Looking at the web-repl.scm file in gambc/examples, I often see situations of:
lock mutex write single char flush output unlock mutex
Why is this necessary? According to the gambit documentation, ports have to be written to handle concurrent read/writes themselves.
Thanks!
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On 21-Jun-09, at 11:14 PM, lowly coder wrote:
Looking at the web-repl.scm file in gambc/examples, I often see situations of:
lock mutex write single char flush output unlock mutex
Why is this necessary? According to the gambit documentation, ports have to be written to handle concurrent read/writes themselves.
The locking is not needed in web-repl.scm . It is there because the code is left over from an implementation of the telnet protocol where I believe exclusive access to the terminal was needed.
Note that the Gambit specs say that *individual calls* to write-char need no locking. But if you want a sequence of calls to write-char to appear uninterrupted, then you need a lock.
Marc
The following code (derived from simplifying web-repl.scm) _appears_ to work
(define s (open-tcp-server (list server-address: "" port-number: 12345 eol-encoding: 'cr-lf)))
(define-macro (forever . body) `(let loop () ,@body (loop)))
(forever (let ((port1 (read s))) (set! ##thread-make-repl-channel (lambda (thread) (##make-repl-channel-ports port1 port1))) (##repl-debug-main)))
however, I'm not sure if there's anything (like race conditions) that I've introduced; and clearly we've lost support for important things like control characters; besides that, any other problems? (I like it's sheer readability)
Thanks!
On Mon, Jun 22, 2009 at 6:36 AM, Marc Feeley feeley@iro.umontreal.cawrote:
On 21-Jun-09, at 11:14 PM, lowly coder wrote:
Looking at the web-repl.scm file in gambc/examples, I often see situations
of:
lock mutex write single char flush output unlock mutex
Why is this necessary? According to the gambit documentation, ports have to be written to handle concurrent read/writes themselves.
The locking is not needed in web-repl.scm . It is there because the code is left over from an implementation of the telnet protocol where I believe exclusive access to the terminal was needed.
Note that the Gambit specs say that *individual calls* to write-char need no locking. But if you want a sequence of calls to write-char to appear uninterrupted, then you need a lock.
Marc
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lowly coder -
Marc Feeley