objectlayout / objectlayout

Java classes designed with optimizable object layout in mind

ObjectLayout


ObjectLayout is aimed at creating some useful core Java classes that are designed with optimizable memory layout in mind

See http://objectlayout.github.io/ObjectLayout/ for some detail

objectlayout's Issues

Creating Intrinsic Objects from Legacy or 3rd party classes

Some times you do not have control over the coding of certain objects. Is it possible to give a mechanism which can intensify without having to add special constructs. Perhaps they can be injected through byte-code manipulation.

Perhaps thee ability to intensify object fields to n levels deep, or from certain packages, etc.

Provide APIs for construction with potentially inaccessible constructors

Pull request #4 raises a need to make some constructors (e.g. default constructor in the specific pull request case) useable when constructing objects using IntrinsicObjectModel. Similar needs exist in StructuredArray, and in some case they are supported by making the constructor accessible via reflection.

I am trying to avoid making constructors accessible this way for both default or non-default constructors, and will probably look to avoid doing the same in some of the StructuredArray cases that currently do (taking away the current accessible-forcing behavior). Making e.g. private or protected constructors accessible can lead to surprising and potentially insecure construction behavior.

Obviously, we have a problem here, in that a class that has access to a certain constructor that is not accessible from IntrinsicObjectModel or IntrinsicStraturedArray may want to declare intrinsic fields, structured arrays or inner classes with such fields or arrays using that accessible-only-to-it constructor. This will not be possible with the current API.

My hope is to address such situations in Java 7 and beyond with method handles. Unlike reflective calls to constructors, which have their accessibility checked at invocation time based on the calling class, Method handle based calls to constructors have the accessibility checked at lookup time. A class with access to a certain constructor can therefore provide a method handle to that constructor in a way that can be executed by IntrinsicObjectModel or IntrinsicStraturedArray.

Will update this issue when we make more progress.

Detect the object memory bloat issue

Hello,

We built a profiler and our profiler reports a problematic object (array intAddressableElements) in AbstractStructuredArrayBase.java file. The life cycles of different instances do not overlap, which means using a singleton pattern of this object (i.e., allocating a single object instance and reusing it without creating more instances) is safe and avoids memory bloat. To apply the singleton pattern, we can hoist intAddressableElements allocation out of allocateInternalStorage method, which is thread-safe.

Objects with factory methods and no public constructors

There are many instances where classes only expose factory methods. It would be desirable to be able to use this in such cases also.

elementCtorAndArgsProvider is missing for PrimitiveArrayBuilder

Having elementwise initialization especially for ReferenceArray. Also other methods in both *Model and *Builder are not consistent.

Prevent cyclic dependencies in IntrinsicObjectModel construction

Currently there is no mechanism to prevent cyclic dependencies when constructing the object models for intrinsic objects.