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/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrProgramElement_DEFINED
#define GrProgramElement_DEFINED
#include "../private/SkTArray.h"
#include "SkRefCnt.h"
class GrGpuResourceRef;
/**
* Note: We are converting GrProcessor from ref counting to a single owner model using move
* semantics. This class will be removed.
*
* This is used to track "refs" for two separate types GrProcessor ownership. A regular ref is owned
* by any client that may continue to issue draws that use the GrProgramElement. A recorded op or
* GrPipeline uses "pending executions" instead of refs. A pending execution is cleared after the
* draw is executed (or aborted).
*
* While a GrProgramElement is ref'ed any resources it owns are also ref'ed. However, once it gets
* into the state where it has pending executions AND no refs then it converts its ownership of
* its GrGpuResources from refs to pending IOs. The pending IOs allow the cache to track when it is
* safe to recycle a resource even though we still have buffered GrOps that read or write to the
* the resource.
*
* To make this work the subclass GrProcessor implements addPendingIOs, removeRefs, and
* pendingIOComplete. addPendingIOs adds pending reads/writes to GrGpuResources owned by the
* processor as appropriate when the processor is recorded in a GrOpList. removeRefs is called when
* the ref count reaches 0 and the GrProcessor is only owned by "pending executions".
* pendingIOComplete occurs if the resource is still owned by a ref but all recorded draws have been
* completed. Whenever pending executions and refs reach zero the processor is deleted.
*
* The GrProcessor may also implement notifyRefCntIsZero in order to change its ownership of child
* processors from ref to pending execution when the processor is first owned exclusively in pending
* execution mode.
*/
class GrProgramElement : public SkNoncopyable {
public:
virtual ~GrProgramElement() {
// fRefCnt can be one when an effect is created statically using GR_CREATE_STATIC_EFFECT
SkASSERT((0 == fRefCnt || 1 == fRefCnt) && 0 == fPendingExecutions);
// Set to invalid values.
SkDEBUGCODE(fRefCnt = fPendingExecutions = -10;)
}
void ref() const {
this->validate();
// Once the ref cnt reaches zero it should never be ref'ed again.
SkASSERT(fRefCnt > 0);
++fRefCnt;
this->validate();
}
void unref() const {
this->validate();
--fRefCnt;
if (0 == fRefCnt) {
this->notifyRefCntIsZero();
if (0 == fPendingExecutions) {
delete this;
return;
} else {
this->removeRefs();
}
}
this->validate();
}
void validate() const {
#ifdef SK_DEBUG
SkASSERT(fRefCnt >= 0);
SkASSERT(fPendingExecutions >= 0);
SkASSERT(fRefCnt + fPendingExecutions > 0);
#endif
}
protected:
GrProgramElement() : fRefCnt(1), fPendingExecutions(0) {}
void addPendingExecution() const {
this->validate();
if (0 == fPendingExecutions) {
this->addPendingIOs();
}
++fPendingExecutions;
this->validate();
}
void completedExecution() const {
this->validate();
--fPendingExecutions;
if (0 == fPendingExecutions) {
if (0 == fRefCnt) {
delete this;
return;
} else {
this->pendingIOComplete();
}
}
this->validate();
}
private:
virtual void addPendingIOs() const = 0;
virtual void removeRefs() const = 0;
virtual void pendingIOComplete() const = 0;
/** This will be called when the ref cnt is zero. The object may or may not have pending
executions. */
virtual void notifyRefCntIsZero() const = 0;
mutable int32_t fRefCnt;
// Count of deferred executions not yet issued to the 3D API.
mutable int32_t fPendingExecutions;
// Only these classes can access addPendingExecution() and completedExecution().
template <typename T> friend class GrPendingProgramElement;
friend class GrProcessorSet;
typedef SkNoncopyable INHERITED;
};
#endif