1. Allow to monitor from application top script or function calls: now they go through ContextFactory.doTopCall which can be overridden.

2. Context.observeInstructionCount now calls ContxtFactory.observeInstructionCount so it can overridden without extra Context class.

js/rhino/src/org/mozilla/javascript/Context.java

@@ -640,11 +640,17 @@ public class Context
     }
 
     /**
-     * Return {@link ContextFactory} instance used to create this Context.
+     * Return {@link ContextFactory} instance used to create this Context
+     * or the result of {@link ContextFactory#getGlobal()} if no factory
+     * was used for Context creation.
      */
-    public ContextFactory getFactory()
+    public final ContextFactory getFactory()
     {
-        return factory;
+        ContextFactory result = factory;
+        if (result == null) {
+            result = ContextFactory.getGlobal();
+        }
+        return result;
     }
 
     /**
@@ -2073,6 +2079,7 @@ public class Context
      * that allows to customize Context behavior without introducing
      * Context subclasses.  {@link ContextFactory} documentation gives
      * an example of hasFeature implementation.
+     *
      * @param featureIndex feature index to check
      * @return true if the <code>featureIndex</code> feature is turned on
      * @see #FEATURE_NON_ECMA_GET_YEAR
@@ -2084,10 +2091,7 @@ public class Context
      */
     public boolean hasFeature(int featureIndex)
     {
-        ContextFactory f = factory;
+        ContextFactory f = getFactory();
-        if (f == null) {
-            f = ContextFactory.getGlobal();
-        }
         return f.hasFeature(this, featureIndex);
     }
 
@@ -2121,6 +2125,13 @@ public class Context
      * <p>
      * The instruction counting support is available only for interpreted
      * scripts generated when the optimization level is set to -1.
+     * <p>
+     * The default implementation calls
+     * {@link ContextFactory#observeInstructionCount(Context cx,
+     *                                               int instructionCount)}
+     * that allows to customize Context behavior without introducing
+     * Context subclasses.
+     *
      * @param instructionCount amount of script instruction executed since
      * last call to <code>observeInstructionCount</code>
      * @throws Error to terminate the script
@@ -2128,6 +2139,8 @@ public class Context
      */
     protected void observeInstructionCount(int instructionCount)
     {
+        ContextFactory f = getFactory();
+        f.observeInstructionCount(this, instructionCount);
     }
 
     public GeneratedClassLoader createClassLoader(ClassLoader parent)

js/rhino/src/org/mozilla/javascript/ContextFactory.java

@@ -61,6 +61,13 @@ package org.mozilla.javascript;
  *
  * class MyFactory extends ContextFactory
  * {
+ *
+ *     // Custom {@link Context} to store execution time.
+ *     private static class MyContext extends Context
+ *     {
+ *         long startTime;
+ *     }
+ *
  *     static {
  *         // Initialize GlobalFactory with custom factory
  *         ContextFactory.initGlobal(new MyFactory());
@@ -71,9 +78,9 @@ package org.mozilla.javascript;
  *     {
  *         MyContext cx = new MyContext();
  *         // Use pure interpreter mode to allow for
- *         // {@link Context#observeInstructionCount(int)} to work
+ *         // {@link #observeInstructionCount(Context, int)} to work
  *         cx.setOptimizationLevel(-1);
- *         // Make Rhino runtime to call MyContext.observeInstructionCount(int)
+ *         // Make Rhino runtime to call observeInstructionCount
  *         // each 10000 bytecode instructions
  *         cx.setInstructionObserverThreshold(10000);
  *         return cx;
@@ -82,33 +89,29 @@ package org.mozilla.javascript;
  *     // Override {@link #hasFeature(Context, int)}
  *     public boolean hasFeature(Context cx, int featureIndex)
  *     {
- *         // Turn on maximim compatibility with MSIE scripts
+ *         // Turn on maximum compatibility with MSIE scripts
  *         switch (featureIndex) {
- *             case Context.FEATURE_NON_ECMA_GET_YEAR:
+ *             case {@link Context#FEATURE_NON_ECMA_GET_YEAR}:
  *                 return true;
  *
- *             case Context.FEATURE_MEMBER_EXPR_AS_FUNCTION_NAME:
+ *             case {@link Context#FEATURE_MEMBER_EXPR_AS_FUNCTION_NAME}:
  *                 return true;
  *
- *             case Context.FEATURE_RESERVED_KEYWORD_AS_IDENTIFIER:
+ *             case {@link Context#FEATURE_RESERVED_KEYWORD_AS_IDENTIFIER}:
  *                 return true;
  *
- *             case Context.FEATURE_PARENT_PROTO_PROPRTIES:
+ *             case {@link Context#FEATURE_PARENT_PROTO_PROPRTIES}:
  *                 return false;
  *         }
  *         return super.hasFeature(cx, featureIndex);
  *     }
- * }
  *
- * class MyContext extends Context
+ *     // Override {@link #observeInstructionCount(Context, int)}
- * {
+ *     protected void observeInstructionCount(Context cx, int instructionCount)
- *     private long creationTime = System.currentTimeMillis();
- *
- *     // Override {@link Context#observeInstructionCount(int)}
- *     protected void observeInstructionCount(int instructionCount)
  *     {
+ *         MyContext mcx = (MyContext)cx;
  *         long currentTime = System.currentTimeMillis();
- *         if (currentTime - creationTime > 10000) {
+ *         if (currentTime - mcx.startTime > 10*1000) {
  *             // More then 10 seconds from Context creation time:
  *             // it is time to stop the script.
  *             // Throw Error instance to ensure that script will never
@@ -117,7 +120,19 @@ package org.mozilla.javascript;
  *         }
  *     }
  *
+ *     // Override {@link #doTopCall(Callable, Context, Scriptable scope, Scriptable thisObj, Object[] args)}
+ *     protected Object doTopCall(Callable callable,
+ *                                Context cx, Scriptable scope,
+ *                                Scriptable thisObj, Object[] args)
+ *     {
+ *         MyContext mcx = (MyContext)cx;
+ *         mcx.startTime = System.currentTimeMillis();
+ *
+ *         return super.doTopCall(callable, cx, scope, thisObj, args);
  *     }
+ *
+ * }
+ *
  * </pre>
  */
 
