What started as an attempt to fix#366 ended up being quite substantial refactoring of the Blockchain->Store and Server->Blockchain interactions. As usually, some additional problems were noted and fixed along the way. It also accidentally fixes#410.
In the very specific case when the list of headers received is exactly one
block ahead of the chain of full blocks requestBlocks() failed to generate
request to get the next full block.
BoltDB doesn't have internal batching mechanism, thus we have a substitute for
it, but this substitute is absolutely identical to MemoryBatch, so it's better
to unify them and import ac5d2f94d3 fix into the
MemoryBatch.
Commit 578ac414d4 was wrong in that it saved
only a part of the block, so depending on how you use blockchain, you may
still see that the block was not really processed properly. To really fix it
this commit introduces intermediate storage layer in form of memStore, which
actually is a MemoryStore that supports full Store API (thus easily fitting
into the existing code) and one extension that allows it to flush its data to
some other Store.
It also changes AddBlock() semantics in that it only accepts now successive
blocks, but when it does it guarantees that they're properly added into the
Blockchain and can be referred to in any way. Pending block queing is now
moved into the server (see 8c0c055ac657813fe3ed10257bce199e9527d5ed).
So the only thing done with persist() now is just a move from memStore to
Store which probably should've always been the case (notice also that
previously headers and some other metadata was written into the Store
bypassing caching/batching mechanism thus leading to some inefficiency).
This one will replace blockCache in Blockchain itself as it can and should be
external from it. The idea is that we only feed successive blocks into the
Blockchain and it only stores valid proper Blockchain and nothing else.
This changes the Blockchain to also return unpersisted (theoretically, verified
in the AddBlock!) blocks and transactions, making Add/Get interfaces
symmetrical. It allows to turn Persist into internal method again and makes it
possible to enable transaction check in GetBlock(), thus fixing #366.
It must copy both the value and the key because they can be reused for other
purposes between Put() and PutBatch(). This actually happens with values in
headers processing, leading to wrong data being written into the DB.
Extend the batch test to check for that.
For example, at the moment our node can't handle `consensus` message, so when
it received it before the patch it just crashed because of uninitialized `p`.
earlier we had an issue with failing test in #353 and other one #305.
Reworked these test to have in-memory database. This led to multiple
changes: made some functions like Hash and Persist public(otherwise
it's not possible to control state of the blockchain); removed
unit_tests storage package which was used mainly for leveldb in unit
tests.
I see these tests not really good since they look like e2e tests and
as for me should be run in separate step against dockerized env or
in case we want to check rpc handler we might want to rework it in order
to have interface for proper unit tests.
As for me this patchset at least makes as safe with not removing totally
previous tests and at the same time CircleCI will be happy now.
