mirror of https://gitee.com/openkylin/qemu.git
trace: Provide a detailed event control interface
This interface decouples event obtaining from interaction. Events can be obtained through three different methods: * identifier * name * simple wildcard pattern Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Lluís Vilanova
Stefan Hajnoczi
parent
45be2f5d0d
commit
b1bae816c4
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@ -100,49 +100,37 @@ respectively. This ensures portability between 32- and 64-bit platforms.
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== Generic interface and monitor commands ==
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You can programmatically query and control the dynamic state of trace events
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through a backend-agnostic interface:
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You can programmatically query and control the state of trace events through a
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backend-agnostic interface provided by the header "trace/control.h".
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* trace_print_events
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Note that some of the backends do not provide an implementation for some parts
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of this interface, in which case QEMU will just print a warning (please refer to
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header "trace/control.h" to see which routines are backend-dependent).
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* trace_event_set_state
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Enables or disables trace events at runtime inside QEMU.
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The function returns "true" if the state of the event has been successfully
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changed, or "false" otherwise:
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#include "trace/control.h"
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trace_event_set_state("virtio_irq", true); /* enable */
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[...]
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trace_event_set_state("virtio_irq", false); /* disable */
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Note that some of the backends do not provide an implementation for this
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interface, in which case QEMU will just print a warning.
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This functionality is also provided through monitor commands:
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The state of events can also be queried and modified through monitor commands:
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* info trace-events
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View available trace events and their state. State 1 means enabled, state 0
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means disabled.
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* trace-event NAME on|off
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Enable/disable a given trace event or a group of events having common prefix
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through wildcard.
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Enable/disable a given trace event or a group of events (using wildcards).
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The "-trace events=<file>" command line argument can be used to enable the
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events listed in <file> from the very beginning of the program. This file must
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contain one event name per line.
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A basic wildcard matching is supported in both the monitor command "trace
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-event" and the events list file. That means you can enable/disable the events
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having a common prefix in a batch. For example, virtio-blk trace events could
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be enabled using:
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trace-event virtio_blk_* on
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If a line in the "-trace events=<file>" file begins with a '-', the trace event
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will be disabled instead of enabled. This is useful when a wildcard was used
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to enable an entire family of events but one noisy event needs to be disabled.
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Wildcard matching is supported in both the monitor command "trace-event" and the
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events list file. That means you can enable/disable the events having a common
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prefix in a batch. For example, virtio-blk trace events could be enabled using
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the following monitor command:
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trace-event virtio_blk_* on
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== Trace backends ==
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The "tracetool" script automates tedious trace event code generation and also
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@ -263,3 +251,7 @@ guard such computations and avoid its compilation when the event is disabled:
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}
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return ptr;
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}
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You can check both if the event has been disabled and is dynamically enabled at
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the same time using the 'trace_event_get_state' routine (see header
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"trace/control.h" for more information).
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@ -0,0 +1,67 @@
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/*
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* Interface for configuring and controlling the state of tracing events.
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*
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* Copyright (C) 2011-2012 Lluís Vilanova <vilanova@ac.upc.edu>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#ifndef TRACE__CONTROL_INTERNAL_H
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#define TRACE__CONTROL_INTERNAL_H
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#include <string.h>
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extern TraceEvent trace_events[];
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static inline TraceEvent *trace_event_id(TraceEventID id)
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{
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assert(id < trace_event_count());
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return &trace_events[id];
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}
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static inline TraceEventID trace_event_count(void)
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{
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return TRACE_EVENT_COUNT;
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}
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static inline bool trace_event_is_pattern(const char *str)
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{
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assert(str != NULL);
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return strchr(str, '*') != NULL;
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}
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static inline TraceEventID trace_event_get_id(TraceEvent *ev)
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{
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assert(ev != NULL);
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return ev->id;
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}
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static inline const char * trace_event_get_name(TraceEvent *ev)
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{
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assert(ev != NULL);
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return ev->name;
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}
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static inline bool trace_event_get_state_static(TraceEvent *ev)
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{
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assert(ev != NULL);
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return ev->sstate;
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}
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static inline bool trace_event_get_state_dynamic(TraceEvent *ev)
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{
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assert(ev != NULL);
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return ev->dstate;
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}
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static inline void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
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{
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assert(ev != NULL);
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assert(trace_event_get_state_static(ev));
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return trace_event_set_state_dynamic_backend(ev, state);
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}
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#endif /* TRACE__CONTROL_INTERNAL_H */
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106
trace/control.c
106
trace/control.c
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@ -1,19 +1,86 @@
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/*
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* Interface for configuring and controlling the state of tracing events.