@@ -258,6 +273,30 @@ public class ContextFactory
         throw new IllegalArgumentException(String.valueOf(featureIndex));
     }
 
+    /**
+     * Execute top call to script or function.
+     * When the runtime is about to execute a script or function that will
+     * create the first stack frame with scriptable code, it calls this method
+     * to perform the real call. In this way execution of any script
+     * happens inside this function.
+     */
+    protected Object doTopCall(Callable callable,
+                               Context cx, Scriptable scope,
+                               Scriptable thisObj, Object[] args)
+    {
+        return callable.call(cx, scope, thisObj, args);
+    }
+
+    /**
+     * Implementation of
+     * {@link Context#observeInstructionCount(int instructionCount)}.
+     * This can be used to customize {@link Context} without introducing
+     * additional subclasses.
+     */
+    protected void observeInstructionCount(Context cx, int instructionCount)
+    {
+    }
+
     protected void onContextCreated(Context cx)
     {
         Object listeners = this.listeners;

js/rhino/src/org/mozilla/javascript/ScriptRuntime.java

@@ -2787,6 +2787,33 @@ public class ScriptRuntime {
         return (cx.topCallScope != null);
     }
 
+    public static Object doTopCall(Callable callable,
+                                   Context cx, Scriptable scope,
+                                   Scriptable thisObj, Object[] args)
+    {
+        if (scope == null) throw new IllegalArgumentException();
+        if (cx.topCallScope != null) throw new IllegalStateException();
+
+        Object result;
+        cx.topCallScope = ScriptableObject.getTopLevelScope(scope);
+        cx.useDynamicScope = cx.hasFeature(Context.FEATURE_DYNAMIC_SCOPE);
+        ContextFactory f = cx.getFactory();
+        try {
+            result = f.doTopCall(callable, cx, scope, thisObj, args);
+        } finally {
+            cx.topCallScope = null;
+            // Cleanup cached references
+            cx.cachedXMLLib = null;
+
+            if (cx.currentActivationCall != null) {
+                // Function should always call exitActivationFunction
+                // if it creates activation record
+                throw new IllegalStateException();
+            }
+        }
+        return result;
+    }
+
     private static Scriptable locateDynamicScope(Context cx, Scriptable scope)
     {
         // Return cx.topCallScope is scope is present on its prototype chain
@@ -2807,37 +2834,6 @@ public class ScriptRuntime {
         }
     }
 
-    public static Object doTopCall(Callable callable,
-                                   Context cx, Scriptable scope,
-                                   Scriptable thisObj, Object[] args)
-    {
-        if (cx.topCallScope != null)
-            throw new IllegalStateException();
-
-        Object result;
-        cx.topCallScope = ScriptableObject.getTopLevelScope(scope);
-        cx.useDynamicScope = cx.hasFeature(Context.FEATURE_DYNAMIC_SCOPE);
-        try {
-            result = callable.call(cx, scope, thisObj, args);
-        } finally {
-            releaseTopCall(cx);
-        }
-        return result;
-    }
-
-    private static void releaseTopCall(Context cx)
-    {
-        cx.topCallScope = null;
-        // Cleanup cached references
-        cx.cachedXMLLib = null;
-
-        if (cx.currentActivationCall != null) {
-            // Function should always call exitActivationFunction
-            // if it creates activation record
-            throw new IllegalStateException();
-        }
-    }
-
     public static void initScript(NativeFunction funObj, Scriptable thisObj,
                                   Context cx, Scriptable scope,
                                   boolean evalScript)