sled/3party/gperftools/src/profiler.cc

// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
// Copyright (c) 2005, Google Inc.
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// 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 <assert.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>// for getpid()
#endif
#if HAVE_SYS_UCONTEXT_H
#include <sys/ucontext.h>
#elif 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 "base/commandlineflags.h"
#include "base/googleinit.h"
#include "base/logging.h"
#include "base/spinlock.h"
#include "base/sysinfo.h" /* for GetUniquePathFromEnv, etc */
#include "profile-handler.h"
#include "profiledata.h"
#include <gperftools/profiler.h>
#include <gperftools/stacktrace.h>
#include <string>
#include <sys/time.h>
#include <thread>

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;
        }
    }

    char full_profile_name[PATH_MAX + 16];
    snprintf(full_profile_name, sizeof(full_profile_name), "%s.%u", base_profile_name, profile_count);
    if (!started) {
        if (!ProfilerStart(full_profile_name)) {
            RAW_LOG(FATAL, "Can't turn on cpu profiling for '%s': %s\n", full_profile_name, strerror(errno));
        }
        RAW_LOG(INFO, "Start New cpu Profiling for '%s'", full_profile_name);

        char *auto_stop_interval = getenv("CPUPROFILESTOP");
        if (auto_stop_interval != NULL) {
            long int interval = strtol(auto_stop_interval, NULL, 10);
            if (interval > 0) {
                RAW_LOG(INFO, "Auto Stop cpu Profiling After %ss", interval);
                int cur_profile_count = profile_count;
                std::thread([interval, cur_profile_count] {
                    std::this_thread::sleep_for(std::chrono::seconds(interval));
                    if (profile_count == cur_profile_count) {
                        RAW_LOG(INFO, "Trigger Auto stop CPU Profiling, duration=%ss", interval);
                        ProfilerStop();
                    }
                }).detach();
            }
        }

        ++profile_count;
    } else {
        ProfilerStop();
        RAW_LOG(INFO, "Stop cpu Profiling for '%s'", full_profile_name);
    }
    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()
{}