Re: interacting with a process with redirected stdin/stdout/stderr
On Monday, 15 July 2013 at 06:46:52 UTC, timotheecour wrote:
On Monday, 15 July 2013 at 03:49:10 UTC, Timothee Cour wrote:
I'm trying to interact with a process using std.process and
redirected stdin/stdout/stderr.
What would be the recommended way?
For example:
auto pipes=pipeShell(myprocess,Redirect.all);
while(true){
pipes.stdin.rawWrite(some_command);
foreach (line; pipes.stdout.byLine) {
//do something with line
}
}
This doesn't work because it might block inside
pipes.stdout.byLine, as the
process is requesting more inputs to be written to its stdin
before
outputting more bytes to its stdout.
What's the right approach?
* fcntl(fd, F_SETFL, O_NONBLOCK); didn't seem to work
* reading pipes.stdout inside a separate thread?
In that second case, how to cleanly dispose of a blocked
thread when we no
longer need it?
Any detailed example would help.
Thanks!
I tried using a separate thread for reading the process'
stdout. It works, except that sometimes the output is shuffled
out of order.
Is there anything buggy in this:
__gshared string output;
void readBlocking(){
while ((c = fgetc(filepointer)) = 0)
output~=cast(char) c;
//NOTE: i can use something more efficient here but that's
beside the question
}
thread = new Thread( readBlocking);
output=null;
while(true){
Thread.sleep(...);
if(condition) break;
}
//now output is shuffled out of order sometimes
Furthermore, is there a standard way to tell when a process is
waiting for stdin input ? (cf condition above). Currently I'm
checking whether 'output' was modified within a timeout period
T, but that's fragile and incurs of penalty of T at least.
Are you looking for select() or poll()
Poll I believe is posix only but I think select is more widely
available.
Not much of an answer but I hope it helps
Re: interacting with a process with redirected stdin/stdout/stderr
On Tue, Jul 16, 2013 at 10:01 AM, Anthony Goins neonto...@gmail.com wrote:
On Monday, 15 July 2013 at 06:46:52 UTC, timotheecour wrote:
On Monday, 15 July 2013 at 03:49:10 UTC, Timothee Cour wrote:
I'm trying to interact with a process using std.process and
redirected stdin/stdout/stderr.
What would be the recommended way?
For example:
auto pipes=pipeShell(myprocess,**Redirect.all);
while(true){
pipes.stdin.rawWrite(some_**command);
foreach (line; pipes.stdout.byLine) {
//do something with line
}
}
This doesn't work because it might block inside pipes.stdout.byLine, as
the
process is requesting more inputs to be written to its stdin before
outputting more bytes to its stdout.
What's the right approach?
* fcntl(fd, F_SETFL, O_NONBLOCK); didn't seem to work
* reading pipes.stdout inside a separate thread?
In that second case, how to cleanly dispose of a blocked thread when we
no
longer need it?
Any detailed example would help.
Thanks!
I tried using a separate thread for reading the process' stdout. It
works, except that sometimes the output is shuffled out of order.
Is there anything buggy in this:
__gshared string output;
void readBlocking(){
while ((c = fgetc(filepointer)) = 0)
output~=cast(char) c;
//NOTE: i can use something more efficient here but that's beside the
question
}
thread = new Thread( readBlocking);
output=null;
while(true){
Thread.sleep(...);
if(condition) break;
}
//now output is shuffled out of order sometimes
Furthermore, is there a standard way to tell when a process is waiting
for stdin input ? (cf condition above). Currently I'm checking whether
'output' was modified within a timeout period T, but that's fragile and
incurs of penalty of T at least.
Are you looking for select() or poll()
Poll I believe is posix only but I think select is more widely available.
Not much of an answer but I hope it helps
Thanks, I had actually used select to solve another problem I had:
[std.process: how to process stdout chunk by chunk without waiting for
process termination]
That should work for here as well.
I think std.process is a bit limited currently, I keep having to implement
basic stuff it doesn't support.
Re: interacting with a process with redirected stdin/stdout/stderr
On Monday, 15 July 2013 at 03:49:10 UTC, Timothee Cour wrote:
I'm trying to interact with a process using std.process and
redirected stdin/stdout/stderr.
What would be the recommended way?
For example:
auto pipes=pipeShell(myprocess,Redirect.all);
while(true){
pipes.stdin.rawWrite(some_command);
foreach (line; pipes.stdout.byLine) {
//do something with line
}
}
This doesn't work because it might block inside
pipes.stdout.byLine, as the
process is requesting more inputs to be written to its stdin
before
outputting more bytes to its stdout.
What's the right approach?
* fcntl(fd, F_SETFL, O_NONBLOCK); didn't seem to work
* reading pipes.stdout inside a separate thread?
In that second case, how to cleanly dispose of a blocked thread
when we no
longer need it?
Any detailed example would help.
Thanks!
I tried using a separate thread for reading the process' stdout.
It works, except that sometimes the output is shuffled out of
order.
Is there anything buggy in this:
__gshared string output;
void readBlocking(){
while ((c = fgetc(filepointer)) = 0)
output~=cast(char) c;
//NOTE: i can use something more efficient here but that's beside
the question
}
thread = new Thread( readBlocking);
output=null;
while(true){
Thread.sleep(...);
if(condition) break;
}
//now output is shuffled out of order sometimes
Furthermore, is there a standard way to tell when a process is
waiting for stdin input ? (cf condition above). Currently I'm
checking whether 'output' was modified within a timeout period T,
but that's fragile and incurs of penalty of T at least.
interacting with a process with redirected stdin/stdout/stderr
I'm trying to interact with a process using std.process and
redirected stdin/stdout/stderr.
What would be the recommended way?
For example:
auto pipes=pipeShell(myprocess,Redirect.all);
while(true){
pipes.stdin.rawWrite(some_command);
foreach (line; pipes.stdout.byLine) {
//do something with line
}
}
This doesn't work because it might block inside pipes.stdout.byLine, as the
process is requesting more inputs to be written to its stdin before
outputting more bytes to its stdout.
What's the right approach?
* fcntl(fd, F_SETFL, O_NONBLOCK); didn't seem to work
* reading pipes.stdout inside a separate thread?
In that second case, how to cleanly dispose of a blocked thread when we no
longer need it?
Any detailed example would help.
Thanks!
