nimbus-eth1/nimbus/sync/sync_sched.nim

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Nim

# 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]; tickerOK: bool): 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.
##
## *runRelease(ctx: CtxRef[S])*
## Global clean up, done with all the worker peers.
##
##
## *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)*
## Once started, the function `runPool()` is called for all worker peers in
## sequence as the body of an iteration. 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 is the responsibility of the `runPool()`
## instance to reset the flag `buddy.ctx.poolMode`, typically at the first
## peer instance.
##
## The argument `last` is set `true` if the last entry is reached.
##
## Note that this function does not run in `async` mode.
##
##
## *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 workers, there can be only one `runSingle()` function active
## simultaneously for all worker peers.
## * There will be no `runMulti()` function active for the same worker peer
## simultaneously
## * There will be no `runPool()` iterator active simultaneously.
##
## 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.
##
##
## Additional import files needed when using this template:
## * eth/[common/eth_types, p2p]
## * chronicles
## * chronos
## * stew/[interval_set, sorted_set],
## * "."/[sync_desc, sync_sched, protocol]
##
import
std/hashes,
chronos,
eth/[common/eth_types, p2p, p2p/peer_pool, p2p/private/p2p_types],
stew/keyed_queue,
./sync_desc
{.push raises: [Defect].}
type
ActiveBuddies[S,W] = ##\
## List of active workers, using `Hash(Peer)` rather than `Peer`
KeyedQueue[Hash,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
tickerOk: bool ## Ticker logger
singleRunLock: bool ## For worker initialisation
monitorLock: bool ## For worker monitor
activeMulti: int ## Activated runners
RunnerBuddyRef[S,W] = ref object
## Per worker peer descriptor
dsc: RunnerSyncRef[S,W] ## Scheduler descriptor
worker: BuddyRef[S,W] ## Worker peer data
# ------------------------------------------------------------------------------
# Private helpers
# ------------------------------------------------------------------------------
proc hash(peer: Peer): Hash =
## Needed for `buddies` table key comparison
peer.remote.id.hash
# ------------------------------------------------------------------------------
# Private functions
# ------------------------------------------------------------------------------
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
while not worker.ctrl.stopped:
if dsc.monitorLock:
await sleepAsync(50.milliseconds)
continue
# Invoke `runPool()` over all buddies if requested
if 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:
await sleepAsync(50.milliseconds)
while dsc.singleRunLock:
await sleepAsync(50.milliseconds)
var count = dsc.buddies.len
for w in dsc.buddies.nextValues:
count.dec
worker.runPool(count == 0)
dsc.monitorLock = false
continue
# 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.hash)
# Allow task switch
await sleepAsync(50.milliseconds)
# 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
continue
# Single mode as requested. The `multiOk` flag for this worker was just
# found `false` in the pervious clause.
if not dsc.singleRunLock:
# Lock single instance mode and wait for other workers to finish
dsc.singleRunLock = true
while 0 < dsc.activeMulti:
await sleepAsync(50.milliseconds)
# Run single instance and release afterwards
await worker.runSingle()
dsc.singleRunLock = false
# End while
# Note that `runStart()` was dispatched in `onPeerConnected()`
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 = dsc.ctx.buddiesMax
peers = dsc.pool.len
workers = dsc.buddies.len
if dsc.buddies.hasKey(peer.hash):
trace "Reconnecting zombie peer rejected", peer, peers, workers, maxWorkers
return
# Initialise worker for this peer
let buddy = RunnerBuddyRef[S,W](
dsc: dsc,
worker: BuddyRef[S,W](
ctx: dsc.ctx,
peer: peer))
if not buddy.worker.runStart():
trace "Ignoring useless peer", peer, peers, workers, 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 <= workers:
let leastPeer = dsc.buddies.shift.value.data
if leastPeer.worker.ctrl.zombie:
trace "Dequeuing zombie peer",
oldest=leastPeer.worker, peers, workers=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, peers, workers=dsc.buddies.len, maxWorkers
leastPeer.worker.runStop()
leastPeer.worker.ctrl.zombie = true
# Add peer entry
discard dsc.buddies.lruAppend(peer.hash, buddy, dsc.ctx.buddiesMax)
trace "Running peer worker", peer, peers,
workers=dsc.buddies.len, maxWorkers
asyncSpawn buddy.workerLoop()
proc onPeerDisconnected[S,W](dsc: RunnerSyncRef[S,W], peer: Peer) =
let
peers = dsc.pool.len
maxWorkers = dsc.ctx.buddiesMax
workers = dsc.buddies.len
rc = dsc.buddies.eq(peer.hash)
if rc.isErr:
debug "Disconnected, unregistered peer", peer, peers, workers, 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.
trace "Disconnected, zombie", peer, peers, workers, maxWorkers
else:
rc.value.worker.ctrl.stopped = true # in case it is hanging somewhere
dsc.buddies.del(peer.hash)
trace "Disconnected buddy", peer, peers, workers=dsc.buddies.len, maxWorkers
# ------------------------------------------------------------------------------
# Public functions
# ------------------------------------------------------------------------------
proc initSync*[S,W](
dsc: RunnerSyncRef[S,W];
node: EthereumNode;
slots: int;
noisy = false) =
## 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](
buddiesMax: max(1, slots + 1),
chain: node.chain)
dsc.pool = node.peerPool
dsc.tickerOk = noisy
dsc.buddies.init(dsc.ctx.buddiesMax)
proc startSync*[S,W](dsc: RunnerSyncRef[S,W]): bool =
## Set up syncing. This call should come early.
mixin runSetup
# Initialise sub-systems
if dsc.ctx.runSetup(dsc.tickerOk):
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)
return true
proc stopSync*[S,W](dsc: RunnerSyncRef[S,W]) =
## Stop syncing
mixin runRelease
dsc.pool.delObserver(dsc)
dsc.ctx.runRelease()
# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------