js/src/builtin/Profilers.cpp
author Morgan Reschenberg <mreschenberg@mozilla.com>
Fri, 07 Aug 2020 16:54:36 +0000
changeset 543807 768023eab2270602610ef80988e29773f52d1be8
parent 454520 5f4630838d46dd81dadb13220a4af0da9e23a619
permissions -rw-r--r--
Bug 1652809: Add rotor mochitest for headings. r=eeejay Differential Revision: https://phabricator.services.mozilla.com/D85917

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* Profiling-related API */

#include "builtin/Profilers.h"

#include "mozilla/Compiler.h"
#include "mozilla/Sprintf.h"

#include <stdarg.h>

#ifdef MOZ_CALLGRIND
#  include <valgrind/callgrind.h>
#endif

#ifdef __APPLE__
#  ifdef MOZ_INSTRUMENTS
#    include "devtools/Instruments.h"
#  endif
#endif

#ifdef XP_WIN
#  include <process.h>
#  define getpid _getpid
#endif

#include "js/CharacterEncoding.h"
#include "js/PropertySpec.h"
#include "js/Utility.h"
#include "util/Text.h"
#include "vm/Probes.h"

#include "vm/JSContext-inl.h"

using namespace js;

using mozilla::ArrayLength;

/* Thread-unsafe error management */

static char gLastError[2000];

#if defined(__APPLE__) || defined(__linux__) || defined(MOZ_CALLGRIND)
static void MOZ_FORMAT_PRINTF(1, 2) UnsafeError(const char* format, ...) {
  va_list args;
  va_start(args, format);
  (void)VsprintfLiteral(gLastError, format, args);
  va_end(args);
}
#endif

JS_PUBLIC_API const char* JS_UnsafeGetLastProfilingError() {
  return gLastError;
}

#ifdef __APPLE__
static bool StartOSXProfiling(const char* profileName, pid_t pid) {
  bool ok = true;
  const char* profiler = nullptr;
#  ifdef MOZ_INSTRUMENTS
  ok = Instruments::Start(pid);
  profiler = "Instruments";
#  endif
  if (!ok) {
    if (profileName) {
      UnsafeError("Failed to start %s for %s", profiler, profileName);
    } else {
      UnsafeError("Failed to start %s", profiler);
    }
    return false;
  }
  return true;
}
#endif

JS_PUBLIC_API bool JS_StartProfiling(const char* profileName, pid_t pid) {
  bool ok = true;
#ifdef __APPLE__
  ok = StartOSXProfiling(profileName, pid);
#endif
#ifdef __linux__
  if (!js_StartPerf()) {
    ok = false;
  }
#endif
  return ok;
}

JS_PUBLIC_API bool JS_StopProfiling(const char* profileName) {
  bool ok = true;
#ifdef __APPLE__
#  ifdef MOZ_INSTRUMENTS
  Instruments::Stop(profileName);
#  endif
#endif
#ifdef __linux__
  if (!js_StopPerf()) {
    ok = false;
  }
#endif
  return ok;
}

/*
 * Start or stop whatever platform- and configuration-specific profiling
 * backends are available.
 */
static bool ControlProfilers(bool toState) {
  bool ok = true;

  if (!probes::ProfilingActive && toState) {
#ifdef __APPLE__
#  if defined(MOZ_INSTRUMENTS)
    const char* profiler;
#    ifdef MOZ_INSTRUMENTS
    ok = Instruments::Resume();
    profiler = "Instruments";
#    endif
    if (!ok) {
      UnsafeError("Failed to start %s", profiler);
    }
#  endif
#endif
#ifdef MOZ_CALLGRIND
    if (!js_StartCallgrind()) {
      UnsafeError("Failed to start Callgrind");
      ok = false;
    }
#endif
  } else if (probes::ProfilingActive && !toState) {
#ifdef __APPLE__
#  ifdef MOZ_INSTRUMENTS
    Instruments::Pause();
#  endif
#endif
#ifdef MOZ_CALLGRIND
    if (!js_StopCallgrind()) {
      UnsafeError("failed to stop Callgrind");
      ok = false;
    }
#endif
  }

  probes::ProfilingActive = toState;

  return ok;
}

/*
 * Pause/resume whatever profiling mechanism is currently compiled
 * in, if applicable. This will not affect things like dtrace.
 *
 * Do not mix calls to these APIs with calls to the individual
 * profilers' pause/resume functions, because only overall state is
 * tracked, not the state of each profiler.
 */
JS_PUBLIC_API bool JS_PauseProfilers(const char* profileName) {
  return ControlProfilers(false);
}

