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lnd/chainntnfs
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Olaoluwa Osuntokun 9c18c3d9a4
chainntnfs: ensure all block epoch notifications are sent *in order* 
In this commit, we fix a lingering bug related to the way that we
deliver block epoch notifications to end users. Before this commit, we
would launch a new goroutine for *each block*. This was done in order
to ensure that the notification dispatch wouldn’t block the main
goroutine that was dispatching the notifications. This method archived
the goal, but had a nasty side effect that the goroutines could be
re-ordered during scheduling, meaning that in the case of fast
successive blocks, then notifications would be delivered out of order.
Receiving out of order notifications is either disallowed, or can cause
sub-systems that rely on these notifications to get into weird states.

In order to fix this issue, we’ll no longer launch a new goroutine to
deliver each notification to an awaiting client. Instead, each client
will now gain a concurrent in-order queue for notification delivery.
Due to the internal design of chainntnfs.ConcurrentQueue, the caller
should never block, yet the receivers will receive notifications in
order. This change solves the re-ordering issue and also minimizes the
number of goroutines that we’ll create in order to deliver block epoch
notifications.
 		2018-02-09 16:13:28 -08:00
..
bitcoindnotify chainntnfs: ensure all block epoch notifications are sent *in order* 2018-02-09 16:13:28 -08:00
btcdnotify chainntnfs: ensure all block epoch notifications are sent *in order* 2018-02-09 16:13:28 -08:00
neutrinonotify chainntnfs: ensure all block epoch notifications are sent *in order* 2018-02-09 16:13:28 -08:00
README.md multi: fix formatting issues in packge README's 2017-03-27 16:25:25 -07:00
interface.go multi: comprehensive typo fixes across all packages 2018-02-06 19:11:11 -08:00
interface_test.go multi: comprehensive typo fixes across all packages 2018-02-06 19:11:11 -08:00
log.go lnd: remove seelog logger 2017-06-25 14:19:56 +01:00
queue.go chainntnfs: Implement unbounded concurrent-safe FIFO queue. 2017-11-16 15:15:22 -08:00
queue_test.go chainntnfs: Implement unbounded concurrent-safe FIFO queue. 2017-11-16 15:15:22 -08:00
txconfnotifier.go multi: fix several typos in godoc comments 2017-12-17 18:40:05 -08:00
txconfnotifier_test.go chainntnfs: Send negative confirmation notifications. 2017-12-14 19:16:15 -08:00

README.md

chainntnfs

Build Status MIT licensed GoDoc

The chainntnfs package implements a set of interfaces which allow callers to receive notifications in response to specific on-chain events. The set of notifications available include:

  • Notifications for each new block connected to the current best chain.
  • Notifications once a txid has reached a specified number of confirmations.
  • Notifications once a target outpoint (txid:index) has been spent.

These notifications are used within lnd in order to properly handle the workflows for: channel funding, cooperative channel closures, forced channel closures, channel contract breaches, sweeping time-locked outputs, and finally pruning the channel graph.

This package is intentionally general enough to be applicable outside the specific use cases within lnd outlined above. The current sole concrete implementation of the ChainNotifier interface depends on btcd.

Installation and Updating

$ go get -u github.com/lightningnetwork/lnd/chainntnfs