Test with monitor #79
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| println("TEST STARTS") | ||
| val promise = scala.concurrent.Promise[Unit]() | ||
| val byte = 10.toByte | ||
| scheduler.monitor(r, reads = true, writes = false)( |
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Is the test or the test suite hanging? Note that the test suite will hang until all monitors are de-registered.
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You're right, in fact I had poll.stop() in the test I'm trying to port from scala-native-loop. stopping in the callback makes the test pass...
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This is fantastic! I am so happy to have a test that exercises fd monitoring without the complications of sockets, I've been wanting this for a while. |
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Required reading: https://lwn.net/Articles/864947/ Seems that edge-triggered polling for pipes is a bit different. This is because it was actually broken, and not possible to fully fix without breaking compatibility. |
| val make: Resource[IO, Pipe] = Resource.make { | ||
| zoneResource.use { implicit zone => | ||
| val fildes = alloc[CInt](2) | ||
| if (pipe(fildes) != 0) { | ||
| IO.raiseError(new Exception("Failed to create pipe")) | ||
| } else { | ||
| IO(new Pipe(fildes(0), fildes(1))) | ||
| } | ||
| } | ||
| }(pipe => |
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Note that calling pipe(fildes) is a side-effect and should be wrapped in IO.
Indeed, can we wrap this entire expression IO, and use a stack allocation for fildes instead of a zone?
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Indeed, can we wrap this entire expression IO, and use a stack allocation for fildes instead of a zone?
Done ✅
| val readBuf = stackalloc[Byte]() | ||
| val bytesRead = read(pipe.readFd, readBuf, 1L.toULong) | ||
| assertEquals(bytesRead, 1) | ||
| assertEquals(readBuf(0), byte) | ||
| stop.run() | ||
| cb(Right(())) |
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Oh, sorry, something else I just realized: if there is an assertion failure here, does it actually fail the test? Or maybe we need to capture it and return it as a cb(Left(ex))?
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You're right! It hands if the assert fails instead of failing the test. On it!
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Done ✅
Now exceptions fail the test and also stops the monitoring.
The test now pass. It can be part of the test suite if you think is valuable, otherwise we can just drop it.
P.S. Programming with
IOis so much fun! I have to use it more!