urbit/pkg/arvo/sur/eth-watcher.hoon
Fang 2223a85666
eth-watcher: separate timeout from refresh-rate
Previously, when the refresh-rate timer activated, and the thread from
the previous activation was still running, we would kill it and start
a new one. For low refresh rates, on slower machines, nodes, or network
connections, this could cause the update to never conclude.

Here we add a timeout-time to eth-watcher's config. If the refresh-rate
timer activates, and a thread exists, but hasn't been running for at
least the specified timeout-time yet, we simply take no action, and wait
for the next refresh timer.

Note that we opted for "at least timeout-time", instead of killing &
restarting directly after the specified timeout-time has passed, to
avoid having to handle an extra timer flow.

In the +on-load logic, we configure the timeout-time for existing
watchdogs as six times the refresh-rate. We want to set
azimuth-tracker's timeout-time to ~m30, and don't care much about other,
less-likely-to-be-active use cases of eth-watcher.
2020-04-01 12:47:38 +02:00

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:: eth-watcher: ethereum event log collector
::
=, able:jael
|%
+$ config
$: :: url: ethereum node rpc endpoint
:: eager: if true, give logs asap, send disavows in case of reorg
:: refresh-rate: rate at which to check for updates
:: timeout-time: time an update check is allowed to take
:: from: oldest block number to look at
:: contracts: contract addresses to look at
:: topics: event descriptions to look for
::
url=@ta
eager=?
refresh-rate=@dr
timeout-time=@dr
from=number:block
contracts=(list address:ethereum)
=topics
==
::
+$ loglist (list event-log:rpc:ethereum)
+$ topics (list ?(@ux (list @ux)))
+$ watchpup
$: config
=number:block
=pending-logs
blocks=(list block)
==
::
:: disavows: newest block first
+$ disavows (list id:block)
+$ pending-logs (map number:block loglist)
::
+$ poke
$% :: %watch: configure a watchdog and fetch initial logs
::
[%watch =path =config]
:: %clear: remove a watchdog
::
[%clear =path]
==
::
+$ diff
$% :: %history: full event log history, oldest first
::
[%history =loglist]
:: %log: newly added log
::
[%log =event-log:rpc:ethereum]
:: %disavow: forget logs
::
:: this is sent when a reorg happens that invalidates
:: previously-sent logs
::
[%disavow =id:block]
==
--