simulation: synchronized logger

2 files changed, 16 insertions, 2 deletions

diff --git a/TODO.md b/TODO.md
index 344a6ff..6a7305e 100644
--- a/TODO.md
+++ b/TODO.md
@@ -10,4 +10,3 @@
       retransmissions)
 - Fix interference calculation -> IMPORTANT
 - Signal strength, location and rssi (complex, just an extra)
-- Make logger concurrency-friendly -> IMPORTANT
diff --git a/simulation.scm b/simulation.scm
index 09cc16d..01bc347 100644
--- a/simulation.scm
+++ b/simulation.scm
@@ -25,9 +25,21 @@
     (begin exp ...)
     (loop)))
 
+;; Synchronized logger
+(define *output-channel* (make-channel))
+(define (logger)
+  (forever
+    (let ((msg (get-message *output-channel*)))
+      (display msg))))
+
 (define (ll f . data)
   (let ((now (gettimeofday)))
-    (format #t "~a~a - ~?~%" (car now) (cdr now) f data)))
+    (spawn-fiber
+      (lambda ()
+        (put-message
+          *output-channel*
+          (format #f "~a~a - ~?~%" (car now) (cdr now) f data))))))
+
 
 ;; type can be:
 ;; 'start
@@ -197,6 +209,9 @@
 
 
 (define (run-simulation)
+  ;; We need a synchronized logger running in a fiber
+  (spawn-fiber logger)
+
   (let* ((radio-chn   (make-channel))
          (end-devices (make-hash-table))
          (gateways    (make-hash-table)))