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// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
// Copyright (c) 2005, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ---
// Author: Sanjay Ghemawat
// Chris Demetriou (refactoring)
//
// Profile current program by sampling stack-trace every so often
#include "config.h"
#include "getpc.h" // should be first to get the _GNU_SOURCE dfn
#include <signal.h>
#include <assert.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h> // for getpid()
#endif
#if defined(HAVE_SYS_UCONTEXT_H)
#include <sys/ucontext.h>
#elif defined(HAVE_UCONTEXT_H)
#include <ucontext.h>
#elif defined(HAVE_CYGWIN_SIGNAL_H)
#include <cygwin/signal.h>
typedef ucontext ucontext_t;
#else
typedef int ucontext_t; // just to quiet the compiler, mostly
#endif
#include <sys/time.h>
#include <string>
#include <gperftools/profiler.h>
#include <gperftools/stacktrace.h>
#include "base/commandlineflags.h"
#include "base/logging.h"
#include "base/googleinit.h"
#include "base/spinlock.h"
#include "base/sysinfo.h" /* for GetUniquePathFromEnv, etc */
#include "profiledata.h"
#include "profile-handler.h"
#ifdef HAVE_CONFLICT_SIGNAL_H
#include "conflict-signal.h" /* used on msvc machines */
#endif
using std::string;
DEFINE_bool(cpu_profiler_unittest,
EnvToBool("PERFTOOLS_UNITTEST", true),
"Determines whether or not we are running under the \
control of a unit test. This allows us to include or \
exclude certain behaviours.");
// Collects up all profile data. This is a singleton, which is
// initialized by a constructor at startup. If no cpu profiler
// signal is specified then the profiler lifecycle is either
// manaully controlled via the API or attached to the scope of
// the singleton (program scope). Otherwise the cpu toggle is
// used to allow for user selectable control via signal generation.
// This is very useful for profiling a daemon process without
// having to start and stop the daemon or having to modify the
// source code to use the cpu profiler API.
class CpuProfiler {
public:
CpuProfiler();
~CpuProfiler();
// Start profiler to write profile info into fname
bool Start(const char* fname, const ProfilerOptions* options);
// Stop profiling and write the data to disk.
void Stop();
// Write the data to disk (and continue profiling).
void FlushTable();
bool Enabled();
void GetCurrentState(ProfilerState* state);
static CpuProfiler instance_;
private:
// This lock implements the locking requirements described in the ProfileData
// documentation, specifically:
//
// lock_ is held all over all collector_ method calls except for the 'Add'
// call made from the signal handler, to protect against concurrent use of
// collector_'s control routines. Code other than signal handler must
// unregister the signal handler before calling any collector_ method.
// 'Add' method in the collector is protected by a guarantee from
// ProfileHandle that only one instance of prof_handler can run at a time.
SpinLock lock_;
ProfileData collector_;
// Filter function and its argument, if any. (NULL means include all
// samples). Set at start, read-only while running. Written while holding
// lock_, read and executed in the context of SIGPROF interrupt.
int (*filter_)(void*);
void* filter_arg_;
// Opaque token returned by the profile handler. To be used when calling
// ProfileHandlerUnregisterCallback.
ProfileHandlerToken* prof_handler_token_;
// Sets up a callback to receive SIGPROF interrupt.
void EnableHandler();
// Disables receiving SIGPROF interrupt.
void DisableHandler();
// Signal handler that records the interrupted pc in the profile data.
static void prof_handler(int sig, siginfo_t*, void* signal_ucontext,
void* cpu_profiler);
};
// Signal handler that is registered when a user selectable signal
// number is defined in the environment variable CPUPROFILESIGNAL.
static void CpuProfilerSwitch(int signal_number)
{
static unsigned profile_count;
static char base_profile_name[PATH_MAX];
static bool started = false;
if (base_profile_name[0] == '\0') {
if (!GetUniquePathFromEnv("CPUPROFILE", base_profile_name)) {
RAW_LOG(FATAL,"Cpu profiler switch is registered but no CPUPROFILE is defined");
return;
}
}
if (!started) {
char full_profile_name[PATH_MAX + 16];
snprintf(full_profile_name, sizeof(full_profile_name), "%s.%u",
base_profile_name, profile_count++);
if(!ProfilerStart(full_profile_name)) {
RAW_LOG(FATAL, "Can't turn on cpu profiling for '%s': %s\n",
full_profile_name, strerror(errno));
}
} else {
ProfilerStop();
}
started = !started;
}
// Profile data structure singleton: Constructor will check to see if
// profiling should be enabled. Destructor will write profile data
// out to disk.
