A Duration represents a signed, fixed-length span of time represented as a count of seconds and fractions of seconds at nanosecond resolution. It is independent of any calendar and concepts like "day" or "month". It is related to Timestamp in that the difference between two Timestamp values is a Duration and it can be added or subtracted from a Timestamp. Range is approximately +-10,000 years.

Examples

Example 1: Compute Duration from two Timestamps in pseudo code.

 Timestamp start = ...;
 Timestamp end = ...;
 Duration duration = ...;

 duration.seconds = end.seconds - start.seconds;
 duration.nanos = end.nanos - start.nanos;

 if (duration.seconds < 0 && duration.nanos > 0) {
   duration.seconds += 1;
   duration.nanos -= 1000000000;
 } else if (duration.seconds > 0 && duration.nanos < 0) {
   duration.seconds -= 1;
   duration.nanos += 1000000000;
 }

Example 2: Compute Timestamp from Timestamp + Duration in pseudo code.

 Timestamp start = ...;
 Duration duration = ...;
 Timestamp end = ...;

 end.seconds = start.seconds + duration.seconds;
 end.nanos = start.nanos + duration.nanos;

 if (end.nanos < 0) {
   end.seconds -= 1;
   end.nanos += 1000000000;
 } else if (end.nanos >= 1000000000) {
   end.seconds += 1;
   end.nanos -= 1000000000;
 }

Example 3: Compute Duration from datetime.timedelta in Python.

 td = datetime.timedelta(days=3, minutes=10)
 duration = Duration()
 duration.FromTimedelta(td)

JSON Mapping

In JSON format, the Duration type is encoded as a string rather than an object, where the string ends in the suffix "s" (indicating seconds) and is preceded by the number of seconds, with nanoseconds expressed as fractional seconds. For example, 3 seconds with 0 nanoseconds should be encoded in JSON format as "3s", while 3 seconds and 1 nanosecond should be expressed in JSON format as "3.000000001s", and 3 seconds and 1 microsecond should be expressed in JSON format as "3.000001s".