--- /dev/null
+/*
+ * Copyright (C) 2018 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License, version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "thread.h"
+#include <urcu/list.h>
+#include <urcu/ref.h>
+#include <pthread.h>
+#include <common/macros.h>
+#include <common/error.h>
+#include <common/defaults.h>
+
+static struct thread_list {
+ struct cds_list_head head;
+ pthread_mutex_t lock;
+} thread_list = {
+ .head = CDS_LIST_HEAD_INIT(thread_list.head),
+ .lock = PTHREAD_MUTEX_INITIALIZER,
+};
+
+struct lttng_thread {
+ struct urcu_ref ref;
+ struct cds_list_head node;
+ pthread_t thread;
+ const char *name;
+ /* Main thread function */
+ lttng_thread_entry_point entry;
+ /*
+ * Thread-specific shutdown method. Allows threads to implement their
+ * own shutdown mechanism as some of them use a structured message
+ * passed through a command queue and some rely on a dedicated "quit"
+ * pipe.
+ */
+ lttng_thread_shutdown_cb shutdown;
+ lttng_thread_cleanup_cb cleanup;
+ /* Thread implementation-specific data. */
+ void *data;
+};
+
+static
+void lttng_thread_destroy(struct lttng_thread *thread)
+{
+ if (thread->cleanup) {
+ thread->cleanup(thread->data);
+ }
+ free(thread);
+}
+
+static
+void lttng_thread_release(struct urcu_ref *ref)
+{
+ lttng_thread_destroy(container_of(ref, struct lttng_thread, ref));
+}
+
+static
+void *launch_thread(void *data)
+{
+ void *ret;
+ struct lttng_thread *thread = (struct lttng_thread *) data;
+
+ DBG("Launching \"%s\" thread", thread->name);
+ ret = thread->entry(thread->data);
+ DBG("Thread \"%s\" has returned", thread->name);
+ return ret;
+}
+
+struct lttng_thread *lttng_thread_create(const char *name,
+ lttng_thread_entry_point entry,
+ lttng_thread_shutdown_cb shutdown,
+ lttng_thread_cleanup_cb cleanup,
+ void *thread_data)
+{
+ int ret;
+ struct lttng_thread *thread;
+
+ thread = zmalloc(sizeof(*thread));
+ if (!thread) {
+ goto error;
+ }
+
+ urcu_ref_init(&thread->ref);
+ CDS_INIT_LIST_HEAD(&thread->node);
+ /*
+ * Thread names are assumed to be statically allocated strings.
+ * It is unnecessary to copy this attribute.
+ */
+ thread->name = name;
+ thread->entry = entry;
+ thread->shutdown = shutdown;
+ thread->cleanup = cleanup;
+ thread->data = thread_data;
+
+ pthread_mutex_lock(&thread_list.lock);
+ /*
+ * Add the thread at the head of the list to shutdown threads in the
+ * opposite order of their creation. A reference is taken for the
+ * thread list which will be released on shutdown of the thread.