CpuProfiler CpuProfiler::instance_;
// Initialize profiling: activated if getenv("CPUPROFILE") exists.
CpuProfiler::CpuProfiler()
: prof_handler_token_(NULL) {
// TODO(cgd) Move this code *out* of the CpuProfile constructor into a
// separate object responsible for initialization. With ProfileHandler there
// is no need to limit the number of profilers.
if (getenv("CPUPROFILE") == NULL) {
if (!FLAGS_cpu_profiler_unittest) {
RAW_LOG(WARNING, "CPU profiler linked but no valid CPUPROFILE environment variable found\n");
}
return;
}
// We don't enable profiling if setuid -- it's a security risk
#ifdef HAVE_GETEUID
if (getuid() != geteuid()) {
if (!FLAGS_cpu_profiler_unittest) {
RAW_LOG(WARNING, "Cannot perform CPU profiling when running with setuid\n");
}
return;
}
#endif
char *signal_number_str = getenv("CPUPROFILESIGNAL");
if (signal_number_str != NULL) {
long int signal_number = strtol(signal_number_str, NULL, 10);
if (signal_number >= 1 && signal_number <= 64) {
intptr_t old_signal_handler = reinterpret_cast<intptr_t>(signal(signal_number, CpuProfilerSwitch));
if (old_signal_handler == 0) {
RAW_LOG(INFO,"Using signal %d as cpu profiling switch", signal_number);
} else {
RAW_LOG(FATAL, "Signal %d already in use\n", signal_number);
}
} else {
RAW_LOG(FATAL, "Signal number %s is invalid\n", signal_number_str);
}
} else {
char fname[PATH_MAX];
if (!GetUniquePathFromEnv("CPUPROFILE", fname)) {
if (!FLAGS_cpu_profiler_unittest) {
RAW_LOG(WARNING, "CPU profiler linked but no valid CPUPROFILE environment variable found\n");
}
return;
}
if (!Start(fname, NULL)) {
RAW_LOG(FATAL, "Can't turn on cpu profiling for '%s': %s\n",
fname, strerror(errno));
}
}
}
bool CpuProfiler::Start(const char* fname, const ProfilerOptions* options) {
SpinLockHolder cl(&lock_);
if (collector_.enabled()) {
return false;
}
ProfileHandlerState prof_handler_state;
ProfileHandlerGetState(&prof_handler_state);
ProfileData::Options collector_options;
collector_options.set_frequency(prof_handler_state.frequency);
if (!collector_.Start(fname, collector_options)) {
return false;
}
filter_ = NULL;
if (options != NULL && options->filter_in_thread != NULL) {
filter_ = options->filter_in_thread;
filter_arg_ = options->filter_in_thread_arg;
}
// Setup handler for SIGPROF interrupts
EnableHandler();
return true;
}
CpuProfiler::~CpuProfiler() {
Stop();
}
// Stop profiling and write out any collected profile data
void CpuProfiler::Stop() {
SpinLockHolder cl(&lock_);
if (!collector_.enabled()) {
return;
}
// Unregister prof_handler to stop receiving SIGPROF interrupts before
// stopping the collector.
DisableHandler();
// DisableHandler waits for the currently running callback to complete and
// guarantees no future invocations. It is safe to stop the collector.
collector_.Stop();
}
void CpuProfiler::FlushTable() {
SpinLockHolder cl(&lock_);
if (!collector_.enabled()) {
return;
}
// Unregister prof_handler to stop receiving SIGPROF interrupts before
// flushing the profile data.
DisableHandler();
// DisableHandler waits for the currently running callback to complete and
// guarantees no future invocations. It is safe to flush the profile data.
collector_.FlushTable();
EnableHandler();
}
bool CpuProfiler::Enabled() {
SpinLockHolder cl(&lock_);
return collector_.enabled();
}
void CpuProfiler::GetCurrentState(ProfilerState* state) {
ProfileData::State collector_state;
{
SpinLockHolder cl(&lock_);
collector_.GetCurrentState(&collector_state);
}
state->enabled = collector_state.enabled;
state->start_time = static_cast<time_t>(collector_state.start_time);
state->samples_gathered = collector_state.samples_gathered;
int buf_size = sizeof(state->profile_name);
strncpy(state->profile_name, collector_state.profile_name, buf_size);
state->profile_name[buf_size-1] = '\0';
}
void CpuProfiler::EnableHandler() {
RAW_CHECK(prof_handler_token_ == NULL, "SIGPROF handler already registered");
prof_handler_token_ = ProfileHandlerRegisterCallback(prof_handler, this);
RAW_CHECK(prof_handler_token_ != NULL, "Failed to set up SIGPROF handler");
}
void CpuProfiler::DisableHandler() {
RAW_CHECK(prof_handler_token_ != NULL, "SIGPROF handler is not registered");
ProfileHandlerUnregisterCallback(prof_handler_token_);
prof_handler_token_ = NULL;
}
// Signal handler that records the pc in the profile-data structure. We do no
// synchronization here. profile-handler.cc guarantees that at most one
// instance of prof_handler() will run at a time. All other routines that
// access the data touched by prof_handler() disable this signal handler before
// accessing the data and therefore cannot execute concurrently with
// prof_handler().
