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>
20 #include <lttng/lttng.h>
32 class registry_session;
35 void locked_registry_session_release(registry_session *session);
36 } /* namespace details */
38 class registry_session : public lttng::sessiond::trace::trace_class {
41 std::unique_ptr<registry_session,
42 lttng::memory::create_deleter_class<
44 details::locked_registry_session_release>::deleter>;
46 virtual lttng_buffer_type buffering_scheme() const noexcept = 0;
47 locked_ref lock() noexcept;
49 void add_channel(uint64_t channel_key);
51 /* A channel is protected by its parent registry session's lock. */
52 lttng::sessiond::ust::registry_channel& channel(uint64_t channel_key) const;
54 void remove_channel(uint64_t channel_key, bool notify);
56 void create_or_find_enum(int session_objd,
57 const char *enum_name,
58 struct lttng_ust_ctl_enum_entry *raw_entries,
61 registry_enum::const_rcu_protected_reference enumeration(const char *enum_name,
62 uint64_t enum_id) const;
64 void regenerate_metadata();
66 ~registry_session() override;
67 registry_session(const registry_session&) = delete;
68 registry_session(registry_session&&) = delete;
69 registry_session& operator=(registry_session&&) = delete;
70 registry_session& operator=(const registry_session&) = delete;
72 const lttng::sessiond::trace::type *packet_header() const noexcept override;
75 * With multiple writers and readers, use this lock to access
76 * the registry. Can nest within the ust app session lock.
77 * Also acts as a registry serialization lock. Used by registry
78 * readers to serialize the registry information sent from the
79 * sessiond to the consumerd.
81 * The consumer socket lock nests within this lock.
83 mutable pthread_mutex_t _lock;
85 /* Generated metadata, not null-terminated. */
86 char *_metadata = nullptr; /* */
87 size_t _metadata_len = 0;
88 /* Length of bytes sent to the consumer. */
89 size_t _metadata_len_sent = 0;
90 /* Current version of the metadata. */
91 uint64_t _metadata_version = 0;
94 * Unique key to identify the metadata on the consumer side.
96 uint64_t _metadata_key = 0;
98 * Indicates if the metadata is closed on the consumer side. This is to
99 * avoid double close of metadata when an application unregisters AND
100 * deletes its sessions.
102 bool _metadata_closed = false;
105 /* Prevent instanciation of this base class. */
106 registry_session(const struct lttng::sessiond::trace::abi& abi,
107 unsigned int app_tracer_version_major,
108 unsigned int app_tracer_version_minor,
109 const char *root_shm_path,
110 const char *shm_path,
113 uint64_t tracing_id);
114 void accept(trace::trace_class_environment_visitor& environment_visitor) const override;
115 void _generate_metadata();
118 uint32_t _get_next_channel_id();
119 void _increase_metadata_size(size_t reservation_length);
120 void _append_metadata_fragment(const std::string& fragment);
121 void _reset_metadata();
122 void _destroy_enum(registry_enum *reg_enum) noexcept;
123 registry_enum *_lookup_enum(const registry_enum *target_enum) const;
124 lttng::sessiond::trace::type::cuptr _create_packet_header() const;
126 void _accept_on_clock_classes(
127 lttng::sessiond::trace::trace_class_visitor& trace_class_visitor) const final;
128 void _accept_on_stream_classes(
129 lttng::sessiond::trace::trace_class_visitor& trace_class_visitor) const final;
131 /* Next channel ID available for a newly registered channel. */
132 uint32_t _next_channel_id = 0;
134 /* Once this value reaches UINT32_MAX, no more id can be allocated. */
135 uint32_t _used_channel_id = 0;
137 /* Next enumeration ID available. */
138 uint64_t _next_enum_id = 0;
140 size_t _metadata_alloc_len = 0;
143 * Those fields are only used when a session is created with
144 * the --shm-path option. In this case, the metadata is output
145 * twice: once to the consumer, as ususal, but a second time
146 * also in the shm path directly. This is done so that a copy
147 * of the metadata that is as fresh as possible is available
148 * on the event of a crash.
150 * root_shm_path contains the shm-path provided by the user, along with
151 * the session's name and timestamp:
152 * e.g. /tmp/my_shm/my_session-20180612-135822
154 * shm_path contains the full path of the memory buffers:
155 * e.g. /tmp/my_shm/my_session-20180612-135822/ust/uid/1000/64-bit
157 * metadata_path contains the full path to the metadata file that
158 * is kept for the "crash buffer" extraction:
160 * /tmp/my_shm/my_session-20180612-135822/ust/uid/1000/64-bit/metadata
162 * Note that this is not the trace's final metadata file. It is
163 * only meant to be used to read the contents of the ring buffers
164 * in the event of a crash.
166 * metadata_fd is a file descriptor that points to the file at
169 const std::string _root_shm_path;
170 const std::string _shm_path;
171 const std::string _metadata_path;
173 /* File-backed metadata FD */
174 int _metadata_fd = -1;
177 * Hash table containing channels sent by the UST tracer. MUST
178 * be accessed with a RCU read side lock acquired.
180 lttng_ht::uptr _channels;
182 /* Enumerations table. */
183 lttng_ht::uptr _enums;
185 /* User and group owning the session. */
190 * Copy of the tracer version when the first app is registered.
191 * It is used if we need to regenerate the metadata.
194 uint32_t major, minor;
195 } _app_tracer_version;
197 /* The id of the parent session. */
198 const ltt_session::id_t _tracing_id;
200 lttng::sessiond::ust::clock_class::cuptr _clock;
201 const lttng::sessiond::trace::trace_class_visitor::cuptr _metadata_generating_visitor;
202 lttng::sessiond::trace::type::cuptr _packet_header;
205 } /* namespace ust */
206 } /* namespace sessiond */
207 } /* namespace lttng */
209 #ifdef HAVE_LIBLTTNG_UST_CTL
210 ssize_t ust_app_push_metadata(const lttng::sessiond::ust::registry_session::locked_ref& registry,
211 struct consumer_socket *socket,
213 #else /* HAVE_LIBLTTNG_UST_CTL */
214 static inline ssize_t ust_app_push_metadata(lttng::sessiond::ust::registry_session *registry
215 __attribute__((unused)),
216 struct consumer_socket *socket __attribute__((unused)),
217 int send_zero_data __attribute__((unused)))
221 #endif /* HAVE_LIBLTTNG_UST_CTL */
223 #endif /* LTTNG_UST_REGISTRY_SESSION_H */