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ddcbc1a58f
Fixes #15003.
This is a serious bug which occurs when data cannot be read/sent
immediately and there are a bunch of other read/write events
pending. What happens is that the new events are dropped which
results in the case of the reported bug resulted in some data not
being sent (!).
(cherry picked from commit 1e3a0ef1e1)
67 lines
1.9 KiB
Nim
67 lines
1.9 KiB
Nim
discard """
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disabled: "windows"
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exitcode: 0
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"""
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# AsyncSocketBug.nim
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# Jens Alfke (@snej) -- 16 July 2020
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# Demonstrates data loss by Nim's AsyncSocket.
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# Just run it, and it will raise an assertion failure within a minute.
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import asyncdispatch, asyncnet, strformat, strutils, sugar
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const FrameSize = 9999 # Exact size not important, but larger sizes fail quicker
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proc runServer() {.async.} =
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# Server side:
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var server = newAsyncSocket()
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server.bindAddr(Port(9001))
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server.listen()
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let client = await server.accept()
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echo "Server got client connection"
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var lastN = 0
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while true:
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let frame = await client.recv(FrameSize)
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assert frame.len == FrameSize
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let n = frame[0..<6].parseInt()
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echo "RCVD #", n, ": ", frame[0..80], "..."
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if n != lastN + 1:
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echo &"******** ERROR: Server received #{n}, but last was #{lastN}!"
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assert n == lastN + 1
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lastN = n
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await sleepAsync 100
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proc main() {.async.} =
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asyncCheck runServer()
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# Client side:
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let socket = newAsyncSocket(buffered = false)
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await socket.connect("localhost", Port(9001))
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echo "Client socket connected"
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var sentCount = 0
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var completedCount = 0
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while sentCount < 2000:
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sentCount += 1
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let n = sentCount
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var message = &"{n:06} This is message #{n} of ∞. Please stay tuned for more. "
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#echo ">>> ", message
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while message.len < FrameSize:
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message = message & message
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let frame = message[0..<FrameSize]
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capture n:
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socket.send(frame).addCallback proc(f: Future[void]) =
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# Callback when the send completes:
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assert not f.failed
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echo "SENT #", n
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if n != completedCount + 1:
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echo &"******** ERROR: Client completed #{n}, but last completed was #{completedCount}!"
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# If this assert is enabled, it will trigger earlier than the server-side assert above:
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assert n == completedCount + 1
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completedCount = n
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await sleepAsync 1
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waitFor main() |