Event manager tests

These are a couple of regression tests for GHC bug #10317. See the discussion on D849.

These must be built with ghc -threaded and should be run with the included shell scripts.

TestMultipleReg

This test verifies that multiple registrations against the same fd fire as expected. The Haskell test opens an AF_INET socket and registers read and write event registrations. The shell script is listening on this socket and writes to it after a delay. Consequently, the write registration should trigger immediately upon connection and the read registration should fire after the delay.

Expected output

$ ./test-multiple-reg.sh 
write callback
("hello",5)

Failed output

$ ./test-multiple-reg.sh 
write callback
TestMultipleReg: thread blocked indefinitely in an MVar operation

TestMultiShot

This test verifies that MultiShot registrations indeed fire multiple times. The Haskell test opens a fifo filled with data by the shell script. We then register a multi-shot read event against this fd and in the callback perform several short reads. The callback should be called several times.

Expected output

$ ./test-multishot.sh 
ok

Failed output

$ ./test-multishot.sh 
TestMultishot: thread blocked indefinitely in an MVar operation