Add client notification API

[lttng-tools.git] / include / lttng / notification / channel-internal.h

diff --git a/include/lttng/notification/channel-internal.h b/include/lttng/notification/channel-internal.h
new file mode 100644 (file)
index 0000000..efe502f
--- /dev/null
+++ b/include/lttng/notification/channel-internal.h
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2017 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License, version 2.1 only,
+ * as published by the Free Software Foundation.
+ *
+ * This library 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 Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef LTTNG_NOTIFICATION_CHANNEL_INTERNAL_H
+#define LTTNG_NOTIFICATION_CHANNEL_INTERNAL_H
+
+#include <lttng/notification/channel.h>
+#include <common/macros.h>
+#include <common/dynamic-buffer.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <pthread.h>
+#include <urcu/list.h>
+
+#define LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR 1
+#define LTTNG_NOTIFICATION_CHANNEL_VERSION_MINOR 0
+
+enum lttng_notification_channel_message_type {
+       LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNKNOWN = -1,
+       LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE = 0,
+       LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE = 1,
+       LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE = 2,
+       LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_COMMAND_REPLY = 3,
+       LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION = 4,
+       LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED = 5,
+};
+
+struct lttng_notification_channel_message {
+       /* enum lttng_notification_channel_message_type */
+       int8_t type;
+       /* Size of the payload following this field. */
+       uint32_t size;
+       char payload[];
+} LTTNG_PACKED;
+
+struct lttng_notification_channel_command_handshake {
+       uint8_t major;
+       uint8_t minor;
+} LTTNG_PACKED;
+
+struct lttng_notification_channel_command_reply {
+       /* enum lttng_notification_channel_status */
+       int8_t status;
+} LTTNG_PACKED;
+
+struct pending_notification {
+       /* NULL means "notification dropped". */
+       struct lttng_notification *notification;
+       struct cds_list_head node;
+};
+
+/*
+ * The notification channel protocol is bidirectional and accomodates
+ * synchronous and asynchronous communication modes:
+ *
+ *   - Synchronous: commands emitted by the client to which a reply is expected
+ *     (e.g. subscribing/unsubscribing to conditions),
+ *   - Asynchronous: notifications which are sent by the lttng_endpoint to the
+ *     client as one of the subscribed condition has occured.
+ *
+ * The nature of this hybrid communication mode means that asynchronous messages
+ * (e.g. notifications) may be interleaved between synchronous messages (e.g. a
+ * command and its reply).
+ *
+ * Notifications that are received between a command and its reply and enqueued
+ * in the pending_notifications list.
+ */
+struct lttng_notification_channel {
+       pthread_mutex_t lock;
+       int socket;
+       struct {
+               /* Count of pending notifications. */
+               unsigned int count;
+               /* List of struct pending_notification. */
+               struct cds_list_head list;
+       } pending_notifications;
+       struct lttng_dynamic_buffer reception_buffer;
+       /* Sessiond notification protocol version. */
+       struct {
+               bool set;
+               int8_t major, minor;
+       } version;
+};
+
+#endif /* LTTNG_NOTIFICATION_CHANNEL_INTERNAL_H */