vault backup: 2025-04-03 00:10:03

Concurrent Systems/test/Untitled.md

@@ -33,4 +33,39 @@ end_write() :=
 	PRR_MUTEX.up()
 	GLOB_MUTEX.up()
 	return
+```
+
+```
+monitor RW_READERS :=
+	AR, WR, AW, WW init at 0
+	condition CR, CW, CR_PR
+
+operation begin_read() :=
+	WR++
+	if WW != 0 then
+		CR_PR.wait()
+	if AW != 0 then
+		CR.wait()
+		CR.signal()
+	AR++
+	WR--
+
+operation end_read() :=
+	AR--
+	if AR = 0 then
+		CW.signal()
+
+operation begin_write() :=
+	WW++
+	if (AR + AW != 0) then
+		CW.wait()
+	AW++
+	WW--
+
+operation end_write() :=
+	AW--
+	if WR > 0 then
+		CR.signal()
+	else
+		CW.signal()
 ```