include/lttng/notification/channel-internal.hpp

   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 <common/macros.hpp>
  12 #include <common/make-unique-wrapper.hpp>
  13 #include <common/payload.hpp>
  14
  15 #include <lttng/notification/channel.h>
  16
  17 #include <pthread.h>
  18 #include <stdbool.h>
  19 #include <stdint.h>
  20 #include <urcu/list.h>
  21
  22 /*
  23  * Protocol version change log:
  24  * - v1.0
  25  *   - Initial implementation of the notification channel protocol,
  26  *   - Supported conditions are LOW/HIGH buffer usage conditions,
  27  * - v1.1
  28  *   - New condition type "LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE" added,
  29  *   - New condition type "LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING" added,
  30  *   - New condition type "LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED" added,
  31  */
  32 #define LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR 1
  33 #define LTTNG_NOTIFICATION_CHANNEL_VERSION_MINOR 1
  34
  35 enum lttng_notification_channel_message_type {
  36         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNKNOWN = -1,
  37         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE = 0,
  38         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE = 1,
  39         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE = 2,
  40         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_COMMAND_REPLY = 3,
  41         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION = 4,
  42         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED = 5,
  43 };
  44
  45 struct lttng_notification_channel_message {
  46         /* enum lttng_notification_channel_message_type */
  47         int8_t type;
  48         /* Size of the payload following this field. */
  49         uint32_t size;
  50         /* Number of FDs sent. */
  51         uint32_t fds;
  52         char payload[];
  53 } LTTNG_PACKED;
  54
  55 struct lttng_notification_channel_command_handshake {
  56         uint8_t major;
  57         uint8_t minor;
  58 } LTTNG_PACKED;
  59
  60 struct lttng_notification_channel_command_reply {
  61         /* enum lttng_notification_channel_status */
  62         int8_t status;
  63 } LTTNG_PACKED;
  64
  65 struct pending_notification {
  66         /* NULL means "notification dropped". */
  67         struct lttng_notification *notification;
  68         struct cds_list_head node;
  69 };
  70
  71 /*
  72  * The notification channel protocol is bidirectional and accommodates
  73  * synchronous and asynchronous communication modes:
  74  *
  75  *   - Synchronous: commands emitted by the client to which a reply is expected
  76  *     (e.g. subscribing/unsubscribing to conditions),
  77  *   - Asynchronous: notifications which are sent by the lttng_endpoint to the
  78  *     client as one of the subscribed condition has occurred.
  79  *
  80  * The nature of this hybrid communication mode means that asynchronous messages
  81  * (e.g. notifications) may be interleaved between synchronous messages (e.g. a
  82  * command and its reply).
  83  *
  84  * Notifications that are received between a command and its reply and enqueued
  85  * in the pending_notifications list.
  86  */
  87 struct lttng_notification_channel {
  88         using uptr = std::unique_ptr<
  89                 lttng_notification_channel,
  90                 lttng::memory::create_deleter_class<lttng_notification_channel,
  91                                                     lttng_notification_channel_destroy>::deleter>;
  92
  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_payload reception_payload;
 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 */