clock.cpp

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/* SPDX-License-Identifier: MPL-2.0 */
 
#include "precompiled.hpp"
#include "clock.hpp"
#include "likely.hpp"
#include "config.hpp"
#include "err.hpp"
#include "mutex.hpp"
 
#include <stddef.h>
 
#if defined _MSC_VER
#if defined _WIN32_WCE
#include <cmnintrin.h>
#else
#include <intrin.h>
#if defined(_M_ARM) || defined(_M_ARM64)
#include <arm_neon.h>
#endif
#endif
#endif
 
#if !defined ZMQ_HAVE_WINDOWS
#include <sys/time.h>
#endif
 
#if defined HAVE_CLOCK_GETTIME || defined HAVE_GETHRTIME
#include <time.h>
#endif
 
#if defined ZMQ_HAVE_VXWORKS
#include "timers.h"
#endif
 
#if defined ZMQ_HAVE_OSX
int alt_clock_gettime (int clock_id, timespec *ts)
{
    clock_serv_t cclock;
    mach_timespec_t mts;
    host_get_clock_service (mach_host_self (), clock_id, &cclock);
    clock_get_time (cclock, &mts);
    mach_port_deallocate (mach_task_self (), cclock);
    ts->tv_sec = mts.tv_sec;
    ts->tv_nsec = mts.tv_nsec;
    return 0;
}
#endif
 
#ifdef ZMQ_HAVE_WINDOWS
typedef ULONGLONG (*f_compatible_get_tick_count64) ();
 
static zmq::mutex_t compatible_get_tick_count64_mutex;
 
ULONGLONG compatible_get_tick_count64 ()
{
#ifdef ZMQ_HAVE_WINDOWS_UWP
    const ULONGLONG result = ::GetTickCount64 ();
    return result;
#else
    zmq::scoped_lock_t locker (compatible_get_tick_count64_mutex);
 
    static DWORD s_wrap = 0;
    static DWORD s_last_tick = 0;
    const DWORD current_tick = ::GetTickCount ();
 
    if (current_tick < s_last_tick)
        ++s_wrap;
 
    s_last_tick = current_tick;
    const ULONGLONG result = (static_cast<ULONGLONG> (s_wrap) << 32)
                             + static_cast<ULONGLONG> (current_tick);
 
    return result;
#endif
}
 
f_compatible_get_tick_count64 init_compatible_get_tick_count64 ()
{
    f_compatible_get_tick_count64 func = NULL;
#if !defined ZMQ_HAVE_WINDOWS_UWP
 
    const HMODULE module = ::LoadLibraryA ("Kernel32.dll");
    if (module != NULL)
        func = reinterpret_cast<f_compatible_get_tick_count64> (
          ::GetProcAddress (module, "GetTickCount64"));
#endif
    if (func == NULL)
        func = compatible_get_tick_count64;
 
#if !defined ZMQ_HAVE_WINDOWS_UWP
    if (module != NULL)
        ::FreeLibrary (module);
#endif
 
    return func;
}
 
static f_compatible_get_tick_count64 my_get_tick_count64 =
  init_compatible_get_tick_count64 ();
#endif
 
#ifndef ZMQ_HAVE_WINDOWS
const uint64_t usecs_per_msec = 1000;
const uint64_t nsecs_per_usec = 1000;
#endif
const uint64_t usecs_per_sec = 1000000;
 
zmq::clock_t::clock_t () :
    _last_tsc (rdtsc ()),
#ifdef ZMQ_HAVE_WINDOWS
    _last_time (static_cast<uint64_t> ((*my_get_tick_count64) ()))
#else
    _last_time (now_us () / usecs_per_msec)
#endif
{
}
 
uint64_t zmq::clock_t::now_us ()
{
#if defined ZMQ_HAVE_WINDOWS
 
    //  Get the high resolution counter's accuracy.
    //  While QueryPerformanceFrequency only needs to be called once, since its
    //  value does not change during runtime, we query it here since this is a
    //  static function. It might make sense to cache it, though.
    LARGE_INTEGER ticks_per_second;
    QueryPerformanceFrequency (&ticks_per_second);
 
    //  What time is it?
    LARGE_INTEGER tick;
    QueryPerformanceCounter (&tick);
 
    //  Convert the tick number into the number of seconds
    //  since the system was started.
    const double ticks_div =
      static_cast<double> (ticks_per_second.QuadPart) / usecs_per_sec;
    return static_cast<uint64_t> (tick.QuadPart / ticks_div);
 
#elif defined HAVE_CLOCK_GETTIME                                               \
  && (defined CLOCK_MONOTONIC || defined ZMQ_HAVE_VXWORKS)
 
    //  Use POSIX clock_gettime function to get precise monotonic time.
    struct timespec tv;
 
