From 110db2ace3386e6ea865f40b8aa9387e00fdff1d Mon Sep 17 00:00:00 2001
From: Marco Realacci <marco@marcorealacci.me>
Date: Mon, 17 Mar 2025 21:47:45 +0100
Subject: [PATCH] vault backup: 2025-03-17 21:47:45

---
 .obsidian/workspace.json                      |  6 ++---
 .../5 - Software Transactional Memory.md      | 22 ++++++++++++++++++-
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json
index 9db05b2..7d3ebd9 100644
--- a/.obsidian/workspace.json
+++ b/.obsidian/workspace.json
@@ -36,7 +36,7 @@
                 "file": "Concurrent Systems/slides/class 5.pdf",
                 "page": 4,
                 "left": -23,
-                "top": 240,
+                "top": 102,
                 "zoom": 0.652019002375297
               },
               "icon": "lucide-file-text",
@@ -215,10 +215,10 @@
       "companion:Toggle completion": false
     }
   },
-  "active": "51157f32453cba69",
+  "active": "6edd4157a160e462",
   "lastOpenFiles": [
-    "Concurrent Systems/notes/5 - Software Transactional Memory.md",
     "Concurrent Systems/slides/class 5.pdf",
+    "Concurrent Systems/notes/5 - Software Transactional Memory.md",
     "Concurrent Systems/notes/4c - Dining Philosophers.md",
     "Concurrent Systems/notes/3a - Hardware primitives & Lamport Bakery algorithm.md",
     "Concurrent Systems/notes/2b - Round Robin algorithm.md",
diff --git a/Concurrent Systems/notes/5 - Software Transactional Memory.md b/Concurrent Systems/notes/5 - Software Transactional Memory.md
index d8c4f0c..6fd8f81 100644
--- a/Concurrent Systems/notes/5 - Software Transactional Memory.md	
+++ b/Concurrent Systems/notes/5 - Software Transactional Memory.md	
@@ -63,7 +63,27 @@ begin_T() :=
 	birthdate(T) <- CLOCK + 1
 
 X.read_T() :=
-	if lc?(XX) != 
+	if lc?(XX) != ⊥ then
+		return lc(XX).val
+	lc(XX) <- XX
+	if lc(XX).date >= birthdate(T) then
+		ABORT
+	read_set(T) <- read_set(T) U {X}
+	return lc(XX).val
+
+X.write_T(v) :=
+	if lc(XX) = ⊥ then
+		lc(XX) <- newloc
+	lc(XX).val <- v
+	write_set(T) <- write_set(T) U {X}
+
+try_to_commit_T() :=
+	lock all read_set(T) U write_set(T)
+	∀ X ∈ read_set(T)
+		if XX.date >= birthdate(T) then
+			release all locks
+			ABORT
+	
 ```
 
 ### Virtual World Consistency