minitrace.h

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#ifndef MINITRACE_H
#define MINITRACE_H

// Minitrace
//
// Copyright 2014 by Henrik Rydgård
// http://www.github.com/hrydgard/minitrace
// Released under the MIT license.
//
// Ultra-light dependency free library for performance tracing C/C++ applications.
// Produces traces compatible with Google Chrome's trace viewer.
// Simply open "about:tracing" in Chrome and load the produced JSON.
//
// This contains far less template magic than the original libraries from Chrome
// because this is meant to be usable from C.
//
// See README.md for a tutorial.
//
// The trace format is documented here:
// https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/edit
// More:
// http://www.altdevblogaday.com/2012/08/21/using-chrometracing-to-view-your-inline-profiling-data/

#include <inttypes.h>

#define MTR_ENABLED

// If MTR_ENABLED is not defined, Minitrace does nothing and has near zero overhead.
// Preferably, set this flag in your build system. If you can't just uncomment this line.
// #define MTR_ENABLED

// By default, will collect up to 1000000 events, then you must flush.
// It's recommended that you simply call mtr_flush on a background thread
// occasionally. It's safe...ish.
#define INTERNAL_MINITRACE_BUFFER_SIZE 1000000

//#define MTR_ENABLED

namespace minitrace {

// Initializes Minitrace. Must be called very early during startup of your executable,
// before any MTR_ statements..
void mtr_init(const char *json_file);

// Shuts down minitrace cleanly, flushing the trace buffer.
void mtr_shutdown();

// Lets you enable and disable Minitrace at runtime.
// May cause strange discontinuities in the output.
// Minitrace is enabled on startup by default.
void mtr_start();
void mtr_stop();

// Flushes the collected data to disk, clearing the buffer for new data.
void mtr_flush();

// Returns the current time in seconds. Used internally by Minitrace. No caching.
int64_t mtr_time_usec();

// Registers a handler that will flush the trace on Ctrl+C.
// Works on Linux and MacOSX, and in Win32 console applications.
void mtr_register_sigint_handler();

// Utility function that should rarely be used.
// If str is semi dynamic, store it permanently in a small pool so we don't need to malloc it.
// The pool fills up fast though and performance isn't great.
// Returns a fixed string if the pool is full.
const char *mtr_pool_string(const char *str);

// Commented-out types will be supported in the future.
typedef enum {
        MTR_ARG_TYPE_NONE = 0,
        MTR_ARG_TYPE_INT = 1,   // I
        // MTR_ARG_TYPE_FLOAT = 2,  // TODO
        // MTR_ARG_TYPE_DOUBLE = 3,  // TODO
        MTR_ARG_TYPE_STRING_CONST = 8,  // C
        MTR_ARG_TYPE_STRING_COPY = 9,
        // MTR_ARG_TYPE_JSON_COPY = 10,
} mtr_arg_type;

// TODO: Add support for more than one argument (metadata) per event
// Having more costs speed and memory.
#define MTR_MAX_ARGS 1

// Only use the macros to call these.
void internal_mtr_raw_event(const char *category, const char *name, char ph, void *id);
void internal_mtr_raw_event_arg(const char *category, const char *name, char ph, void *id, mtr_arg_type arg_type, const char *arg_name, void *arg_value);

#ifdef MTR_ENABLED

// c - category. Can be filtered by in trace viewer (or at least that's the intention).
//     A good use is to pass __FILE__, there are macros further below that will do it for you.
// n - name. Pass __FUNCTION__ in most cases, unless you are marking up parts of one.

// Scopes. In C++, use MTR_SCOPE. In C, always match them within the same scope.
#define MTR_BEGIN(c, n) internal_mtr_raw_event(c, n, 'B', nullptr)
#define MTR_END(c, n) internal_mtr_raw_event(c, n, 'E', nullptr)
#define MTR_SCOPE(c, n) MTRScopedTrace ____mtr_scope(c, n)
#define MTR_SCOPE_LIMIT(c, n, l) MTRScopedTraceLimit ____mtr_scope(c, n, l)

// Async events. Can span threads. ID identifies which events to connect in the view.
#define MTR_START(c, n, id) internal_mtr_raw_event(c, n, 'S', (void *)(id))
#define MTR_STEP(c, n, id, step) internal_mtr_raw_event_arg(c, n, 'T', (void *)(id), MTR_ARG_TYPE_STRING_CONST, "step", (void *)(step))
#define MTR_FINISH(c, n, id) internal_mtr_raw_event(c, n, 'F', (void *)(id))

// Flow events. Like async events, but displayed in a more fancy way in the viewer.
#define MTR_FLOW_START(c, n, id) internal_mtr_raw_event(c, n, 's', (void *)(id))
#define MTR_FLOW_STEP(c, n, id, step) internal_mtr_raw_event_arg(c, n, 't', (void *)(id), MTR_ARG_TYPE_STRING_CONST, "step", (void *)(step))
#define MTR_FLOW_FINISH(c, n, id) internal_mtr_raw_event(c, n, 'f', (void *)(id))

// The same macros, but with a single named argument which shows up as metadata in the viewer.
// _I for int.
// _C is for a const string arg.
// _S will copy the string, freeing on flush (expensive but sometimes necessary).
// but required if the string was generated dynamically.

