Problem in serializing negative Duration values

[jpsyri]

When SerializationFeature.WRITE_DURATIONS_AS_TIMESTAMPS is true, Durations with negative value get serialized wrong. For example Duration.ofMillis(-1) gets serialized as "-1.999000000"

Problem seems to be in DurationSerializer where following code is used for serializing

                generator.writeNumber(DecimalUtils.toBigDecimal(
                        duration.getSeconds(), duration.getNano()
                ));

However Duration internally stores duration in format where seconds part basically contains floor(duration) and nanoseconds part contains offset from that value to the actual duration. So n case of duration of -1 millisecond, the seconds part value will be -1 and nanoseconds part will be 999000000. getSeconds() and getNano() return values according to that internal representation, which leads to the problem.

[kupci]

Will take a look, but in the meantime, what release are you seeing this in, and what flags do you have set. (If you have a test case, that would be great.) Taking a quick look, the DurationSerializer should be using millis, unless otherwise specified.

However, we happened to just be discussing this the other day and I think the nanos flag WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS is (probably incorrectly) defaulting to true:

      if (useTimestamp(provider)) {
           if (useNanoseconds(provider)) {
               generator.writeNumber(DecimalUtils.toBigDecimal(
                       duration.getSeconds(), duration.getNano()
               ));
           } else {
               **generator.writeNumber(duration.toMillis());**
           }

jackson-modules-java8/datetime/src/main/java/com/fasterxml/jackson/datatype/jsr310/ser/DurationSerializer.java

Line 82 in ff084de

if (useTimestamp(provider)) {

[jpsyri]

I think we are using 2.10.2 (can't check at the moment). Only feature we have set is the "write datetimes as timestamps"- one. I however did run the serialization on debugger while investigating and both if-conditions on that snippet were evaluating to true, but I didn't really think about that further

I might be able to provide test case tomorrow

[kupci]

and both if-conditions on that snippet were evaluating to true,

Would you please try setting the SerializationFeature WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS to false and retry, and see if that resolves the issue? You can see some examples here:

https://github.com/FasterXML/jackson-modules-java8/blob/master/datetime/src/test/java/com/fasterxml/jackson/datatype/jsr310/ser/DurationSerTest.java

[jpsyri]

I created some test cases at https://github.com/jpsyri/jackson-duration-serialization

Disabling the WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS seems to result serialization as whole milliseconds as expected: Duration of -1 milliseconds is serialized as "-1". That feature enabled (including when state of that feature is not explicitly changed) results "-1.999000000"