X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=include%2Fust%2Ftracepoint.h;h=11de23dcffde26dea9b05c9e14d8184a8019603d;hb=bf1624c03b3e4e42e8ea6456a5702d4f7e105213;hp=3d61f72883c762cc44ad64fb5c4c005d281d2084;hpb=9edd34bd25f52dd39b354a84f02697254121aefd;p=ust.git diff --git a/include/ust/tracepoint.h b/include/ust/tracepoint.h index 3d61f72..11de23d 100644 --- a/include/ust/tracepoint.h +++ b/include/ust/tracepoint.h @@ -2,7 +2,7 @@ #define _UST_TRACEPOINT_H /* - * Copyright (C) 2008 Mathieu Desnoyers + * Copyright (C) 2008-2011 Mathieu Desnoyers * Copyright (C) 2009 Pierre-Marc Fournier * Copyright (C) 2009 Steven Rostedt * @@ -45,28 +45,6 @@ struct tracepoint { */ #define tracepoint(name, args...) __trace_##name(args) -/* - * Library should be made known to libust by declaring TRACEPOINT_LIB in - * the source file. (Usually at the end of the file, in the outermost - * scope). - */ -#define TRACEPOINT_LIB \ - extern struct tracepoint * const __start___tracepoints_ptrs[] __attribute__((weak, visibility("hidden"))); \ - extern struct tracepoint * const __stop___tracepoints_ptrs[] __attribute__((weak, visibility("hidden"))); \ - static struct tracepoint * __tracepoint_ptr_dummy \ - __attribute__((used, section("__tracepoints_ptrs"))); \ - static void __attribute__((constructor)) __tracepoints__init(void) \ - { \ - tracepoint_register_lib(__start___tracepoints_ptrs, \ - __stop___tracepoints_ptrs - \ - __start___tracepoints_ptrs); \ - } \ - \ - static void __attribute__((destructor)) __tracepoints__destroy(void) \ - { \ - tracepoint_unregister_lib(__start___tracepoints_ptrs); \ - } - /* * it_func[0] is never NULL because there is at least one element in the array * when the array itself is non NULL. @@ -182,34 +160,119 @@ int __tracepoint_probe_register(const char *name, void *probe, void *data); extern int __tracepoint_probe_unregister(const char *name, void *probe, void *data); -struct tracepoint_lib { - struct tracepoint * const *tracepoints_start; - int tracepoints_count; - struct cds_list_head list; -}; - extern int tracepoint_register_lib(struct tracepoint * const *tracepoints_start, int tracepoints_count); extern int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start); +/* + * These weak symbols, the constructor, and destructor take care of + * registering only _one_ instance of the tracepoints per shared-ojbect + * (or for the whole main program). + */ +extern struct tracepoint * const __start___tracepoints_ptrs[] + __attribute__((weak, visibility("hidden"))); +extern struct tracepoint * const __stop___tracepoints_ptrs[] + __attribute__((weak, visibility("hidden"))); +int __tracepoint_registered + __attribute__((weak, visibility("hidden"))); + +static void __attribute__((constructor)) __tracepoints__init(void) +{ + if (__tracepoint_registered++) + return; + tracepoint_register_lib(__start___tracepoints_ptrs, + __stop___tracepoints_ptrs - + __start___tracepoints_ptrs); +} + +static void __attribute__((destructor)) __tracepoints__destroy(void) +{ + if (--__tracepoint_registered) + return; + tracepoint_unregister_lib(__start___tracepoints_ptrs); +} #ifndef TRACEPOINT_EVENT /* - * For use with the TRACEPOINT_EVENT macro: + * Usage of the TRACEPOINT_EVENT macro: + * + * In short, an example: + * + * TRACEPOINT_EVENT(< [com_company_]project_[component_]event >, + * TP_PROTO(int arg0, void *arg1, char *string, size_t strlen, + * long *arg4, size_t arg4_len), + * TP_ARGS(arg0, arg1, string, strlen, arg4, arg4_len), + * TP_FIELDS( + * + * * Integer, printed in base 10 * + * ctf_integer(int, field_a, arg0) + * + * * Integer, printed with 0x base 16 * + * ctf_integer_hex(unsigned long, field_d, arg1) + * + * * Array Sequence, printed as UTF8-encoded array of bytes * + * ctf_array_text(char, field_b, string, FIXED_LEN) + * ctf_sequence_text(char, field_c, string, size_t, strlen) + * + * * String, printed as UTF8-encoded string * + * ctf_string(field_e, string) + * + * * Array sequence of signed integer values * + * ctf_array(long, field_f, arg4, FIXED_LEN4) + * ctf_sequence(long, field_g, arg4, size_t, arg4_len) + * ) + * ) + * + * In more detail: + * + * We define a tracepoint, its arguments, and its 'fast binary record' + * layout. * - * We define a tracepoint, its arguments, its printf format - * and its 'fast binary record' layout. + * Firstly, name your tracepoint via TRACEPOINT_EVENT(name, * - * Firstly, name your tracepoint via TRACEPOINT_EVENT(name : the - * 'subsystem_event' notation is fine. + * The "name" MUST follow these rules to ensure no namespace clash + * occurs: * - * Think about this whole construct as the - * 'trace_sched_switch() function' from now on. + * For projects (applications and libraries) for which an entity + * specific to the project controls the source code and thus its + * tracepoints (typically with a scope larger than a single company): * + * either: + * project_component_event + * or: + * project_event * - * TRACEPOINT_EVENT(sched_switch, + * Where "project" is the name of the project, + * "component" is the name of the project component (which may + * include several levels of sub-components, e.g. + * ...component_subcomponent_...) where the tracepoint is located + * (optional), + * "event" is the name of the tracepoint event. + * + * For projects issued from a single company wishing to advertise that + * the company controls the source code and thus the tracepoints, the + * "com_" prefix should be used: + * + * either: + * com_company_project_component_event + * or: + * com_company_project_event + * + * Where "company" is the name of the company, + * "project" is the name of the project, + * "component" is the name of the project component (which may + * include several levels of sub-components, e.g. + * ...component_subcomponent_...) where the tracepoint is located + * (optional), + * "event" is the name of the tracepoint event. + * + * + * As an example, let's consider a user-space application "someproject" + * that would have an internal thread scheduler: + * + * TRACEPOINT_EVENT(someproject_sched_switch, * * * * * A function has a regular function arguments @@ -236,7 +299,7 @@ int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start); * * be saved into the ring buffer. These are the fields * * that will be exposed to readers. * * - * * tp_field(pid_t, prev_pid, prev->pid) is equivalent + * * ctf_integer(pid_t, prev_pid, prev->pid) is equivalent * * to a standard declaraton: * * * * pid_t prev_pid; @@ -245,7 +308,7 @@ int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start); * * * * prev_pid = prev->pid; * * - * * tp_array(char, prev_comm, TASK_COMM_LEN, prev->comm) is + * * ctf_array(char, prev_comm, prev->comm, TASK_COMM_LEN) is * * equivalent to: * * * * char prev_comm[TASK_COMM_LEN]; @@ -256,14 +319,14 @@ int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start); * * * * TP_FIELDS( - * tp_array(char, prev_comm, TASK_COMM_LEN, prev->comm) - * tp_field(pid_t, prev_pid, prev->pid) - * tp_field(int, prev_prio, prev->prio) - * tp_array(char, next_comm, TASK_COMM_LEN, next->comm) - * tp_field(pid_t, next_pid, next->pid) - * tp_field(int, next_prio, next->prio) + * ctf_array(char, prev_comm, prev->comm, TASK_COMM_LEN) + * ctf_integer(pid_t, prev_pid, prev->pid) + * ctf_integer(int, prev_prio, prev->prio) + * ctf_array(char, next_comm, next->comm, TASK_COMM_LEN) + * ctf_integer(pid_t, next_pid, next->pid) + * ctf_integer(int, next_prio, next->prio) * ) - * ); + * ) */ #define TRACEPOINT_EVENT(name, proto, args, fields) \ @@ -283,45 +346,6 @@ int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start); #define TRACEPOINT_EVENT_INSTANCE_NOARGS(template, name) \ _DECLARE_TRACEPOINT_NOARGS(name) - - -#define TRACEPOINT_EVENT_LIB \ - extern struct trace_event * const __start___trace_events_ptrs[] \ - __attribute__((weak, visibility("hidden"))); \ - extern struct trace_event * const __stop___trace_events_ptrs[] \ - __attribute__((weak, visibility("hidden"))); \ - static struct trace_event * __event_ptrs_dummy \ - __attribute__((used, section("__trace_events_ptrs"))); \ - static void __attribute__((constructor)) \ - __trace_events__init(void) \ - { \ - trace_event_register_lib(__start___trace_events_ptrs, \ - __stop___trace_events_ptrs - \ - __start___trace_events_ptrs); \ - } \ - \ - static void __attribute__((destructor)) \ - __trace_event__destroy(void) \ - { \ - trace_event_unregister_lib(__start___trace_events_ptrs);\ - } - -struct trace_event { - const char *name; -}; - -struct trace_event_lib { - struct trace_event * const *trace_events_start; - int trace_events_count; - struct cds_list_head list; -}; - -extern -int trace_event_register_lib(struct trace_event * const *start_trace_events, - int trace_event_count); -extern -int trace_event_unregister_lib(struct trace_event * const *start_trace_events); - #endif /* #ifndef TRACEPOINT_EVENT */ #endif /* _UST_TRACEPOINT_H */