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

Media was exposing max timedeltas to JSON, which wasn't working with
infinity.

R=scherkus@chromium.org
TBR=ajwong@chromium.org,jar@chromium.org,jamesr@chomium.org,acolwell@chromium.org,nick@chromium.org
BUG=None

Review URL: https://codereview.chromium.org/183763011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254717 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 115 insertions, 6 deletions

diff --git a/base/time/time.cc b/base/time/time.cc
index 4605d56..2c63886 100644
--- a/base/time/time.cc
+++ b/base/time/time.cc
@@ -17,40 +17,81 @@ namespace base {
 
 // TimeDelta ------------------------------------------------------------------
 
+// static
+TimeDelta TimeDelta::Max() {
+  return TimeDelta(std::numeric_limits<int64>::max());
+}
+
 int TimeDelta::InDays() const {
+  if (is_max()) {
+    // Preserve max to prevent overflow.
+    return std::numeric_limits<int>::max();
+  }
   return static_cast<int>(delta_ / Time::kMicrosecondsPerDay);
 }
 
 int TimeDelta::InHours() const {
+  if (is_max()) {
+    // Preserve max to prevent overflow.
+    return std::numeric_limits<int>::max();
+  }
   return static_cast<int>(delta_ / Time::kMicrosecondsPerHour);
 }
 
 int TimeDelta::InMinutes() const {
+  if (is_max()) {
+    // Preserve max to prevent overflow.
+    return std::numeric_limits<int>::max();
+  }
   return static_cast<int>(delta_ / Time::kMicrosecondsPerMinute);
 }
 
 double TimeDelta::InSecondsF() const {
+  if (is_max()) {
+    // Preserve max to prevent overflow.
+    return std::numeric_limits<double>::infinity();
+  }
   return static_cast<double>(delta_) / Time::kMicrosecondsPerSecond;
 }
 
 int64 TimeDelta::InSeconds() const {
+  if (is_max()) {
+    // Preserve max to prevent overflow.
+    return std::numeric_limits<int64>::max();
+  }
   return delta_ / Time::kMicrosecondsPerSecond;
 }
 
 double TimeDelta::InMillisecondsF() const {
+  if (is_max()) {
+    // Preserve max to prevent overflow.
+    return std::numeric_limits<double>::infinity();
+  }
   return static_cast<double>(delta_) / Time::kMicrosecondsPerMillisecond;
 }
 
 int64 TimeDelta::InMilliseconds() const {
+  if (is_max()) {
+    // Preserve max to prevent overflow.
+    return std::numeric_limits<int64>::max();
+  }
   return delta_ / Time::kMicrosecondsPerMillisecond;
 }
 
 int64 TimeDelta::InMillisecondsRoundedUp() const {
+  if (is_max()) {
+    // Preserve max to prevent overflow.
+    return std::numeric_limits<int64>::max();
+  }
   return (delta_ + Time::kMicrosecondsPerMillisecond - 1) /
       Time::kMicrosecondsPerMillisecond;
 }
 
 int64 TimeDelta::InMicroseconds() const {
+  if (is_max()) {
+    // Preserve max to prevent overflow.
+    return std::numeric_limits<int64>::max();
+  }
   return delta_;
 }
 
diff --git a/base/time/time.h b/base/time/time.h
index 40566b9..69a1324 100644
--- a/base/time/time.h
+++ b/base/time/time.h
@@ -61,9 +61,9 @@ class BASE_EXPORT TimeDelta {
   }
 
   // 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);
@@ -79,6 +79,11 @@ class BASE_EXPORT TimeDelta {
     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.
@@ -87,6 +92,11 @@ class BASE_EXPORT TimeDelta {
     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
@@ -493,32 +503,50 @@ class BASE_EXPORT Time {
 // 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);
 }
 
diff --git a/base/time/time_unittest.cc b/base/time/time_unittest.cc
index b5d2493..40d7bd4 100644
--- a/base/time/time_unittest.cc
+++ b/base/time/time_unittest.cc
@@ -481,6 +481,46 @@ TEST_F(TimeTest, ExplodeBeforeUnixEpoch) {
   EXPECT_EQ(1, exploded.millisecond);
 }
 
+TEST_F(TimeTest, TimeDeltaMax) {
+  TimeDelta max = TimeDelta::Max();
+  EXPECT_TRUE(max.is_max());
+  EXPECT_EQ(max, TimeDelta::Max());
+  EXPECT_GT(max, TimeDelta::FromDays(100 * 365));
+  EXPECT_GT(max, TimeDelta());
+}
+
+TEST_F(TimeTest, TimeDeltaMaxConversions) {
+  TimeDelta t = TimeDelta::Max();
+  EXPECT_EQ(std::numeric_limits<int64>::max(), t.ToInternalValue());
+
+  EXPECT_EQ(std::numeric_limits<int>::max(), t.InDays());
+  EXPECT_EQ(std::numeric_limits<int>::max(), t.InHours());
+  EXPECT_EQ(std::numeric_limits<int>::max(), t.InMinutes());
+  EXPECT_EQ(std::numeric_limits<double>::infinity(), t.InSecondsF());
+  EXPECT_EQ(std::numeric_limits<int64>::max(), t.InSeconds());
+  EXPECT_EQ(std::numeric_limits<double>::infinity(), t.InMillisecondsF());
+  EXPECT_EQ(std::numeric_limits<int64>::max(), t.InMilliseconds());
+  EXPECT_EQ(std::numeric_limits<int64>::max(), t.InMillisecondsRoundedUp());
+
+  t = TimeDelta::FromDays(std::numeric_limits<int>::max());
+  EXPECT_TRUE(t.is_max());
+
+  t = TimeDelta::FromHours(std::numeric_limits<int>::max());
+  EXPECT_TRUE(t.is_max());
+
+  t = TimeDelta::FromMinutes(std::numeric_limits<int>::max());
+  EXPECT_TRUE(t.is_max());
+
+  t = TimeDelta::FromSeconds(std::numeric_limits<int64>::max());
+  EXPECT_TRUE(t.is_max());
+
+  t = TimeDelta::FromMilliseconds(std::numeric_limits<int64>::max());
+  EXPECT_TRUE(t.is_max());
+
+  t = TimeDelta::FromMicroseconds(std::numeric_limits<int64>::max());
+  EXPECT_TRUE(t.is_max());
+}
+
 TEST_F(TimeTest, Max) {
   Time max = Time::Max();
   EXPECT_TRUE(max.is_max());