Fixes issue 408.
This bug was introduced by PR 393, which changed how txids are
determined. That PR changed each call to the zcash getblock call into a
pair of calls, the first to get the raw block data, the second to
retrieve the txids in the block. (Unfortunately, you can't get both in a
single getblock RPC.) But this ordering introduced a timing window in
which the block at the given height can change, if a reorg occurred
between the two calls.
This PR reorders the getblock calls, so that the first call gets the
transaction IDs, which also happens to return the block hash, so then
the second getblock call can specify the block hash, rather than the
height. This ensures that the two RPC calls return consistent data,
definitely the same block.
Now "go test ./..." passes, it had broken due to the V5 transaction
(NU5) changes in #392. I didn't have time to fix the tests at the time.
Also, this fixes a few lint problems.
This causes lightwalletd to discard cached blocks at the given height
and beyond. This in turn causes it to re-fetch those blocks from zcashd.
It's similar to --redownload, except that option discards all blocks
(equivalent to --sync-from-height 0, but the existing --redownload is
retained for compatibility).
This is mostly intended for testing. It's sometimes useful to force the
node to (re)sync some recent blocks, but redownloading all of them takes
around an hour.
Larry Ruane
Larry Ruane