* Clean server shutdown, generalizes usage of `Weak`. Introduces 2 main changes:
* A shared `AtomicBool` that signals server shutdown. All server
threads regularly check it to break out of their main loops when
it changes to `true`.
* Breaking of circular `Arc` references, which can never be
destroyed, by downgrading to `Weak` instead. Only the main server
keeps the `Arc` while all other components get the `Weak` variant.
Both of these are required for all long-living structs to be
cleanly destroyed. Note that in Rust this is fairly important as
most resource-freeing logic is associated with `drop`,
which is only called when said struct is free of scope or `Arc`
references.
Should address most of #536 (only need the stop hook to call
`Server` shutdown).
* Test for fast sync, followed by restart, followed by re-fast-sync
* P2P test fix
* Double sync taking too long for Travis, commenting out for now
* Util to zip and unzip directories
* First pass at sumtree request/response. Add message types, implement the exchange in the protocol, zip up the sumtree directory and stream the file over, with necessary adapter hooks.
* Implement the sumtree archive receive logicGets the sumtree archive data stream from the network and write it to a file. Unzip the file, place it at the right spot and reconstruct the sumtree data structure, rewinding where to the right spot.
* Sumtree hash structure validation
* Simplify sumtree backend buffering logic. The backend for a sumtree has to implement some in-memory buffering logic to provide a commit/rollback interface. The backend itself is an aggregate of 3 underlying storages (an append only file, a remove log and a skip list). The buffering was previously implemented both by the backend and some of the underlying storages. Now pushing back all buffering logic to the storages to keep the backend simpler.
* Add kernel append only store file to sumtrees. The chain sumtrees structure now also saves all kernels to a dedicated file. As that storage is implemented by the append only file wrapper, it's also rewind-aware.
* Full state validation. Checks that:
- MMRs are sane (hash and sum each node)
- Tree roots match the corresponding header
- Kernel signatures are valid
- Sum of all kernel excesses equals the sum of UTXO commitments
minus the supply
* Fast sync handoff to body sync. Once the fast-sync state is fully setup, get bacj in body sync
mode to get the full bodies of the last blocks we're missing.
* First fully working fast sync
* Facility in p2p conn to deal with attachments (raw binary after message).
* Re-introduced sumtree send and receive message handling using the above.
* Fixed test and finished updating all required db state after sumtree validation.
* Massaged a little bit the pipeline orphan check to still work after the new sumtrees have been setup.
* Various cleanup. Consolidated fast sync and full sync into a single function as they're very similar. Proper conditions to trigger a sumtree request and some checks on receiving it.
* Re-introduce peer regular ping/pong
* Fix partial header reads. Turns out that on async tcp streams, even a small chunk like a
header can be read partially. So header read needs to rely on our
fixed-up `read_exact`, with an additional boolean to allow yield
when no bytes were read.