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*
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* Copyright (C) 2011 Lluís Vilanova <vilanova@ac.upc.edu>
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* Copyright (C) 2011-2012 Lluís Vilanova <vilanova@ac.upc.edu>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include "trace/control.h"
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TraceEvent *trace_event_name(const char *name)
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{
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assert(name != NULL);
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TraceEventID i;
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for (i = 0; i < trace_event_count(); i++) {
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TraceEvent *ev = trace_event_id(i);
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if (strcmp(trace_event_get_name(ev), name) == 0) {
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return ev;
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}
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}
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return NULL;
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}
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static bool pattern_glob(const char *pat, const char *ev)
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{
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while (*pat != '\0' && *ev != '\0') {
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if (*pat == *ev) {
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pat++;
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ev++;
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}
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else if (*pat == '*') {
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if (pattern_glob(pat, ev+1)) {
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return true;
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} else if (pattern_glob(pat+1, ev)) {
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return true;
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} else {
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return false;
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}
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} else {
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return false;
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}
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}
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while (*pat == '*') {
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pat++;
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}
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if (*pat == '\0' && *ev == '\0') {
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return true;
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} else {
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return false;
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}
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}
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TraceEvent *trace_event_pattern(const char *pat, TraceEvent *ev)
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{
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assert(pat != NULL);
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TraceEventID i;
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if (ev == NULL) {
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i = -1;
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} else {
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i = trace_event_get_id(ev);
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}
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i++;
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while (i < trace_event_count()) {
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TraceEvent *res = trace_event_id(i);
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if (pattern_glob(pat, trace_event_get_name(res))) {
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return res;
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}
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i++;
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}
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return NULL;
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}
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void trace_backend_init_events(const char *fname)
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{
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int ret;
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if (fname == NULL) {
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return;
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}
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@ -32,15 +99,28 @@ void trace_backend_init_events(const char *fname)
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if ('#' == line_buf[0]) { /* skip commented lines */
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continue;
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}
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if ('-' == line_buf[0]) {
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ret = trace_event_set_state(line_buf+1, false);
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const bool enable = ('-' != line_buf[0]);
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char *line_ptr = enable ? line_buf : line_buf + 1;
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if (trace_event_is_pattern(line_ptr)) {
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TraceEvent *ev = NULL;
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while ((ev = trace_event_pattern(line_ptr, ev)) != NULL) {
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if (trace_event_get_state_static(ev)) {
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trace_event_set_state_dynamic(ev, enable);
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}
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}
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} else {
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ret = trace_event_set_state(line_buf, true);
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}
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if (!ret) {
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fprintf(stderr,
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"error: trace event '%s' does not exist\n", line_buf);
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exit(1);
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TraceEvent *ev = trace_event_name(line_ptr);
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if (ev == NULL) {
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fprintf(stderr,
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"error: trace event '%s' does not exist\n", line_ptr);
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exit(1);
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}
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if (!trace_event_get_state_static(ev)) {
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fprintf(stderr,
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"error: trace event '%s' is not traceable\n", line_ptr);
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exit(1);
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}
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trace_event_set_state_dynamic(ev, enable);
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}
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}
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}
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192
trace/control.h
192
trace/control.h
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@ -1,41 +1,193 @@
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/*
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* Interface for configuring and controlling the state of tracing events.
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*
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* Copyright (C) 2011 Lluís Vilanova <vilanova@ac.upc.edu>
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* Copyright (C) 2011-2012 Lluís Vilanova <vilanova@ac.upc.edu>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#ifndef TRACE_CONTROL_H
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#define TRACE_CONTROL_H
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#ifndef TRACE__CONTROL_H
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#define TRACE__CONTROL_H
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#include "qemu-common.h"
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#include "trace/generated-events.h"
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/** Print the state of all events. */
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void trace_print_events(FILE *stream, fprintf_function stream_printf);
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/** Set the state of an event.
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/**
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* TraceEventID:
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*
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* @return Whether the state changed.
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* Unique tracing event identifier.
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*
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* These are named as 'TRACE_${EVENT_NAME}'.
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*
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* See also: "trace/generated-events.h"
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*/
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bool trace_event_set_state(const char *name, bool state);
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enum TraceEventID;
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/** Initialize the tracing backend.
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/**
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* trace_event_id:
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* @id: Event identifier.
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*
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* @events Name of file with events to be enabled at startup; may be NULL.
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* Corresponds to commandline option "-trace events=...".
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* @file Name of trace output file; may be NULL.
