Update #0 - First Release

sources/main/java/com/google/common/base/Ticker.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2011 The Guava Authors
+ *
+ * Licensed 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 com.google.common.base;
+
+import com.google.common.annotations.Beta;
+import com.google.common.annotations.GwtCompatible;
+
+/**
+ * A time source; returns a time value representing the number of nanoseconds
+ * elapsed since some fixed but arbitrary point in time. Note that most users
+ * should use {@link Stopwatch} instead of interacting with this class directly.
+ *
+ * <p>
+ * <b>Warning:</b> this interface can only be used to measure elapsed time, not
+ * wall time.
+ *
+ * @author Kevin Bourrillion
+ * @since 10.0
+ *        (<a href="http://code.google.com/p/guava-libraries/wiki/Compatibility"
+ *        >mostly source-compatible</a> since 9.0)
+ */
+@Beta
+@GwtCompatible
+public abstract class Ticker {
+	/**
+	 * Constructor for use by subclasses.
+	 */
+	protected Ticker() {
+	}
+
+	/**
+	 * Returns the number of nanoseconds elapsed since this ticker's fixed point of
+	 * reference.
+	 */
+	public abstract long read();
+
+	/**
+	 * A ticker that reads the current time using {@link System#nanoTime}.
+	 *
+	 * @since 10.0
+	 */
+	public static Ticker systemTicker() {
+		return SYSTEM_TICKER;
+	}
+
+	private static final Ticker SYSTEM_TICKER = new Ticker() {
+		@Override
+		public long read() {
+			return Platform.systemNanoTime();
+		}
+	};
+}