vault backup: 2025-03-12 11:59:27

Concurrent Systems/notes/4 - Semaphores.md

@@ -101,7 +101,7 @@ B.consume() :=
 B.produce(v) :=
 	FREE.down()
 	SP.down()
-		while not EMPTY[in] do
+	while not EMPTY[in] do
 		IN <- (IN+1) mod k
 	i <- IN
 	EMPTY[IN] <- ff
@@ -153,6 +153,14 @@ B.consume() :=
 	FREE.up()
 	return tmp
 ```
+okay, so the difference seems to be just the fact that there are no while loops to find the first free location, or the first location with data.
+
+Let's imagine to have quick producers and a slow consumer:
+producer A:
+- writes at BUF[0], so IN becomes 1
+
+consumer A:
+- reads 
 
 #### The Readers/Writers problem
 - Several processes want to access a file