org.mozilla.javascript
Class ClassCache

java.lang.Object
  extended byorg.mozilla.javascript.ClassCache

public class ClassCache
extends java.lang.Object

Cache of generated classes and data structures to access Java runtime from JavaScript.

Since:
Rhino 1.5 Release 5
Author:
Igor Bukanov

Constructor Summary
ClassCache()
           
 
Method Summary
 boolean associate(ScriptableObject topScope)
          Associate ClassCache object with the given top-level scope.
 void clearCaches()
          Empty caches of generated Java classes and Java reflection information.
static ClassCache get(Scriptable scope)
          Search for ClassCache object in the given scope.
 boolean isCachingEnabled()
          Check if generated Java classes and Java reflection information is cached.
 boolean isInvokerOptimizationEnabled()
           
 int newClassSerialNumber()
          Internal engine method to return serial number for generated classes to ensure name uniqueness.
 void setCachingEnabled(boolean enabled)
          Set whether to cache some values.
 void setInvokerOptimizationEnabled(boolean enabled)
          Control if invocation of Java methods in subclasses of ScriptableObject through reflection should be replaced by direct calls to invoker code generated at runtime.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ClassCache

public ClassCache()
Method Detail

get

public static ClassCache get(Scriptable scope)
Search for ClassCache object in the given scope. The method first calls ScriptableObject.getTopLevelScope(Scriptable scope) to get the top most scope and then tries to locate associated ClassCache object in the prototype chain of the top scope.

Parameters:
scope - scope to search for ClassCache object.
Returns:
previously associated ClassCache object or a new instance of ClassCache if no ClassCache object was found.
See Also:
associate(ScriptableObject topScope)

associate

public boolean associate(ScriptableObject topScope)
Associate ClassCache object with the given top-level scope. The ClassCache object can only be associated with the given scope once.

Parameters:
topScope - scope to associate this ClassCache object with.
Returns:
true if no prevous ClassCache objects were embedded into the scope and this ClassCache were successfully associated or false otherwise.
See Also:
get(Scriptable scope)

clearCaches

public void clearCaches()
Empty caches of generated Java classes and Java reflection information.


isCachingEnabled

public final boolean isCachingEnabled()
Check if generated Java classes and Java reflection information is cached.


setCachingEnabled

public void setCachingEnabled(boolean enabled)
Set whether to cache some values.

By default, the engine will cache the results of Class.getMethods() and similar calls. This can speed execution dramatically, but increases the memory footprint. Also, with caching enabled, references may be held to objects past the lifetime of any real usage.

If caching is enabled and this method is called with a false argument, the caches will be emptied.

Caching is enabled by default.

Parameters:
enabled - if true, caching is enabled
See Also:
clearCaches()

isInvokerOptimizationEnabled

public boolean isInvokerOptimizationEnabled()
See Also:
setInvokerOptimizationEnabled(boolean enabled)

setInvokerOptimizationEnabled

public void setInvokerOptimizationEnabled(boolean enabled)
Control if invocation of Java methods in subclasses of ScriptableObject through reflection should be replaced by direct calls to invoker code generated at runtime. On many JVMs cost of calling Java method through reflection can be reduced significantly if a special invoker classes are generated at runtime to call the Java methods directly. For example, under JDK 1.3.1 on Linux the reflection calls can be speedup by 10-15 times. On JDK 1.4.2 the the speedup can reach the factor of 1.5-2.

The drawback of the optimization is increased memory consumption and longer runtime initialization since class generating and loading is slow. In addition the current implementation assumes that the classes under optimization are reachable through Context.getApplicationClassLoader() which may not be feasible to implement.

By default the optimization is disabled.

Parameters:
enabled - if true enable invoker optimization or if false disable it and clear all cached generated classes.
See Also:
isInvokerOptimizationEnabled()

newClassSerialNumber

public final int newClassSerialNumber()
Internal engine method to return serial number for generated classes to ensure name uniqueness.