Adding the Locks class.

1 files changed, 73 insertions, 0 deletions

diff --git a/src/test/java/org/apache/commons/lang3/LocksTest.java b/src/test/java/org/apache/commons/lang3/LocksTest.java
new file mode 100644
index 000000000..e2dd6b0b8
--- /dev/null
+++ b/src/test/java/org/apache/commons/lang3/LocksTest.java
@@ -0,0 +1,73 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.lang3;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.apache.commons.lang3.Functions.FailableConsumer;
+import org.apache.commons.lang3.Locks.Lock;
+import org.junit.jupiter.api.Test;
+
+class LocksTest {
+	@Test
+	void testReadLock() throws Exception {
+		final long DELAY=3000;
+		final boolean[] booleanValues = new boolean[10];
+		final Lock<boolean[]> lock = Locks.lock(booleanValues);
+		final boolean[] runningValues = new boolean[10];
+
+		final long startTime = System.currentTimeMillis();
+		for (int i = 0;  i < booleanValues.length;  i++) {
+			final int index = i;
+			final FailableConsumer<boolean[],?> consumer = (b) -> {
+				b[index] = false;
+				Thread.sleep(DELAY);
+				b[index] = true;
+				modify(runningValues, index, false);
+			};
+			final Thread t = new Thread(() -> lock.runReadLocked(consumer));
+			modify(runningValues, i, true);
+			t.start();
+		}
+		while (someValueIsTrue(runningValues)) {
+			Thread.sleep(100);
+		}
+		final long endTime = System.currentTimeMillis();
+		for (int i = 0;  i < booleanValues.length;  i++) {
+			assertTrue(booleanValues[i]);
+		}
+		// If our threads would be running in exclusive mode, then we'd need
+		// at least DELAY milliseconds for each.
+		assertTrue((endTime-startTime) < booleanValues.length*DELAY);
+	}
+
+	protected void modify(boolean[] booleanArray, int offset, boolean value) {
+		synchronized(booleanArray) {
+			booleanArray[offset] = value;
+		}
+	}
+	protected boolean someValueIsTrue(boolean[] booleanArray) {
+		synchronized(booleanArray) {
+			for (int i = 0;  i < booleanArray.length;  i++) {
+				if (booleanArray[i]) {
+					return true;
+				}
+			}
+			return false;
+		}
+	}
+}