vault backup: 2025-03-25 17:17:22

.obsidian/workspace.json

@@ -229,9 +229,9 @@
   },
   "active": "0d64f519fd7f9420",
   "lastOpenFiles": [
-    "Concurrent Systems/slides/class 8.pdf",
-    "Concurrent Systems/notes/8 - Enhancing Liveness Properties.md",
     "Concurrent Systems/notes/7- MUTEX-free concurrency.md",
+    "Concurrent Systems/notes/8 - Enhancing Liveness Properties.md",
+    "Concurrent Systems/slides/class 8.pdf",
     "Concurrent Systems/slides/class 7.pdf",
     "Concurrent Systems/notes/6a - Alternatives to Atomicity.md",
     "Concurrent Systems/notes/3a - Hardware primitives & Lamport Bakery algorithm.md",

Concurrent Systems/notes/8 - Enhancing Liveness Properties.md

@@ -103,5 +103,15 @@ We assume a weak timestamp generator, i.e. a function such that, if it returns a
 TS[1..n] : SWMR atomic R/W registers init at 0
 
 need_help(i) :=
-	TS[i]
+	TS[i] <- weak_ts()
+	repeat
+		competing <- {j : TS[j] != 0 and j ∉ suspected_i}
+		⟨t,j⟩ <- min{⟨TS[x],x⟩ | x ∈ competing}
+	until j = i
+
+stop_help(i) :=
+	TS[i] <- 0
 ```
+
+##### Theorem:
+the contention manager just seen transforms an obstruction-free implementation into a wait-free enriched implementation.