Fixit: Fork base::TimeTicks --> TimeTicks + ThreadTicks + TraceTicks

base/time/time_mac.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/time/time.h"
 
 #include <CoreFoundation/CFDate.h>
 #include <CoreFoundation/CFTimeZone.h>
 #include <mach/mach.h>
 #include <mach/mach_time.h>
 #include <stdint.h>
 #include <sys/sysctl.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <time.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/mac/mach_logging.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/mac/scoped_mach_port.h"
+#include "base/numerics/safe_conversions.h"
 
 namespace {
 
-uint64_t ComputeCurrentTicks() {
+int64_t ComputeCurrentTicks() {
 #if defined(OS_IOS)
   // On iOS mach_absolute_time stops while the device is sleeping. Instead use
   // now - KERN_BOOTTIME to get a time difference that is not impacted by clock
   // changes. KERN_BOOTTIME will be updated by the system whenever the system
   // clock change.
   struct timeval boottime;
   int mib[2] = {CTL_KERN, KERN_BOOTTIME};
   size_t size = sizeof(boottime);
   int kr = sysctl(mib, arraysize(mib), &boottime, &size, NULL, 0);
   DCHECK_EQ(KERN_SUCCESS, kr);
   base::TimeDelta time_difference = base::Time::Now() -
       (base::Time::FromTimeT(boottime.tv_sec) +
        base::TimeDelta::FromMicroseconds(boottime.tv_usec));
   return time_difference.InMicroseconds();
 #else
-  uint64_t absolute_micro;
-
   static mach_timebase_info_data_t timebase_info;
   if (timebase_info.denom == 0) {
     // Zero-initialization of statics guarantees that denom will be 0 before
     // calling mach_timebase_info.  mach_timebase_info will never set denom to
     // 0 as that would be invalid, so the zero-check can be used to determine
     // whether mach_timebase_info has already been called.  This is
     // recommended by Apple's QA1398.
     kern_return_t kr = mach_timebase_info(&timebase_info);
     MACH_DCHECK(kr == KERN_SUCCESS, kr) << "mach_timebase_info";
   }
 
   // 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.
 
   // timebase_info converts absolute time tick units into nanoseconds.  Convert
   // to microseconds up front to stave off overflows.
-  absolute_micro =
-      mach_absolute_time() / base::Time::kNanosecondsPerMicrosecond *
-      timebase_info.numer / timebase_info.denom;
+  base::CheckedNumeric<uint64_t> result(
+      mach_absolute_time() / base::Time::kNanosecondsPerMicrosecond);
+  result *= timebase_info.numer;
+  result /= timebase_info.denom;
 
   // Don't bother with the rollover handling that the Windows version does.
   // With numer and denom = 1 (the expected case), the 64-bit absolute time
   // reported in nanoseconds is enough to last nearly 585 years.
-  return absolute_micro;
+  return base::checked_cast<int64_t>(result.ValueOrDie());
 #endif  // defined(OS_IOS)
 }
 
-uint64_t ComputeThreadTicks() {
+int64_t ComputeThreadTicks() {
 #if defined(OS_IOS)
   NOTREACHED();
   return 0;
 #else
   base::mac::ScopedMachSendRight thread(mach_thread_self());
   mach_msg_type_number_t thread_info_count = THREAD_BASIC_INFO_COUNT;
   thread_basic_info_data_t thread_info_data;
 
   if (thread.get() == MACH_PORT_NULL) {
     DLOG(ERROR) << "Failed to get mach_thread_self()";
     return 0;
   }
 
   kern_return_t kr = thread_info(
       thread,
       THREAD_BASIC_INFO,
       reinterpret_cast<thread_info_t>(&thread_info_data),
       &thread_info_count);
   MACH_DCHECK(kr == KERN_SUCCESS, kr) << "thread_info";
 
-  return (thread_info_data.user_time.seconds *
-              base::Time::kMicrosecondsPerSecond) +
-         thread_info_data.user_time.microseconds;
+  base::CheckedNumeric<int64_t> absolute_micros(
+      thread_info_data.user_time.seconds);
+  absolute_micros *= base::Time::kMicrosecondsPerSecond;
+  absolute_micros += thread_info_data.user_time.microseconds;
+  return absolute_micros.ValueOrDie();
 #endif  // defined(OS_IOS)
 }
 
 }  // namespace
 
 namespace base {
 
 // The Time routines in this file use Mach and CoreFoundation APIs, since the
 // POSIX definition of time_t in Mac OS X wraps around after 2038--and
 // there are already cookie expiration dates, etc., past that time out in
@@ skipping 113 matching lines @@
 TimeTicks TimeTicks::Now() {
   return TimeTicks(ComputeCurrentTicks());
 }
 
 // static
 bool TimeTicks::IsHighResolution() {
   return true;
 }
 
 // static
-TimeTicks TimeTicks::ThreadNow() {
-  return TimeTicks(ComputeThreadTicks());
+ThreadTicks ThreadTicks::Now() {
+  return ThreadTicks(ComputeThreadTicks());
 }
 
 // static
-TimeTicks TimeTicks::NowFromSystemTraceTime() {
-  return Now();
+TraceTicks TraceTicks::Now() {
+  return TraceTicks(ComputeCurrentTicks());
 }
 
 }  // namespace base