/*
* Copyright (C) 2012, 2016 higherfrequencytrading.com
* Copyright (C) 2016 Roman Leventov
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package net.openhft.chronicle.hash.impl.stage.entry;
import net.openhft.chronicle.algo.hashing.LongHashFunction;
import net.openhft.sg.StageRef;
import net.openhft.sg.Staged;
import static net.openhft.chronicle.hash.impl.stage.entry.ChecksumHashing.hash8To16Bytes;
@Staged
public class HashEntryChecksumStrategy implements ChecksumStrategy {
@StageRef SegmentStages s;
@StageRef HashEntryStages<?> e;
@StageRef KeyHashCode h;
@Override
public void computeAndStoreChecksum() {
int checksum = computeChecksum();
s.segmentBS.writeInt(e.entryEnd(), checksum);
}
@Override
public int computeChecksum() {
long keyHashCode = h.keyHashCode();
long keyEnd = e.keyEnd();
long len = e.entryEnd() - keyEnd;
long checksum;
if (len > 0) {
long addr = s.tierBaseAddr + keyEnd;
long payloadChecksum = LongHashFunction.xx_r39().hashMemory(addr, len);
checksum = hash8To16Bytes(e.keySize, keyHashCode, payloadChecksum);
} else {
// non replicated ChronicleSet has no payload
checksum = keyHashCode;
}
return (int) ((checksum >>> 32) ^ checksum);
}
@Override
public boolean innerCheckSum() {
int oldChecksum = storedChecksum();
int checksum = computeChecksum();
return oldChecksum == checksum;
}
@Override
public int storedChecksum() {
return s.segmentBS.readInt(e.entryEnd());
}
@Override
public long extraEntryBytes() {
return CHECKSUM_STORED_BYTES;
}
}