X-Git-Url: https://git.liburcu.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Fwaiter.cpp;h=d185e299720617e64e7514d114e33cea4a0eb386;hp=c0ea3392fceea52f1438b6e839c1742e7348503b;hb=f40b76aed659ff694cf948bf8ebd1d4b5741c986;hpb=a968a9e069d76bfb1ac416dc834994c6a82b085e

diff --git a/src/common/waiter.cpp b/src/common/waiter.cpp
index c0ea3392f..d185e2997 100644
--- a/src/common/waiter.cpp
+++ b/src/common/waiter.cpp
@@ -7,6 +7,7 @@
  */
 
 #include "error.hpp"
+#include "macros.hpp"
 #include "waiter.hpp"
 
 #include <poll.h>
@@ -41,15 +42,18 @@ void lttng_waiter_wait(struct lttng_waiter *waiter)
 {
 	unsigned int i;
 
-	DBG("Beginning of waiter wait period");
-	/* Load and test condition before read state */
+	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) {
 			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)) {
@@ -63,6 +67,7 @@ void lttng_waiter_wait(struct lttng_waiter *waiter)
 			 */
 			continue;
 		}
+
 		switch (errno) {
 		case EAGAIN:
 			/* Value already changed. */
@@ -89,13 +94,16 @@ skip_futex_wait:
 		if (uatomic_read(&waiter->state) & WAITER_TEARDOWN) {
 			break;
 		}
+
 		caa_cpu_relax();
 	}
+
 	while (!(uatomic_read(&waiter->state) & WAITER_TEARDOWN)) {
 		poll(nullptr, 0, 10);
 	}
+
 	LTTNG_ASSERT(uatomic_read(&waiter->state) & WAITER_TEARDOWN);
-	DBG("End of waiter wait period");
+	DBG("End of waiter \"wait\" period");
 }
 
 /*
@@ -103,7 +111,7 @@ skip_futex_wait:
  * 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_up(struct lttng_waiter *waiter)
+void lttng_waiter_wake(struct lttng_waiter *waiter)
 {
 	cmm_smp_mb();
 	LTTNG_ASSERT(uatomic_read(&waiter->state) == WAITER_WAITING);
@@ -114,6 +122,38 @@ void lttng_waiter_wake_up(struct lttng_waiter *waiter)
 			abort();
 		}
 	}
+
 	/* Allow teardown of struct urcu_wait memory. */
 	uatomic_or(&waiter->state, WAITER_TEARDOWN);
 }
+
+void lttng_wait_queue_init(struct lttng_wait_queue *queue)
+{
+	cds_wfs_init(&queue->stack);
+}
+
+void lttng_wait_queue_add(struct lttng_wait_queue *queue, struct lttng_waiter *waiter)
+{
+	(void) cds_wfs_push(&queue->stack, &waiter->wait_queue_node);
+}
+
+void lttng_wait_queue_wake_all(struct lttng_wait_queue *queue)
+{
+	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);
+
+	/* Wake all waiters in our stack head. */
+	cds_wfs_for_each_blocking_safe (waiters, iter, iter_n) {
+		auto *waiter = lttng::utils::container_of(iter, &lttng_waiter::wait_queue_node);
+
+		/* Don't wake already running threads. */
+		if (waiter->state & WAITER_RUNNING) {
+			continue;
+		}
+
+		lttng_waiter_wake(waiter);
+	}
+}