The Tor Browser: xpcom/ds/TimeStamp_darwin.cpp@129ffea94266 (annotated)

xpcom/ds/TimeStamp_darwin.cpp@129ffea94266 (annotated)

xpcom/ds/TimeStamp_darwin.cpp

Sat, 03 Jan 2015 20:18:00 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Sat, 03 Jan 2015 20:18:00 +0100
branch: TOR_BUG_3246
changeset 7: 129ffea94266
permissions: -rw-r--r--

Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.

 /* -*- 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 <sys/time.h>
 #include <sys/sysctl.h>
 #include <time.h>
 #include <unistd.h>
 #include "mozilla/TimeStamp.h"
 #include "nsDebug.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
 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));
 }
 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(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

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xpcom/ds/TimeStamp_darwin.cpp@129ffea94266 (annotated)

xpcom/ds/TimeStamp_darwin.cpp