void CpuProfiler::prof_handler(int sig, siginfo_t*, void* signal_ucontext,
void* cpu_profiler) {
CpuProfiler* instance = static_cast<CpuProfiler*>(cpu_profiler);
if (instance->filter_ == NULL ||
(*instance->filter_)(instance->filter_arg_)) {
void* stack[ProfileData::kMaxStackDepth];
// Under frame-pointer-based unwinding at least on x86, the
// top-most active routine doesn't show up as a normal frame, but
// as the "pc" value in the signal handler context.
stack[0] = GetPC(*reinterpret_cast<ucontext_t*>(signal_ucontext));
// We skip the top three stack trace entries (this function,
// SignalHandler::SignalHandler and one signal handler frame)
// since they are artifacts of profiling and should not be
// measured. Other profiling related frames may be removed by
// "pprof" at analysis time. Instead of skipping the top frames,
// we could skip nothing, but that would increase the profile size
// unnecessarily.
int depth = GetStackTraceWithContext(stack + 1, arraysize(stack) - 1,
3, signal_ucontext);
void **used_stack;
if (depth > 0 && stack[1] == stack[0]) {
// in case of non-frame-pointer-based unwinding we will get
// duplicate of PC in stack[1], which we don't want
used_stack = stack + 1;
} else {
used_stack = stack;
depth++; // To account for pc value in stack[0];
}
instance->collector_.Add(depth, used_stack);
}
}
#if !(defined(__CYGWIN__) || defined(__CYGWIN32__))
extern "C" PERFTOOLS_DLL_DECL void ProfilerRegisterThread() {
ProfileHandlerRegisterThread();
}
extern "C" PERFTOOLS_DLL_DECL void ProfilerFlush() {
CpuProfiler::instance_.FlushTable();
}
extern "C" PERFTOOLS_DLL_DECL int ProfilingIsEnabledForAllThreads() {
return CpuProfiler::instance_.Enabled();
}
extern "C" PERFTOOLS_DLL_DECL int ProfilerStart(const char* fname) {
return CpuProfiler::instance_.Start(fname, NULL);
}
extern "C" PERFTOOLS_DLL_DECL int ProfilerStartWithOptions(
const char *fname, const ProfilerOptions *options) {
return CpuProfiler::instance_.Start(fname, options);
}
extern "C" PERFTOOLS_DLL_DECL void ProfilerStop() {
CpuProfiler::instance_.Stop();
}
extern "C" PERFTOOLS_DLL_DECL void ProfilerGetCurrentState(
ProfilerState* state) {
CpuProfiler::instance_.GetCurrentState(state);
}
extern "C" PERFTOOLS_DLL_DECL int ProfilerGetStackTrace(
void** result, int max_depth, int skip_count, const void *uc) {
return GetStackTraceWithContext(result, max_depth, skip_count, uc);
}
#else // OS_CYGWIN
// ITIMER_PROF doesn't work under cygwin. ITIMER_REAL is available, but doesn't
// work as well for profiling, and also interferes with alarm(). Because of
// these issues, unless a specific need is identified, profiler support is
// disabled under Cygwin.
extern "C" void ProfilerRegisterThread() { }
extern "C" void ProfilerFlush() { }
extern "C" int ProfilingIsEnabledForAllThreads() { return 0; }
extern "C" int ProfilerStart(const char* fname) { return 0; }
extern "C" int ProfilerStartWithOptions(const char *fname,
const ProfilerOptions *options) {
return 0;
}
extern "C" void ProfilerStop() { }
extern "C" void ProfilerGetCurrentState(ProfilerState* state) {
memset(state, 0, sizeof(*state));
}
extern "C" int ProfilerGetStackTrace(
void** result, int max_depth, int skip_count, const void *uc) {
return 0;
}
#endif // OS_CYGWIN
// DEPRECATED routines
extern "C" PERFTOOLS_DLL_DECL void ProfilerEnable() { }
extern "C" PERFTOOLS_DLL_DECL void ProfilerDisable() { }