Initial commit

CPS/src/lu/list/itis/dkd/tui/utility/ThrottlingExecutor.java

+/**
+ * Copyright Luxembourg Institute of Science and Technology, 2020. All rights reserved. If you wish
+ * to use this code for any purpose, please contact the author(s).
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
+ * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package lu.list.itis.dkd.tui.utility;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.TimerTask;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * @author nico.mack@list.lu
+ * @since 2.8
+ * @version 1.0.0
+ */
+// ***************************************************************************
+// * Class Definition *
+// ***************************************************************************
+
+public class ThrottlingExecutor {
+
+    private long last;
+    private ScheduledFuture<?> scheduled;
+    private long coalescePeriod;
+
+    private static ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
+
+    // ***************************************************************************
+    // * Constants *
+    // ***************************************************************************
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(ThrottlingExecutor.class.getSimpleName());
+
+    // ---------------------------------------------------------------------------
+    // ***************************************************************************
+    // * Constructor(s)
+    // ***************************************************************************
+    // ---------------------------------------------------------------------------
+
+    public ThrottlingExecutor() {
+        this.coalescePeriod = 0;
+        this.last = 0;
+    }
+
+    // ---------------------------------------------------------------------------
+    // ***************************************************************************
+    // * Class Body
+    // ***************************************************************************
+    // ---------------------------------------------------------------------------
+    /**
+     * Method for setting the minimum time between subsequent calls to this end point.
+     * 
+     * @param millis
+     *        The minimum number of milliseconds between subsequent calls to this end point.
+     */
+    // ---------------------------------------------------------------------------
+
+    public void setCoalescePeriod(int millis) {
+        this.coalescePeriod = millis;
+    }
+
+    // ---------------------------------------------------------------------------
+    /**
+     * Checks whether this end point was previously called without being ready.
+     * 
+     * @return <code>True</code> if end point was called without being ready to be called,
+     *         <code>False</code> otherwise.
+     */
+    // ---------------------------------------------------------------------------
+
+    public boolean isCallPending() {
+        return (scheduled != null);
+    }
+
+    // ---------------------------------------------------------------------------
+
+    public void submit(TimerTask task) {
+        long now = System.currentTimeMillis();
+
+        if ((this.coalescePeriod > 0) && (last > 0)) {
+            long elapsed = now - last;
+
+            if (elapsed < this.coalescePeriod) {
+                if (LOGGER.isDebugEnabled()) {
+                    LOGGER.debug("Task submitted within {} ms coalesce period! Deferred execution in {} ms!", this.coalescePeriod, (this.coalescePeriod - elapsed)); //$NON-NLS-1$
+                }
+
+                if (scheduled != null) {
+                    scheduled.cancel(true);
+                    if (LOGGER.isDebugEnabled()) {
+                        LOGGER.debug("Cancelled previously scheduled task!"); //$NON-NLS-1$
+                    }
+
+                }
+                scheduled = executor.schedule(task, (this.coalescePeriod - elapsed), TimeUnit.MILLISECONDS);
+                return;
+            }
+        }
+        executor.schedule(task, 0, TimeUnit.MILLISECONDS);
+        last = now;
+        scheduled = null;
+    }
+
+    // ---------------------------------------------------------------------------
+    // ***************************************************************************
+    // * End of Class
+    // ***************************************************************************
+    // ---------------------------------------------------------------------------
+}