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nimbus-eth1/nimbus/sync/sync_sched.nim

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# Nimbus
# Copyright (c) 2021 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
# http://www.apache.org/licenses/LICENSE-2.0)
# * MIT license ([LICENSE-MIT](LICENSE-MIT) or
# http://opensource.org/licenses/MIT)
# at your option. This file may not be copied, modified, or distributed
# except according to those terms.
## Sync worker peers scheduler template
## ====================================
##
## Virtual method/interface functions to be provided as `mixin`:
##
## *runSetup(ctx: CtxRef[S]): bool*
## Global set up. This function will be called before any worker peer is
## started. If that function returns `false`, no worker peers will be run.
##
## Also, this function should decide whether the `runDaemon()` job will be
## started next by controlling the `ctx.daemon` flag (default is `false`.)
##
## *runRelease(ctx: CtxRef[S])*
## Global clean up, done with all the worker peers.
##
## *runDaemon(ctx: CtxRef[S]) {.async.}*
## Global background job that will be re-started as long as the variable
## `ctx.daemon` is set `true`. If that job was stopped due to re-setting
## `ctx.daemon` to `false`, it will be restarted next after it was reset
## as `true` not before there is some activity on the `runPool()`,
## `runSingle()`, or `runMulti()` functions.
##
##
## *runStart(buddy: BuddyRef[S,W]): bool*
## Initialise a new worker peer.
##
## *runStop(buddy: BuddyRef[S,W])*
## Clean up this worker peer.
##
##
## *runPool(buddy: BuddyRef[S,W], last: bool; laps: int): bool*
## Once started, the function `runPool()` is called for all worker peers in
## sequence as the body of an iteration as long as the function returns
## `false`. There will be no other worker peer functions activated
## simultaneously.
##
## This procedure is started if the global flag `buddy.ctx.poolMode` is set
## `true` (default is `false`.) It will be automatically reset before the
## the loop starts. Re-setting it again results in repeating the loop. The
## argument `laps` (starting with `0`) indicated the currend lap of the
## repeated loops. To avoid continous looping, the number of `laps` is
## limited (see `execPoolModeMax`, below.)
##
## The argument `last` is set `true` if the last entry of the current loop
## has been reached.
##
## Note:
## + This function does *not* runs in `async` mode.
## + The flag `buddy.ctx.poolMode` has priority over the flag
## `buddy.ctrl.multiOk` which controls `runSingle()` and `runMulti()`.
##
##
## *runSingle(buddy: BuddyRef[S,W]) {.async.}*
## This worker peer method is invoked if the peer-local flag
## `buddy.ctrl.multiOk` is set `false` which is the default mode. This flag
## is updated by the worker peer when deemed appropriate.
## + For all worker peerss, there can be only one `runSingle()` function
## active simultaneously.
## + There will be no `runMulti()` function active for the very same worker
## peer that runs the `runSingle()` function.
## + There will be no `runPool()` iterator active.
##
## Note that this function runs in `async` mode.
##
##
## *runMulti(buddy: BuddyRef[S,W]) {.async.}*
## This worker peer method is invoked if the `buddy.ctrl.multiOk` flag is
## set `true` which is typically done after finishing `runSingle()`. This
## instance can be simultaneously active for all worker peers.
##
## Note that this function runs in `async` mode.
##
##
## Additional import files needed when using this template:
## * eth/[common, p2p]
## * chronicles
## * chronos
## * stew/[interval_set, sorted_set],
## * "."/[sync_desc, sync_sched, protocol]
##
{.push raises: [].}
import
std/hashes,
chronos,
eth/[keys, p2p, p2p/peer_pool],
stew/keyed_queue,
"."/[handlers, sync_desc]
static:
# type `EthWireRef` is needed in `initSync()`
type silenceUnusedhandlerComplaint = EthWireRef # dummy directive
type
ActiveBuddies[S,W] = ##\
## List of active workers, using `Hash(Peer)` rather than `Peer`
KeyedQueue[ENode,RunnerBuddyRef[S,W]]
RunnerSyncRef*[S,W] = ref object
## Module descriptor
ctx*: CtxRef[S] ## Shared data
pool: PeerPool ## For starting the system
buddies: ActiveBuddies[S,W] ## LRU cache with worker descriptors
daemonRunning: bool ## Run global background job
singleRunLock: bool ## Some single mode runner is activated
monitorLock: bool ## Monitor mode is activated
activeMulti: int ## Number of activated runners in multi-mode
shutdown: bool ## Internal shut down flag
RunnerBuddyRef[S,W] = ref object
## Per worker peer descriptor
dsc: RunnerSyncRef[S,W] ## Scheduler descriptor
worker: BuddyRef[S,W] ## Worker peer data
zombified: Moment ## When it became undead (if any)
