We can use this network upgrade to implement different consensus rules
and chain context handling for genesis blocks.
Part of the chain state design in #682.
We had a brief discussion on discord and it seemed like we had consensus on the
following versioning policy:
* zebrad: match major version to NU version, so we will start by releasing
zebrad 3.0.0;
* zebra-* libraries: start by matching zebrad's version, then increment major
versions of each library as we need to make breaking changes (potentially
faster than the zebrad version, always respecting semver but making no
guarantees about the longevity of major releases).
This commit sets all of the crate versions to 3.0.0-alpha.0 -- the -alpha.0
marks it as a prerelease not subject to perfect adherence to compatibility
guarantees.
When the connection sees the client_rx channel close it knows it will never get
any more requests, and it should terminate. But instead of terminating, it
errored itself, and the method to error itself tries to pull all the
outstanding client requests from the channel in order to fail them before it
shuts down. This results in reading from a closed channel, causing a panic.
Instead we return cleanly rather than failing (since we know there are no
outstanding requests, as the channel is closed).
This fixes a bug introduced when we added heartbeat support. Recall that we
handle the Bitcoin connection state machine on a per-peer basis. Each
connection has a task created from the `Connection` struct, and a `Client:
tower::Service` "frontend" that passes requests to it via a channel. In the
`Connection` event loop, the connection checks whether the request channel has
been closed, indicating no further requests from the `Client`, in which case it
shuts itself down and cleans up resources. This occurs when all of the senders
have been dropped.
However, this behavior broke when we introduced heartbeat support, because we
spawned an additional task to send heartbeat messages along the request
channel. This meant that instead of having a single sender, dropped by the
`Client`, we have two senders, the `Client` and the "shadow client" task that
generates heartbeat messages. This means that when the `Client` is dropped, we
still have a live sender and the connection is not closed. To fix this, the
`Client` now uses a `oneshot` to shut down its corresponding heartbeat task.
This closes all senders.
Each subsection has to have `serde(default)` to get the behaviour we want
(delete all fields except the ones that have been changed); otherwise, we can
delete only entire sections.
Prior to this change, we required that services that are canceled do not
have a cancel handle in the `cancel_handles` list, based on the
assumption that the handle must have been removed in the process of
canceling this service.
This doesn't holding up though, because it is currently possible for us
to have the same peer connect to us multiple times, the second connect
removes the cancel handle of the original connect and inserts it's own
cancel handle in its place. In this scenario, when the first service is
polled for readiness it will see that it has been canceled and go to
clean itself up, but when it asserts that it doesn't have a cancel
handle it will see the cancel handle of the second connect event, which
uses the same key as the first connect, and fail its debug assertion.
This change removes that debug assert on the assumption that it is okay
for a peer to connect multiple times consecutively, and that the correct
behavior in that case is to just cancel the first connection and
continue as normal.
Prior to this change, the service returned by `zebra_network::init` would spawn background tasks that could silently fail, causing unexpected errors in the zebra_network service.
This change modifies the `PeerSet` that backs `zebra_network::init` to store all of the `JoinHandle`s for each background task it depends on. The `PeerSet` then checks this set of futures to see if any of them have exited with an error or a panic, and if they have it returns the error as part of `poll_ready`.
Co-authored-by: Jane Lusby <jane@zfnd.org>
Prior to this change, the seed subcommand would consistently encounter a panic in one of the background tasks, but would continue running after the panic. This is indicative of two bugs.
First, zebrad was not configured to treat panics as non recoverable and instead defaulted to the tokio defaults, which are to catch panics in tasks and return them via the join handle if available, or to print them if the join handle has been discarded. This is likely a poor fit for zebrad as an application, we do not need to maximize uptime or minimize the extent of an outage should one of our tasks / services start encountering panics. Ignoring a panic increases our risk of observing invalid state, causing all sorts of wild and bad bugs. To deal with this we've switched the default panic behavior from `unwind` to `abort`. This makes panics fail immediately and take down the entire application, regardless of where they occur, which is consistent with our treatment of misbehaving connections.
The second bug is the panic itself. This was triggered by a duplicate entry in the initial_peers set. To fix this we've switched the storage for the peers from a `Vec` to a `HashSet`, which has similar properties but guarantees uniqueness of its keys.
teor
Henry de Valence
Jack Grigg
Jane Lusby
Jane Lusby
dependabot[bot]
Alfredo Garcia
Dimitris Apostolou
Deirdre Connolly
George Tankersley
dependabot-preview[bot]
George Tankersley