From f8fef5c5ae63c0933f92a25d82da447ff44c2444 Mon Sep 17 00:00:00 2001
From: Ibrahim Mkusa <ibrahimmkusa@gmail.com>
Date: Fri, 14 Apr 2017 00:44:42 -0400
Subject: [PATCH] now handles disconnected clients

---
 Hermes/TODO       |  2 +-
 Hermes/server.rkt | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/Hermes/TODO b/Hermes/TODO
index bff56e6..c8dbc75 100644
--- a/Hermes/TODO
+++ b/Hermes/TODO
@@ -9,6 +9,6 @@
 11. user can ask for no of logged in users. Server has to pars
 e
 12. Hide user's own input in command line
-** 13. Need to gracefully handle disconnected clients by removing from list
+** 13. Need to gracefully handle disconnected clients by removing from list user filter
 of connections
 14. bye message prompt for clients
diff --git a/Hermes/server.rkt b/Hermes/server.rkt
index 5b599a7..5673eca 100644
--- a/Hermes/server.rkt
+++ b/Hermes/server.rkt
@@ -32,9 +32,19 @@
     connections)
    (define (cons-list)
      connections)
+   (define (remove-ports in out)
+     (set! connections
+       (filter 
+         (lambda (ports)
+           (if (and (eq? in (get-input-port ports))
+                    (eq? out (get-output-port ports)))
+             #f
+             #t))
+         connections)))
    (define (dispatch m)
      (cond [(eq? m 'null-cons) null-cons?]
            [(eq? m 'cons-list) cons-list]
+           [(eq? m 'remove-ports) remove-ports]
            [(eq? m 'add) add]))
    dispatch)
 (define c-connections (make-connections '()))
@@ -133,6 +143,11 @@
   (define (something-to-say in)
     (define evt-t0 (sync/timeout 60  (read-line-evt in 'linefeed)))
     (cond [(eof-object? evt-t0)
+           ; TODO remove pair of ports associated with client
+           (semaphore-wait connections-s)
+           ((c-connections 'remove-ports) in out)
+           (semaphore-post connections-s)
+
            (displayln-safe "Connection closed. EOF received"
                            stdout)
            (semaphore-wait c-count-s)