const
zombieTimeToLinger = 20.seconds
## Maximum time a zombie is kept on the database.
execLoopTimeElapsedMin = 50.milliseconds
## Minimum elapsed time an exec loop needs for a single lap. If it is
## faster, asynchroneous sleep seconds are added. in order to avoid
## cpu overload.
execLoopTaskSwitcher = 1.nanoseconds
## Asynchroneous waiting time at the end of an exec loop unless some sleep
## seconds were added as decribed by `execLoopTimeElapsedMin`, above.
execLoopPollingTime = 50.milliseconds
## Single asynchroneous time interval wait state for event polling
execPoolModeLoopMax = 100
## Avoids continuous looping
# ------------------------------------------------------------------------------
# Private helpers
# ------------------------------------------------------------------------------
proc hash*(key: ENode): Hash =
## Mixin, needed for `buddies` table key comparison. Needs to be a public
## function technically although it should be seen logically as a private
## one.
var h: Hash = 0
h = h !& hashes.hash(key.pubkey.toRaw)
h = h !& hashes.hash(key.address)
!$h
proc key(peer: Peer): ENode =
## Map to key for below table methods.
peer.remote.node
# ------------------------------------------------------------------------------
# Private functions
# ------------------------------------------------------------------------------
proc daemonLoop[S,W](dsc: RunnerSyncRef[S,W]) {.async.} =
mixin runDaemon
if dsc.ctx.daemon and not dsc.shutdown:
dsc.daemonRunning = true
# Continue until stopped
while true:
# Enforce minimum time spend on this loop
let startMoment = Moment.now()
await dsc.ctx.runDaemon()
if not dsc.ctx.daemon:
break
# Enforce minimum time spend on this loop so we never each 100% cpu load
# caused by some empty sub-tasks which are out of this scheduler control.
let
elapsed = Moment.now() - startMoment
suspend = if execLoopTimeElapsedMin <= elapsed: execLoopTaskSwitcher
else: execLoopTimeElapsedMin - elapsed
await sleepAsync suspend
# End while
dsc.daemonRunning = false
proc workerLoop[S,W](buddy: RunnerBuddyRef[S,W]) {.async.} =
mixin runMulti, runSingle, runPool, runStop
let
dsc = buddy.dsc
ctx = dsc.ctx
worker = buddy.worker
peer = worker.peer
# Continue until stopped
block taskExecLoop:
while worker.ctrl.running and not dsc.shutdown:
# Enforce minimum time spend on this loop
let startMoment = Moment.now()
if dsc.monitorLock:
discard # suspend some time at the end of loop body
# Invoke `runPool()` over all buddies if requested
elif ctx.poolMode:
# Grab `monitorLock` (was `false` as checked above) and wait until
# clear to run as the only activated instance.
dsc.monitorLock = true
while 0 < dsc.activeMulti or dsc.singleRunLock:
await sleepAsync execLoopPollingTime
if worker.ctrl.stopped:
dsc.monitorLock = false
break taskExecLoop
var count = 0
while count < execPoolModeLoopMax:
ctx.poolMode = false
# Pool mode: stop this round if returned `true`,
# last invocation this round with `true` argument
var delayed = BuddyRef[S,W](nil)
for w in dsc.buddies.nextValues:
# Execute previous (aka delayed) item (unless first)
if delayed.isNil or not delayed.runPool(last=false, laps=count):
delayed = w.worker
else:
delayed = nil # not executing any final item
break # `true` => stop
if not delayed.isNil:
discard delayed.runPool(last=true, laps=count) # final item
if not ctx.poolMode:
break
count.inc
dsc.monitorLock = false
else:
# Rotate connection table so the most used entry is at the top/right
# end. So zombies will end up leftish.
discard dsc.buddies.lruFetch peer.key
# Multi mode
if worker.ctrl.multiOk:
if not dsc.singleRunLock:
dsc.activeMulti.inc
# Continue doing something, work a bit
await worker.runMulti()
dsc.activeMulti.dec
elif dsc.singleRunLock:
# Some other process is running single mode
discard # suspend some time at the end of loop body
else:
# Start single instance mode by grabbing `singleRunLock` (was
# `false` as checked above).
dsc.singleRunLock = true
await worker.runSingle()
dsc.singleRunLock = false
# Dispatch daemon sevice if needed
if not dsc.daemonRunning and dsc.ctx.daemon:
asyncSpawn dsc.daemonLoop()
# Check for termination
if worker.ctrl.stopped:
break taskExecLoop
# Enforce minimum time spend on this loop so we never each 100% cpu load
# caused by some empty sub-tasks which are out of this scheduler control.
let
elapsed = Moment.now() - startMoment
suspend = if execLoopTimeElapsedMin <= elapsed: execLoopTaskSwitcher
else: execLoopTimeElapsedMin - elapsed
await sleepAsync suspend
# End while
# Note that `runStart()` was dispatched in `onPeerConnected()`
worker.ctrl.stopped = true
worker.runStop()
