See issue 397. If the block cache is still populating (lightwalletd is
syncing with zcashd), behave the same as if the cache was fully
populated, other than performance.
This turned out to affect only the GetLatestBlock() gRPC. Previously, it
would return the height and hash of the latest block in the cache. After
this commit, it queries zcashd using the getblockchaininfo, which
contains both of those values.
GetBlock() (and GetBlockRange()) already worked correctly; if the
requested block isn't in the cache, it requests it from zcashd.
Instead of the Sleep function pointer being a standalong global
variable, move it into a new Time struct, and add a Now function
pointer, so that time.Now() can be mocked. Time.Now() isn't used yet.
This will be cleaner if we need to mock more time-related functions in
the future.
This commit is based on adityapk00 streaming mempool interface but
avoids using goroutines, which are difficult to reason about.
Co-authored-by: Aditya Kulkarni <adityapk@gmail.com>
Kris Nuttycombe
Larry Ruane
Aditya Kulkarni