
-
        DBG("Beginning of waiter \"wait\" period");
 
        /* Load and test condition before read state. */
        cmm_smp_rmb();
-       for (i = 0; i < WAIT_ATTEMPTS; i++) {
-               if (uatomic_read(&waiter->state) != WAITER_WAITING) {
+       for (unsigned int i = 0; i < wait_attempt_count; i++) {
+               if (uatomic_read(&_state) != WAITER_WAITING) {
                        goto skip_futex_wait;
                }
 
                caa_cpu_relax();
        }
 
-       while (uatomic_read(&waiter->state) == WAITER_WAITING) {
-               if (!futex_noasync(
-                           &waiter->state, FUTEX_WAIT, WAITER_WAITING, nullptr, nullptr, 0)) {
+       while (uatomic_read(&_state) == WAITER_WAITING) {
+               if (!futex_noasync(&_state, FUTEX_WAIT, WAITER_WAITING, nullptr, nullptr, 0)) {
                        /*
                         * Prior queued wakeups queued by unrelated code
                         * using the same address can cause futex wait to
@@ -84,76 +86,82 @@ void lttng_waiter_wait(struct lttng_waiter *waiter)
 skip_futex_wait:
 
        /* Tell waker thread than we are running. */
-       uatomic_or(&waiter->state, WAITER_RUNNING);
+       uatomic_or(&_state, WAITER_RUNNING);
 
        /*
         * Wait until waker thread lets us know it's ok to tear down
         * memory allocated for struct lttng_waiter.
         */
-       for (i = 0; i < WAIT_ATTEMPTS; i++) {
-               if (uatomic_read(&waiter->state) & WAITER_TEARDOWN) {
+       for (unsigned int i = 0; i < wait_attempt_count; i++) {
+               if (uatomic_read(&_state) & WAITER_TEARDOWN) {
                        break;
                }
 
                caa_cpu_relax();
        }
 
-       while (!(uatomic_read(&waiter->state) & WAITER_TEARDOWN)) {
+       while (!(uatomic_read(&_state) & WAITER_TEARDOWN)) {
                poll(nullptr, 0, 10);
        }
 
-       LTTNG_ASSERT(uatomic_read(&waiter->state) & WAITER_TEARDOWN);
+       LTTNG_ASSERT(uatomic_read(&_state) & WAITER_TEARDOWN);
        DBG("End of waiter \"wait\" period");
 }
 
+lttng::synchro::waker lttng::synchro::waiter::get_waker()
+{
+       return lttng::synchro::waker(_state);
+}
+
 /*
  * Note: lttng_waiter_wake needs waiter to stay allocated throughout its
  * execution. In this scheme, the waiter owns the node memory, and we only allow
  * it to free this memory when it sees the WAITER_TEARDOWN flag.
  */
-void lttng_waiter_wake(struct lttng_waiter *waiter)
+void lttng::synchro::waker::wake()
 {
        cmm_smp_mb();
-       LTTNG_ASSERT(uatomic_read(&waiter->state) == WAITER_WAITING);
-       uatomic_set(&waiter->state, WAITER_WOKEN_UP);
-       if (!(uatomic_read(&waiter->state) & WAITER_RUNNING)) {
-               if (futex_noasync(&waiter->state, FUTEX_WAKE, 1, nullptr, nullptr, 0) < 0) {
+
+       LTTNG_ASSERT(uatomic_read(&_state.get()) == WAITER_WAITING);
+
+       uatomic_set(&_state.get(), WAITER_WOKEN_UP);
+       if (!(uatomic_read(&_state.get()) & WAITER_RUNNING)) {
+               if (futex_noasync(&_state.get(), FUTEX_WAKE, 1, nullptr, nullptr, 0) < 0) {
                        PERROR("futex_noasync");
                        abort();
                }
        }
 
        /* Allow teardown of struct urcu_wait memory. */
-       uatomic_or(&waiter->state, WAITER_TEARDOWN);
+       uatomic_or(&_state.get(), WAITER_TEARDOWN);
 }
 
-void lttng_wait_queue_init(struct lttng_wait_queue *queue)
+lttng::synchro::wait_queue::wait_queue()
 {
-       cds_wfs_init(&queue->stack);
+       cds_wfs_init(&_stack);
 }
 
-void lttng_wait_queue_add(struct lttng_wait_queue *queue, struct lttng_waiter *waiter)
+void lttng::synchro::wait_queue::add(waiter& waiter) noexcept
 {
-       (void) cds_wfs_push(&queue->stack, &waiter->wait_queue_node);
+       (void) cds_wfs_push(&_stack, &waiter._wait_queue_node);
 }
 
-void lttng_wait_queue_wake_all(struct lttng_wait_queue *queue)
+void lttng::synchro::wait_queue::wake_all()
 {
-       cds_wfs_head *waiters;
-       cds_wfs_node *iter, *iter_n;
-
        /* Move all waiters from the queue to our local stack. */
-       waiters = __cds_wfs_pop_all(&queue->stack);
+       auto *waiters = __cds_wfs_pop_all(&_stack);
 
        /* Wake all waiters in our stack head. */
+       cds_wfs_node *iter, *iter_n;
        cds_wfs_for_each_blocking_safe (waiters, iter, iter_n) {
-               auto *waiter = lttng::utils::container_of(iter, &lttng_waiter::wait_queue_node);
+               auto& waiter = *lttng::utils::container_of(
+                       iter, &lttng::synchro::waiter::_wait_queue_node);
 
                /* Don't wake already running threads. */
-               if (waiter->state & WAITER_RUNNING) {
+               if (waiter._state & WAITER_RUNNING) {
                        continue;
                }
 
-               lttng_waiter_wake(waiter);
+               waiter.get_waker().wake();
        }
 }