vault backup: 2025-03-17 21:47:45

.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",

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
+	
 ```
 
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