/**
* Copyright (C) 2009-2013 FoundationDB, LLC
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package com.foundationdb.server;
import com.foundationdb.server.store.FDBHolder;
import com.foundationdb.server.store.FDBStoreDataHelper;
import com.foundationdb.server.store.FDBTransactionService;
import com.foundationdb.server.store.FDBTransactionService.TransactionState;
import com.foundationdb.Database;
import com.foundationdb.MutationType;
import com.foundationdb.Transaction;
import com.foundationdb.ais.model.Table;
import com.foundationdb.async.Function;
import com.foundationdb.qp.memoryadapter.MemoryTableFactory;
import com.foundationdb.server.rowdata.RowDef;
import com.foundationdb.server.service.session.Session;
import com.foundationdb.tuple.ByteArrayUtil;
import com.foundationdb.tuple.Tuple2;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Directory usage:
* <pre>
* root_dir/
* tableStatus/
* </pre>
*
* <p>
* The above directory is used to store auto-inc, unique and/or row count
* information on a per-table basis. Each key is formed by pre-pending the
* directory prefix with the primary key's prefix and the string
* "autoInc", "unique" or "rowCount". The auto-inc and unique values are
* {@link Tuple} encoded longs and the row count is a little-endian encoded
* long (for {@link Transaction#mutate} usage).
* </p>
*/
public class FDBTableStatusCache implements TableStatusCache {
private static final List<String> TABLE_STATUS_DIR_PATH = Arrays.asList("tableStatus");
private static final byte[] AUTO_INC_PACKED = Tuple2.from("autoInc").pack();
private static final byte[] UNIQUE_PACKED = Tuple2.from("unique").pack();
private static final byte[] ROW_COUNT_PACKED = Tuple2.from("rowCount").pack();
private final Database db;
private final FDBTransactionService txnService;
private final Map<Integer,MemoryTableStatus> memoryTableStatusMap = new HashMap<>();
private byte[] packedTableStatusPrefix;
public FDBTableStatusCache(FDBHolder holder, FDBTransactionService txnService) {
this.db = holder.getDatabase();
this.txnService = txnService;
this.packedTableStatusPrefix = holder.getRootDirectory().createOrOpen(holder.getDatabase(),
TABLE_STATUS_DIR_PATH).get().pack();
}
@Override
public synchronized TableStatus createTableStatus(int tableID) {
return new FDBTableStatus(tableID);
}
@Override
public synchronized TableStatus getOrCreateMemoryTableStatus(int tableID, MemoryTableFactory factory) {
MemoryTableStatus status = memoryTableStatusMap.get(tableID);
if(status == null) {
status = new MemoryTableStatus(tableID, factory);
memoryTableStatusMap.put(tableID, status);
}
return status;
}
@Override
public synchronized void detachAIS() {
for(MemoryTableStatus status : memoryTableStatusMap.values()) {
status.setRowDef(null);
}
}
@Override
public synchronized void clearTableStatus(Session session, Table table) {
TableStatus status = table.rowDef().getTableStatus();
if(status instanceof FDBTableStatus) {
((FDBTableStatus)status).clearState(session);
} else if(status != null) {
assert status instanceof MemoryTableStatus : status;
memoryTableStatusMap.remove(table.getTableId());
}
}
public static byte[] packForAtomicOp(long l) {
byte[] bytes = new byte[8];
AkServerUtil.putLong(bytes, 0, l);
return bytes;
}
public static long unpackForAtomicOp(byte[] bytes) {
if(bytes == null) {
return 0;
}
assert bytes.length == 8 : bytes.length;
return AkServerUtil.getLong(bytes, 0);
}
/**
* Use FDBCounter for row count and single k/v for others.
*/
private class FDBTableStatus implements TableStatus {
private final int tableID;
private volatile byte[] rowCountKey;
private volatile byte[] autoIncKey;
public FDBTableStatus(int tableID) {
this.tableID = tableID;
}
@Override
public void rowDeleted(Session session) {
rowsWritten(session, -1);
}
@Override
public void rowsWritten(Session session, long count) {
TransactionState txn = txnService.getTransaction(session);
txn.mutate(MutationType.ADD, rowCountKey, packForAtomicOp(count));
}
@Override
public void truncate(Session session) {
TransactionState txn = txnService.getTransaction(session);
txn.setBytes(rowCountKey, packForAtomicOp(0));
internalSetAutoInc(session, 0, true);
}
@Override
public void setAutoIncrement(Session session, long value) {
internalSetAutoInc(session, value, false);
}
@Override
public void setRowDef(RowDef rowDef) {
if(rowDef == null) {
this.autoIncKey = null;
this.rowCountKey = null;
} else {
assert rowDef.getRowDefId() == tableID;
byte[] prefixBytes = FDBStoreDataHelper.prefixBytes(rowDef.getPKIndex());
this.autoIncKey = ByteArrayUtil.join(packedTableStatusPrefix, prefixBytes, AUTO_INC_PACKED);
this.rowCountKey = ByteArrayUtil.join(packedTableStatusPrefix, prefixBytes, ROW_COUNT_PACKED);
}
}
@Override
public long getAutoIncrement(Session session) {
TransactionState txn = txnService.getTransaction(session);
return decodeOrZero(txn.getValue(autoIncKey));
}
@Override
public long getRowCount(Session session) {
return getRowCount (txnService.getTransaction(session), false);
}
@Override
public long getApproximateRowCount(Session session) {
// TODO: Snapshot avoids conflicts but might still round trip. Cache locally for some time frame?
return getRowCount(txnService.getTransaction(session), true);
}
@Override
public int getTableID() {
return tableID;
}
@Override
public void setRowCount(Session session, long rowCount) {
TransactionState txn = txnService.getTransaction(session);
txn.setBytes(rowCountKey, packForAtomicOp(rowCount));
}
private void clearState(Session session) {
TransactionState txn = txnService.getTransaction(session);
txn.clearKey(rowCountKey);
txn.clearKey(autoIncKey);
}
private void internalSetAutoInc(Session session, long value, boolean evenIfLess) {
TransactionState txn = txnService.getTransaction(session);
long current = decodeOrZero(txn.getValue(autoIncKey));
if(evenIfLess || value > current) {
txn.setBytes(autoIncKey, Tuple2.from(value).pack());
}
}
private long decodeOrZero(byte[] bytes) {
return (bytes == null) ? 0 : Tuple2.fromBytes(bytes).getLong(0);
}
private long getRowCount(TransactionState txn, boolean snapshot) {
if (snapshot) {
return unpackForAtomicOp(txn.getSnapshotValue(rowCountKey));
} else {
return unpackForAtomicOp(txn.getValue(rowCountKey));
}
}
}
}