com.arcadedb.query.sql.executor.ExecutionStepInternal Maven / Gradle / Ivy
/*
* Copyright © 2021-present Arcade Data Ltd ([email protected])
*
* 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.
*
* SPDX-FileCopyrightText: 2021-present Arcade Data Ltd ([email protected])
* SPDX-License-Identifier: Apache-2.0
*/
package com.arcadedb.query.sql.executor;
import com.arcadedb.exception.TimeoutException;
import java.util.*;
/**
* Execution Steps are the building blocks of a query execution plan
Typically an execution plan is made of a chain of
* steps. The execution is pull-based, meaning that the result set that the client iterates is conceptually the one returned by
* last step of the execution plan
At each `next()` invocation, the step typically fetches a record from the previous
* (upstream) step, does its elaboration (eg. for a filtering step, it can discard the record and fetch another one if it doesn't
* match the conditions) and returns the elaborated step
*
* The invocation of {@literal syncPull(context, nResults)} has to return a result set of at most nResults records. If the upstream
* (the previous steps) return more records, they have to be returned by next call of {@literal syncPull()}. The returned result
* set can have less than nResults records ONLY if current step cannot produce any more records (eg. the upstream does not have any
* more records)
*
* @author Luigi Dell'Aquila luigi.dellaquila-(at)-gmail.com
*/
public interface ExecutionStepInternal extends ExecutionStep {
static String getIndent(final int depth, final int indent) {
final StringBuilder result = new StringBuilder();
for (int i = 0; i < depth; i++) {
for (int j = 0; j < indent; j++) {
result.append(" ");
}
}
return result.toString();
}
ResultSet syncPull(CommandContext context, int nRecords) throws TimeoutException;
void sendTimeout();
boolean isTimedOut();
void setPrevious(ExecutionStepInternal step);
void close();
default String prettyPrint(final int depth, final int indent) {
final String spaces = getIndent(depth, indent);
return spaces + getClass().getSimpleName();
}
default String getName() {
return getClass().getSimpleName();
}
default String getType() {
return getClass().getSimpleName();
}
default String getDescription() {
return prettyPrint(0, 3);
}
default List getSubSteps() {
return Collections.emptyList();
}
default List getSubExecutionPlans() {
return Collections.emptyList();
}
default void reset() {
//do nothing
}
default ExecutionStep copy(final CommandContext context) {
throw new UnsupportedOperationException();
}
default boolean canBeCached() {
return false;
}
}