nim-libp2p/libp2p/daemon/transpool.nim

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## Nim-Libp2p
## Copyright (c) 2018 Status Research & Development GmbH
## Licensed under either of
## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
## * MIT license ([LICENSE-MIT](LICENSE-MIT))
## at your option.
## This file may not be copied, modified, or distributed except according to
## those terms.
{.push raises: [Defect].}
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## This module implements Pool of StreamTransport.
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import chronos
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const
DefaultPoolSize* = 8
## Default pool size
type
ConnectionFlags = enum
None, Busy
PoolItem = object
transp*: StreamTransport
flags*: set[ConnectionFlags]
PoolState = enum
Connecting, Connected, Closing, Closed
TransportPool* = ref object
## Transports pool object
transports: seq[PoolItem]
busyCount: int
state: PoolState
bufferSize: int
event: AsyncEvent
TransportPoolError* = object of AsyncError
proc waitAll[T](futs: seq[Future[T]]): Future[void] =
## Performs waiting for all Future[T].
var counter = len(futs)
var retFuture = newFuture[void]("connpool.waitAllConnections")
proc cb(udata: pointer) =
dec(counter)
if counter == 0:
retFuture.complete()
for fut in futs:
fut.addCallback(cb)
return retFuture
proc newPool*(address: TransportAddress, poolsize: int = DefaultPoolSize,
bufferSize = DefaultStreamBufferSize,
): Future[TransportPool] {.async.} =
## Establish pool of connections to address ``address`` with size
## ``poolsize``.
var pool = new TransportPool
pool.bufferSize = bufferSize
pool.transports = newSeq[PoolItem](poolsize)
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var conns = newSeq[Future[StreamTransport]](poolsize)
pool.state = Connecting
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for i in 0..<poolsize:
conns[i] = connect(address, bufferSize)
# Waiting for all connections to be established.
await waitAll(conns)
# Checking connections and preparing pool.
for i in 0..<poolsize:
if conns[i].failed:
raise conns[i].error
else:
let transp = conns[i].read()
let item = PoolItem(transp: transp)
pool.transports[i] = item
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# Setup available connections event
pool.event = newAsyncEvent()
pool.state = Connected
result = pool
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proc acquire*(pool: TransportPool): Future[StreamTransport] {.async.} =
## Acquire non-busy connection from pool ``pool``.
var transp: StreamTransport
if pool.state in {Connected}:
while true:
if pool.busyCount < len(pool.transports):
for conn in pool.transports.mitems():
if Busy notin conn.flags:
conn.flags.incl(Busy)
inc(pool.busyCount)
transp = conn.transp
break
else:
await pool.event.wait()
pool.event.clear()
if not isNil(transp):
break
else:
raise newException(TransportPoolError, "Pool is not ready!")
result = transp
proc release*(pool: TransportPool, transp: StreamTransport) =
## Release connection ``transp`` back to pool ``pool``.
if pool.state in {Connected, Closing}:
var found = false
for conn in pool.transports.mitems():
if conn.transp == transp:
conn.flags.excl(Busy)
dec(pool.busyCount)
pool.event.fire()
found = true
break
if not found:
raise newException(TransportPoolError, "Transport not bound to pool!")
else:
raise newException(TransportPoolError, "Pool is not ready!")
proc join*(pool: TransportPool) {.async.} =
## Waiting for all connection to become available.
if pool.state in {Connected, Closing}:
while true:
if pool.busyCount == 0:
break
else:
await pool.event.wait()
pool.event.clear()
elif pool.state == Connecting:
raise newException(TransportPoolError, "Pool is not ready!")
proc close*(pool: TransportPool) {.async.} =
## Closes transports pool ``pool`` and release all resources.
if pool.state == Connected:
pool.state = Closing
# Waiting for all transports to become available.
await pool.join()
# Closing all transports
var pending = newSeq[Future[void]](len(pool.transports))
for i in 0..<len(pool.transports):
let transp = pool.transports[i].transp
transp.close()
pending[i] = transp.join()
# Waiting for all transports to be closed
await waitAll(pending)
# Mark pool as `Closed`.
pool.state = Closed