foundationdb/fdbclient/KeyRangeMap.actor.cpp

/*
 * KeyRangeMap.actor.cpp
 *
 * This source file is part of the FoundationDB open source project
 *
 * Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "KeyRangeMap.h"
#include "NativeAPI.h"
#include "CommitTransaction.h"
#include "FDBTypes.h"
#include "ReadYourWrites.h"

void KeyRangeActorMap::getRangesAffectedByInsertion( const KeyRangeRef& keys, vector< KeyRange >& affectedRanges ) {
	auto s = map.rangeContaining( keys.begin );
	if (s.begin() != keys.begin && s.value().isValid() && !s.value().isReady())
		affectedRanges.push_back( KeyRangeRef( s.begin(), keys.begin ) );
	affectedRanges.push_back( keys );
	auto e = map.rangeContaining( keys.end );
	if (e.begin() != keys.end && e.value().isValid() && !e.value().isReady())
		affectedRanges.push_back( KeyRangeRef( keys.end, e.end() ) );
}

Standalone<RangeResultRef> krmDecodeRanges(
	KeyRef mapPrefix,
	KeyRange keys,
	Standalone<RangeResultRef> kv )
{
	ASSERT(!kv.more || kv.size() > 1);
	KeyRange withPrefix = KeyRangeRef( mapPrefix.toString() + keys.begin.toString(), mapPrefix.toString() + keys.end.toString() );

	ValueRef beginValue, endValue;
	if (kv.size() && kv[0].key.startsWith(mapPrefix))
		beginValue = kv[0].value;
	if (kv.size() && kv.end()[-1].key.startsWith(mapPrefix))
		endValue = kv.end()[-1].value;

	Standalone<RangeResultRef> result;
	result.arena().dependsOn( kv.arena() );
	result.arena().dependsOn( keys.arena() );

	result.push_back(result.arena(), KeyValueRef(keys.begin, beginValue));
	for(int i=0; i<kv.size(); i++) {
		if (kv[i].key > withPrefix.begin && kv[i].key < withPrefix.end) {
			KeyRef k = kv[i].key.removePrefix(mapPrefix);
			result.push_back(result.arena(), KeyValueRef( k, kv[i].value ));
		}
		else if(kv[i].key >= withPrefix.end)
			kv.more = false;
	}

	if(!kv.more)
		result.push_back(result.arena(), KeyValueRef(keys.end, endValue));
	result.more = kv.more;

	return result;
}

// Returns keys.begin, all transitional points in keys, and keys.end, and their values
ACTOR Future<Standalone<RangeResultRef>> krmGetRanges( Transaction* tr, Key mapPrefix, KeyRange keys, int limit, int limitBytes )
{
	KeyRange withPrefix = KeyRangeRef( mapPrefix.toString() + keys.begin.toString(), mapPrefix.toString() + keys.end.toString() );

	state GetRangeLimits limits(limit, limitBytes);
	limits.minRows = 2;
	Standalone<RangeResultRef> kv = wait( tr->getRange( lastLessOrEqual(withPrefix.begin), firstGreaterThan(withPrefix.end), limits ) );

	return krmDecodeRanges( mapPrefix, keys, kv );
}

ACTOR Future<Standalone<RangeResultRef>> krmGetRanges( Reference<ReadYourWritesTransaction> tr, Key mapPrefix, KeyRange keys, int limit, int limitBytes )
{
	KeyRange withPrefix = KeyRangeRef( mapPrefix.toString() + keys.begin.toString(), mapPrefix.toString() + keys.end.toString() );

	state GetRangeLimits limits(limit, limitBytes);
	limits.minRows = 2;
	Standalone<RangeResultRef> kv = wait( tr->getRange( lastLessOrEqual(withPrefix.begin), firstGreaterThan(withPrefix.end), limits ) );

	return krmDecodeRanges( mapPrefix, keys, kv );
}

void krmSetPreviouslyEmptyRange( Transaction* tr, const KeyRef& mapPrefix, const KeyRangeRef& keys, const ValueRef& newValue, const ValueRef& oldEndValue )
{
	KeyRange withPrefix = KeyRangeRef( mapPrefix.toString() + keys.begin.toString(), mapPrefix.toString() + keys.end.toString() );
	tr->set( withPrefix.begin, newValue );
	tr->set( withPrefix.end, oldEndValue );
}

void krmSetPreviouslyEmptyRange( CommitTransactionRef& tr, Arena& trArena, const KeyRef& mapPrefix, const KeyRangeRef& keys, const ValueRef& newValue, const ValueRef& oldEndValue )
{
	KeyRange withPrefix = KeyRangeRef( mapPrefix.toString() + keys.begin.toString(), mapPrefix.toString() + keys.end.toString() );
	tr.set( trArena, withPrefix.begin, newValue );
	tr.set( trArena, withPrefix.end, oldEndValue );
}

ACTOR Future<Void> krmSetRange( Transaction* tr, Key mapPrefix, KeyRange range, Value value ) {
	state KeyRange withPrefix = KeyRangeRef( mapPrefix.toString() + range.begin.toString(), mapPrefix.toString() + range.end.toString() );
	Standalone<RangeResultRef> old = wait(tr->getRange(lastLessOrEqual(withPrefix.end), firstGreaterThan(withPrefix.end), 1, true));
	
