From f5a0517ac704b36e3d94aa3d5547ddf95889ab95 Mon Sep 17 00:00:00 2001
From: Sven Gothel <sgothel@jausoft.com>
Date: Fri, 31 Jan 2014 07:36:16 +0100
Subject: JNLPClassLoader: Introduce pending removal of cached CLs (1 min) to
 enhance performance for single applet reload.

---
 .../sourceforge/jnlp/runtime/JNLPClassLoader.java  | 52 +++++++++++++++++++---
 1 file changed, 47 insertions(+), 5 deletions(-)

diff --git a/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java b/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java
index f889161..b4cd315 100644
--- a/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java
+++ b/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java
@@ -123,11 +123,17 @@ public class JNLPClassLoader extends URLClassLoader {
     private boolean isSignedJNLP = false;
 
     /** map from JNLPFile unique key to shared classloader */
-    private static Map<String, JNLPClassLoader> uniqueKeyToLoader = new ConcurrentHashMap<String, JNLPClassLoader>();
+    private static final Object uniqueKeyMapLock = new Object();
+    /** Cached ClassLoaders in active state */
+    private static final Map<String, JNLPClassLoader> uniqueKeyToLoaderActive = new HashMap<String, JNLPClassLoader>();
+    /** Cached ClassLoaders which removal is pending, i.e. {@link #PENDING_REMOVAL_TO} */
+    private static final Map<String, JNLPClassLoader> uniqueKeyToLoaderPending = new HashMap<String, JNLPClassLoader>();
+    /** Period in milliseconds to wait until removing pending ClassLoaders, i.e. {@value} ms */
+    private static final long PENDING_REMOVAL_TO = 60*1000;
 
     /** map from JNLPFile unique key to lock, the lock is needed to enforce correct
      * initialization of applets that share a unique key*/
-    private static Map<String, ReentrantLock> uniqueKeyToLock = new HashMap<String, ReentrantLock>();
+    private static final Map<String, ReentrantLock> uniqueKeyToLock = new HashMap<String, ReentrantLock>();
 
     /** Provides a search path & temporary storage for native code */
     private final NativeLibraryStorage nativeLibraryStorage;
@@ -435,6 +441,21 @@ public class JNLPClassLoader extends URLClassLoader {
         final JNLPFile f = getJNLPFile();
         return "JNLPClassLoader@"+hashCode()+"[refCnt "+useCount+", file "+f.getFileLocation()+", code "+f.getCodeBase()+"]";
     }
+
+    private static JNLPClassLoader getCached(final String uniqueKey) {
+        synchronized(uniqueKeyMapLock) {
+            JNLPClassLoader res = uniqueKeyToLoaderActive.get(uniqueKey);
+            if( null == res ) {
+                res = uniqueKeyToLoaderPending.remove(uniqueKey);
+                if( null != res ) {
+                    uniqueKeyToLoaderActive.put(uniqueKey, res);
+                    OutputController.getLogger().log("JNLPClassLoader.Cache.reactivated: key "+uniqueKey +" -> "+res);
+                }
+            }
+            return res;
+        }
+    }
+
     /**
      * Returns a JNLP classloader for the specified JNLP file.
      *
@@ -449,7 +470,7 @@ public class JNLPClassLoader extends URLClassLoader {
         final OutputController out = OutputController.getLogger();
 
         synchronized ( getUniqueKeyLock(uniqueKey) ) {
-            baseLoader = uniqueKeyToLoader.get(uniqueKey);
+            baseLoader = getCached(uniqueKey);
             out.log("JNLPClassLoader.Cache: file isApp "+file.isApplication()+", file "+file.getFileLocation()+", code "+file.getCodeBase());
             out.log("JNLPClassLoader.Cache: key "+uniqueKey +" -> "+baseLoader);
             final int mode;
@@ -513,7 +534,7 @@ public class JNLPClassLoader extends URLClassLoader {
         JNLPClassLoader loader;
 
         synchronized ( getUniqueKeyLock(uniqueKey) ) {
-            loader = uniqueKeyToLoader.get(uniqueKey);
+            loader = getCached(uniqueKey);
 
             if (loader == null || !location.equals(loader.getJNLPFile().getFileLocation())) {
                 JNLPFile jnlpFile = new JNLPFile(location, uniqueKey, version, settings, policy);
@@ -2230,7 +2251,28 @@ public class JNLPClassLoader extends URLClassLoader {
             useCount--;
 
             if (useCount <= 0) {
-                uniqueKeyToLoader.remove(uniqueKey);
+                synchronized(uniqueKeyMapLock) {
+                    final JNLPClassLoader pending = uniqueKeyToLoaderActive.remove(uniqueKey);
+                    uniqueKeyToLoaderPending.put(uniqueKey, pending);
+                    OutputController.getLogger().log("JNLPClassLoader.Cache.removed: Pending "+pending);
+                    final Thread removePendingThread = new Thread("Pending removal of "+pending.toString()) {
+                        @Override
+                        public void run() {
+                            try {
+                                Thread.sleep(PENDING_REMOVAL_TO);
+                            } catch (InterruptedException e) { }
+                            final JNLPClassLoader removed = uniqueKeyToLoaderPending.remove(uniqueKey);
+                            if( null != removed ) {
+                                OutputController.getLogger().log("JNLPClassLoader.Cache.removed: Terminated "+removed);
+                            }
+                        } };
+                    removePendingThread.setDaemon(true);
+                    removePendingThread.start();
+                    /** FIXME: When to remove the uniqueKeyToLock ?
+                    synchronized (uniqueKeyToLock) {
+                        uniqueKeyToLock.remove(uniqueKey);
+                    } */
+                }
             }
         }
     }
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