From 5f8de423f190bbb79a62f804151bc24824fa32d8 Mon Sep 17 00:00:00 2001 From: "Matt A. Tobin" Date: Fri, 2 Feb 2018 04:16:08 -0500 Subject: Add m-esr52 at 52.6.0 --- mozglue/misc/TimeStamp_darwin.cpp | 206 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 206 insertions(+) create mode 100644 mozglue/misc/TimeStamp_darwin.cpp (limited to 'mozglue/misc/TimeStamp_darwin.cpp') diff --git a/mozglue/misc/TimeStamp_darwin.cpp b/mozglue/misc/TimeStamp_darwin.cpp new file mode 100644 index 000000000..f30bc9846 --- /dev/null +++ b/mozglue/misc/TimeStamp_darwin.cpp @@ -0,0 +1,206 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* 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 +#include +#include +#include +#include + +#include "mozilla/TimeStamp.h" + +// Estimate of the smallest duration of time we can measure. +static uint64_t sResolution; +static uint64_t sResolutionSigDigs; + +static const uint64_t kNsPerMs = 1000000; +static const uint64_t kUsPerSec = 1000000; +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 +BaseTimeDurationPlatformUtils::ToSeconds(int64_t aTicks) +{ + MOZ_ASSERT(gInitialized, "calling TimeDuration too early"); + return (aTicks * sNsPerTick) / kNsPerSecd; +} + +double +BaseTimeDurationPlatformUtils::ToSecondsSigDigits(int64_t aTicks) +{ + MOZ_ASSERT(gInitialized, "calling TimeDuration too early"); + // don't report a value < mResolution ... + int64_t valueSigDigs = sResolution * (aTicks / sResolution); + // and chop off insignificant digits + valueSigDigs = sResolutionSigDigs * (valueSigDigs / sResolutionSigDigs); + return (valueSigDigs * sNsPerTick) / kNsPerSecd; +} + +int64_t +BaseTimeDurationPlatformUtils::TicksFromMilliseconds(double aMilliseconds) +{ + MOZ_ASSERT(gInitialized, "calling TimeDuration too early"); + double result = (aMilliseconds * kNsPerMsd) / sNsPerTick; + if (result > INT64_MAX) { + return INT64_MAX; + } else if (result < INT64_MIN) { + return INT64_MIN; + } + + return result; +} + +int64_t +BaseTimeDurationPlatformUtils::ResolutionInTicks() +{ + MOZ_ASSERT(gInitialized, "calling TimeDuration too early"); + return static_cast(sResolution); +} + +void +TimeStamp::Startup() +{ + if (gInitialized) { + return; + } + + 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) { + MOZ_RELEASE_ASSERT(false, "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; +} + +void +TimeStamp::Shutdown() +{ +} + +TimeStamp +TimeStamp::Now(bool aHighResolution) +{ + return TimeStamp(ClockTime()); +} + +// Computes and returns the process uptime in microseconds. +// Returns 0 if an error was encountered. + +uint64_t +TimeStamp::ComputeProcessUptime() +{ + struct timeval tv; + int rv = gettimeofday(&tv, nullptr); + + if (rv == -1) { + return 0; + } + + int mib[] = { + CTL_KERN, + KERN_PROC, + KERN_PROC_PID, + getpid(), + }; + u_int mibLen = sizeof(mib) / sizeof(mib[0]); + + struct kinfo_proc proc; + size_t bufferSize = sizeof(proc); + rv = sysctl(mib, mibLen, &proc, &bufferSize, nullptr, 0); + + if (rv == -1) { + return 0; + } + + uint64_t startTime = + ((uint64_t)proc.kp_proc.p_un.__p_starttime.tv_sec * kUsPerSec) + + proc.kp_proc.p_un.__p_starttime.tv_usec; + uint64_t now = (tv.tv_sec * kUsPerSec) + tv.tv_usec; + + if (startTime > now) { + return 0; + } + + return now - startTime; +} + +} // namespace mozilla -- cgit v1.2.3