include/lttng/notification/channel-internal.h

   1 /*
   2  * Copyright (C) 2017 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU Lesser General Public License, version 2.1 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This library is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
  11  * for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this library; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18 #ifndef LTTNG_NOTIFICATION_CHANNEL_INTERNAL_H
  19 #define LTTNG_NOTIFICATION_CHANNEL_INTERNAL_H
  20
  21 #include <lttng/notification/channel.h>
  22 #include <common/macros.h>
  23 #include <common/dynamic-buffer.h>
  24 #include <stdint.h>
  25 #include <stdbool.h>
  26 #include <pthread.h>
  27 #include <urcu/list.h>
  28
  29 /*
  30  * Protocol version change log:
  31  * - v1.0
  32  *   - Initial implementation of the notification channel protocol,
  33  *   - Supported conditions are LOW/HIGH buffer usage conditions,
  34  * - v1.1
  35  *   - New condition type "LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE" added,
  36  *   - New condition type "LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING" added,
  37  *   - New condition type "LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED" added,
  38  */
  39 #define LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR 1
  40 #define LTTNG_NOTIFICATION_CHANNEL_VERSION_MINOR 1
  41
  42 enum lttng_notification_channel_message_type {
  43         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNKNOWN = -1,
  44         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE = 0,
  45         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE = 1,
  46         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE = 2,
  47         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_COMMAND_REPLY = 3,
  48         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION = 4,
  49         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED = 5,
  50 };
  51
  52 struct lttng_notification_channel_message {
  53         /* enum lttng_notification_channel_message_type */
  54         int8_t type;
  55         /* Size of the payload following this field. */
  56         uint32_t size;
  57         char payload[];
  58 } LTTNG_PACKED;
  59
  60 struct lttng_notification_channel_command_handshake {
  61         uint8_t major;
  62         uint8_t minor;
  63 } LTTNG_PACKED;
  64
  65 struct lttng_notification_channel_command_reply {
  66         /* enum lttng_notification_channel_status */
  67         int8_t status;
  68 } LTTNG_PACKED;
  69
  70 struct pending_notification {
  71         /* NULL means "notification dropped". */
  72         struct lttng_notification *notification;
  73         struct cds_list_head node;
  74 };
  75
  76 /*
  77  * The notification channel protocol is bidirectional and accomodates
  78  * synchronous and asynchronous communication modes:
  79  *
  80  *   - Synchronous: commands emitted by the client to which a reply is expected
  81  *     (e.g. subscribing/unsubscribing to conditions),
  82  *   - Asynchronous: notifications which are sent by the lttng_endpoint to the
  83  *     client as one of the subscribed condition has occurred.
  84  *
  85  * The nature of this hybrid communication mode means that asynchronous messages
  86  * (e.g. notifications) may be interleaved between synchronous messages (e.g. a
  87  * command and its reply).
  88  *
  89  * Notifications that are received between a command and its reply and enqueued
  90  * in the pending_notifications list.
  91  */
  92 struct lttng_notification_channel {
  93         pthread_mutex_t lock;
  94         int socket;
  95         struct {
  96                 /* Count of pending notifications. */
  97                 unsigned int count;
  98                 /* List of struct pending_notification. */
  99                 struct cds_list_head list;
 100         } pending_notifications;
 101         struct lttng_dynamic_buffer reception_buffer;
 102         /* Sessiond notification protocol version. */
 103         struct {
 104                 bool set;
 105                 int8_t major, minor;
 106         } version;
 107 };
 108
 109 #endif /* LTTNG_NOTIFICATION_CHANNEL_INTERNAL_H */