2 * Copyright (C) 2022 Jérémie Galarneau <jeremie.galarneau@efficios.com>
4 * SPDX-License-Identifier: GPL-2.0-only
8 #ifndef LTTNG_UST_REGISTRY_SESSION_H
9 #define LTTNG_UST_REGISTRY_SESSION_H
11 #include "clock-class.hpp"
12 #include "session.hpp"
13 #include "trace-class.hpp"
14 #include "ust-clock-class.hpp"
15 #include "ust-registry-channel.hpp"
16 #include "ust-registry.hpp"
18 #include <common/make-unique-wrapper.hpp>
22 #include <lttng/lttng.h>
31 class registry_session;
34 void locked_registry_session_release(registry_session *session);
35 } /* namespace details */
37 class registry_session : public lttng::sessiond::trace::trace_class {
39 using locked_ptr = std::unique_ptr<registry_session,
40 lttng::details::create_unique_class<registry_session,
41 details::locked_registry_session_release>::
44 virtual lttng_buffer_type get_buffering_scheme() const noexcept = 0;
45 locked_ptr lock() noexcept;
47 void add_channel(uint64_t channel_key);
49 /* A channel is protected by its parent registry session's lock. */
50 lttng::sessiond::ust::registry_channel& get_channel(uint64_t channel_key) const;
52 void remove_channel(uint64_t channel_key, bool notify);
54 void create_or_find_enum(int session_objd,
55 const char *enum_name,
56 struct lttng_ust_ctl_enum_entry *raw_entries,
59 registry_enum::const_rcu_protected_reference get_enumeration(
60 const char *enum_name, uint64_t enum_id) const;
62 void regenerate_metadata();
63 virtual ~registry_session();
66 * With multiple writers and readers, use this lock to access
67 * the registry. Can nest within the ust app session lock.
68 * Also acts as a registry serialization lock. Used by registry
69 * readers to serialize the registry information sent from the
70 * sessiond to the consumerd.
72 * The consumer socket lock nests within this lock.
74 mutable pthread_mutex_t _lock;
76 /* Generated metadata, not null-terminated. */
77 char *_metadata = nullptr; /* */
78 size_t _metadata_len = 0;
79 /* Length of bytes sent to the consumer. */
80 size_t _metadata_len_sent = 0;
81 /* Current version of the metadata. */
82 uint64_t _metadata_version = 0;
85 * Unique key to identify the metadata on the consumer side.
87 uint64_t _metadata_key = 0;
89 * Indicates if the metadata is closed on the consumer side. This is to
90 * avoid double close of metadata when an application unregisters AND
91 * deletes its sessions.
93 bool _metadata_closed = false;
96 /* Prevent instanciation of this base class. */
97 registry_session(const struct lttng::sessiond::trace::abi& abi,
98 unsigned int app_tracer_version_major,
99 unsigned int app_tracer_version_minor,
100 const char *root_shm_path,
101 const char *shm_path,
104 uint64_t tracing_id);
105 virtual void _visit_environment(
106 lttng::sessiond::trace::trace_class_visitor& trace_class_visitor)
108 void _generate_metadata();
111 uint32_t _get_next_channel_id();
112 void _increase_metadata_size(size_t reservation_length);
113 void _append_metadata_fragment(const std::string& fragment);
114 void _reset_metadata();
115 void _destroy_enum(registry_enum *reg_enum);
116 registry_enum *_lookup_enum(const registry_enum *target_enum) const;
118 virtual void _accept_on_clock_classes(
119 lttng::sessiond::trace::trace_class_visitor& trace_class_visitor)
120 const override final;
121 virtual void _accept_on_stream_classes(
122 lttng::sessiond::trace::trace_class_visitor& trace_class_visitor)
123 const override final;
125 /* Next channel ID available for a newly registered channel. */
126 uint32_t _next_channel_id = 0;
128 /* Once this value reaches UINT32_MAX, no more id can be allocated. */
129 uint32_t _used_channel_id = 0;
131 /* Next enumeration ID available. */
132 uint64_t _next_enum_id = 0;
134 size_t _metadata_alloc_len = 0;
137 * Those fields are only used when a session is created with
138 * the --shm-path option. In this case, the metadata is output
139 * twice: once to the consumer, as ususal, but a second time
140 * also in the shm path directly. This is done so that a copy
141 * of the metadata that is as fresh as possible is available
142 * on the event of a crash.
144 * root_shm_path contains the shm-path provided by the user, along with
145 * the session's name and timestamp:
146 * e.g. /tmp/my_shm/my_session-20180612-135822
148 * shm_path contains the full path of the memory buffers:
149 * e.g. /tmp/my_shm/my_session-20180612-135822/ust/uid/1000/64-bit
151 * metadata_path contains the full path to the metadata file that
152 * is kept for the "crash buffer" extraction:
154 * /tmp/my_shm/my_session-20180612-135822/ust/uid/1000/64-bit/metadata
156 * Note that this is not the trace's final metadata file. It is
157 * only meant to be used to read the contents of the ring buffers
158 * in the event of a crash.
160 * metadata_fd is a file descriptor that points to the file at
163 const std::string _root_shm_path;
164 const std::string _shm_path;
165 const std::string _metadata_path;
167 /* File-backed metadata FD */
168 int _metadata_fd = -1;
171 * Hash table containing channels sent by the UST tracer. MUST
172 * be accessed with a RCU read side lock acquired.
174 lttng_ht::uptr _channels;
176 /* Enumerations table. */
177 lttng_ht::uptr _enums;
179 /* User and group owning the session. */
184 * Copy of the tracer version when the first app is registered.
185 * It is used if we need to regenerate the metadata.
188 uint32_t major, minor;
189 } _app_tracer_version;
191 /* The id of the parent session. */
192 const ltt_session::id_t _tracing_id;
194 lttng::sessiond::ust::clock_class _clock;
195 const lttng::sessiond::trace::trace_class_visitor::cuptr _metadata_generating_visitor;
198 } /* namespace ust */
199 } /* namespace sessiond */
200 } /* namespace lttng */
202 #endif /* LTTNG_UST_REGISTRY_SESSION_H */