qemu/trace/control.h
Lluís Vilanova 5b808275f3 trace: Multi-backend tracing
Adds support to compile QEMU with multiple tracing backends at the same time.

For example, you can compile QEMU with:

  $ ./configure --enable-trace-backends=ftrace,dtrace

Where 'ftrace' can be handy for having an in-flight record of events, and 'dtrace' can be later used to extract more information from the system.

This patch allows having both available without recompiling QEMU.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-06-09 15:43:40 +02:00

175 lines
4.1 KiB
C

/*
* Interface for configuring and controlling the state of tracing events.
*
* Copyright (C) 2011-2014 Lluís Vilanova <vilanova@ac.upc.edu>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef TRACE__CONTROL_H
#define TRACE__CONTROL_H
#include "qemu-common.h"
#include "trace/generated-events.h"
/**
* TraceEventID:
*
* Unique tracing event identifier.
*
* These are named as 'TRACE_${EVENT_NAME}'.
*
* See also: "trace/generated-events.h"
*/
enum TraceEventID;
/**
* trace_event_id:
* @id: Event identifier.
*
* Get an event by its identifier.
*
* This routine has a constant cost, as opposed to trace_event_name and
* trace_event_pattern.
*
* Pre-conditions: The identifier is valid.
*
* Returns: pointer to #TraceEvent.
*
*/
static TraceEvent *trace_event_id(TraceEventID id);
/**
* trace_event_name:
* @id: Event name.
*
* Search an event by its name.
*
* Returns: pointer to #TraceEvent or NULL if not found.
*/
TraceEvent *trace_event_name(const char *name);
/**
* trace_event_pattern:
* @pat: Event name pattern.
* @ev: Event to start searching from (not included).
*
* Get all events with a given name pattern.
*
* Returns: pointer to #TraceEvent or NULL if not found.
*/
TraceEvent *trace_event_pattern(const char *pat, TraceEvent *ev);
/**
* trace_event_is_pattern:
*
* Whether the given string is an event name pattern.
*/
static bool trace_event_is_pattern(const char *str);
/**
* trace_event_count:
*
* Return the number of events.
*/
static TraceEventID trace_event_count(void);
/**
* trace_event_get_id:
*
* Get the identifier of an event.
*/
static TraceEventID trace_event_get_id(TraceEvent *ev);
/**
* trace_event_get_name:
*
* Get the name of an event.
*/
static const char * trace_event_get_name(TraceEvent *ev);
/**
* trace_event_get_state:
* @id: Event identifier.
*
* Get the tracing state of an event (both static and dynamic).
*
* If the event has the disabled property, the check will have no performance
* impact.
*
* As a down side, you must always use an immediate #TraceEventID value.
*/
#define trace_event_get_state(id) \
((id ##_ENABLED) && trace_event_get_state_dynamic(trace_event_id(id)))
/**
* trace_event_get_state_static:
* @id: Event identifier.
*
* Get the static tracing state of an event.
*
* Use the define 'TRACE_${EVENT_NAME}_ENABLED' for compile-time checks (it will
* be set to 1 or 0 according to the presence of the disabled property).
*/
static bool trace_event_get_state_static(TraceEvent *ev);
/**
* trace_event_get_state_dynamic:
*
* Get the dynamic tracing state of an event.
*/
static bool trace_event_get_state_dynamic(TraceEvent *ev);
/**
* trace_event_set_state:
*
* Set the tracing state of an event (only if possible).
*/
#define trace_event_set_state(id, state) \
do { \
if ((id ##_ENABLED)) { \
TraceEvent *_e = trace_event_id(id); \
trace_event_set_state_dynamic(_e, state); \
} \
} while (0)
/**
* trace_event_set_state_dynamic:
*
* Set the dynamic tracing state of an event.
*
* Pre-condition: trace_event_get_state_static(ev) == true
*/
static void trace_event_set_state_dynamic(TraceEvent *ev, bool state);
/**
* trace_print_events:
*
* Print the state of all events.
*/
void trace_print_events(FILE *stream, fprintf_function stream_printf);
/**
* trace_init_backends:
* @events: Name of file with events to be enabled at startup; may be NULL.
* Corresponds to commandline option "-trace events=...".
* @file: Name of trace output file; may be NULL.
* Corresponds to commandline option "-trace file=...".
*
* Initialize the tracing backend.
*
* Returns: Whether the backends could be successfully initialized.
*/
bool trace_init_backends(const char *events, const char *file);
#include "trace/control-internal.h"
#endif /* TRACE__CONTROL_H */