Proper handling of two consecutive UserInterrupt in Haskell
0
My program is running a quite long iterative IO computation. At each iteration, I'm saving an intermediary result in case of a shutdown request. Upon such a request I want to stop the computation and print the intermediary result before terminating the program. Here is what I achieved, it works, but when I press CTRL-C more than once in my terminal, the final print is not done. This is the first time I have to deal with asynchronous exceptions, so I may be wrong.
main :: String -> IO ()
main query = uninterruptibleMask $ restore -> do
results <- newIORef
xe <- try $ restore $ search query results
case xe of
Right x -> printCompleted >> printResults x
Left e -> do
printInterrupted
readIORef results >>= printResults
case e of
UserInterrupt -> return ()
_ -> throw e
Thanks!
haskell asynchronous exception
asked Nov 12 '18 at 19:14
Timothée JourdeTimothée Jourde
518
|
show 4 more comments
0
My program is running a quite long iterative IO computation. At each iteration, I'm saving an intermediary result in case of a shutdown request. Upon such a request I want to stop the computation and print the intermediary result before terminating the program. Here is what I achieved, it works, but when I press CTRL-C more than once in my terminal, the final print is not done. This is the first time I have to deal with asynchronous exceptions, so I may be wrong.
main :: String -> IO ()
main query = uninterruptibleMask $ restore -> do
results <- newIORef
xe <- try $ restore $ search query results
case xe of
Right x -> printCompleted >> printResults x
Left e -> do
printInterrupted
readIORef results >>= printResults
case e of
UserInterrupt -> return ()
_ -> throw e
Thanks!
haskell asynchronous exception
asked Nov 12 '18 at 19:14
Timothée JourdeTimothée Jourde
518
This seems like a pretty normal behavior for a program to have. The user hits^Conce: okay, fine, you want me to quit, give me a minute and I'll print what I know so far. The user hits^Cagain while this is happening? They are tired of waiting for the program to quit, and want it to just get out of the way so they can run some other command.
– amalloy
Nov 12 '18 at 19:23
@amalloy sure, but sinceCTRL-C(always?) sendsSIGINT, I would expect this piece of code to always work since it's usinguninterruptibleMask.
– Timothée Jourde
Nov 12 '18 at 19:28
You are interruptible while printing, because you have calledrestoreoncequerycompletes, no? I am not very familiar with async exceptions either, but from reading the Control.Exception docs it seems that therestoreargument exists to allow you to restore the masking state so you can say you no longer need to be masked.
– amalloy
Nov 12 '18 at 19:41
@amalloy I'm only callingrestoreinsidetryand the final print (printInterruptedandprintResults) is done outsidetry.
– Timothée Jourde
Nov 12 '18 at 19:46
1
Apparently, the Haskell runtime kills the program on the second Ctrl-C by default, unless a signal handler is installed stackoverflow.com/questions/2349233/…
– danidiaz
Nov 12 '18 at 20:27
|
show 4 more comments
0
0
0
My program is running a quite long iterative IO computation. At each iteration, I'm saving an intermediary result in case of a shutdown request. Upon such a request I want to stop the computation and print the intermediary result before terminating the program. Here is what I achieved, it works, but when I press CTRL-C more than once in my terminal, the final print is not done. This is the first time I have to deal with asynchronous exceptions, so I may be wrong.
main :: String -> IO ()
main query = uninterruptibleMask $ restore -> do
results <- newIORef
xe <- try $ restore $ search query results
case xe of
Right x -> printCompleted >> printResults x
Left e -> do
printInterrupted
readIORef results >>= printResults
case e of
UserInterrupt -> return ()
_ -> throw e
Thanks!
haskell asynchronous exception
asked Nov 12 '18 at 19:14
Timothée JourdeTimothée Jourde
518
My program is running a quite long iterative IO computation. At each iteration, I'm saving an intermediary result in case of a shutdown request. Upon such a request I want to stop the computation and print the intermediary result before terminating the program. Here is what I achieved, it works, but when I press CTRL-C more than once in my terminal, the final print is not done. This is the first time I have to deal with asynchronous exceptions, so I may be wrong.
main :: String -> IO ()
main query = uninterruptibleMask $ restore -> do
results <- newIORef
xe <- try $ restore $ search query results
case xe of
Right x -> printCompleted >> printResults x
Left e -> do
printInterrupted
readIORef results >>= printResults
case e of
UserInterrupt -> return ()
_ -> throw e
Thanks!
haskell asynchronous exception
haskell asynchronous exception
asked Nov 12 '18 at 19:14
Timothée JourdeTimothée Jourde
518
asked Nov 12 '18 at 19:14
Timothée JourdeTimothée Jourde
518
asked Nov 12 '18 at 19:14
Timothée JourdeTimothée Jourde
518
asked Nov 12 '18 at 19:14
Timothée JourdeTimothée Jourde
518
asked Nov 12 '18 at 19:14
Timothée JourdeTimothée Jourde
518
518
This seems like a pretty normal behavior for a program to have. The user hits^Conce: okay, fine, you want me to quit, give me a minute and I'll print what I know so far. The user hits^Cagain while this is happening? They are tired of waiting for the program to quit, and want it to just get out of the way so they can run some other command.
– amalloy
Nov 12 '18 at 19:23
@amalloy sure, but sinceCTRL-C(always?) sendsSIGINT, I would expect this piece of code to always work since it's usinguninterruptibleMask.