// Note that it's fine to match BEGIN_S with END and BEGIN with END_S, etc.
#define MTR_BEGIN_C(c, n, aname, astrval) internal_mtr_raw_event_arg(c, n, 'B', 0, MTR_ARG_TYPE_STRING_CONST, aname, (void *)(astrval))
#define MTR_END_C(c, n, aname, astrval) internal_mtr_raw_event_arg(c, n, 'E', 0, MTR_ARG_TYPE_STRING_CONST, aname, (void *)(astrval))
#define MTR_SCOPE_C(c, n, aname, astrval) MTRScopedTraceArg ____mtr_scope(c, n, MTR_ARG_TYPE_STRING_CONST, aname, (void *)(astrval))

#define MTR_BEGIN_S(c, n, aname, astrval) internal_mtr_raw_event_arg(c, n, 'B', 0, MTR_ARG_TYPE_STRING_COPY, aname, (void *)(astrval))
#define MTR_END_S(c, n, aname, astrval) internal_mtr_raw_event_arg(c, n, 'E', 0, MTR_ARG_TYPE_STRING_COPY, aname, (void *)(astrval))
#define MTR_SCOPE_S(c, n, aname, astrval) MTRScopedTraceArg ____mtr_scope(c, n, MTR_ARG_TYPE_STRING_COPY, aname, (void *)(astrval))

#define MTR_BEGIN_I(c, n, aname, aintval) internal_mtr_raw_event_arg(c, n, 'B', 0, MTR_ARG_TYPE_INT, aname, (void*)(intptr_t)(aintval))
#define MTR_END_I(c, n, aname, aintval) internal_mtr_raw_event_arg(c, n, 'E', 0, MTR_ARG_TYPE_INT, aname, (void*)(intptr_t)(aintval))
#define MTR_SCOPE_I(c, n, aname, aintval) MTRScopedTraceArg ____mtr_scope(c, n, MTR_ARG_TYPE_INT, aname, (void*)(intptr_t)(aintval))

// Instant events. For things with no duration.
#define MTR_INSTANT(c, n) internal_mtr_raw_event(c, n, 'I', nullptr)
#define MTR_INSTANT_C(c, n, aname, astrval) internal_mtr_raw_event(c, n, 'I', 0, MTR_ARG_TYPE_STRING_CONST, aname, (void *)(astrval))
#define MTR_INSTANT_I(c, n, aname, aintval) internal_mtr_raw_event(c, n, 'I', 0, MTR_ARG_TYPE_INT, aname, (void *)(aintval))

// Counters (can't do multi-value counters yet)
#define MTR_COUNTER(c, n, val) internal_mtr_raw_event_arg(c, n, 'C', 0, MTR_ARG_TYPE_INT, n, (void *)(intptr_t)(val))

// Metadata. Call at the start preferably. Must be const strings.

#define MTR_META_PROCESS_NAME(n) internal_mtr_raw_event_arg("", "process_name", 'M', 0, MTR_ARG_TYPE_STRING_COPY, "name", (void *)(n))
#define MTR_META_THREAD_NAME(n) internal_mtr_raw_event_arg("", "thread_name", 'M', 0, MTR_ARG_TYPE_STRING_COPY, "name", (void *)(n))
#define MTR_META_THREAD_SORT_INDEX(i) internal_mtr_raw_event_arg("", "thread_sort_index", 'M', 0, MTR_ARG_TYPE_INT, "sort_index", (void *)(i))

#else

#define MTR_BEGIN(c, n)
#define MTR_END(c, n)
#define MTR_SCOPE(c, n)
#define MTR_START(c, n, id)
#define MTR_STEP(c, n, id, step)
#define MTR_FINISH(c, n, id)
#define MTR_FLOW_START(c, n, id)
#define MTR_FLOW_STEP(c, n, id, step)
#define MTR_FLOW_FINISH(c, n, id)
#define MTR_INSTANT(c, n)

#define MTR_BEGIN_C(c, n, aname, astrval)
#define MTR_END_C(c, n, aname, astrval)
#define MTR_SCOPE_C(c, n, aname, astrval)

#define MTR_BEGIN_S(c, n, aname, astrval)
#define MTR_END_S(c, n, aname, astrval)
#define MTR_SCOPE_S(c, n, aname, astrval)

#define MTR_BEGIN_I(c, n, aname, aintval)
#define MTR_END_I(c, n, aname, aintval)
#define MTR_SCOPE_I(c, n, aname, aintval)

#define MTR_INSTANT(c, n)
#define MTR_INSTANT_C(c, n, aname, astrval)
#define MTR_INSTANT_I(c, n, aname, aintval)

// Counters (can't do multi-value counters yet)
#define MTR_COUNTER(c, n, val)

// Metadata. Call at the start preferably. Must be const strings.

