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Step 4 of fixing storage server range reads: remove another unneeded iteration case in the forward direction when we don't exhaust our limits in the disk read. This also hopefully makes the code a bit clearer.

This commit is contained in:
A.J. Beamon 2020-02-06 13:27:04 -08:00
parent df2b0452b4
commit 16167b07d5
1 changed files with 7 additions and 8 deletions
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15
fdbserver/storageserver.actor.cpp
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@ -1126,20 +1126,19 @@ ACTOR Future<GetKeyValuesReply> readRange( StorageServer* data, Version version,
ASSERT( atStorageVersion.size() <= limit );
if (data->storageVersion() > version) throw transaction_too_old();
bool more = atStorageVersion.size()!=0;
// merge the sets in [vStart,vEnd) with the sets on disk, stopping at the last key from disk if we read anything
// merge the sets in [vStart,vEnd) with the sets on disk, stopping at the last key from disk if we were limited
int prevSize = result.data.size();
merge( result.arena, result.data, atStorageVersion, vStart, vEnd, vCount, limit, more, *pLimitBytes );
merge( result.arena, result.data, atStorageVersion, vStart, vEnd, vCount, limit, atStorageVersion.more, *pLimitBytes );
limit -= result.data.size() - prevSize;
for (auto i = result.data.begin() + prevSize; i != result.data.end(); i++)
*pLimitBytes -= sizeof(KeyValueRef) + i->expectedSize();
// Setup for the next iteration
if (more) { // if there might be more data on disk, begin reading right after the last key read
readBegin = readBeginTemp = keyAfter( result.data.end()[-1].key );
ASSERT( limit<=0 || *pLimitBytes<=0 || result.data.end()[-1].key == atStorageVersion.end()[-1].key );
// We may have reached our limits in the read from disk, but combining with the MVCC window could have
// given us back some room
if (atStorageVersion.more && limit > 0 && *pLimitBytes > 0) {
ASSERT(result.data.end()[-1].key == atStorageVersion.end()[-1].key);
readBegin = readBeginTemp = keyAfter(result.data.end()[-1].key);
} else if (vEnd && vEnd->isClearTo()) {
ASSERT(vEnd->getEndKey() > readBegin);
readBegin = vEnd->getEndKey();