From 19763a448397c3dae66df41e5fa61df1e6036686 Mon Sep 17 00:00:00 2001
From: Marco Realacci <marco@marcorealacci.me>
Date: Wed, 12 Mar 2025 11:14:27 +0100
Subject: [PATCH] vault backup: 2025-03-12 11:14:27

---
 .obsidian/workspace.json                   |  4 ++--
 Concurrent Systems/notes/4 - Semaphores.md | 10 ++++++++--
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json
index fbaa41b..f8b3faf 100644
--- a/.obsidian/workspace.json
+++ b/.obsidian/workspace.json
@@ -34,9 +34,9 @@
               "type": "pdf",
               "state": {
                 "file": "Concurrent Systems/slides/class 4.pdf",
-                "page": 5,
+                "page": 7,
                 "left": -23,
-                "top": 391,
+                "top": 248,
                 "zoom": 0.652019002375297
               },
               "icon": "lucide-file-text",
diff --git a/Concurrent Systems/notes/4 - Semaphores.md b/Concurrent Systems/notes/4 - Semaphores.md
index f1a1ebf..7c2d90a 100644
--- a/Concurrent Systems/notes/4 - Semaphores.md	
+++ b/Concurrent Systems/notes/4 - Semaphores.md	
@@ -101,7 +101,7 @@ B.consume() :=
 B.produce(v) :=
 	FREE.down()
 	SP.down()
-	while not EMPTY[in] do # there is at least an EMPTY cell, otherwise it would have been blocked
+		while not EMPTY[in] do
 		IN <- (IN+1) mod k
 	i <- IN
 	EMPTY[IN] <- ff
@@ -123,4 +123,10 @@ B.consume() :=
 	EMPTY[o] <- tt
 	FREE.up()
 	return tmp		
-```
\ No newline at end of file
+```
+Thanks to the semaphores, we are sure that while loops will not go on forever! The loops starts only if there is at least a FREE / BUSY cell.
+
+#### (Multiple) Producers/Consumers - Wrong solution
+EXERCISE - will do later
+
+#### The Readers/Writers problem