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Merge pull request #742 from psl-felipefarinon/master

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Fixing issue #583. Using low resolution timer for clock::now_ms
This commit is contained in:
Pieter Hintjens 2013-11-07 08:12:48 -08:00
commit de5a787868
1 changed files with 56 additions and 2 deletions
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58
src/clock.cpp
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@ -22,6 +22,7 @@
#include "likely.hpp"
#include "config.hpp"
#include "err.hpp"
#include "mutex.hpp"
#include <stddef.h>
@ -41,9 +42,47 @@
#include <time.h>
#endif
typedef ULONGLONG (*f_compatible_get_tick_count64)();
static zmq::mutex_t compatible_get_tick_count64_mutex;
ULONGLONG compatible_get_tick_count64()
{
compatible_get_tick_count64_mutex.lock();
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);
compatible_get_tick_count64_mutex.unlock();
return result;
}
f_compatible_get_tick_count64 init_compatible_get_tick_count64()
{
f_compatible_get_tick_count64 func = NULL;
HMODULE module = ::LoadLibraryA("Kernel32.dll");
if (module != NULL)
func = reinterpret_cast<f_compatible_get_tick_count64>(::GetProcAddress(module, "GetTickCount64"));
if (func == NULL)
func = compatible_get_tick_count64;
return func;
}
static f_compatible_get_tick_count64 my_get_tick_count64 = init_compatible_get_tick_count64();
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 () / 1000)
#endif
{
}
@ -65,7 +104,7 @@ uint64_t zmq::clock_t::now_us ()
// Convert the tick number into the number of seconds
// since the system was started.
double ticks_div = ticksPerSecond.QuadPart / 1000000.0;
double ticks_div = ticksPerSecond.QuadPart / 1000000.0;
return (uint64_t) (tick.QuadPart / ticks_div);
#elif defined HAVE_CLOCK_GETTIME && defined CLOCK_MONOTONIC
@ -74,7 +113,7 @@ uint64_t zmq::clock_t::now_us ()
struct timespec tv;
int rc = clock_gettime (CLOCK_MONOTONIC, &tv);
// 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
// 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) {
// Use POSIX gettimeofday function to get precise time.
@ -106,7 +145,18 @@ uint64_t zmq::clock_t::now_ms ()
// 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.
static_assert(sizeof(uint64_t) >= sizeof(ULONGLONG), "Loosing timer information");
return static_cast<uint64_t>((*my_get_tick_count64)());
#else
return now_us () / 1000;
#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,
@ -115,7 +165,11 @@ uint64_t zmq::clock_t::now_ms ()
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 () / 1000;
#endif
return last_time;
}