pluto: Added a generic event queue.

This allows to easily execute arbitrary callbacks in the context of the pluto
main thread (e.g. in order to synchronize with threads from the thread-pool).

src/pluto/event_queue.c

@@ -0,0 +1,195 @@
+/*
+ * Copyright (C) 2010 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "event_queue.h"
+
+#include <debug.h>
+#include <threading/mutex.h>
+#include <utils/linked_list.h>
+
+typedef struct private_event_queue_t private_event_queue_t;
+
+/**
+ * Private data of event_queue_t class.
+ */
+struct private_event_queue_t {
+	/**
+	 * Public event_queue_t interface.
+	 */
+	event_queue_t public;
+
+	/**
+	 * List of queued events (event_t*).
+	 */
+	linked_list_t *events;
+
+	/**
+	 * Mutex for event list.
+	 */
+	mutex_t *mutex;
+
+	/**
+	 * Read end of the notification pipe.
+	 */
+	int read_fd;
+
+	/**
+	 * Write end of the notification pipe.
+	 */
+	int write_fd;
+
+};
+
+typedef struct event_t event_t;
+
+struct event_t {
+	/**
+	 * Callback function.
+	 */
+	void (*callback)(void *data);
+
+	/**
+	 * Data to supply to the callback.
+	 */
+	void *data;
+
+	/**
+	 * Cleanup function.
+	 */
+	void (*cleanup)(void *data);
+};
+
+static event_t *event_create(void (*callback)(void *data), void *data,
+							 void (*cleanup)(void *data))
+{
+	event_t *this;
+	INIT(this,
+		.callback = callback,
+		.data = data,
+		.cleanup = cleanup,
+	);
+	return this;
+}
+
+static void event_destroy(event_t *this)
+{
+	if (this->cleanup)
+	{
+		this->cleanup(this->data);
+	}
+	free(this);
+}
+
+METHOD(event_queue_t, get_event_fd, int,
+	   private_event_queue_t *this)
+{
+	return this->read_fd;
+}
+
+METHOD(event_queue_t, handle, void,
+	   private_event_queue_t *this)
+{
+	char buf[10];
+	linked_list_t *events;
+	event_t *event;
+	this->mutex->lock(this->mutex);
+	/* flush pipe */
+	while (read(this->read_fd, &buf, sizeof(buf)) == sizeof(buf));
+	/* replace the list, so we can unlock the mutex while executing the jobs */
+	events = this->events;
+	this->events = linked_list_create();
+	this->mutex->unlock(this->mutex);
+
+	while (events->remove_first(events, (void**)&event) == SUCCESS)
+	{
+		event->callback(event->data);
+		event_destroy(event);
+	}
+	events->destroy(events);
+}
+
+METHOD(event_queue_t, queue, void,
+	   private_event_queue_t *this, void (*callback)(void *data), void *data,
+	   void (*cleanup)(void *data))
+{
+	event_t *event = event_create(callback, data, cleanup);
+	char c = 0;
+	this->mutex->lock(this->mutex);
+	this->events->insert_last(this->events, event);
+	ignore_result(write(this->write_fd, &c, 1));
+	this->mutex->unlock(this->mutex);
+}
+
+METHOD(event_queue_t, destroy, void,
+	   private_event_queue_t *this)
+{
+	this->mutex->lock(this->mutex);
+	this->events->destroy_function(this->events, (void*)event_destroy);
+	this->mutex->unlock(this->mutex);
+	this->mutex->destroy(this->mutex);
+	close(this->read_fd);
+	close(this->write_fd);
+	free(this);
+}
+
+bool set_nonblock(int socket)
+{
+	int flags = fcntl(socket, F_GETFL);
+	return flags != -1 && fcntl(socket, F_SETFL, flags | O_NONBLOCK) != -1;
+}
+
+bool set_cloexec(int socket)
+{
+	int flags = fcntl(socket, F_GETFD);
+	return flags != -1 && fcntl(socket, F_SETFD, flags | FD_CLOEXEC) != -1;
+}
+
+/*
+ * Described in header.
+ */
+event_queue_t *event_queue_create()
+{
+	private_event_queue_t *this;
+	int fd[2];
+
+	INIT(this,
+		.public = {
+			.get_event_fd = _get_event_fd,
+			.handle = _handle,
+			.queue = _queue,
+			.destroy = _destroy,
+		},
+		.events = linked_list_create(),
+		.mutex = mutex_create(MUTEX_TYPE_DEFAULT),
+	);
+
+	if (pipe(fd) == -1 ||
+		!set_nonblock(fd[0]) || !set_cloexec(fd[0]) ||
+		!set_nonblock(fd[1]) || !set_cloexec(fd[1]))
+	{
+		DBG1(DBG_JOB, "failed to create pipe for job queue");
+		_destroy(this);
+		return NULL;
+	}
+
+	this->read_fd = fd[0];
+	this->write_fd = fd[1];
+
+	return &this->public;
+}
+