maspack.render.GL

Class GLDeferredDeleteQueue

java.lang.Object

maspack.render.GL.GLDeferredDeleteQueue

public class GLDeferredDeleteQueue
extends java.lang.Object

Thread-safe queue of GLResources that a background sweep has found to be unreferenced and that are awaiting deletion.

The point of this class is to move the actual GL delete calls (glDeleteBuffers, glDeleteTextures, ...) off the background garbage collector thread and onto a render thread that owns a live GL context. A sweep running on the collector thread only needs to do cheap, context-free reference-count bookkeeping and enqueue(maspack.render.GL.GLResource) the dead resources here; each viewer then calls drain(com.jogamp.opengl.GL) during its own frame to perform the GL deletes on its own context. This avoids issuing GL operations against a context shared with the renderer, which on Windows forces driver-level synchronization and produces rendering stalls.

A LinkedHashSet backs the queue so that repeated enqueues of the same resource (which happen when several sweeps run before a drain) collapse to a single entry while preserving insertion order.

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	enabled Global switch for deferred deletion of GL resources.

Constructor Summary

Constructors

Constructor and Description
GLDeferredDeleteQueue()

Method Summary

Modifier and Type	Method and Description
void	clear() Discards all pending entries without disposing them.
int	drain(com.jogamp.opengl.GL gl) Disposes all pending resources that are still unreferenced, using the supplied context.
void	enqueue(GLResource resource) Marks a resource for deferred deletion.
int	size() Number of resources currently awaiting deletion.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

enabled

public static boolean enabled

Global switch for deferred deletion of GL resources. When true (the default), background garbage sweeps only enqueue unreferenced resources and the actual GL deletes happen on a render thread (see class comment). When false, the original behaviour is restored and sweeps delete resources inline on whatever thread runs them.

Consulted dynamically at each sweep/drain, so it may be toggled at runtime. May also be set at startup via the system property maspack.render.deferredDelete=false.

Constructor Detail

GLDeferredDeleteQueue

public GLDeferredDeleteQueue()

Method Detail

enqueue

public void enqueue(GLResource resource)

Marks a resource for deferred deletion. Does no GL work, so this is safe to call from the garbage collector thread. Resources that are already disposed are ignored.

size

public int size()

Number of resources currently awaiting deletion.

drain

public int drain(com.jogamp.opengl.GL gl)

Disposes all pending resources that are still unreferenced, using the supplied context. Must be called on a thread that has gl current (i.e. from within a viewer's render callback).

Each resource's reference count is re-checked immediately before disposal: a resource that has been re-acquired since it was enqueued is simply dropped from the queue (its owning list is still tracking it), so a resurrected resource is never deleted out from under a live user. The GL deletes themselves are performed outside the lock so that the collector thread can keep enqueueing while a drain is in progress.

Returns:

the number of resources actually disposed

clear

public void clear()

Discards all pending entries without disposing them. Intended for teardown paths where a blanket dispose has already run.