	Value oldValue;
	bool hasResult = old.size() > 0 && old[0].key.startsWith(mapPrefix);
	if(hasResult)
		oldValue = old[0].value;

	KeyRange conflictRange = KeyRangeRef( hasResult ? old[0].key : mapPrefix.toString(), keyAfter(withPrefix.end) );
	if( !conflictRange.empty() )
		tr->addReadConflictRange( conflictRange );
	
	tr->clear(withPrefix);
	tr->set( withPrefix.begin, value );
	tr->set( withPrefix.end, oldValue );

	return Void();
}

ACTOR Future<Void> krmSetRange( Reference<ReadYourWritesTransaction> tr, Key mapPrefix, KeyRange range, Value value ) {
	state KeyRange withPrefix = KeyRangeRef( mapPrefix.toString() + range.begin.toString(), mapPrefix.toString() + range.end.toString() );
	Standalone<RangeResultRef> old = wait(tr->getRange(lastLessOrEqual(withPrefix.end), firstGreaterThan(withPrefix.end), 1, true));
	
	Value oldValue;
	bool hasResult = old.size() > 0 && old[0].key.startsWith(mapPrefix);
	if(hasResult)
		oldValue = old[0].value;

	KeyRange conflictRange = KeyRangeRef( hasResult ? old[0].key : mapPrefix.toString(), keyAfter(withPrefix.end) );
	if( !conflictRange.empty() )
		tr->addReadConflictRange( conflictRange );
	
	tr->clear(withPrefix);
	tr->set( withPrefix.begin, value );
	tr->set( withPrefix.end, oldValue );

	return Void();
}

//Sets a range of keys in a key range map, coalescing with adjacent regions if the values match
//Ranges outside of maxRange will not be coalesced
//CAUTION: use care when attempting to coalesce multiple ranges in the same prefix in a single transaction
ACTOR Future<Void> krmSetRangeCoalescing( Transaction *tr, Key mapPrefix, KeyRange range, KeyRange maxRange, Value value ) {
	ASSERT(maxRange.contains(range));

	state KeyRange withPrefix = KeyRangeRef( mapPrefix.toString() + range.begin.toString(), mapPrefix.toString() + range.end.toString() );
	state KeyRange maxWithPrefix = KeyRangeRef( mapPrefix.toString() + maxRange.begin.toString(), mapPrefix.toString() + maxRange.end.toString() );

	state vector<Future<Standalone<RangeResultRef>>> keys;
	keys.push_back(tr->getRange(lastLessThan(withPrefix.begin), firstGreaterOrEqual(withPrefix.begin), 1, true));
	keys.push_back(tr->getRange(lastLessOrEqual(withPrefix.end), firstGreaterThan(withPrefix.end) + 1, 2, true));
	Void _ = wait(waitForAll(keys));

	//Determine how far to extend this range at the beginning
	auto beginRange = keys[0].get();
	bool hasBegin = beginRange.size() > 0 && beginRange[0].key.startsWith(mapPrefix);
	Value beginValue = hasBegin ? beginRange[0].value : LiteralStringRef("");

	state Key beginKey = withPrefix.begin;
	if(beginValue == value) {
		bool outsideRange = !hasBegin || beginRange[0].key < maxWithPrefix.begin;
		beginKey = outsideRange ? maxWithPrefix.begin : beginRange[0].key;
	}

	//Determine how far to extend this range at the end
	auto endRange = keys[1].get();
	bool hasEnd = endRange.size() >= 1 && endRange[0].key.startsWith(mapPrefix) && endRange[0].key <= withPrefix.end;
	bool hasNext = (endRange.size() == 2 && endRange[1].key.startsWith(mapPrefix)) || (endRange.size() == 1 && withPrefix.end < endRange[0].key && endRange[0].key.startsWith(mapPrefix));
	Value existingValue = hasEnd ? endRange[0].value : LiteralStringRef("");
	bool valueMatches = value == existingValue;

	KeyRange conflictRange = KeyRangeRef( hasBegin ? beginRange[0].key : mapPrefix, withPrefix.begin );
	if( !conflictRange.empty() )
		tr->addReadConflictRange( conflictRange );

	conflictRange = KeyRangeRef( hasEnd ? endRange[0].key : mapPrefix, hasNext ? keyAfter(endRange.end()[-1].key) : strinc( mapPrefix ) );
	if( !conflictRange.empty() )
		tr->addReadConflictRange( conflictRange );

	state Key endKey;
	state Value endValue;

	//Case 1: Coalesce completely with the following range
	if(hasNext && endRange.end()[-1].key <= maxWithPrefix.end && valueMatches) {
		endKey = endRange.end()[-1].key;
		endValue = endRange.end()[-1].value;
	}

	//Case 2: Coalesce with the following range only up to the end of maxRange
	else if(valueMatches) {
		endKey = maxWithPrefix.end;
		endValue = existingValue;
	}

	//Case 3: Don't coalesce
	else {
		endKey = withPrefix.end;
		endValue = existingValue;
	}

	tr->clear(KeyRangeRef(beginKey, endKey));

	ASSERT(value != endValue || endKey == maxWithPrefix.end);
	tr->set(beginKey, value);
	tr->set(endKey, endValue);

	return Void();
}