trace/control.h

/*
 * 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_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 */