vault backup: 2025-03-17 23:27:45

Concurrent Systems/notes/5 - Software Transactional Memory.md

@@ -146,24 +146,27 @@ X.read_T(i) :=
 
 	return lc(XX).val
 
-X.write_T(v) :=
+X.write_T(i, v) :=
 	if lc(XX) = ⊥ then
 		lc(XX) <- newloc
 	lc(XX).val <- v
 	write_set(T) <- write_set(T) U {X}
 
-try_to_commit_T() :=
+try_to_commit_T(i) :=
 	lock all read_set(T) U write_set(T)
 
-	if ∃ Y ∈ read_set(T) s.t.
-
-	∀ X ∈ read_set(T)
-		if XX.date >= birthdate(T) then
-			release all locks
-			ABORT
-		tmp <- CLOCK.fetch&add(1)+1
-		∀ X ∈ write_set(T)
-			XX <- ⟨lc(XX).val, tmp⟩
+	if ∃ Y ∈ read_set(T) s.t. t_dependT[Y] < YY.depend[Y] then
 		release all locks
-		COMMIT
+		ABORT
+		# abortisco se ho letto un Y che è stato modificato dopo che io l'ho letto, giusto?
+
+	∀ X ∈ write_set(T) do
+		t_dependT[X] <- XX.depend[X]+1
+
+	∀ X ∈ write_set(T) do
+		XX <- ⟨lc(XX).val, t_dependT⟩
+
+	release all locks
+	p_depend_i <- t_depend_T
+	COMMIT
 ```