icu4c DateIntervalFormat objects are expensive enough that we need to cache them.
It takes ~1ms to create a DateIntervalFormat on a z620, and around 8ms on a
current mobile device (Nexus 4). Add a small cache of recently-used formatters,
using a big lock rather than per-thread caches since this typically only
happens on the UI thread anyway, and because all the other frameworks date/time
formatting is behind a single lock too.
Bug: 10696944
Change-Id: I8ccbe0b31b722a95a08fbc5a119173b7a0f44807
3 files changed