| |
| /* |
| * Copyright 2014 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "GrGLNameAllocator.h" |
| |
| /** |
| * This is the abstract base class for a nonempty AVL tree that tracks allocated |
| * names within the half-open range [fFirst, fEnd). The inner nodes can be |
| * sparse (meaning not every name within the range is necessarily allocated), |
| * but the bounds are tight, so fFirst *is* guaranteed to be allocated, and so |
| * is fEnd - 1. |
| */ |
| class GrGLNameAllocator::SparseNameRange : public SkRefCnt { |
| public: |
| virtual ~SparseNameRange() {} |
| |
| /** |
| * Return the beginning of the range. first() is guaranteed to be allocated. |
| * |
| * @return The first name in the range. |
| */ |
| GrGLuint first() const { return fFirst; } |
| |
| /** |
| * Return the end of the range. end() - 1 is guaranteed to be allocated. |
| * |
| * @return One plus the final name in the range. |
| */ |
| GrGLuint end() const { return fEnd; } |
| |
| /** |
| * Return the height of the tree. This can only be nonzero at an inner node. |
| * |
| * @return 0 if the implementation is a leaf node, |
| * The nonzero height of the tree otherwise. |
| */ |
| GrGLuint height() const { return fHeight; } |
| |
| /** |
| * Allocate a name from strictly inside this range. The call will fail if |
| * there is not a free name within. |
| * |
| * @param outName A pointer that receives the allocated name. outName will |
| * be set to zero if there were no free names within the |
| * range [fFirst, fEnd). |
| * @return The resulting SparseNameRange after the allocation. Note that |
| * this call is destructive, so the original SparseNameRange will no |
| * longer be valid afterward. The caller must always update its |
| * pointer with the new SparseNameRange. |
| */ |
| virtual SparseNameRange* SK_WARN_UNUSED_RESULT internalAllocate(GrGLuint* outName) = 0; |
| |
| /** |
| * Remove the leftmost leaf node from this range (or the entire thing if it |
| * *is* a leaf node). This is an internal helper method that is used after |
| * an allocation if one contiguous range became adjacent to another. (The |
| * range gets removed so the one immediately before can be extended, |
| * collapsing the two into one.) |
| * |
| * @param removedCount A pointer that receives the size of the contiguous |
| range that was removed. |
| * @return The resulting SparseNameRange after the removal (or NULL if it |
| * became empty). Note that this call is destructive, so the |
| * original SparseNameRange will no longer be valid afterward. The |
| * caller must always update its pointer with the new |
| * SparseNameRange. |
| */ |
| virtual SparseNameRange* SK_WARN_UNUSED_RESULT removeLeftmostContiguousRange(GrGLuint* removedCount) = 0; |
| |
| /** |
| * Append adjacent allocated names to the end of this range. This operation |
| * does not affect the structure of the tree. The caller is responsible for |
| * ensuring the new names won't overlap sibling ranges, if any. |
| * |
| * @param count The number of adjacent names to append. |
| * @return The first name appended. |
| */ |
| virtual GrGLuint appendNames(GrGLuint count) = 0; |
| |
| /** |
| * Prepend adjacent allocated names behind the beginning of this range. This |
| * operation does not affect the structure of the tree. The caller is |
| * responsible for ensuring the new names won't overlap sibling ranges, if |
| * any. |
| * |
| * @param count The number of adjacent names to prepend. |
| * @return The final name prepended (the one with the lowest value). |
| */ |
| virtual GrGLuint prependNames(GrGLuint count) = 0; |
| |
| /** |
| * Free a name so it is no longer tracked as allocated. If the name is at |
| * the very beginning or very end of the range, the boundaries [fFirst, fEnd) |
| * will be tightened. |
| * |
| * @param name The name to free. Not-allocated names are silently ignored |
| * the same way they are in the OpenGL spec. |
| * @return The resulting SparseNameRange after the free (or NULL if it |
| * became empty). Note that this call is destructive, so the |
