/*
* 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.
*/
package com.facebook.presto.execution;
import com.facebook.presto.spi.QueryId;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableSet;
import com.google.common.primitives.Chars;
import com.google.common.util.concurrent.Uninterruptibles;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;
import javax.annotation.concurrent.GuardedBy;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;
import static com.google.common.base.Preconditions.checkState;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
public class QueryIdGenerator
{
// a-z, 0-9, except: l, o, 0, 1
private static final char[] BASE_32 = {
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h',
'i', 'j', 'k', 'm', 'n', 'p', 'q', 'r',
's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'2', '3', '4', '5', '6', '7', '8', '9'};
static {
checkState(BASE_32.length == 32);
checkState(ImmutableSet.copyOf(Chars.asList(BASE_32)).size() == 32);
}
private static final DateTimeFormatter TIMESTAMP_FORMAT = DateTimeFormat.forPattern("YYYYMMdd_HHmmss").withZoneUTC();
private static final long BASE_SYSTEM_TIME_MILLIS = System.currentTimeMillis();
private static final long BASE_NANO_TIME = System.nanoTime();
private final String coordinatorId;
@GuardedBy("this")
private long lastTimeInDays;
@GuardedBy("this")
private long lastTimeInSeconds;
@GuardedBy("this")
private String lastTimestamp;
@GuardedBy("this")
private int counter;
public QueryIdGenerator()
{
StringBuilder coordinatorId = new StringBuilder(5);
for (int i = 0; i < 5; i++) {
coordinatorId.append(BASE_32[ThreadLocalRandom.current().nextInt(32)]);
}
this.coordinatorId = coordinatorId.toString();
}
public String getCoordinatorId()
{
return coordinatorId;
}
/**
* Generate next queryId using the following format:
* <tt>YYYYMMdd_HHmmss_index_coordId</tt>
* <p/>
* Index rolls at the start of every day or when it reaches 99,999, and the
* coordId is a randomly generated when this instance is created.
*/
public synchronized QueryId createNextQueryId()
{
// only generate 100,000 ids per day
if (counter > 99_999) {
// wait for the second to rollover
while (MILLISECONDS.toSeconds(nowInMillis()) == lastTimeInSeconds) {
Uninterruptibles.sleepUninterruptibly(1, TimeUnit.SECONDS);
}
counter = 0;
}
// if it has been a second since the last id was generated, generate a new timestamp
long now = nowInMillis();
if (MILLISECONDS.toSeconds(now) != lastTimeInSeconds) {
// generate new timestamp
lastTimeInSeconds = MILLISECONDS.toSeconds(now);
lastTimestamp = TIMESTAMP_FORMAT.print(now);
// if the day has rolled over, restart the counter
if (MILLISECONDS.toDays(now) != lastTimeInDays) {
lastTimeInDays = MILLISECONDS.toDays(now);
counter = 0;
}
}
return new QueryId(String.format("%s_%05d_%s", lastTimestamp, counter++, coordinatorId));
}
@VisibleForTesting
protected long nowInMillis()
{
// avoid problems with the clock moving backwards
return BASE_SYSTEM_TIME_MILLIS + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - BASE_NANO_TIME);
}
}