– Timothée Jourde
Nov 12 '18 at 19:28
You are interruptible while printing, because you have calledrestoreoncequerycompletes, no? I am not very familiar with async exceptions either, but from reading the Control.Exception docs it seems that therestoreargument exists to allow you to restore the masking state so you can say you no longer need to be masked.
– amalloy
Nov 12 '18 at 19:41
@amalloy I'm only callingrestoreinsidetryand the final print (printInterruptedandprintResults) is done outsidetry.
– Timothée Jourde
Nov 12 '18 at 19:46
1
Apparently, the Haskell runtime kills the program on the second Ctrl-C by default, unless a signal handler is installed stackoverflow.com/questions/2349233/…
– danidiaz
Nov 12 '18 at 20:27
|
show 4 more comments
This seems like a pretty normal behavior for a program to have. The user hits^Conce: okay, fine, you want me to quit, give me a minute and I'll print what I know so far. The user hits^Cagain while this is happening? They are tired of waiting for the program to quit, and want it to just get out of the way so they can run some other command.
– amalloy
Nov 12 '18 at 19:23
@amalloy sure, but sinceCTRL-C(always?) sendsSIGINT, I would expect this piece of code to always work since it's usinguninterruptibleMask.
– Timothée Jourde
Nov 12 '18 at 19:28
You are interruptible while printing, because you have calledrestoreoncequerycompletes, no? I am not very familiar with async exceptions either, but from reading the Control.Exception docs it seems that therestoreargument exists to allow you to restore the masking state so you can say you no longer need to be masked.
– amalloy
Nov 12 '18 at 19:41
@amalloy I'm only callingrestoreinsidetryand the final print (printInterruptedandprintResults) is done outsidetry.
– Timothée Jourde
Nov 12 '18 at 19:46
1
Apparently, the Haskell runtime kills the program on the second Ctrl-C by default, unless a signal handler is installed stackoverflow.com/questions/2349233/…
– danidiaz
Nov 12 '18 at 20:27
This seems like a pretty normal behavior for a program to have. The user hits
^C once: okay, fine, you want me to quit, give me a minute and I'll print what I know so far. The user hits ^C again while this is happening? They are tired of waiting for the program to quit, and want it to just get out of the way so they can run some other command.– amalloy
Nov 12 '18 at 19:23
This seems like a pretty normal behavior for a program to have. The user hits
^C once: okay, fine, you want me to quit, give me a minute and I'll print what I know so far. The user hits ^C again while this is happening? They are tired of waiting for the program to quit, and want it to just get out of the way so they can run some other command.– amalloy
Nov 12 '18 at 19:23
@amalloy sure, but since
CTRL-C (always?) sends SIGINT, I would expect this piece of code to always work since it's using uninterruptibleMask.– Timothée Jourde
Nov 12 '18 at 19:28
@amalloy sure, but since
CTRL-C (always?) sends SIGINT, I would expect this piece of code to always work since it's using uninterruptibleMask.– Timothée Jourde
Nov 12 '18 at 19:28
You are interruptible while printing, because you have called
restore once query completes, no? I am not very familiar with async exceptions either, but from reading the Control.Exception docs it seems that the restore argument exists to allow you to restore the masking state so you can say you no longer need to be masked.– amalloy
Nov 12 '18 at 19:41
You are interruptible while printing, because you have called
restore once query completes, no? I am not very familiar with async exceptions either, but from reading the Control.Exception docs it seems that the restore argument exists to allow you to restore the masking state so you can say you no longer need to be masked.– amalloy
Nov 12 '18 at 19:41
@amalloy I'm only calling
restore inside try and the final print (printInterrupted and printResults) is done outside try.– Timothée Jourde
Nov 12 '18 at 19:46
@amalloy I'm only calling
restore inside try and the final print (printInterrupted and printResults) is done outside try.– Timothée Jourde
Nov 12 '18 at 19:46
1
1
Apparently, the Haskell runtime kills the program on the second Ctrl-C by default, unless a signal handler is installed stackoverflow.com/questions/2349233/…
– danidiaz
Nov 12 '18 at 20:27
Apparently, the Haskell runtime kills the program on the second Ctrl-C by default, unless a signal handler is installed stackoverflow.com/questions/2349233/…
– danidiaz
Nov 12 '18 at 20:27
|
show 4 more comments
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This seems like a pretty normal behavior for a program to have. The user hits
^Conce: okay, fine, you want me to quit, give me a minute and I'll print what I know so far. The user hits^Cagain while this is happening? They are tired of waiting for the program to quit, and want it to just get out of the way so they can run some other command.– amalloy
Nov 12 '18 at 19:23
@amalloy sure, but since
CTRL-C(always?) sendsSIGINT, I would expect this piece of code to always work since it's usinguninterruptibleMask.– Timothée Jourde
Nov 12 '18 at 19:28
You are interruptible while printing, because you have called
restoreoncequerycompletes, no? I am not very familiar with async exceptions either, but from reading the Control.Exception docs it seems that therestoreargument exists to allow you to restore the masking state so you can say you no longer need to be masked.– amalloy
Nov 12 '18 at 19:41
@amalloy I'm only calling
restoreinsidetryand the final print (printInterruptedandprintResults) is done outsidetry.– Timothée Jourde
Nov 12 '18 at 19:46
1
Apparently, the Haskell runtime kills the program on the second Ctrl-C by default, unless a signal handler is installed stackoverflow.com/questions/2349233/…
– danidiaz
Nov 12 '18 at 20:27