| * original SparseNameRange will no longer be valid afterward. The |
| * caller must always update its pointer with the new |
| * SparseNameRange. |
| */ |
| virtual SparseNameRange* SK_WARN_UNUSED_RESULT free(GrGLuint name) = 0; |
| |
| protected: |
| SparseNameRange* takeRef() { |
| this->ref(); |
| return this; |
| } |
| |
| GrGLuint fFirst; |
| GrGLuint fEnd; |
| GrGLuint fHeight; |
| }; |
| |
| /** |
| * This class is the SparseNameRange implementation for an inner node. It is an |
| * AVL tree with non-null, non-adjacent left and right children. |
| */ |
| class GrGLNameAllocator::SparseNameTree : public SparseNameRange { |
| public: |
| SparseNameTree(SparseNameRange* left, SparseNameRange* right) |
| : fLeft(left), |
| fRight(right) { |
| SkASSERT(fLeft.get()); |
| SkASSERT(fRight.get()); |
| this->updateStats(); |
| } |
| |
| virtual SparseNameRange* SK_WARN_UNUSED_RESULT internalAllocate(GrGLuint* outName) SK_OVERRIDE { |
| // Try allocating the range inside fLeft's internal gaps. |
| fLeft.reset(fLeft->internalAllocate(outName)); |
| if (0 != *outName) { |
| this->updateStats(); |
| return this->rebalance(); |
| } |
| |
| if (fLeft->end() + 1 == fRight->first()) { |
| // It closed the gap between fLeft and fRight; merge. |
| GrGLuint removedCount; |
| fRight.reset(fRight->removeLeftmostContiguousRange(&removedCount)); |
| *outName = fLeft->appendNames(1 + removedCount); |
| if (NULL == fRight.get()) { |
| return fLeft.detach(); |
| } |
| this->updateStats(); |
| return this->rebalance(); |
| } |
| |
| // There is guaranteed to be a gap between fLeft and fRight, and the |
| // "size 1" case has already been covered. |
| SkASSERT(fLeft->end() + 1 < fRight->first()); |
| *outName = fLeft->appendNames(1); |
| return this->takeRef(); |
| } |
| |
| virtual SparseNameRange* SK_WARN_UNUSED_RESULT removeLeftmostContiguousRange(GrGLuint* removedCount) SK_OVERRIDE { |
| fLeft.reset(fLeft->removeLeftmostContiguousRange(removedCount)); |
| if (NULL == fLeft) { |
| return fRight.detach(); |
| } |
| this->updateStats(); |
| return this->rebalance(); |
| } |
| |
| virtual GrGLuint appendNames(GrGLuint count) SK_OVERRIDE { |
| SkASSERT(fEnd + count > fEnd); // Check for integer wrap. |
| GrGLuint name = fRight->appendNames(count); |
| SkASSERT(fRight->end() == fEnd + count); |
| this->updateStats(); |
| return name; |
| } |
| |
| virtual GrGLuint prependNames(GrGLuint count) SK_OVERRIDE { |
| SkASSERT(fFirst > count); // We can't allocate at or below 0. |
| GrGLuint name = fLeft->prependNames(count); |
| SkASSERT(fLeft->first() == fFirst - count); |
| this->updateStats(); |
| return name; |
| } |
| |
| virtual SparseNameRange* SK_WARN_UNUSED_RESULT free(GrGLuint name) SK_OVERRIDE { |
| if (name < fLeft->end()) { |
| fLeft.reset(fLeft->free(name)); |
| if (NULL == fLeft) { |
| // fLeft became empty after the free. |
| return fRight.detach(); |
| } |
| this->updateStats(); |
| return this->rebalance(); |
| } else { |
| fRight.reset(fRight->free(name)); |
| if (NULL == fRight) { |
| // fRight became empty after the free. |
| return fLeft.detach(); |
| } |
| this->updateStats(); |
| return this->rebalance(); |
| } |
| } |
| |
| private: |
| typedef SkAutoTUnref<SparseNameRange> SparseNameTree::* ChildRange; |
| |
| SparseNameRange* SK_WARN_UNUSED_RESULT rebalance() { |
| if (fLeft->height() > fRight->height() + 1) { |
| return this->rebalanceImpl<&SparseNameTree::fLeft, &SparseNameTree::fRight>(); |
| } |
| if (fRight->height() > fLeft->height() + 1) { |
| return this->rebalanceImpl<&SparseNameTree::fRight, &SparseNameTree::fLeft>(); |
| } |
| return this->takeRef(); |
| } |
| |
| /** |
| * Rebalance the tree using rotations, as described in the AVL algorithm: |
| * http://en.wikipedia.org/wiki/AVL_tree#Insertion |
| */ |
| template<ChildRange Tall, ChildRange Short> |
| SparseNameRange* SK_WARN_UNUSED_RESULT rebalanceImpl() { |
| // We should be calling rebalance() enough that the tree never gets more |
| // than one rotation off balance. |
| SkASSERT(2 == (this->*Tall)->height() - (this->*Short)->height()); |
| |
