/* * Copyright (C) 2014 - David Goulet * Copyright (C) 2019 - Jérémie Galarneau * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License, version 2.1 only, * as published by the Free Software Foundation. * * This library is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License * for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this library; if not, write to the Free Software Foundation, * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #ifndef LTTNG_SESSION_H #define LTTNG_SESSION_H #ifdef __cplusplus extern "C" { #endif struct lttng_session_descriptor; struct lttng_destruction_handle; /* * Basic session information. * * The "enabled" field is only used when listing the sessions which indicate if * it's started or not. * * The structures should be initialized to zero before use. */ #define LTTNG_SESSION_PADDING1 8 struct lttng_session { char name[LTTNG_NAME_MAX]; /* * Human-readable representation of the trace's destination. * In the case of a local tracing session, a path is provided: * /path/to/the/output * * In the case of a remote (network) tracing session, the string has * the following format: * net://hostname/path:ctrl_port [data: data_port] */ char path[PATH_MAX]; uint32_t enabled; /* enabled/started: 1, disabled/stopped: 0 */ uint32_t snapshot_mode; unsigned int live_timer_interval; /* usec */ /* * End of public attributes. * The remaining fields are used to deal with ABI management concerns. */ /* * 32-bit architectures are already naturally aligned on 4 bytes after * 'live_timer_interval'. However, the offset does not result in a * natural alignment on 64-bit architectures. Adding 4 bytes of * padding here results in an aligned offset after 'alignement_padding' * for both bitnesses. * * This was added since not all compilers appear to align unions in the * same way. Some (e.g. MSVC) do not seem to impose an alignement * constraint while others (e.g. gcc, clang, icc) seem to align it to * ensure 'ptr' is naturally aligned. */ char alignment_padding[4]; union { /* * Ensure the 'extended' union has the same size for both * 32-bit and 64-bit builds. */ char padding[LTTNG_SESSION_PADDING1]; void *ptr; } extended; }; /* * Create a session on the session daemon from a session descriptor. * * See the session descriptor API description in session-descriptor.h * * Note that unspecified session descriptor parameters, such as a session's * name, are updated in the session descriptor if the creation of the session * succeeds. This allows users to query the session's auto-generated name * after its creation. Note that other attributes can be queried using the * session listing API. * * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other * return codes. */ extern enum lttng_error_code lttng_create_session_ext( struct lttng_session_descriptor *session_descriptor); /* * Create a tracing session using a name and an optional URL. * * If _url_ is NULL, no consumer is created for the session. The name can't be * NULL here. * * Return 0 on success else a negative LTTng error code. */ extern int lttng_create_session(const char *name, const char *url); /* * Create a tracing session that will exclusively be used for snapshot meaning * the session will be in no output mode and every channel enabled for that * session will be set in overwrite mode and in mmap output since splice is not * supported. * * Name can't be NULL. If an url is given, it will be used to create a default * snapshot output using it as a destination. If NULL, no output will be * defined and an add-output call will be needed. * * Return 0 on success else a negative LTTng error code. */ extern int lttng_create_session_snapshot(const char *name, const char *snapshot_url); /* * Create a session exclusively used for live reading. * * In this mode, the switch-timer parameter is forced for each UST channel, a * live-switch-timer is enabled for kernel channels, manually setting * switch-timer is forbidden. Synchronization beacons are sent to the relayd, * indexes are sent and metadata is checked for each packet. * * Name can't be NULL. If no URL is given, the default is to send the data to * net://127.0.0.1. The timer_interval is in usec. * * Return 0 on success else a negative LTTng error code. */ extern int lttng_create_session_live(const char *name, const char *url, unsigned int timer_interval); /* * Destroy a tracing session. * * The session will not be usable, tracing will be stopped thus buffers will be * flushed. * * This call will wait for data availability for each domain of the session, * which can take an arbitrary amount of time. However, when returning the * tracing data is guaranteed to be ready to be read and analyzed. * * lttng_destroy_session_no_wait() may be used if such a guarantee is not * needed. * * The name can't be NULL here. * * Return 0 on success else a negative LTTng error code. */ extern int lttng_destroy_session(const char *name); /* * Destroy a tracing session. * * Performs the same function as lttng_destroy_session(), but provides * an lttng_destruction_handle which can be used to wait for the completion * of the session's destruction. The lttng_destroy_handle can also be used * obtain the status and archive location of any implicit session * rotation that may have occurred during the session's destruction. * * Returns LTTNG_OK on success. The returned handle is owned by the caller * and must be free'd using lttng_destruction_handle_destroy(). */ extern enum lttng_error_code lttng_destroy_session_ext(const char *session_name, struct lttng_destruction_handle **handle); /* * Behaves exactly like lttng_destroy_session but does not wait for data * availability. */ extern int lttng_destroy_session_no_wait(const char *name); /* * List all the tracing sessions. * * Return the number of entries of the "lttng_session" array. The caller * must free the returned sessions array directly using free(). * * On error, a negative LTTng error code is returned. */ extern int lttng_list_sessions(struct lttng_session **sessions); /* * Get the creation time of an lttng_session object on the session daemon. * * This function must only be used with lttng_session objects returned * by lttng_list_sessions() or lttng_session_create(). * * The creation time returned is a UNIX timestamp; the number of seconds since * Epoch (1970-01-01 00:00:00 +0000 (UTC)). * * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other * return codes. */ extern enum lttng_error_code lttng_session_get_creation_time( const struct lttng_session *session, uint64_t *creation_time); /* * Set the shared memory path for a session. * * Sets the (optional) file system path where shared memory buffers will * be created for the session. This is useful for buffer extraction on * crash, when used with filesystems like pramfs. * * Return 0 on success else a negative LTTng error code. */ extern int lttng_set_session_shm_path(const char *session_name, const char *shm_path); /* * Add PID to session tracker. * * A pid argument >= 0 adds the PID to the session tracker. * A pid argument of -1 means "track all PIDs". * * Return 0 on success else a negative LTTng error code. */ extern int lttng_track_pid(struct lttng_handle *handle, int pid); /* * Remove PID from session tracker. * * A pid argument >= 0 removes the PID from the session tracker. * A pid argument of -1 means "untrack all PIDs". * * Return 0 on success else a negative LTTng error code. */ extern int lttng_untrack_pid(struct lttng_handle *handle, int pid); /* * List PIDs in the tracker. * * enabled is set to whether the PID tracker is enabled. * pids is set to an allocated array of PIDs currently tracked. On * success, pids must be freed by the caller. * nr_pids is set to the number of entries contained by the pids array. * * Returns 0 on success, else a negative LTTng error code. */ extern int lttng_list_tracker_pids(struct lttng_handle *handle, int *enabled, int32_t **pids, size_t *nr_pids); #ifdef __cplusplus } #endif #endif /* LTTNG_SESSION_H */