StampedLock examples

winterbe · winterbe · commit fe20d0c0a5b3 · 2015-04-20T17:43:49.000+02:00
diff --git a/src/com/winterbe/java8/samples/concurrent/Lock4.java b/src/com/winterbe/java8/samples/concurrent/Lock4.java
@@ -0,0 +1,59 @@
+package com.winterbe.java8.samples.concurrent;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.StampedLock;
+
+/**
+ * @author Benjamin Winterberg
+ */
+public class Lock4 {
+
+    private static int count = 0;
+
+    public static void main(String[] args) {
+        ExecutorService executor = Executors.newFixedThreadPool(2);
+
+        StampedLock lock = new StampedLock();
+
+        executor.submit(() -> {
+            long stamp = lock.writeLock();
+            try {
+                count++;
+                TimeUnit.SECONDS.sleep(1);
+            } catch (InterruptedException e) {
+                throw new IllegalStateException(e);
+            } finally {
+                lock.unlockWrite(stamp);
+            }
+        });
+
+        executor.submit(() -> {
+            long stamp = lock.readLock();
+            try {
+                System.out.println(Thread.currentThread().getName() + ": " + count);
+                TimeUnit.SECONDS.sleep(1);
+            } catch (InterruptedException e) {
+                throw new IllegalStateException(e);
+            } finally {
+                lock.unlockRead(stamp);
+            }
+        });
+
+        executor.submit(() -> {
+            long stamp = lock.readLock();
+            try {
+                System.out.println(Thread.currentThread().getName() + ": " + count);
+                TimeUnit.SECONDS.sleep(1);
+            } catch (InterruptedException e) {
+                throw new IllegalStateException(e);
+            } finally {
+                lock.unlockRead(stamp);
+            }
+        });
+
+        ConcurrentUtils.stop(executor);
+    }
+
+}
diff --git a/src/com/winterbe/java8/samples/concurrent/Lock5.java b/src/com/winterbe/java8/samples/concurrent/Lock5.java
@@ -0,0 +1,56 @@
+package com.winterbe.java8.samples.concurrent;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.StampedLock;
+
+/**
+ * @author Benjamin Winterberg
+ */
+public class Lock5 {
+
+    private static int count = 0;
+
+    public static void main(String[] args) {
+        ExecutorService executor = Executors.newFixedThreadPool(2);
+
+        StampedLock lock = new StampedLock();
+
+        executor.submit(() -> {
+            long stamp = lock.tryOptimisticRead();
+            try {
+                System.out.println("Optimistic Lock Valid: " + lock.validate(stamp));
+                TimeUnit.SECONDS.sleep(1);
+                System.out.println("Optimistic Lock Valid: " + lock.validate(stamp));
+            } catch (InterruptedException e) {
+                throw new IllegalStateException(e);
+            } finally {
+                lock.unlock(stamp);
+            }
+        });
+
+        executor.submit(() -> {
+            long stamp = lock.writeLock();
+            try {
+                System.out.println("Write Lock acquired");
+                incrementAndSleep(2);
+            } finally {
+                lock.unlock(stamp);
+                System.out.println("Write done");
+            }
+        });
+
+
+        ConcurrentUtils.stop(executor);
+    }
+
+    private static void incrementAndSleep(int sleepSeconds) {
+        try {
+            count++;
+            TimeUnit.SECONDS.sleep(sleepSeconds);
+        } catch (InterruptedException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+}
diff --git a/src/com/winterbe/java8/samples/concurrent/Lock6.java b/src/com/winterbe/java8/samples/concurrent/Lock6.java
@@ -0,0 +1,39 @@
+package com.winterbe.java8.samples.concurrent;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.locks.StampedLock;
+
+/**
+ * @author Benjamin Winterberg
+ */
+public class Lock6 {
+
+    private static int count = 0;
+
+    public static void main(String[] args) {
+        ExecutorService executor = Executors.newFixedThreadPool(2);
+
+        StampedLock lock = new StampedLock();
+
+        executor.submit(() -> {
+            long stamp = lock.readLock();
+            try {
+                if (count == 0) {
+                    stamp = lock.tryConvertToWriteLock(stamp);
+                    if (stamp == 0L) {
+                        System.out.println("Could not convert to write lock");
+                        stamp = lock.writeLock();
+                    }
+                    count = 23;
+                }
+                System.out.println(count);
+            } finally {
+                lock.unlock(stamp);
+            }
+        });
+
+        ConcurrentUtils.stop(executor);
+    }
+
+}