JS_PUBLIC_API bool JS_ResumeProfilers(const char* profileName) {
  return ControlProfilers(true);
}

JS_PUBLIC_API bool JS_DumpProfile(const char* outfile,
                                  const char* profileName) {
  bool ok = true;
#ifdef MOZ_CALLGRIND
  ok = js_DumpCallgrind(outfile);
#endif
  return ok;
}

#ifdef MOZ_PROFILING

static UniqueChars RequiredStringArg(JSContext* cx, const CallArgs& args,
                                     size_t argi, const char* caller) {
  if (args.length() <= argi) {
    JS_ReportErrorASCII(cx, "%s: not enough arguments", caller);
    return nullptr;
  }

  if (!args[argi].isString()) {
    JS_ReportErrorASCII(cx, "%s: invalid arguments (string expected)", caller);
    return nullptr;
  }

  return JS_EncodeStringToLatin1(cx, args[argi].toString());
}

static bool StartProfiling(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  if (args.length() == 0) {
    args.rval().setBoolean(JS_StartProfiling(nullptr, getpid()));
    return true;
  }

  UniqueChars profileName = RequiredStringArg(cx, args, 0, "startProfiling");
  if (!profileName) {
    return false;
  }

  if (args.length() == 1) {
    args.rval().setBoolean(JS_StartProfiling(profileName.get(), getpid()));
    return true;
  }

  if (!args[1].isInt32()) {
    JS_ReportErrorASCII(cx, "startProfiling: invalid arguments (int expected)");
    return false;
  }
  pid_t pid = static_cast<pid_t>(args[1].toInt32());
  args.rval().setBoolean(JS_StartProfiling(profileName.get(), pid));
  return true;
}

static bool StopProfiling(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  if (args.length() == 0) {
    args.rval().setBoolean(JS_StopProfiling(nullptr));
    return true;
  }

  UniqueChars profileName = RequiredStringArg(cx, args, 0, "stopProfiling");
  if (!profileName) {
    return false;
  }
  args.rval().setBoolean(JS_StopProfiling(profileName.get()));
  return true;
}

static bool PauseProfilers(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  if (args.length() == 0) {
    args.rval().setBoolean(JS_PauseProfilers(nullptr));
    return true;
  }

  UniqueChars profileName = RequiredStringArg(cx, args, 0, "pauseProfiling");
  if (!profileName) {
    return false;
  }
  args.rval().setBoolean(JS_PauseProfilers(profileName.get()));
  return true;
}

static bool ResumeProfilers(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  if (args.length() == 0) {
    args.rval().setBoolean(JS_ResumeProfilers(nullptr));
    return true;
  }

  UniqueChars profileName = RequiredStringArg(cx, args, 0, "resumeProfiling");
  if (!profileName) {
    return false;
  }
  args.rval().setBoolean(JS_ResumeProfilers(profileName.get()));
  return true;
}

/* Usage: DumpProfile([filename[, profileName]]) */
static bool DumpProfile(JSContext* cx, unsigned argc, Value* vp) {
  bool ret;
  CallArgs args = CallArgsFromVp(argc, vp);
  if (args.length() == 0) {
    ret = JS_DumpProfile(nullptr, nullptr);
  } else {
    UniqueChars filename = RequiredStringArg(cx, args, 0, "dumpProfile");
    if (!filename) {
      return false;
    }

    if (args.length() == 1) {
      ret = JS_DumpProfile(filename.get(), nullptr);
    } else {
      UniqueChars profileName = RequiredStringArg(cx, args, 1, "dumpProfile");
      if (!profileName) {
        return false;
      }

      ret = JS_DumpProfile(filename.get(), profileName.get());
    }
  }

  args.rval().setBoolean(ret);
  return true;
}

static bool GetMaxGCPauseSinceClear(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  args.rval().setNumber(
      cx->runtime()->gc.stats().getMaxGCPauseSinceClear().ToMicroseconds());
  return true;
}

static bool ClearMaxGCPauseAccumulator(JSContext* cx, unsigned argc,
                                       Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  args.rval().setNumber(
      cx->runtime()->gc.stats().clearMaxGCPauseAccumulator().ToMicroseconds());
  return true;
}

#  if defined(MOZ_INSTRUMENTS)

static bool IgnoreAndReturnTrue(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  args.rval().setBoolean(true);
  return true;
}