#define MTR_META_PROCESS_NAME(n)

#define MTR_META_THREAD_NAME(n)
#define MTR_META_THREAD_SORT_INDEX(i)

#endif

// Shortcuts for simple function timing with automatic categories and names.

#define MTR_BEGIN_FUNC() MTR_BEGIN(__FILE__, __FUNCTION__)
#define MTR_END_FUNC() MTR_END(__FILE__, __FUNCTION__)
#define MTR_SCOPE_FUNC() MTR_SCOPE(__FILE__, __FUNCTION__)
#define MTR_INSTANT_FUNC() MTR_INSTANT(__FILE__, __FUNCTION__)
#define MTR_SCOPE_FUNC_LIMIT_S(l) MTRScopedTraceLimit ____mtr_scope(__FILE__, __FUNCTION__, l)
#define MTR_SCOPE_FUNC_LIMIT_MS(l) MTRScopedTraceLimit ____mtr_scope(__FILE__, __FUNCTION__, 1)

// Same, but with a single argument of the usual types.
#define MTR_BEGIN_FUNC_S(aname, arg) MTR_BEGIN_S(__FILE__, __FUNCTION__, aname, arg)
#define MTR_END_FUNC_S(aname, arg) MTR_END_S(__FILE__, __FUNCTION__, aname, arg)
#define MTR_SCOPE_FUNC_S(aname, arg) MTR_SCOPE_S(__FILE__, __FUNCTION__, aname, arg)

#define MTR_BEGIN_FUNC_C(aname, arg) MTR_BEGIN_C(__FILE__, __FUNCTION__, aname, arg)
#define MTR_END_FUNC_C(aname, arg) MTR_END_C(__FILE__, __FUNCTION__, aname, arg)
#define MTR_SCOPE_FUNC_C(aname, arg) MTR_SCOPE_C(__FILE__, __FUNCTION__, aname, arg)

#define MTR_BEGIN_FUNC_I(aname, arg) MTR_BEGIN_I(__FILE__, __FUNCTION__, aname, arg)
#define MTR_END_FUNC_I(aname, arg) MTR_END_I(__FILE__, __FUNCTION__, aname, arg)
#define MTR_SCOPE_FUNC_I(aname, arg) MTR_SCOPE_I(__FILE__, __FUNCTION__, aname, arg)


#ifdef MTR_ENABLED
// These are optimized to use X events (combined B and E). Much easier to do in C++ than in C.
class MTRScopedTrace {
public:
        MTRScopedTrace(const char *category, const char *name)
                : category_(category), name_(name) {
    start_time_ = mtr_time_usec();
        }
        ~MTRScopedTrace() {
                internal_mtr_raw_event(category_, name_, 'X', &start_time_);
        }

private:
        const char *category_;
        const char *name_;
    int64_t start_time_;
};

// Only outputs a block if execution time exceeded the limit.
// TODO: This will effectively call mtr_time_usec twice at the end, which is bad.
class MTRScopedTraceLimit {
public:
    MTRScopedTraceLimit(const char* category, const char* name, int64_t limit_s)
                : category_(category), name_(name), limit_(limit_s) {
    start_time_ = mtr_time_usec();
        }
        ~MTRScopedTraceLimit() {
    int64_t end_time = mtr_time_usec();
                if (end_time - start_time_ >= limit_) {
                        internal_mtr_raw_event(category_, name_, 'X', &start_time_);
                }
        }

private:
        const char *category_;
        const char *name_;
    int64_t start_time_;
    int64_t limit_;
};

class MTRScopedTraceArg {
public:
        MTRScopedTraceArg(const char *category, const char *name, mtr_arg_type arg_type, const char *arg_name, void *arg_value)
                : category_(category), name_(name) {
                internal_mtr_raw_event_arg(category, name, 'B', 0, arg_type, arg_name, arg_value);
        }
        ~MTRScopedTraceArg() {
                internal_mtr_raw_event(category_, name_, 'E', 0);
        }

private:
        const char *category_;
        const char *name_;
};

#endif

} //end namespace

#endif