337 lines
10 KiB
Text
337 lines
10 KiB
Text
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/**
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* PANDA 3D SOFTWARE
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* Copyright (c) Carnegie Mellon University. All rights reserved.
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*
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* All use of this software is subject to the terms of the revised BSD
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* license. You should have received a copy of this license along
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* with this source code in a file named "LICENSE."
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*
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* @file pipelineCyclerTrivialImpl.I
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* @author drose
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* @date 2006-01-31
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*/
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/**
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*
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*/
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INLINE PipelineCyclerTrivialImpl::
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PipelineCyclerTrivialImpl(CycleData *initial_data, Pipeline *) {
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// In the trivial implementation, a derived class (the PipelineCycler
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// template class) stores the CycleData object directly within itself, and
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// since we have no data members or virtual functions, we get away with
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// assuming the pointer is the same as the 'this' pointer.
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// If this turns out not to be true on a particular platform, we will have
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// to store the pointer in this class, for a little bit of extra overhead.
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#ifdef SIMPLE_STRUCT_POINTERS
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nassertv(initial_data == (CycleData *)this);
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#else
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_data = initial_data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Grabs an overall lock on the cycler. Release it with a call to release().
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* This lock should be held while walking the list of stages.
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*/
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INLINE void PipelineCyclerTrivialImpl::
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acquire(Thread *) {
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}
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/**
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* Release the overall lock on the cycler that was grabbed via acquire().
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*/
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INLINE void PipelineCyclerTrivialImpl::
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release() {
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}
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/**
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* Returns a const CycleData pointer, filled with the data for the current
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* stage of the pipeline as seen by this thread. No lock is made on the
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* contents; there is no guarantee that some other thread won't modify this
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* object's data while you are working on it. (However, the data within the
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* returned CycleData object itself is safe from modification; if another
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* thread modifies the data, it will perform a copy-on-write, and thereby
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* change the pointer stored within the object.)
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*/
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INLINE const CycleData *PipelineCyclerTrivialImpl::
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read_unlocked(Thread *) const {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (const CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Returns a const CycleData pointer, filled with the data for the current
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* stage of the pipeline as seen by this thread. This pointer should
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* eventually be released by calling release_read().
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*/
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INLINE const CycleData *PipelineCyclerTrivialImpl::
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read(Thread *) const {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (const CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Increments the count on a pointer previously retrieved by read(); now the
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* pointer will need to be released twice.
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*/
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INLINE void PipelineCyclerTrivialImpl::
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increment_read(const CycleData *) const {
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}
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/**
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* Releases a pointer previously obtained via a call to read().
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*/
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INLINE void PipelineCyclerTrivialImpl::
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release_read(const CycleData *) const {
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}
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/**
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* Returns a non-const CycleData pointer, filled with a unique copy of the
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* data for the current stage of the pipeline as seen by this thread. This
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* pointer may now be used to write to the data, and that copy of the data
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* will be propagated to all later stages of the pipeline. This pointer
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* should eventually be released by calling release_write().
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*
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* There may only be one outstanding write pointer on a given stage at a time,
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* and if there is a write pointer there may be no read pointers on the same
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* stage (but see elevate_read).
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*/
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INLINE CycleData *PipelineCyclerTrivialImpl::
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write(Thread *) {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* This special variant on write() will automatically propagate changes back
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* to upstream pipeline stages. If force_to_0 is false, then it propagates
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* back only as long as the CycleData pointers are equivalent, guaranteeing
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* that it does not modify upstream data (other than the modification that
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* will be performed by the code that returns this pointer). This is
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* particularly appropriate for minor updates, where it doesn't matter much if
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* the update is lost, such as storing a cached value.
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*
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* If force_to_0 is trivial, then the CycleData pointer for the current
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* pipeline stage is propagated all the way back up to stage 0; after this
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* call, there will be only one CycleData pointer that is duplicated in all
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* stages between stage 0 and the current stage. This may undo some recent
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* changes that were made independently at pipeline stage 0 (or any other
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* upstream stage). However, it guarantees that the change that is to be
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* applied at this pipeline stage will stick. This is slightly dangerous
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* because of the risk of losing upstream changes; generally, this should only
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* be done when you are confident that there are no upstream changes to be
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* lost (for instance, for an object that has been recently created).
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*/
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CycleData *PipelineCyclerTrivialImpl::
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write_upstream(bool, Thread *) {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Elevates a currently-held read pointer into a write pointer. This may or
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* may not change the value of the pointer. It is only valid to do this if
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* this is the only currently-outstanding read pointer on the current stage.