#  endif

#  ifdef MOZ_CALLGRIND
static bool StartCallgrind(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  args.rval().setBoolean(js_StartCallgrind());
  return true;
}

static bool StopCallgrind(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  args.rval().setBoolean(js_StopCallgrind());
  return true;
}

static bool DumpCallgrind(JSContext* cx, unsigned argc, Value* vp) {
  CallArgs args = CallArgsFromVp(argc, vp);
  if (args.length() == 0) {
    args.rval().setBoolean(js_DumpCallgrind(nullptr));
    return true;
  }

  UniqueChars outFile = RequiredStringArg(cx, args, 0, "dumpCallgrind");
  if (!outFile) {
    return false;
  }

  args.rval().setBoolean(js_DumpCallgrind(outFile.get()));
  return true;
}
#  endif

static const JSFunctionSpec profiling_functions[] = {
    JS_FN("startProfiling", StartProfiling, 1, 0),
    JS_FN("stopProfiling", StopProfiling, 1, 0),
    JS_FN("pauseProfilers", PauseProfilers, 1, 0),
    JS_FN("resumeProfilers", ResumeProfilers, 1, 0),
    JS_FN("dumpProfile", DumpProfile, 2, 0),
    JS_FN("getMaxGCPauseSinceClear", GetMaxGCPauseSinceClear, 0, 0),
    JS_FN("clearMaxGCPauseAccumulator", ClearMaxGCPauseAccumulator, 0, 0),
#  if defined(MOZ_INSTRUMENTS)
    /* Keep users of the old shark API happy. */
    JS_FN("connectShark", IgnoreAndReturnTrue, 0, 0),
    JS_FN("disconnectShark", IgnoreAndReturnTrue, 0, 0),
    JS_FN("startShark", StartProfiling, 0, 0),
    JS_FN("stopShark", StopProfiling, 0, 0),
#  endif
#  ifdef MOZ_CALLGRIND
    JS_FN("startCallgrind", StartCallgrind, 0, 0),
    JS_FN("stopCallgrind", StopCallgrind, 0, 0),
    JS_FN("dumpCallgrind", DumpCallgrind, 1, 0),
#  endif
    JS_FS_END};

#endif

JS_PUBLIC_API bool JS_DefineProfilingFunctions(JSContext* cx,
                                               HandleObject obj) {
  cx->check(obj);
#ifdef MOZ_PROFILING
  return JS_DefineFunctions(cx, obj, profiling_functions);
#else
  return true;
#endif
}

#ifdef MOZ_CALLGRIND

/* Wrapper for various macros to stop warnings coming from their expansions. */
#  if defined(__clang__)
#    define JS_SILENCE_UNUSED_VALUE_IN_EXPR(expr)                             \
      JS_BEGIN_MACRO                                                          \
        _Pragma("clang diagnostic push") /* If these _Pragmas cause warnings  \
                                            for you, try disabling ccache. */ \
            _Pragma("clang diagnostic ignored \"-Wunused-value\"") {          \
          expr;                                                               \
        }                                                                     \
        _Pragma("clang diagnostic pop")                                       \
      JS_END_MACRO
#  elif MOZ_IS_GCC

#    define JS_SILENCE_UNUSED_VALUE_IN_EXPR(expr)                           \
      JS_BEGIN_MACRO                                                        \
        _Pragma("GCC diagnostic push")                                      \
            _Pragma("GCC diagnostic ignored \"-Wunused-but-set-variable\"") \
                expr;                                                       \
        _Pragma("GCC diagnostic pop")                                       \
      JS_END_MACRO
#  endif

#  if !defined(JS_SILENCE_UNUSED_VALUE_IN_EXPR)
#    define JS_SILENCE_UNUSED_VALUE_IN_EXPR(expr) \
      JS_BEGIN_MACRO                              \
        expr;                                     \
      JS_END_MACRO
#  endif

JS_FRIEND_API bool js_StartCallgrind() {
  JS_SILENCE_UNUSED_VALUE_IN_EXPR(CALLGRIND_START_INSTRUMENTATION);
  JS_SILENCE_UNUSED_VALUE_IN_EXPR(CALLGRIND_ZERO_STATS);
  return true;
}

JS_FRIEND_API bool js_StopCallgrind() {
  JS_SILENCE_UNUSED_VALUE_IN_EXPR(CALLGRIND_STOP_INSTRUMENTATION);
  return true;
}

