Fixes to TimeDelta::InX methods

- Improve the documentation of TimeDelta::InXYZ methods to clarify that they return a truncated value (aka rounded towards zero).
- Add a new InDaysFloored method to convert a TimeDelta into a floored number of days.
- Fix the implementation of InMillisecondsRoundedUp for negative time deltas.

Bug: 831545
Change-Id: I4afd256308f6f28ff459925772059fdfc5824995
Reviewed-on: https://chromium-review.googlesource.com/1049906Reviewed-by: Yuri Wiitala <miu@chromium.org>
Commit-Queue: Quentin Fiard <qfiard@google.com>
Cr-Commit-Position: refs/heads/master@{#561334}

base/time/time.cc

@@ -45,6 +45,19 @@ int TimeDelta::InDays() const {
   return static_cast<int>(delta_ / Time::kMicrosecondsPerDay);
 }
 
+int TimeDelta::InDaysFloored() const {
+  if (is_max()) {
+    // Preserve max to prevent overflow.
+    return std::numeric_limits<int>::max();
+  }
+  int result = delta_ / Time::kMicrosecondsPerDay;
+  int64_t remainder = delta_ - (result * Time::kMicrosecondsPerDay);
+  if (remainder < 0) {
+    --result;  // Use floor(), not trunc() rounding behavior.
+  }
+  return result;
+}
+
 int TimeDelta::InHours() const {
   if (is_max()) {
     // Preserve max to prevent overflow.
@@ -98,8 +111,12 @@ int64_t TimeDelta::InMillisecondsRoundedUp() const {
     // Preserve max to prevent overflow.
     return std::numeric_limits<int64_t>::max();
   }
-  return (delta_ + Time::kMicrosecondsPerMillisecond - 1) /
-      Time::kMicrosecondsPerMillisecond;
+  int64_t result = delta_ / Time::kMicrosecondsPerMillisecond;
+  int64_t remainder = delta_ - (result * Time::kMicrosecondsPerMillisecond);
+  if (remainder > 0) {
+    ++result;  // Use ceil(), not trunc() rounding behavior.
+  }
+  return result;
 }
 
 int64_t TimeDelta::InMicroseconds() const {

base/time/time.h

@@ -181,12 +181,13 @@ class BASE_EXPORT TimeDelta {
   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.
+  // Returns the time delta in some unit. The InXYZF versions return a floating
+  // point value. The InXYZ versions return a truncated value (aka rounded
+  // towards zero, std::trunc() behavior). The InXYZFloored() versions round to
+  // lesser integers (std::floor() behavior). The XYZRoundedUp() versions round
+  // up to greater integers (std::ceil() behavior).
   int InDays() const;
+  int InDaysFloored() const;
   int InHours() const;
   int InMinutes() const;
   double InSecondsF() const;

base/time/time_unittest.cc

@@ -1129,6 +1129,47 @@ TEST(TimeDelta, FromAndIn) {
   EXPECT_EQ(TimeDelta::FromNanosecondsD(12345.678).InNanoseconds(), 12000);
 }
 
+TEST(TimeDelta, InRoundsTowardsZero) {
+  EXPECT_EQ(TimeDelta::FromHours(23).InDays(), 0);
+  EXPECT_EQ(TimeDelta::FromHours(-23).InDays(), 0);
+  EXPECT_EQ(TimeDelta::FromMinutes(59).InHours(), 0);
+  EXPECT_EQ(TimeDelta::FromMinutes(-59).InHours(), 0);
+  EXPECT_EQ(TimeDelta::FromSeconds(59).InMinutes(), 0);
+  EXPECT_EQ(TimeDelta::FromSeconds(-59).InMinutes(), 0);
+  EXPECT_EQ(TimeDelta::FromMilliseconds(999).InSeconds(), 0);
+  EXPECT_EQ(TimeDelta::FromMilliseconds(-999).InSeconds(), 0);
+  EXPECT_EQ(TimeDelta::FromMicroseconds(999).InMilliseconds(), 0);
+  EXPECT_EQ(TimeDelta::FromMicroseconds(-999).InMilliseconds(), 0);
+}
+
+TEST(TimeDelta, InDaysFloored) {
+  EXPECT_EQ(TimeDelta::FromHours(-25).InDaysFloored(), -2);
+  EXPECT_EQ(TimeDelta::FromHours(-24).InDaysFloored(), -1);
+  EXPECT_EQ(TimeDelta::FromHours(-23).InDaysFloored(), -1);
+
+  EXPECT_EQ(TimeDelta::FromHours(-1).InDaysFloored(), -1);
+  EXPECT_EQ(TimeDelta::FromHours(0).InDaysFloored(), 0);
+  EXPECT_EQ(TimeDelta::FromHours(1).InDaysFloored(), 0);
+
+  EXPECT_EQ(TimeDelta::FromHours(23).InDaysFloored(), 0);
+  EXPECT_EQ(TimeDelta::FromHours(24).InDaysFloored(), 1);
+  EXPECT_EQ(TimeDelta::FromHours(25).InDaysFloored(), 1);
+}
+
+TEST(TimeDelta, InMillisecondsRoundedUp) {
+  EXPECT_EQ(TimeDelta::FromMicroseconds(-1001).InMillisecondsRoundedUp(), -1);
+  EXPECT_EQ(TimeDelta::FromMicroseconds(-1000).InMillisecondsRoundedUp(), -1);
+  EXPECT_EQ(TimeDelta::FromMicroseconds(-999).InMillisecondsRoundedUp(), 0);
+
+  EXPECT_EQ(TimeDelta::FromMicroseconds(-1).InMillisecondsRoundedUp(), 0);
+  EXPECT_EQ(TimeDelta::FromMicroseconds(0).InMillisecondsRoundedUp(), 0);
+  EXPECT_EQ(TimeDelta::FromMicroseconds(1).InMillisecondsRoundedUp(), 1);
+
+  EXPECT_EQ(TimeDelta::FromMicroseconds(999).InMillisecondsRoundedUp(), 1);
+  EXPECT_EQ(TimeDelta::FromMicroseconds(1000).InMillisecondsRoundedUp(), 1);
+  EXPECT_EQ(TimeDelta::FromMicroseconds(1001).InMillisecondsRoundedUp(), 2);
+}
+
 #if defined(OS_POSIX) || defined(OS_FUCHSIA)
 TEST(TimeDelta, TimeSpecConversion) {
   TimeDelta delta = TimeDelta::FromSeconds(0);