The components are accessed by a lock on application state. When some command
calls block_on to enter an async context, it obtained a write lock on the
entire application state. This meant that if the application state were
accessed later in an async context, a deadlock would occur. Instead the
TokioComponent holds an Option<Runtime> now, so that before calling block_on,
the caller can .take() the runtime and release the lock. Since we only ever
enter an async context once, it's not a problem that the component is then
missing its runtime, as once we are inside of a task we can access the runtime.
With a 'Transactions' response that gets turned into an 'Inv(Vec<InventoryHash::Tx>)' message.
We don't yet handle a response from our peer for a 'mempool', which will have to be
a more generic 'Inv' type because we might receive transaction hashes we don't know about yet.
Pertains to #26
Moved SeedService out of the command closure Command currently spawns
a tokio task to DOS the seed service with `Request::GetPeers` every
second.
Pertains to #54
This splits out the connection handling code into a try_connect closure, which
could be refactored into a Service of its own.
On creation, when we are likely to have very few peers, launch many concurrent
connections to the first few candidates in the initial candidate set, before
continuing to grow the peer set according to demand signals.
The previous implementation failed when timestamps were duplicated between
peers, because there was not a 1-1 relationship between timestamps and peers.
The disconnected_peers() function allows us to prevent duplicate
connections without maintaining shared state between the peerset and the
dial-additional-peers task.
Previously, the TimestampCollector was intended to own the address book
data, so it was intended to be cloneable and hold shared state among all
of its handles. This is now modeled more directly by an
`Arc<Mutex<AddressBook>>`, so the only functionality left in the
`TimestampCollector` is setting up the inital worker, which is better
called `spawn` than `new`.
This also fixes a problem introduced in the previous commit where the
`TimestampCollector` was dropped, causing the worker task to shut down
early.
This allows us to hide the `TimestampCollector` and to expose only the
address book data required by the inbound request service. It also lets
us have a common data structure (the `AddressBook`) for collecting peer
information that can be used to manage information that other peers
report to us.
This was commented out because making the PeerConnector take a TcpStream
meant that the PeerConnector futures couldn't be constructed in the same
way as before, but now that the PeerConnector is Buffer'able, we can
just clone a buffered copy.
* Don't expose submodules of zebra_network::peer.
* PeerSet, PeerDiscover stubs.
Co-authored-by: Deirdre Connolly <deirdre@zfnd.org>
* Initial work on PeerSet.
This is adapted from the MIT-licensed tower-balance implementation.
* Use PeerSet in the connect stub.
dependabot-preview[bot]
Deirdre Connolly
Henry de Valence
Tony Arcieri