+ */
+ cds_list_add(&thread->node, &thread_list.head);
+ (void) lttng_thread_get(thread);
+
+ ret = pthread_create(&thread->thread, default_pthread_attr(),
+ launch_thread, thread);
+ if (ret) {
+ PERROR("Failed to create \"%s\" thread", thread->name);
+ goto error_pthread_create;
+ }
+
+ pthread_mutex_unlock(&thread_list.lock);
+ return thread;
+
+error_pthread_create:
+ cds_list_del(&thread->node);
+ /* Release list reference. */
+ lttng_thread_put(thread);
+ pthread_mutex_unlock(&thread_list.lock);
+error:
+ /* Release initial reference. */
+ lttng_thread_put(thread);
+ return NULL;
+}
+
+bool lttng_thread_get(struct lttng_thread *thread)
+{
+ return urcu_ref_get_unless_zero(&thread->ref);
+}
+
+void lttng_thread_put(struct lttng_thread *thread)
+{
+ assert(thread->ref.refcount);
+ urcu_ref_put(&thread->ref, lttng_thread_release);
+}
+
+const char *lttng_thread_get_name(const struct lttng_thread *thread)
+{
+ return thread->name;
+}
+
+static
+bool _lttng_thread_shutdown(struct lttng_thread *thread)
+{
+ int ret;
+ void *status;
+ bool result = true;
+
+ DBG("Shutting down \"%s\" thread", thread->name);
+ if (thread->shutdown) {
+ result = thread->shutdown(thread->data);
+ if (!result) {
+ result = false;
+ goto end;
+ }
+ }
+
+ ret = pthread_join(thread->thread, &status);
+ if (ret) {
+ PERROR("Failed to join \"%s\" thread", thread->name);
+ result = false;
+ }
+ /* Release the list's reference to the thread. */
+ cds_list_del(&thread->node);
+ lttng_thread_put(thread);
+end:
+ return result;
+}
+
+bool lttng_thread_shutdown(struct lttng_thread *thread)
+{
+ bool result;
+
+ pthread_mutex_lock(&thread_list.lock);
+ result = _lttng_thread_shutdown(thread);
+ pthread_mutex_unlock(&thread_list.lock);
+ return result;
+}
+
+void lttng_thread_list_shutdown_orphans(void)
+{
+ struct lttng_thread *thread, *tmp;
+
+ pthread_mutex_lock(&thread_list.lock);
+ cds_list_for_each_entry_safe(thread, tmp, &thread_list.head, node) {
+ bool result;
+ const long ref = uatomic_read(&thread->ref.refcount);
+
+ if (ref != 1) {
+ /*
+ * Other external references to the thread exist, skip.
+ */
+ continue;
+ }
+
+ result = _lttng_thread_shutdown(thread);
+ if (!result) {
+ ERR("Failed to shutdown thread \"%s\"", thread->name);
+ }
+ }
+ pthread_mutex_unlock(&thread_list.lock);
+}
--- /dev/null
+/*
+ * Copyright (C) 2018 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License, version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdbool.h>
+
+#ifndef THREAD_H
+#define THREAD_H
+
+struct lttng_thread;
+
+/* Main function of the new thread. */
+typedef void *(*lttng_thread_entry_point)(void *);
+
+/* Callback invoked to initiate the shutdown a thread. */
+typedef bool (*lttng_thread_shutdown_cb)(void *);
+
+/*
+ * Callback invoked to clean-up the thread data.
+ * Invoked when the thread is destroyed to ensure there is no
+ * race between a use by the "thread shutdown callback" and
+ * a use by the thread itself.
+ */
+typedef void (*lttng_thread_cleanup_cb)(void *);
+
+/*
+ * Returns a reference to the newly-created thread.
+ * The shutdown and cleanup callbacks are optional.
+ */
+struct lttng_thread *lttng_thread_create(const char *name,
+ lttng_thread_entry_point entry,
+ lttng_thread_shutdown_cb shutdown,
+ lttng_thread_cleanup_cb cleanup,
+ void *thread_data);
+
+bool lttng_thread_get(struct lttng_thread *thread);
+void lttng_thread_put(struct lttng_thread *thread);
+
+const char *lttng_thread_get_name(const struct lttng_thread *thread);
+
+/*
+ * Explicitly shutdown a thread. This function returns once the
+ * thread has returned and been joined.
+ *
+ * It is invalid to call this function more than once on a thread.
+ *
+ * Returns true on success, false on error.
+ */
+bool lttng_thread_shutdown(struct lttng_thread *thread);
+
+/*
+ * Shutdown all orphaned threads (threads to which no external reference
+ * exist).
+ *
+ * Returns once all orphaned threads have been joined.
+ */
+void lttng_thread_list_shutdown_orphans(void);
+
+#endif /* THREAD_H */
projects / lttng-tools.git / commitdiff
