common: compile libcommon as C++

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

diff --git a/src/common/waiter.c b/src/common/waiter.c
deleted file mode 100644 (file)
index aca88eb..0000000
--- a/src/common/waiter.c
+++ /dev/null
@@ -1,108 +0,0 @@
-/*
- * Copyright (C) 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
- *
- * SPDX-License-Identifier: LGPL-2.1-only
- *
- */
-
-#include "waiter.h"
-#include <urcu/uatomic.h>
-#include <urcu/futex.h>
-#include "error.h"
-#include <poll.h>
-
-/*
- * Number of busy-loop attempts before waiting on futex.
- */
-#define WAIT_ATTEMPTS 1000
-
-enum waiter_state {
-       /* WAITER_WAITING is compared directly (futex compares it). */
-       WAITER_WAITING =        0,
-       /* non-zero are used as masks. */
-       WAITER_WOKEN_UP =       (1 << 0),
-       WAITER_RUNNING =        (1 << 1),
-       WAITER_TEARDOWN =       (1 << 2),
-};
-
-void lttng_waiter_init(struct lttng_waiter *waiter)
-{
-       cds_wfs_node_init(&waiter->wait_queue_node);
-       uatomic_set(&waiter->state, WAITER_WAITING);
-       cmm_smp_mb();
-}
-
-/*
- * User must init "waiter" before passing its memory to waker thread.
- */
-void lttng_waiter_wait(struct lttng_waiter *waiter)
-{
-       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) {
-                       goto skip_futex_wait;
-               }
-               caa_cpu_relax();
-       }
-       while (futex_noasync(&waiter->state, FUTEX_WAIT, WAITER_WAITING,
-                       NULL, NULL, 0)) {
-               switch (errno) {
-               case EWOULDBLOCK:
-                       /* Value already changed. */
-                       goto skip_futex_wait;
-               case EINTR:
-                       /* Retry if interrupted by signal. */
-                       break;  /* Get out of switch. */
-               default:
-                       /* Unexpected error. */
-                       PERROR("futex_noasync");
-                       abort();
-               }
-       }
-skip_futex_wait:
-
-       /* Tell waker thread than we are running. */
-       uatomic_or(&waiter->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) {
-                       break;
-               }
-               caa_cpu_relax();
-       }
-       while (!(uatomic_read(&waiter->state) & WAITER_TEARDOWN)) {
-               poll(NULL, 0, 10);
-       }
-       LTTNG_ASSERT(uatomic_read(&waiter->state) & WAITER_TEARDOWN);
-       DBG("End of waiter wait period");
-}
-
-/*
- * 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_up(struct lttng_waiter *waiter)
-{
-       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,
-                               NULL, NULL, 0) < 0) {
-                       PERROR("futex_noasync");
-                       abort();
-               }
-       }
-       /* Allow teardown of struct urcu_wait memory. */
-       uatomic_or(&waiter->state, WAITER_TEARDOWN);
-}