| // Ensure we are in the 'Left Left' or 'Right Right' case: |
| // http://en.wikipedia.org/wiki/AVL_tree#Insertion |
| SparseNameTree* tallChild = static_cast<SparseNameTree*>((this->*Tall).get()); |
| if ((tallChild->*Tall)->height() < (tallChild->*Short)->height()) { |
| (this->*Tall).reset(tallChild->rotate<Short, Tall>()); |
| } |
| |
| // Perform a rotation to balance the tree. |
| return this->rotate<Tall, Short>(); |
| } |
| |
| /** |
| * Perform a node rotation, as described in the AVL algorithm: |
| * http://en.wikipedia.org/wiki/AVL_tree#Insertion |
| */ |
| template<ChildRange Tall, ChildRange Short> |
| SparseNameRange* SK_WARN_UNUSED_RESULT rotate() { |
| SparseNameTree* newRoot = static_cast<SparseNameTree*>((this->*Tall).detach()); |
| |
| (this->*Tall).reset((newRoot->*Short).detach()); |
| this->updateStats(); |
| |
| (newRoot->*Short).reset(this->takeRef()); |
| newRoot->updateStats(); |
| |
| return newRoot; |
| } |
| |
| void updateStats() { |
| SkASSERT(fLeft->end() < fRight->first()); // There must be a gap between left and right. |
| fFirst = fLeft->first(); |
| fEnd = fRight->end(); |
| fHeight = 1 + SkMax32(fLeft->height(), fRight->height()); |
| } |
| |
| SkAutoTUnref<SparseNameRange> fLeft; |
| SkAutoTUnref<SparseNameRange> fRight; |
| }; |
| |
| /** |
| * This class is the SparseNameRange implementation for a leaf node. It just a |
| * contiguous range of allocated names. |
| */ |
| class GrGLNameAllocator::ContiguousNameRange : public SparseNameRange { |
| public: |
| ContiguousNameRange(GrGLuint first, GrGLuint end) { |
| SkASSERT(first < end); |
| fFirst = first; |
| fEnd = end; |
| fHeight = 0; |
| } |
| |
| virtual SparseNameRange* SK_WARN_UNUSED_RESULT internalAllocate(GrGLuint* outName) SK_OVERRIDE { |
| *outName = 0; // No internal gaps, we are contiguous. |
| return this->takeRef(); |
| } |
| |
| virtual SparseNameRange* SK_WARN_UNUSED_RESULT removeLeftmostContiguousRange(GrGLuint* removedCount) SK_OVERRIDE { |
| *removedCount = fEnd - fFirst; |
| return NULL; |
| } |
| |
| virtual GrGLuint appendNames(GrGLuint count) SK_OVERRIDE { |
| SkASSERT(fEnd + count > fEnd); // Check for integer wrap. |
| GrGLuint name = fEnd; |
| fEnd += count; |
| return name; |
| } |
| |
| virtual GrGLuint prependNames(GrGLuint count) SK_OVERRIDE { |
| SkASSERT(fFirst > count); // We can't allocate at or below 0. |
| fFirst -= count; |
| return fFirst; |
| } |
| |
| virtual SparseNameRange* SK_WARN_UNUSED_RESULT free(GrGLuint name) SK_OVERRIDE { |
| if (name < fFirst || name >= fEnd) { |
| // Not-allocated names are silently ignored. |
| return this->takeRef(); |
| } |
| |
| if (fFirst == name) { |
| ++fFirst; |
| return (fEnd == fFirst) ? NULL : this->takeRef(); |
| } |
| |
| if (fEnd == name + 1) { |
| --fEnd; |
| return this->takeRef(); |
| } |
| |
| SparseNameRange* left = SkNEW_ARGS(ContiguousNameRange, (fFirst, name)); |
| SparseNameRange* right = this->takeRef(); |
| fFirst = name + 1; |
| return SkNEW_ARGS(SparseNameTree, (left, right)); |
| } |
| }; |
| |
| GrGLNameAllocator::GrGLNameAllocator(GrGLuint firstName, GrGLuint endName) |
| : fFirstName(firstName), |
| fEndName(endName) { |
| SkASSERT(firstName > 0); |
| SkASSERT(endName > firstName); |
| } |
| |
| GrGLNameAllocator::~GrGLNameAllocator() { |
| } |
| |
| GrGLuint GrGLNameAllocator::allocateName() { |
| if (NULL == fAllocatedNames.get()) { |
| fAllocatedNames.reset(SkNEW_ARGS(ContiguousNameRange, (fFirstName, fFirstName + 1))); |
| return fFirstName; |
| } |
| |
| if (fAllocatedNames->first() > fFirstName) { |
| return fAllocatedNames->prependNames(1); |
| } |
| |
| GrGLuint name; |
| fAllocatedNames.reset(fAllocatedNames->internalAllocate(&name)); |
| if (0 != name) { |
| return name; |
| } |
| |
| if (fAllocatedNames->end() < fEndName) { |
| return fAllocatedNames->appendNames(1); |
| } |
| |
| // Out of names. |
| return 0; |
| } |
| |
| void GrGLNameAllocator::free(GrGLuint name) { |
| if (!fAllocatedNames.get()) { |
| // Not-allocated names are silently ignored. |
| return; |
| } |
| |
| fAllocatedNames.reset(fAllocatedNames->free(name)); |
| } |