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Don't query size on traversal

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This commit is contained in:
Sebastian Messmer 2016-07-12 01:09:30 +02:00
parent 582c9c1a4c
commit 58f2212043
1 changed files with 7 additions and 5 deletions
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12
src/blobstore/implementations/onblocks/BlobOnBlocks.cpp
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@ -42,19 +42,21 @@ void BlobOnBlocks::traverseLeaves(uint64_t beginByte, uint64_t sizeBytes, functi
uint64_t maxBytesPerLeaf = _datatree->maxBytesPerLeaf();
uint32_t firstLeaf = beginByte / maxBytesPerLeaf;
uint32_t endLeaf = utils::ceilDivision(endByte, maxBytesPerLeaf);
bool writingOutside = size() < endByte; // TODO Calling size() is slow because it has to traverse the tree. Instead: recognize situation by looking at current leaf size in lambda below
auto _onExistingLeaf = [&onExistingLeaf, beginByte, endByte, endLeaf, writingOutside, maxBytesPerLeaf] (uint32_t leafIndex, DataLeafNode *leaf) {
bool blobIsGrowingFromThisTraversal = false;
auto _onExistingLeaf = [&onExistingLeaf, beginByte, endByte, endLeaf, maxBytesPerLeaf, &blobIsGrowingFromThisTraversal] (uint32_t leafIndex, DataLeafNode *leaf) {
uint64_t indexOfFirstLeafByte = leafIndex * maxBytesPerLeaf;
ASSERT(endByte > indexOfFirstLeafByte, "Traversal went too far right");
uint32_t dataBegin = utils::maxZeroSubtraction(beginByte, indexOfFirstLeafByte);
uint32_t dataEnd = std::min(maxBytesPerLeaf, endByte - indexOfFirstLeafByte);
if (leafIndex == endLeaf-1 && writingOutside) {
if (leafIndex == endLeaf-1 && leaf->numBytes() < dataEnd) {
// If we are traversing an area that didn't exist before (i.e. in the area of the last leaf that wasn't used before), then the last leaf might have a wrong size. We have to fix it.
leaf->resize(dataEnd);
blobIsGrowingFromThisTraversal = true;
}
onExistingLeaf(indexOfFirstLeafByte, leaf, dataBegin, dataEnd-dataBegin);
};
auto _onCreateLeaf = [&onCreateLeaf, maxBytesPerLeaf, beginByte, endByte] (uint32_t leafIndex) -> Data {
auto _onCreateLeaf = [&onCreateLeaf, maxBytesPerLeaf, beginByte, endByte, &blobIsGrowingFromThisTraversal] (uint32_t leafIndex) -> Data {
blobIsGrowingFromThisTraversal = true;
uint64_t indexOfFirstLeafByte = leafIndex * maxBytesPerLeaf;
ASSERT(endByte > indexOfFirstLeafByte, "Traversal went too far right");
uint32_t dataBegin = utils::maxZeroSubtraction(beginByte, indexOfFirstLeafByte);
@ -71,7 +73,7 @@ void BlobOnBlocks::traverseLeaves(uint64_t beginByte, uint64_t sizeBytes, functi
return data;
};
_datatree->traverseLeaves(firstLeaf, endLeaf, _onExistingLeaf, _onCreateLeaf);
if (writingOutside) {
if (blobIsGrowingFromThisTraversal) {
ASSERT(_datatree->numStoredBytes() == endByte, "Writing didn't grow by the correct number of bytes");
_sizeCache = endByte;
}