com.hazelcast.jet.sql.impl.connector.generator.StreamTable Maven / Gradle / Ivy
/*
* Copyright 2021 Hazelcast Inc.
*
* Licensed under the Hazelcast Community License (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://hazelcast.com/hazelcast-community-license
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.jet.sql.impl.connector.generator;
import com.hazelcast.jet.pipeline.SourceBuilder;
import com.hazelcast.jet.pipeline.SourceBuilder.SourceBuffer;
import com.hazelcast.jet.pipeline.StreamSource;
import com.hazelcast.jet.sql.impl.ExpressionUtil;
import com.hazelcast.jet.sql.impl.connector.SqlConnector;
import com.hazelcast.sql.impl.row.JetSqlRow;
import com.hazelcast.jet.sql.impl.schema.JetTable;
import com.hazelcast.sql.impl.QueryException;
import com.hazelcast.sql.impl.expression.Expression;
import com.hazelcast.sql.impl.expression.ExpressionEvalContext;
import com.hazelcast.sql.impl.optimizer.PlanObjectKey;
import com.hazelcast.sql.impl.row.EmptyRow;
import com.hazelcast.sql.impl.schema.ConstantTableStatistics;
import com.hazelcast.sql.impl.schema.TableField;
import java.util.List;
import static java.util.concurrent.TimeUnit.MICROSECONDS;
import static java.util.concurrent.TimeUnit.SECONDS;
class StreamTable extends JetTable {
private final List> argumentExpressions;
StreamTable(
SqlConnector sqlConnector,
List fields,
String schemaName,
String name,
List> argumentExpressions
) {
super(sqlConnector, fields, schemaName, name, new ConstantTableStatistics(Integer.MAX_VALUE));
this.argumentExpressions = argumentExpressions;
}
StreamSource items(Expression predicate, List> projections) {
List> argumentExpressions = this.argumentExpressions;
return SourceBuilder
.stream("stream", ctx -> {
ExpressionEvalContext evalContext = ExpressionEvalContext.from(ctx);
Integer rate = evaluate(argumentExpressions.get(0), evalContext);
if (rate == null) {
throw QueryException.error("Invalid argument of a call to function GENERATE_STREAM" +
" - rate cannot be null");
}
if (rate < 0) {
throw QueryException.error("Invalid argument of a call to function GENERATE_STREAM" +
" - rate cannot be less than zero");
}
return new DataGenerator(rate, predicate, projections, evalContext);
})
.fillBufferFn(DataGenerator::fillBuffer)
.build();
}
private static Integer evaluate(Expression argumentExpression, ExpressionEvalContext evalContext) {
if (argumentExpression == null) {
return null;
}
return (Integer) argumentExpression.eval(EmptyRow.INSTANCE, evalContext);
}
@Override
public PlanObjectKey getObjectKey() {
// table is always available and its field list does not change
return null;
}
private static final class DataGenerator {
private static final int MAX_BATCH_SIZE = 1024;
private static final long NANOS_PER_MICRO = MICROSECONDS.toNanos(1);
private static final long MICROS_PER_SECOND = SECONDS.toMicros(1);
private final long startTime;
private final int rate;
private final Expression predicate;
private final List> projections;
private final ExpressionEvalContext evalContext;
private long sequence;
private DataGenerator(
int rate,
Expression predicate,
List> projections,
ExpressionEvalContext evalContext
) {
this.startTime = System.nanoTime();
this.rate = rate;
this.predicate = predicate;
this.projections = projections;
this.evalContext = evalContext;
}
private void fillBuffer(SourceBuffer buffer) {
long now = System.nanoTime();
long emitValuesUpTo = (now - startTime) / NANOS_PER_MICRO * rate / MICROS_PER_SECOND;
for (int i = 0; i < MAX_BATCH_SIZE && sequence < emitValuesUpTo; i++) {
JetSqlRow row = ExpressionUtil.evaluate(predicate, projections,
new JetSqlRow(evalContext.getSerializationService(), new Object[]{sequence}), evalContext);
if (row != null) {
buffer.add(row);
}
sequence++;
}
}
}
}