com.hazelcast.org.apache.calcite.plan.hep.HepState Maven / Gradle / Ivy
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* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to you 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,
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* See the License for the specific language governing permissions and
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package com.hazelcast.org.apache.calcite.plan.hep;
/** Able to execute an instruction or program, and contains all mutable state
* for that instruction.
*
* The goal is that programs are re-entrant - they can be used by more than
* one thread at a time. We achieve this by making instructions and programs
* immutable. All mutable state is held in the state objects.
*
*
State objects are allocated, just before the program is executed, by
* calling {@link HepInstruction#prepare(HepInstruction.PrepareContext)} on the
* program and recursively on all of its instructions. */
abstract class HepState {
final HepPlanner planner;
final HepProgram.State programState;
HepState(HepInstruction.PrepareContext px) {
this.planner = px.planner;
this.programState = px.programState;
}
/** Executes the instruction. */
abstract void execute();
/** Re-initializes the state. (The state was initialized when it was created
* via {@link HepInstruction#prepare}.) */
void init() {
}
}