nim-codex/codex/streams/asyncstreamwrapper.nim

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## Nim-LibP2P
## Copyright (c) 2019 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.
import pkg/upraises
push: {.upraises: [].}
import pkg/chronos
import pkg/chronicles
import pkg/libp2p
logScope:
topics = "libp2p asyncstreamwrapper"
const
AsyncStreamWrapperName* = "AsyncStreamWrapper"
type
AsyncStreamWrapper* = ref object of LPStream
reader*: AsyncStreamReader
writer*: AsyncStreamWriter
method initStream*(self: AsyncStreamWrapper) =
if self.objName.len == 0:
self.objName = AsyncStreamWrapperName
procCall LPStream(self).initStream()
proc new*(
C: type AsyncStreamWrapper,
reader: AsyncStreamReader = nil,
writer: AsyncStreamWriter = nil): AsyncStreamWrapper =
let
stream = C(reader: reader, writer: writer)
stream.initStream()
return stream
template withExceptions(body: untyped) =
try:
body
except CancelledError as exc:
raise exc
except AsyncStreamIncompleteError:
# for all intents and purposes this is an EOF
raise newLPStreamIncompleteError()
except AsyncStreamLimitError:
raise newLPStreamLimitError()
except AsyncStreamUseClosedError:
raise newLPStreamEOFError()
except AsyncStreamError as exc:
raise newException(LPStreamError, exc.msg)
method readOnce*(
self: AsyncStreamWrapper,
pbytes: pointer,
nbytes: int): Future[int] {.async.} =
trace "Reading bytes from reader", bytes = nbytes
if isNil(self.reader):
error "Async stream wrapper reader nil"
raiseAssert("Async stream wrapper reader nil")
if self.atEof:
raise newLPStreamEOFError()
withExceptions:
return await self.reader.readOnce(pbytes, nbytes)
proc completeWrite(
self: AsyncStreamWrapper,
fut: Future[void],
msgLen: int): Future[void] {.async.} =
withExceptions:
await fut
method write*(self: AsyncStreamWrapper, msg: seq[byte]): Future[void] =
# Avoid a copy of msg being kept in the closure created by `{.async.}` as this
# drives up memory usage
trace "Writing bytes to writer", bytes = msg.len
if isNil(self.writer):
error "Async stream wrapper writer nil"
raiseAssert("Async stream wrapper writer nil")
if self.closed:
let fut = newFuture[void]("asyncstreamwrapper.write.closed")
fut.fail(newLPStreamClosedError())
return fut
self.completeWrite(self.writer.write(msg, msg.len), msg.len)
method closed*(self: AsyncStreamWrapper): bool =
var
readerClosed = true
writerClosed = true
if not isNil(self.reader):
readerClosed = self.reader.closed
if not isNil(self.writer):
writerClosed = self.writer.closed
return readerClosed and writerClosed
method atEof*(self: AsyncStreamWrapper): bool =
self.reader.atEof()
method closeImpl*(self: AsyncStreamWrapper) {.async.} =
try:
trace "Shutting down async chronos stream"
if not self.closed():
if not isNil(self.reader) and not self.reader.closed():
await self.reader.closeWait()
if not isNil(self.writer) and not self.writer.closed():
await self.writer.closeWait()
trace "Shutdown async chronos stream"
except CancelledError as exc:
raise exc
except CatchableError as exc:
trace "Error closing async chronos stream", msg = exc.msg
await procCall LPStream(self).closeImpl()