/* This file is part of VoltDB.
* Copyright (C) 2008-2017 VoltDB Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER DEALINGS IN THE SOFTWARE.
*/
package uniquedevices;
import java.io.IOException;
import org.voltdb.SQLStmt;
import org.voltdb.VoltProcedure;
import org.voltdb.VoltTable;
import org.voltdb_hll.HyperLogLog;
public class CountDeviceEstimate extends VoltProcedure {
final static SQLStmt estimatesSelect = new SQLStmt("select devicecount, hll from estimates where appid = ?;");
final static SQLStmt estimatesUpsert = new SQLStmt("upsert into estimates (appid, devicecount, hll) values (?, ?, ?);");
public VoltTable[] run(long appId, long hashedDeviceId) throws IOException {
// get the HLL from the db
voltQueueSQL(estimatesSelect, EXPECT_ZERO_OR_ONE_ROW, appId);
VoltTable estimatesTable = voltExecuteSQL()[0];
HyperLogLog hll = null;
// if the row with the hyperloglog blob exists...
if (estimatesTable.advanceRow()) {
byte[] hllBytes = estimatesTable.getVarbinary("hll");
hll = HyperLogLog.fromBytes(hllBytes);
}
// otherwise create a hyperloglog blob
else {
hll = new HyperLogLog(12);
}
// offer the hashed device id to the HLL
hll.offerHashed(hashedDeviceId);
// if the estimates row needs updating, upsert it
if (hll.getDirty()) {
// update the state with exact estimate and update blob for the hll
voltQueueSQL(estimatesUpsert, EXPECT_SCALAR_MATCH(1), appId, hll.cardinality(), hll.toBytes());
return voltExecuteSQL(true);
}
return null;
}
}