Issue #1628 clean up Inflaters used by HttpClient.

Former-commit-id: ef2dd2a031 [formerly ef2dd2a031 [formerly 765b3b00362cbe9a5d6c3e392e005b42d968d268]]
Former-commit-id: e2efad85fe
Former-commit-id: 2debab14f5

edexOsgi/com.raytheon.uf.common.comm/src/com/raytheon/uf/common/comm/HttpClient.java

@@ -37,7 +37,6 @@ import org.apache.http.HttpRequest;
 import org.apache.http.HttpRequestInterceptor;
 import org.apache.http.HttpResponse;
 import org.apache.http.HttpResponseInterceptor;
-import org.apache.http.client.entity.GzipDecompressingEntity;
 import org.apache.http.client.methods.HttpPost;
 import org.apache.http.client.methods.HttpUriRequest;
 import org.apache.http.conn.ConnectionPoolTimeoutException;
@@ -77,6 +76,8 @@ import com.raytheon.uf.common.util.ByteArrayOutputStreamPool.ByteArrayOutputStre
  *    08/09/12     15307        snaples   Added putEntitiy in postStreamingEntity.
  *    01/07/13     DR 15294     D. Friedman  Added streaming requests.
  *    Jan 24, 2013     1526     njensen     Added postDynamicSerialize()
+ *    Feb 20, 2013  1628        bsteffen    clean up Inflaters used by
+ *                                          HttpClient.
  * 
  * </pre>
  * 
@@ -386,6 +387,11 @@ public class HttpClient {
                     statusHandler.handle(Priority.EVENTB,
                             "Error reading InputStream, assuming closed", e);
                 }
+                try {
+                    SafeGzipDecompressingEntity.close();
+                } catch (IOException e) {
+                    // ignore
+                }
             }
         }
     }
@@ -747,7 +753,7 @@ public class HttpClient {
                 HeaderElement[] codecs = ceheader.getElements();
                 for (HeaderElement codec : codecs) {
                     if (codec.getName().equalsIgnoreCase("gzip")) {
-                        response.setEntity(new GzipDecompressingEntity(response
+                        response.setEntity(new SafeGzipDecompressingEntity(response
                                 .getEntity()));
                         return;
                     }

edexOsgi/com.raytheon.uf.common.comm/src/com/raytheon/uf/common/comm/SafeGzipDecompressingEntity.java

@@ -0,0 +1,126 @@
+/**
+ * This software was developed and / or modified by Raytheon Company,
+ * pursuant to Contract DG133W-05-CQ-1067 with the US Government.
+ * 
+ * U.S. EXPORT CONTROLLED TECHNICAL DATA
+ * This software product contains export-restricted data whose
+ * export/transfer/disclosure is restricted by U.S. law. Dissemination
+ * to non-U.S. persons whether in the United States or abroad requires
+ * an export license or other authorization.
+ * 
+ * Contractor Name:        Raytheon Company
+ * Contractor Address:     6825 Pine Street, Suite 340
+ *                         Mail Stop B8
+ *                         Omaha, NE 68106
+ *                         402.291.0100
+ * 
+ * See the AWIPS II Master Rights File ("Master Rights File.pdf") for
+ * further licensing information.
+ **/
+package com.raytheon.uf.common.comm;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.lang.ref.WeakReference;
+import java.util.zip.GZIPInputStream;
+
+import org.apache.http.HttpEntity;
+import org.apache.http.client.entity.GzipDecompressingEntity;
+
+/**
+ * <pre>
+ * 
+ * This class obsessively closes GZIPInputStreams to end Inflaters
+ * and keep native memory free.
+ * 
+ * Assumptions:
+ * This class can only be used if the content in this entity is going to be
+ * created and consumed on the same thread. If a new entity is created on the
+ * same thread, the content of the previous entity will be closed so don't use
+ * if a single thread is managing multiple responses at the same time.
+ * 
+ * The Back Story:
+ * java.util.zip.Inflater is known to hold native memory until it is garbage
+ * collected or until end() is
+ * called(http://bugs.sun.com/view_bug.do?bug_id=4797189). The default
+ * GzipDecompressingEntity uses GZIPInputStream which uses Inflater for
+ * decompression. Ideally when the stream is done, it would get closed, which
+ * would trigger the Inflater to end and free the native resources. What really
+ * happens is that this entity gets wrapped in a BasicManagedEntity which wraps
+ * the GZIPInputStream in a EofSensorInputStream and at the end of the day the
+ * Inflater is left unended. The Inflater will still get cleaned when garbage
+ * collection runs and the finalizer gets invoked, but this adds some ambiguity
+ * to the availability of native memory. This calss exists to remove that 
+ * ambiguity. There are a few things which can compound the problem and make
+ * things worse:
+ *  1. When the java heap is excessively large then the garbage collector may 
+ *     run less frequently since it has lots of space but it also means there
+ *     is less native memory available.
+ *  2. When the process is running lots of native code outside the JVM then the
+ *     garbage collector will not run as often but the demand for native memory 
+ *     will be greater.
+ * 
+ * 
+ * There are three ways that this class keeps the number of open
+ * GZIPInputStreams down.
+ *  1. Provides a static close method that can be used by HttpClient to force
+ *     close GZIPInputStream.
+ *  2. Uses a ThreadLocal to limit the number of GZIPInputStreams to one per
+ *     thread. This is also the mechanism used to staticly track which
+ *     GZIPInputStream need to be closed.
+ *  3. Only holds weak references to the GZIPInputStreams so that if the
+ *     garbage collector beats us to it then the Inflaters can get freed early.
+ * 
+ * </pre>
+ * 
+ * <pre>
+ * 
+ * SOFTWARE HISTORY
+ * 
+ * Date         Ticket#    Engineer    Description
+ * ------------ ---------- ----------- --------------------------
+ * Feb 20, 2013            bsteffen     Initial creation
+ * 
+ * </pre>
+ * 
+ * @author bsteffen
+ * @version 1.0
+ */
+class SafeGzipDecompressingEntity extends GzipDecompressingEntity{
+
+    private static ThreadLocal<WeakReference<GZIPInputStream>> stream = new ThreadLocal<WeakReference<GZIPInputStream>>();
+    
+    public SafeGzipDecompressingEntity(HttpEntity entity) {
+        super(entity);
+    }
+
+    @Override
+    public InputStream getContent() throws IOException {
+        close();
+        InputStream istream = super.getContent();
+        if (istream instanceof GZIPInputStream) {
+            // save off a reference to the stream so it can be clsoed later.
+            stream.set(new WeakReference<GZIPInputStream>(
+                    (GZIPInputStream) istream));
+        }
+        return istream;
+    }
+    
+    /**
+     * Closes whatever GZIPInputStream's are open on this Thread, freeing any
+     * native resources used by the Inflater.
+     * 
+     * @throws IOException
+     */
+    public static void close() throws IOException {
+        WeakReference<GZIPInputStream> ref = stream.get();
+        if(ref != null){
+            stream.remove();
+            GZIPInputStream stream = ref.get();
+            if(stream != null){
+                stream.close();
+            }
+        }
+    }
+    
+}