#if defined ZMQ_HAVE_OSX                                                       \
  && __MAC_OS_X_VERSION_MIN_REQUIRED < 101200 // less than macOS 10.12
    int rc = alt_clock_gettime (SYSTEM_CLOCK, &tv);
#else
    int rc = clock_gettime (CLOCK_MONOTONIC, &tv);
#endif
    // Fix case where system has clock_gettime but CLOCK_MONOTONIC is not supported.
    // This should be a configuration check, but I looked into it and writing an
    // AC_FUNC_CLOCK_MONOTONIC seems beyond my powers.
    if (rc != 0) {
#ifndef ZMQ_HAVE_VXWORKS
        //  Use POSIX gettimeofday function to get precise time.
        struct timeval tv;
        int rc = gettimeofday (&tv, NULL);
        errno_assert (rc == 0);
        return tv.tv_sec * usecs_per_sec + tv.tv_usec;
#endif
    }
    return tv.tv_sec * usecs_per_sec + tv.tv_nsec / nsecs_per_usec;
 
#elif defined HAVE_GETHRTIME
 
    return gethrtime () / nsecs_per_usec;
 
#else
 
    LIBZMQ_UNUSED (nsecs_per_usec);
    //  Use POSIX gettimeofday function to get precise time.
    struct timeval tv;
    int rc = gettimeofday (&tv, NULL);
    errno_assert (rc == 0);
    return tv.tv_sec * usecs_per_sec + tv.tv_usec;
 
#endif
}
 
uint64_t zmq::clock_t::now_ms ()
{
    const uint64_t tsc = rdtsc ();
 
    //  If TSC is not supported, get precise time and chop off the microseconds.
    if (!tsc) {
#ifdef ZMQ_HAVE_WINDOWS
        // Under Windows, now_us is not so reliable since QueryPerformanceCounter
        // does not guarantee that it will use a hardware that offers a monotonic timer.
        // So, lets use GetTickCount when GetTickCount64 is not available with an workaround
        // to its 32 bit limitation.
        return static_cast<uint64_t> ((*my_get_tick_count64) ());
#else
        return now_us () / usecs_per_msec;
#endif
    }
 
    //  If TSC haven't jumped back (in case of migration to a different
    //  CPU core) and if not too much time elapsed since last measurement,
    //  we can return cached time value.
    if (likely (tsc - _last_tsc <= (clock_precision / 2) && tsc >= _last_tsc))
        return _last_time;
 
    _last_tsc = tsc;
#ifdef ZMQ_HAVE_WINDOWS
    _last_time = static_cast<uint64_t> ((*my_get_tick_count64) ());
#else
    _last_time = now_us () / usecs_per_msec;
#endif
    return _last_time;
}
 
uint64_t zmq::clock_t::rdtsc ()
{
#if (defined _MSC_VER && (defined _M_IX86 || defined _M_X64))
    return __rdtsc ();
#elif defined(_MSC_VER) && defined(_M_ARM)   // NC => added for windows ARM
    return __rdpmccntr64 ();
#elif defined(_MSC_VER) && defined(_M_ARM64) // NC => added for windows ARM64
    const int64_t pmccntr_el0 = (((3 & 1) << 14) |  // op0
                                 ((3 & 7) << 11) |  // op1
                                 ((9 & 15) << 7) |  // crn
                                 ((13 & 15) << 3) | // crm
                                 ((0 & 7) << 0));   // op2
    return _ReadStatusReg (pmccntr_el0);
#elif (defined(_WIN32) && defined(__GNUC__) && defined(__aarch64__))
    uint64_t val;
    __asm__ volatile("mrs %0, pmccntr_el0" : "=r"(val));
    return val;
#elif (defined __GNUC__ && (defined __i386__ || defined __x86_64__))
    uint32_t low, high;
    __asm__ volatile("rdtsc" : "=a"(low), "=d"(high));
    return static_cast<uint64_t> (high) << 32 | low;
#elif (defined __SUNPRO_CC && (__SUNPRO_CC >= 0x5100)                          \
       && (defined __i386 || defined __amd64 || defined __x86_64))
    union
    {
        uint64_t u64val;
        uint32_t u32val[2];
    } tsc;
    asm("rdtsc" : "=a"(tsc.u32val[0]), "=d"(tsc.u32val[1]));
    return tsc.u64val;
#elif defined(__s390__)
    uint64_t tsc;
    asm("\tstck\t%0\n" : "=Q"(tsc) : : "cc");
    return tsc;
#else
    struct timespec ts;
#if defined ZMQ_HAVE_OSX                                                       \
  && __MAC_OS_X_VERSION_MIN_REQUIRED < 101200 // less than macOS 10.12
    alt_clock_gettime (SYSTEM_CLOCK, &ts);
#else
    clock_gettime (CLOCK_MONOTONIC, &ts);
#endif
    return static_cast<uint64_t> (ts.tv_sec) * nsecs_per_usec * usecs_per_sec
           + ts.tv_nsec;
#endif
}