gecko-dev/xpcom/ds/TimeStamp_darwin.cpp
Ehsan Akhgari e368dc9c85 Bug 579517 - Part 1: Automated conversion of NSPR numeric types to stdint types in Gecko; r=bsmedberg
This patch was generated by a script.  Here's the source of the script for
future reference:

function convert() {
echo "Converting $1 to $2..."
find . ! -wholename "*nsprpub*" \
       ! -wholename "*security/nss*" \
       ! -wholename "*/.hg*" \
       ! -wholename "obj-ff-dbg*" \
       ! -name nsXPCOMCID.h \
       ! -name prtypes.h \
         -type f \
      \( -iname "*.cpp" \
         -o -iname "*.h" \
         -o -iname "*.c" \
         -o -iname "*.cc" \
         -o -iname "*.idl" \
         -o -iname "*.ipdl" \
         -o -iname "*.ipdlh" \
         -o -iname "*.mm" \) | \
    xargs -n 1 sed -i -e "s/\b$1\b/$2/g"
}

convert PRInt8 int8_t
convert PRUint8 uint8_t
convert PRInt16 int16_t
convert PRUint16 uint16_t
convert PRInt32 int32_t
convert PRUint32 uint32_t
convert PRInt64 int64_t
convert PRUint64 uint64_t

convert PRIntn int
convert PRUintn unsigned

convert PRSize size_t

convert PROffset32 int32_t
convert PROffset64 int64_t

convert PRPtrdiff ptrdiff_t

convert PRFloat64 double
2012-08-22 11:56:38 -04:00

165 lines
4.5 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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/. */
//
// Implement TimeStamp::Now() with mach_absolute_time
//
// The "tick" unit for mach_absolute_time is defined using mach_timebase_info() which
// gives a conversion ratio to nanoseconds. For more information see Apple's QA1398.
//
// This code is inspired by Chromium's time_mac.cc. The biggest
// differences are that we explicitly initialize using
// TimeStamp::Initialize() instead of lazily in Now() and that
// we store the time value in ticks and convert when needed instead
// of storing the time value in nanoseconds.
#include <mach/mach_time.h>
#include <time.h>
#include "mozilla/TimeStamp.h"
// Estimate of the smallest duration of time we can measure.
static uint64_t sResolution;
static uint64_t sResolutionSigDigs;
static const uint16_t kNsPerUs = 1000;
static const uint64_t kNsPerMs = 1000000;
static const uint64_t kNsPerSec = 1000000000;
static const double kNsPerMsd = 1000000.0;
static const double kNsPerSecd = 1000000000.0;
static bool gInitialized = false;
static double sNsPerTick;
static uint64_t
ClockTime()
{
// mach_absolute_time is it when it comes to ticks on the Mac. Other calls
// with less precision (such as TickCount) just call through to
// mach_absolute_time.
//
// At the time of writing mach_absolute_time returns the number of nanoseconds
// since boot. This won't overflow 64bits for 500+ years so we aren't going
// to worry about that possiblity
return mach_absolute_time();
}
static uint64_t
ClockResolutionNs()
{
uint64_t start = ClockTime();
uint64_t end = ClockTime();
uint64_t minres = (end - start);
// 10 total trials is arbitrary: what we're trying to avoid by
// looping is getting unlucky and being interrupted by a context
// switch or signal, or being bitten by paging/cache effects
for (int i = 0; i < 9; ++i) {
start = ClockTime();
end = ClockTime();
uint64_t candidate = (start - end);
if (candidate < minres)
minres = candidate;
}
if (0 == minres) {
// measurable resolution is either incredibly low, ~1ns, or very
// high. fall back on NSPR's resolution assumption
minres = 1 * kNsPerMs;
}
return minres;
}
namespace mozilla {
double
TimeDuration::ToSeconds() const
{
NS_ABORT_IF_FALSE(gInitialized, "calling TimeDuration too early");
return (mValue * sNsPerTick) / kNsPerSecd;
}
double
TimeDuration::ToSecondsSigDigits() const
{
NS_ABORT_IF_FALSE(gInitialized, "calling TimeDuration too early");
// don't report a value < mResolution ...
int64_t valueSigDigs = sResolution * (mValue / sResolution);
// and chop off insignificant digits
valueSigDigs = sResolutionSigDigs * (valueSigDigs / sResolutionSigDigs);
return (valueSigDigs * sNsPerTick) / kNsPerSecd;
}
TimeDuration
TimeDuration::FromMilliseconds(double aMilliseconds)
{
NS_ABORT_IF_FALSE(gInitialized, "calling TimeDuration too early");
return TimeDuration::FromTicks(int64_t((aMilliseconds * kNsPerMsd) / sNsPerTick));
}
TimeDuration
TimeDuration::Resolution()
{
NS_ABORT_IF_FALSE(gInitialized, "calling TimeDuration too early");
return TimeDuration::FromTicks(int64_t(sResolution));
}
struct TimeStampInitialization
{
TimeStampInitialization() {
TimeStamp::Startup();
}
~TimeStampInitialization() {
TimeStamp::Shutdown();
}
};
static TimeStampInitialization initOnce;
nsresult
TimeStamp::Startup()
{
if (gInitialized)
return NS_OK;
mach_timebase_info_data_t timebaseInfo;
// Apple's QA1398 suggests that the output from mach_timebase_info
// will not change while a program is running, so it should be safe
// to cache the result.
kern_return_t kr = mach_timebase_info(&timebaseInfo);
if (kr != KERN_SUCCESS)
NS_RUNTIMEABORT("mach_timebase_info failed");
sNsPerTick = double(timebaseInfo.numer) / timebaseInfo.denom;
sResolution = ClockResolutionNs();
// find the number of significant digits in sResolution, for the
// sake of ToSecondsSigDigits()
for (sResolutionSigDigs = 1;
!(sResolutionSigDigs == sResolution
|| 10*sResolutionSigDigs > sResolution);
sResolutionSigDigs *= 10);
gInitialized = true;
return NS_OK;
}
void
TimeStamp::Shutdown()
{
}
TimeStamp
TimeStamp::Now()
{
return TimeStamp(ClockTime());
}
}