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Step 5 of fixing storage server range reads: update the logic of reverse range reads to match forward range reads

This commit is contained in:
A.J. Beamon 2020-02-07 10:02:52 -08:00
parent 16167b07d5
commit fa920a6cef
1 changed files with 33 additions and 20 deletions
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53
fdbserver/storageserver.actor.cpp
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@ -1139,31 +1139,36 @@ ACTOR Future<GetKeyValuesReply> readRange( StorageServer* data, Version version,
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()) {
} else if (vEnd && vEnd->isClearTo() && limit > 0 && *pLimitBytes > 0) {
ASSERT(vStart == vEnd); // vStart will have been advanced by merge()
ASSERT(vEnd->getEndKey() > readBegin);
readBegin = vEnd->getEndKey();
vStart = vEnd;
++vStart;
} else {
ASSERT(limit<=0 || *pLimitBytes<=0 || readEnd == range.end);
break;
}
}
// all but the last item are less than *pLimitBytes
ASSERT( result.data.size() == 0 || *pLimitBytes + result.data.end()[-1].expectedSize() + sizeof(KeyValueRef) > 0 );
} else {
// Reverse read - abandon hope alle ye who enter here
readEnd = range.end;
vStart = view.lastLess(readEnd);
vStart = view.lastLess(range.end);
// A clear might extend all the way to range.end
if (vStart && vStart->isClearTo() && vStart->getEndKey() >= readEnd) {
if (vStart && vStart->isClearTo() && vStart->getEndKey() >= range.end) {
readEnd = vStart.key();
--vStart;
} else {
readEnd = range.end;
}
while (limit < 0 && *pLimitBytes > 0 && readEnd > range.begin) {
ASSERT(!vStart || vStart.key() < readEnd);
if (vStart) {
auto b = vStart;
++b;
ASSERT(!b || b.key() >= readEnd);
}
ASSERT(data->storageVersion() <= version);
vEnd = vStart;
vCount = 0;
int vSize=0;
@ -1173,30 +1178,38 @@ ACTOR Future<GetKeyValuesReply> readRange( StorageServer* data, Version version,
--vEnd;
}
readBegin = range.begin;
if (vEnd)
readBegin = std::max( readBegin, vEnd->isClearTo() ? vEnd->getEndKey() : vEnd.key() );
readBegin = vEnd ? std::max(vEnd->isClearTo() ? vEnd->getEndKey() : vEnd.key(), range.begin) : range.begin;
Standalone<RangeResultRef> atStorageVersion =
wait(data->storage.readRange(KeyRangeRef(readBegin, readEnd), limit, *pLimitBytes));
Standalone<RangeResultRef> atStorageVersion = wait( data->storage.readRange( KeyRangeRef(readBegin, readEnd), limit, *pLimitBytes ) );
ASSERT(atStorageVersion.size() <= -limit);
if (data->storageVersion() > version) throw transaction_too_old();
int prevSize = result.data.size();
merge( result.arena, result.data, atStorageVersion, vStart, vEnd, vCount, limit, false, *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();
vStart = vEnd;
readEnd = readBegin;
if (vStart && vStart->isClearTo()) {
ASSERT( vStart.key() < readEnd );
readEnd = vStart.key();
if (atStorageVersion.more && limit < 0 && *pLimitBytes > 0) {
ASSERT(result.data.end()[-1].key == atStorageVersion.end()[-1].key);
readEnd = result.data.end()[-1].key;
} else if (vEnd && vEnd->isClearTo() && limit < 0 && *pLimitBytes > 0) {
ASSERT(vStart == vEnd);
ASSERT(vEnd.key() < readEnd)
readEnd = vEnd.key();
--vStart;
} else {
ASSERT(limit>=0 || *pLimitBytes<=0 || readBegin == range.begin);
break;
}
}
}
// all but the last item are less than *pLimitBytes
ASSERT(result.data.size() == 0 || *pLimitBytes + result.data.end()[-1].expectedSize() + sizeof(KeyValueRef) > 0);
result.more = limit == 0 || *pLimitBytes<=0; // FIXME: Does this have to be exact?
result.version = version;
return result;