Reland "Add base::TimeDelta::Max()"

base/time/time.h

 // 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.
 
 // Time represents an absolute point in time, internally represented as
 // microseconds (s/1,000,000) since the Windows epoch (1601-01-01 00:00:00 UTC)
 // (See http://crbug.com/14734).  System-dependent clock interface routines are
 // defined in time_PLATFORM.cc.
 //
 // TimeDelta represents a duration of time, internally represented in
@@ skipping 43 matching lines @@
 class TimeTicks;
 
 // TimeDelta ------------------------------------------------------------------
 
 class BASE_EXPORT TimeDelta {
  public:
   TimeDelta() : delta_(0) {
   }
 
   // Converts units of time to TimeDeltas.
-  static TimeDelta FromDays(int64 days);
-  static TimeDelta FromHours(int64 hours);
-  static TimeDelta FromMinutes(int64 minutes);
+  static TimeDelta FromDays(int days);
+  static TimeDelta FromHours(int hours);
+  static TimeDelta FromMinutes(int minutes);
   static TimeDelta FromSeconds(int64 secs);
   static TimeDelta FromMilliseconds(int64 ms);
   static TimeDelta FromMicroseconds(int64 us);
 #if defined(OS_WIN)
   static TimeDelta FromQPCValue(LONGLONG qpc_value);
 #endif
 
   // Converts an integer value representing TimeDelta to a class. This is used
   // when deserializing a |TimeDelta| structure, using a value known to be
   // compatible. It is not provided as a constructor because the integer type
   // may be unclear from the perspective of a caller.
   static TimeDelta FromInternalValue(int64 delta) {
     return TimeDelta(delta);
   }
 
+  // Returns the maximum time delta, which should be greater than any reasonable
+  // time delta we might compare it to. Adding or subtracting the maximum time
+  // delta to a time or another time delta has an undefined result.
+  static TimeDelta Max();
+
   // Returns the internal numeric value of the TimeDelta object. Please don't
   // use this and do arithmetic on it, as it is more error prone than using the
   // provided operators.
   // For serializing, use FromInternalValue to reconstitute.
   int64 ToInternalValue() const {
     return delta_;
   }
 
+  // Returns true if the time delta is the maximum time delta.
+  bool is_max() const {
+    return delta_ == std::numeric_limits<int64>::max();
+  }
+
 #if defined(OS_POSIX)
   struct timespec ToTimeSpec() const;
 #endif
 
   // Returns the time delta in some unit. The F versions return a floating
   // point value, the "regular" versions return a rounded-down value.
   //
   // InMillisecondsRoundedUp() instead returns an integer that is rounded up
   // to the next full millisecond.
   int InDays() const;
@@ skipping 386 matching lines @@
   static int high_resolution_timer_activated_;
 #endif
 
   // Time in microseconds in UTC.
   int64 us_;
 };
 
 // Inline the TimeDelta factory methods, for fast TimeDelta construction.
 
 // static
-inline TimeDelta TimeDelta::FromDays(int64 days) {
+inline TimeDelta TimeDelta::FromDays(int days) {
+  // Preserve max to prevent overflow.
+  if (days == std::numeric_limits<int>::max())
+    return Max();
   return TimeDelta(days * Time::kMicrosecondsPerDay);
 }
 
 // static
-inline TimeDelta TimeDelta::FromHours(int64 hours) {
+inline TimeDelta TimeDelta::FromHours(int hours) {
+  // Preserve max to prevent overflow.
+  if (hours == std::numeric_limits<int>::max())
+    return Max();
   return TimeDelta(hours * Time::kMicrosecondsPerHour);
 }
 
 // static
-inline TimeDelta TimeDelta::FromMinutes(int64 minutes) {
+inline TimeDelta TimeDelta::FromMinutes(int minutes) {
+  // Preserve max to prevent overflow.
+  if (minutes == std::numeric_limits<int>::max())
+    return Max();
   return TimeDelta(minutes * Time::kMicrosecondsPerMinute);
 }
 
 // static
 inline TimeDelta TimeDelta::FromSeconds(int64 secs) {
+  // Preserve max to prevent overflow.
+  if (secs == std::numeric_limits<int64>::max())
+    return Max();
   return TimeDelta(secs * Time::kMicrosecondsPerSecond);
 }
 
 // static
 inline TimeDelta TimeDelta::FromMilliseconds(int64 ms) {
+  // Preserve max to prevent overflow.
+  if (ms == std::numeric_limits<int64>::max())
+    return Max();
   return TimeDelta(ms * Time::kMicrosecondsPerMillisecond);
 }
 
 // static
 inline TimeDelta TimeDelta::FromMicroseconds(int64 us) {
+  // Preserve max to prevent overflow.
+  if (us == std::numeric_limits<int64>::max())
+    return Max();
   return TimeDelta(us);
 }
 
 inline Time TimeDelta::operator+(Time t) const {
   return Time(t.us_ + delta_);
 }
 
 // TimeTicks ------------------------------------------------------------------
 
 class BASE_EXPORT TimeTicks {
@@ skipping 152 matching lines @@
 #endif
 };
 
 inline TimeTicks TimeDelta::operator+(TimeTicks t) const {
   return TimeTicks(t.ticks_ + delta_);
 }
 
 }  // namespace base
 
 #endif  // BASE_TIME_TIME_H_