JS_FRIEND_API bool js_DumpCallgrind(const char* outfile) {
  if (outfile) {
    JS_SILENCE_UNUSED_VALUE_IN_EXPR(CALLGRIND_DUMP_STATS_AT(outfile));
  } else {
    JS_SILENCE_UNUSED_VALUE_IN_EXPR(CALLGRIND_DUMP_STATS);
  }

  return true;
}

#endif /* MOZ_CALLGRIND */

#ifdef __linux__

/*
 * Code for starting and stopping |perf|, the Linux profiler.
 *
 * Output from profiling is written to mozperf.data in your cwd.
 *
 * To enable, set MOZ_PROFILE_WITH_PERF=1 in your environment.
 *
 * To pass additional parameters to |perf record|, provide them in the
 * MOZ_PROFILE_PERF_FLAGS environment variable.  If this variable does not
 * exist, we default it to "--call-graph".  (If you don't want --call-graph but
 * don't want to pass any other args, define MOZ_PROFILE_PERF_FLAGS to the empty
 * string.)
 *
 * If you include --pid or --output in MOZ_PROFILE_PERF_FLAGS, you're just
 * asking for trouble.
 *
 * Our split-on-spaces logic is lame, so don't expect MOZ_PROFILE_PERF_FLAGS to
 * work if you pass an argument which includes a space (e.g.
 * MOZ_PROFILE_PERF_FLAGS="-e 'foo bar'").
 */

#  include <signal.h>
#  include <sys/wait.h>
#  include <unistd.h>

static bool perfInitialized = false;
static pid_t perfPid = 0;

bool js_StartPerf() {
  const char* outfile = "mozperf.data";

  if (perfPid != 0) {
    UnsafeError("js_StartPerf: called while perf was already running!\n");
    return false;
  }

  // Bail if MOZ_PROFILE_WITH_PERF is empty or undefined.
  if (!getenv("MOZ_PROFILE_WITH_PERF") ||
      !strlen(getenv("MOZ_PROFILE_WITH_PERF"))) {
    return true;
  }

  /*
   * Delete mozperf.data the first time through -- we're going to append to it
   * later on, so we want it to be clean when we start out.
   */
  if (!perfInitialized) {
    perfInitialized = true;
    unlink(outfile);
    char cwd[4096];
    printf("Writing perf profiling data to %s/%s\n", getcwd(cwd, sizeof(cwd)),
           outfile);
  }

  pid_t mainPid = getpid();

  pid_t childPid = fork();
  if (childPid == 0) {
    /* perf record --pid $mainPID --output=$outfile $MOZ_PROFILE_PERF_FLAGS */

    char mainPidStr[16];
    SprintfLiteral(mainPidStr, "%d", mainPid);
    const char* defaultArgs[] = {"perf",     "record",   "--pid",
                                 mainPidStr, "--output", outfile};

    Vector<const char*, 0, SystemAllocPolicy> args;
    if (!args.append(defaultArgs, ArrayLength(defaultArgs))) {
      return false;
    }

    const char* flags = getenv("MOZ_PROFILE_PERF_FLAGS");
    if (!flags) {
      flags = "--call-graph";
    }

    UniqueChars flags2 = DuplicateString(flags);
    if (!flags2) {
      return false;
    }

    // Split |flags2| on spaces.
    char* toksave;
    char* tok = strtok_r(flags2.get(), " ", &toksave);
    while (tok) {
      if (!args.append(tok)) {
        return false;
      }
      tok = strtok_r(nullptr, " ", &toksave);
    }

    if (!args.append((char*)nullptr)) {
      return false;
    }

    execvp("perf", const_cast<char**>(args.begin()));

    /* Reached only if execlp fails. */
    fprintf(stderr, "Unable to start perf.\n");
    exit(1);
  }
  if (childPid > 0) {
    perfPid = childPid;

    /* Give perf a chance to warm up. */
    usleep(500 * 1000);
    return true;
  }
  UnsafeError("js_StartPerf: fork() failed\n");
  return false;
}

bool js_StopPerf() {
  if (perfPid == 0) {
    UnsafeError("js_StopPerf: perf is not running.\n");
    return true;
  }

  if (kill(perfPid, SIGINT)) {
    UnsafeError("js_StopPerf: kill failed\n");

    // Try to reap the process anyway.
    waitpid(perfPid, nullptr, WNOHANG);
  } else {
    waitpid(perfPid, nullptr, 0);
  }

  perfPid = 0;
  return true;
}

#endif /* __linux__ */