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* Corresponds to commandline option "-trace file=...".
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* @return Whether the backend could be successfully initialized.
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* Get an event by its identifier.
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*
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* This routine has a constant cost, as opposed to trace_event_name and
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* trace_event_pattern.
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*
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* Pre-conditions: The identifier is valid.
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*
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* Returns: pointer to #TraceEvent.
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*
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*/
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static TraceEvent *trace_event_id(TraceEventID id);
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/**
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* trace_event_name:
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* @id: Event name.
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*
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* Search an event by its name.
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*
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* Returns: pointer to #TraceEvent or NULL if not found.
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*/
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TraceEvent *trace_event_name(const char *name);
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/**
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* trace_event_pattern:
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* @pat: Event name pattern.
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* @ev: Event to start searching from (not included).
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*
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* Get all events with a given name pattern.
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*
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* Returns: pointer to #TraceEvent or NULL if not found.
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*/
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TraceEvent *trace_event_pattern(const char *pat, TraceEvent *ev);
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/**
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* trace_event_is_pattern:
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*
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* Whether the given string is an event name pattern.
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*/
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static bool trace_event_is_pattern(const char *str);
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/**
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* trace_event_count:
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*
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* Return the number of events.
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*/
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static TraceEventID trace_event_count(void);
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/**
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* trace_event_get_id:
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*
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* Get the identifier of an event.
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*/
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static TraceEventID trace_event_get_id(TraceEvent *ev);
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/**
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* trace_event_get_name:
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*
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* Get the name of an event.
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*/
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static const char * trace_event_get_name(TraceEvent *ev);
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/**
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* trace_event_get_state:
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* @id: Event identifier.
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*
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* Get the tracing state of an event (both static and dynamic).
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*
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* If the event has the disabled property, the check will have no performance
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* impact.
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*
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* As a down side, you must always use an immediate #TraceEventID value.
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*/
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#define trace_event_get_state(id) \
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((id ##_ENABLED) && trace_event_get_state_dynamic(trace_event_id(id)))
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/**
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* trace_event_get_state_static:
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* @id: Event identifier.
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*
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* Get the static tracing state of an event.
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*
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* Use the define 'TRACE_${EVENT_NAME}_ENABLED' for compile-time checks (it will
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* be set to 1 or 0 according to the presence of the disabled property).
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*/
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static bool trace_event_get_state_static(TraceEvent *ev);
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/**
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* trace_event_get_state_dynamic:
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*
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* Get the dynamic tracing state of an event.
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*/
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static bool trace_event_get_state_dynamic(TraceEvent *ev);
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/**
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* trace_event_set_state:
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*
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* Set the tracing state of an event (only if possible).
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*/
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#define trace_event_set_state(id, state) \
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do { \
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if ((id ##_ENABLED)) { \
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TraceEvent *_e = trace_event_id(id); \
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trace_event_set_state_dynamic(_e, state); \
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} \
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} while (0)
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/**
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* trace_event_set_state_dynamic:
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*
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* Set the dynamic tracing state of an event.
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*
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* Pre-condition: trace_event_get_state_static(ev) == true
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*/
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static void trace_event_set_state_dynamic(TraceEvent *ev, bool state);
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/**
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* trace_event_set_state_dynamic_backend:
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*
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* Warning: This function must be implemented by each tracing backend.
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*/
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void trace_event_set_state_dynamic_backend(TraceEvent *ev, bool state);
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/**
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* trace_print_events:
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*
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* Print the state of all events.
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*
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* Warning: This function must be implemented by each tracing backend.
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*/
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void trace_print_events(FILE *stream, fprintf_function stream_printf);
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/**
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* trace_backend_init:
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* @events: Name of file with events to be enabled at startup; may be NULL.
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* Corresponds to commandline option "-trace events=...".
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* @file: Name of trace output file; may be NULL.
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* Corresponds to commandline option "-trace file=...".
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*
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* Initialize the tracing backend.
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*
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* Warning: This function must be implemented by each tracing backend.
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*
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* Returns: Whether the backend could be successfully initialized.
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*/
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bool trace_backend_init(const char *events, const char *file);
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/** Generic function to initialize the state of events.
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/**
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* trace_backend_init_events:
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* @fname: Name of file with events to enable; may be NULL.
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*
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* @fname Name of file with events to enable; may be NULL.
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* Generic function to initialize the state of events.
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*/
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void trace_backend_init_events(const char *fname);
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#endif /* TRACE_CONTROL_H */
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#include "trace/control-internal.h"
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#endif /* TRACE__CONTROL_H */
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