include/lttng/notification/channel-internal.h

   1 /*
   2  * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #ifndef LTTNG_NOTIFICATION_CHANNEL_INTERNAL_H
   9 #define LTTNG_NOTIFICATION_CHANNEL_INTERNAL_H
  10
  11 #include <lttng/notification/channel.h>
  12 #include <common/macros.h>
  13 #include <common/dynamic-buffer.h>
  14 #include <stdint.h>
  15 #include <stdbool.h>
  16 #include <pthread.h>
  17 #include <urcu/list.h>
  18
  19 /*
  20  * Protocol version change log:
  21  * - v1.0
  22  *   - Initial implementation of the notification channel protocol,
  23  *   - Supported conditions are LOW/HIGH buffer usage conditions,
  24  * - v1.1
  25  *   - New condition type "LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE" added,
  26  *   - New condition type "LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING" added,
  27  *   - New condition type "LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED" added,
  28  */
  29 #define LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR 1
  30 #define LTTNG_NOTIFICATION_CHANNEL_VERSION_MINOR 1
  31
  32 enum lttng_notification_channel_message_type {
  33         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNKNOWN = -1,
  34         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE = 0,
  35         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE = 1,
  36         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE = 2,
  37         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_COMMAND_REPLY = 3,
  38         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION = 4,
  39         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED = 5,
  40 };
  41
  42 struct lttng_notification_channel_message {
  43         /* enum lttng_notification_channel_message_type */
  44         int8_t type;
  45         /* Size of the payload following this field. */
  46         uint32_t size;
  47         char payload[];
  48 } LTTNG_PACKED;
  49
  50 struct lttng_notification_channel_command_handshake {
  51         uint8_t major;
  52         uint8_t minor;
  53 } LTTNG_PACKED;
  54
  55 struct lttng_notification_channel_command_reply {
  56         /* enum lttng_notification_channel_status */
  57         int8_t status;
  58 } LTTNG_PACKED;
  59
  60 struct pending_notification {
  61         /* NULL means "notification dropped". */
  62         struct lttng_notification *notification;
  63         struct cds_list_head node;
  64 };
  65
  66 /*
  67  * The notification channel protocol is bidirectional and accommodates
  68  * synchronous and asynchronous communication modes:
  69  *
  70  *   - Synchronous: commands emitted by the client to which a reply is expected
  71  *     (e.g. subscribing/unsubscribing to conditions),
  72  *   - Asynchronous: notifications which are sent by the lttng_endpoint to the
  73  *     client as one of the subscribed condition has occurred.
  74  *
  75  * The nature of this hybrid communication mode means that asynchronous messages
  76  * (e.g. notifications) may be interleaved between synchronous messages (e.g. a
  77  * command and its reply).
  78  *
  79  * Notifications that are received between a command and its reply and enqueued
  80  * in the pending_notifications list.
  81  */
  82 struct lttng_notification_channel {
  83         pthread_mutex_t lock;
  84         int socket;
  85         struct {
  86                 /* Count of pending notifications. */
  87                 unsigned int count;
  88                 /* List of struct pending_notification. */
  89                 struct cds_list_head list;
  90         } pending_notifications;
  91         struct lttng_dynamic_buffer reception_buffer;
  92         /* Sessiond notification protocol version. */
  93         struct {
  94                 bool set;
  95                 int8_t major, minor;
  96         } version;
  97 };
  98
  99 #endif /* LTTNG_NOTIFICATION_CHANNEL_INTERNAL_H */