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package org.dcache.srm.request.sql;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.dao.DataAccessException;
import org.springframework.dao.IncorrectResultSizeDataAccessException;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.support.TransactionTemplate;
import javax.sql.DataSource;
import org.dcache.srm.scheduler.JobIdGenerator;
import org.dcache.srm.scheduler.JobIdGeneratorFactory;
import static com.google.common.base.Preconditions.checkState;
/**
* This class is used by srm to generate long and int ids
* that are guaranteed to be unique as long as the database used by the
* class is preserved and can be connected to.
* @author timur
*/
public class RequestsPropertyStorage extends JobIdGeneratorFactory implements JobIdGenerator
{
private static final Logger logger = LoggerFactory.getLogger(RequestsPropertyStorage.class);
private static final int NEXT_INT_STEP = 1000;
private static final long NEXT_LONG_STEP = 10000;
private static RequestsPropertyStorage requestsPropertyStorage;
private final JdbcTemplate jdbcTemplate;
private final TransactionTemplate transactionTemplate;
private int nextIntBase;
private int nextIntIncrement = NEXT_INT_STEP;
private long nextLongBase;
private long nextLongIncrement = NEXT_LONG_STEP;
/** Creates a new instance of RequestsPropertyStorage */
private RequestsPropertyStorage(PlatformTransactionManager transactionManager, DataSource dataSource)
throws DataAccessException
{
this.transactionTemplate = new TransactionTemplate(transactionManager);
this.jdbcTemplate = new JdbcTemplate(dataSource);
}
/**
* Generate a next unique int request id
* Database table is used to preserve the state of the request generator.
* In this table we store a single record with field NEXTINT
* We read the value of this field and increase it by NEXT_INT_STEP (1000 by
* default), Thus reserving the 1000 values for use by this instance.
* Once we used up all of the values we repeat the database update.
* This is done to minimize the number of database operations.
* @return new int request id
*/
public int getNextRequestId() {
return nextInt();
}
public synchronized int nextInt() {
if (nextIntIncrement >= NEXT_INT_STEP) {
nextIntBase = transactionTemplate.execute(status -> {
int base = jdbcTemplate.queryForObject("SELECT NEXTINT FROM srmnextrequestid FOR UPDATE", Integer.class);
int newBase = base + NEXT_INT_STEP;
int n = jdbcTemplate.update("UPDATE srmnextrequestid SET NEXTINT=?", newBase);
if (n != 1) {
throw new IncorrectResultSizeDataAccessException(
"Unexpected number of rows got updated in srmnextrequestid", 1, n);
}
return newBase;
});
nextIntIncrement = 0;
}
int nextInt = nextIntBase + nextIntIncrement++;
logger.trace("RequestsPropertyStorage: return nextInt={}", nextInt);
return nextInt;
}
@Override
public long getNextId() {
return nextInt();
}
/**
* Generate a next unique long id
* Database table is used to preserve the state of the long id generator.
* In this table we store a single record with field NEXTLONG
* We read the value of this field and increase it by NEXT_LONG_STEP (10000
* by default), thus reserving the 10000 values for use by this instance.
* Once we used up all of the values we repeat the database update.
* This is done to minimize the number of database operations.
* @return next unique long number
*/
@Override
public synchronized long nextLong() {
if (nextLongIncrement >= NEXT_LONG_STEP) {
nextLongBase = transactionTemplate.execute(status -> {
long base = jdbcTemplate.queryForObject("SELECT NEXTLONG FROM srmnextrequestid FOR UPDATE", Long.class);
long newBase = base + NEXT_LONG_STEP;
int n = jdbcTemplate.update("UPDATE srmnextrequestid SET NEXTLONG=?", newBase);
if (n != 1) {
throw new IncorrectResultSizeDataAccessException(
"Unexpected number of rows got updated in srmnextrequestid", 1, n);
}
return newBase;
});
nextLongIncrement = 0;
}
long nextLong = nextLongBase + nextLongIncrement++;
logger.debug("RequestsPropertyStorage: return nextLong={}", nextLong);
return nextLong;
}
@Override
public JobIdGenerator getJobIdGenerator() {
return this;
}
public static final synchronized void initPropertyStorage(
PlatformTransactionManager transactionManager, DataSource dataSource)
throws DataAccessException
{
checkState(RequestsPropertyStorage.requestsPropertyStorage == null,
"RequestsPropertyStorage is already initialized");
requestsPropertyStorage =
new RequestsPropertyStorage(transactionManager, dataSource);
initJobIdGeneratorFactory(requestsPropertyStorage);
}
}