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*/
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INLINE CycleData *PipelineCyclerTrivialImpl::
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elevate_read(const CycleData *, Thread *) {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Elevates a currently-held read pointer into a write pointer, like
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* elevate_read(), but also propagates the pointer back to upstream stages,
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* like write_upstream().
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*/
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INLINE CycleData *PipelineCyclerTrivialImpl::
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elevate_read_upstream(const CycleData *, bool, Thread *) {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Increments the count on a pointer previously retrieved by write(); now the
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* pointer will need to be released twice.
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*/
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INLINE void PipelineCyclerTrivialImpl::
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increment_write(CycleData *) const {
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}
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/**
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* Releases a pointer previously obtained via a call to write().
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*/
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INLINE void PipelineCyclerTrivialImpl::
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release_write(CycleData *) {
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}
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/**
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* Returns the number of stages in the pipeline.
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*/
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INLINE int PipelineCyclerTrivialImpl::
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get_num_stages() {
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return 1;
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}
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/**
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* Returns a const CycleData pointer, filled with the data for the indicated
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* stage of the pipeline. As in read_unlocked(), no lock is held on the
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* returned pointer.
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*/
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INLINE const CycleData *PipelineCyclerTrivialImpl::
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read_stage_unlocked(int) const {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (const CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Returns a const CycleData pointer, filled with the data for the indicated
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* pipeline stage. This pointer should eventually be released by calling
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* release_read().
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*/
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INLINE const CycleData *PipelineCyclerTrivialImpl::
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read_stage(int, Thread *) const {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (const CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Releases a pointer previously obtained via a call to read_stage().
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*/
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INLINE void PipelineCyclerTrivialImpl::
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release_read_stage(int, const CycleData *) const {
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}
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/**
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* Returns a pointer suitable for writing to the nth stage of the pipeline.
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* This is for special applications that need to update the entire pipeline at
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* once (for instance, to remove an invalid pointer). This pointer should
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* later be released with release_write_stage().
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*/
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INLINE CycleData *PipelineCyclerTrivialImpl::
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write_stage(int, Thread *) {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Returns a pointer suitable for writing to the nth stage of the pipeline.
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* This is for special applications that need to update the entire pipeline at
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* once (for instance, to remove an invalid pointer). This pointer should
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* later be released with release_write_stage().
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*/
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INLINE CycleData *PipelineCyclerTrivialImpl::
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write_stage_upstream(int, bool, Thread *) {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Elevates a currently-held read pointer into a write pointer. This may or
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* may not change the value of the pointer. It is only valid to do this if
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* this is the only currently-outstanding read pointer on the current stage.
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*/
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INLINE CycleData *PipelineCyclerTrivialImpl::
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elevate_read_stage(int, const CycleData *, Thread *) {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Elevates a currently-held read pointer into a write pointer. This may or
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* may not change the value of the pointer. It is only valid to do this if
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* this is the only currently-outstanding read pointer on the current stage.
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*/
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INLINE CycleData *PipelineCyclerTrivialImpl::
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elevate_read_stage_upstream(int, const CycleData *, bool, Thread *) {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Releases a pointer previously obtained via a call to write_stage().
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*/
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INLINE void PipelineCyclerTrivialImpl::
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release_write_stage(int, CycleData *) {
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}
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/**
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* Returns the type of object that owns this cycler, as reported by
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* CycleData::get_parent_type().
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*/
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INLINE TypeHandle PipelineCyclerTrivialImpl::
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get_parent_type() const {
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return cheat()->get_parent_type();
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}
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/**
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* Returns a pointer without counting it. This is only intended for use as
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* the return value for certain nassertr() functions, so the application can
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* recover after a failure to manage the read and write pointers correctly.
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* You should never call this function directly.
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*/
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INLINE CycleData *PipelineCyclerTrivialImpl::
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cheat() const {
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#ifdef SIMPLE_STRUCT_POINTERS
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return (CycleData *)this;
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#else
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return _data;
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#endif // SIMPLE_STRUCT_POINTERS
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}
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/**
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* Returns the number of handles currently outstanding to read the current
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* stage of the data. This should only be used for debugging purposes.
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*/
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INLINE int PipelineCyclerTrivialImpl::
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get_read_count() const {
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return 0;
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}
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/**
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* Returns the number of handles currently outstanding to read the current
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* stage of the data. This will normally only be either 0 or 1. This should
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* only be used for debugging purposes.
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*/
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INLINE int PipelineCyclerTrivialImpl::
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get_write_count() const {
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return 0;
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}
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