Truncate to millisecond precision.

temporal-sdk/src/main/java/io/temporal/internal/common/ProtobufTimeUtils.java

@@ -32,15 +32,37 @@
 public class ProtobufTimeUtils {
 
   private static final int NANOS_PER_SECOND = 1000000000;
+  private static final int NANOS_PER_MILLI = 1000000;
 
+  /**
+   * Converts a Protobuf Duration to a Java Duration with millisecond precision. Null inputs are
+   * treated as zero.
+   */
   @Nonnull
-  public static Duration toJavaDuration(com.google.protobuf.Duration d) {
-    // TODO we should refactor an implicit conversion of empty values into ZERO and rename the
-    // current method into toJavaDurationSafe, toJavaDurationOrDefault or something like that
+  public static Duration toJavaDuration(@Nullable com.google.protobuf.Duration d) {
     if (Objects.isNull(d)) {
       return Duration.ZERO;
     }
+    return truncateToMillis(toJavaDurationExact(d));
+  }
+
+  /**
+   * Converts a Java Duration to a Protobuf Duration with millisecond precision. Null inputs are
+   * treated as zero.
+   */
+  @Nonnull
+  public static com.google.protobuf.Duration toProtoDuration(@Nullable Duration d) {
+    if (Objects.isNull(d)) {
+      return Durations.ZERO;
+    }
+    return toProtoDurationExact(truncateToMillis(d));
+  }
 
+  /**
+   * Converts a Protobuf Duration to a Java Duration with nanosecond precision.
+   */
+  @Nonnull
+  public static Duration toJavaDurationExact(@Nonnull com.google.protobuf.Duration d) {
     // See the comment in toProtoDuration for details about how Java Duration and Protobuf Duration
     // have almost-but-not-quite identical representations.
     //
@@ -50,14 +72,11 @@ public static Duration toJavaDuration(com.google.protobuf.Duration d) {
     return Duration.ofSeconds(d.getSeconds(), d.getNanos());
   }
 
+  /**
+   * Converts a Java Duration to a Protobuf Duration with nanosecond precision.
+   */
   @Nonnull
-  public static com.google.protobuf.Duration toProtoDuration(Duration d) {
-    // TODO we should refactor an implicit conversion of empty values into ZERO and rename the
-    // current method into toJavaDurationSafe, toJavaDurationOrDefault or something like that
-    if (Objects.isNull(d)) {
-      return Durations.ZERO;
-    }
-
+  public static com.google.protobuf.Duration toProtoDurationExact(@Nonnull Duration d) {
     // Java Duration and Protobuf Duration are *almost* identical in representation: both use a
     // 96-bit value divided between a 64-bit (long) seconds count and a 32-bit (int) nanoseconds
     // count.  However, they represent negative durations slightly differently:
@@ -116,4 +135,14 @@ public static com.uber.m3.util.Duration toM3DurationSinceNow(Timestamp t) {
 
     return Timestamp.newBuilder().setSeconds(t.getEpochSecond()).setNanos(t.getNano()).build();
   }
+
+  @Nonnull
+  private static Duration truncateToMillis(@Nonnull Duration exact) {
+    // In JDK 9+, this would just be a call to Duration.truncatedTo(ChronoUnit.MILLIS).
+    // Alas, we must remain compatible with JDK 8.
+    final long s = exact.getSeconds();
+    final int ns = exact.getNano();
+    final int ms = ns / NANOS_PER_MILLI;
+    return Duration.ofSeconds(s).plusMillis(ms);
+  }
 }