proc onPeerConnected[S,W](dsc: RunnerSyncRef[S,W]; peer: Peer) =
mixin runStart, runStop
# Check for known entry (which should not exist.)
let
maxWorkers {.used.} = dsc.ctx.buddiesMax
nPeers {.used.} = dsc.pool.len
nWorkers = dsc.buddies.len
zombie = dsc.buddies.eq peer.key
if zombie.isOk:
let
now = Moment.now()
ttz = zombie.value.zombified + zombieTimeToLinger
if ttz < Moment.now():
trace "Reconnecting zombie peer ignored", peer,
nPeers, nWorkers, maxWorkers, canRequeue=(now-ttz)
return
# Zombie can be removed from the database
dsc.buddies.del peer.key
trace "Zombie peer timeout, ready for requeing", peer,
nPeers, nWorkers, maxWorkers
# Initialise worker for this peer
let buddy = RunnerBuddyRef[S,W](
dsc: dsc,
worker: BuddyRef[S,W](
ctx: dsc.ctx,
ctrl: BuddyCtrlRef(),
peer: peer))
if not buddy.worker.runStart():
trace "Ignoring useless peer", peer, nPeers, nWorkers, maxWorkers
buddy.worker.ctrl.zombie = true
return
# Check for table overflow. An overflow might happen if there are zombies
# in the table (though preventing them from re-connecting for a while.)
if dsc.ctx.buddiesMax <= nWorkers:
let leastPeer = dsc.buddies.shift.value.data
if leastPeer.worker.ctrl.zombie:
trace "Dequeuing zombie peer",
oldest=leastPeer.worker, nPeers, nWorkers=dsc.buddies.len, maxWorkers
discard
else:
# This could happen if there are idle entries in the table, i.e.
# somehow hanging runners.
trace "Peer table full! Dequeuing least used entry",
oldest=leastPeer.worker, nPeers, nWorkers=dsc.buddies.len, maxWorkers
leastPeer.worker.ctrl.zombie = true
leastPeer.worker.runStop()
# Add peer entry
discard dsc.buddies.lruAppend(peer.key, buddy, dsc.ctx.buddiesMax)
trace "Running peer worker", peer, nPeers,
nWorkers=dsc.buddies.len, maxWorkers
asyncSpawn buddy.workerLoop()
proc onPeerDisconnected[S,W](dsc: RunnerSyncRef[S,W], peer: Peer) =
let
nPeers = dsc.pool.len
maxWorkers = dsc.ctx.buddiesMax
nWorkers = dsc.buddies.len
rc = dsc.buddies.eq peer.key
if rc.isErr:
debug "Disconnected, unregistered peer", peer, nPeers, nWorkers, maxWorkers
return
if rc.value.worker.ctrl.zombie:
# Don't disconnect, leave them fall out of the LRU cache. The effect is,
# that reconnecting might be blocked, for a while. For few peers cases,
# the start of zombification is registered so that a zombie can eventually
# be let die and buried.
rc.value.worker = nil
rc.value.dsc = nil
rc.value.zombified = Moment.now()
trace "Disconnected, zombie", peer, nPeers, nWorkers, maxWorkers
else:
rc.value.worker.ctrl.stopped = true # in case it is hanging somewhere
dsc.buddies.del peer.key
trace "Disconnected buddy", peer, nPeers,
nWorkers=dsc.buddies.len, maxWorkers
# ------------------------------------------------------------------------------
# Public functions
# ------------------------------------------------------------------------------
proc initSync*[S,W](
dsc: RunnerSyncRef[S,W];
node: EthereumNode;
chain: ChainRef,
slots: int;
exCtrlFile = none(string);
) =
## Constructor
# Leave one extra slot so that it can holds a *zombie* even if all slots
# are full. The effect is that a re-connect on the latest zombie will be
# rejected as long as its worker descriptor is registered.
dsc.ctx = CtxRef[S](
ethWireCtx: cast[EthWireRef](node.protocolState protocol.eth),
buddiesMax: max(1, slots + 1),
exCtrlFile: exCtrlFile,
chain: chain)
dsc.pool = node.peerPool
dsc.buddies.init(dsc.ctx.buddiesMax)
proc startSync*[S,W](dsc: RunnerSyncRef[S,W]): bool =
## Set up `PeerObserver` handlers and start syncing.
mixin runSetup
# Initialise sub-systems
if dsc.ctx.runSetup():
var po = PeerObserver(
onPeerConnected:
proc(p: Peer) {.gcsafe.} =
dsc.onPeerConnected(p),
onPeerDisconnected:
proc(p: Peer) {.gcsafe.} =
dsc.onPeerDisconnected(p))
po.setProtocol eth
dsc.pool.addObserver(dsc, po)
if dsc.ctx.daemon:
asyncSpawn dsc.daemonLoop()
return true
proc stopSync*[S,W](dsc: RunnerSyncRef[S,W]) =
## Stop syncing and free peer handlers .
mixin runRelease
dsc.pool.delObserver(dsc)
# Gracefully shut down async services
dsc.shutdown = true
for buddy in dsc.buddies.nextValues:
buddy.worker.ctrl.stopped = true
dsc.ctx.daemon = false
# Final shutdown (note that some workers might still linger on)
dsc.ctx.runRelease()
# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------
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