| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more 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, |
| * 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 org.apache.cassandra.cql3.functions; |
| |
| import java.nio.ByteBuffer; |
| import java.util.List; |
| |
| import org.apache.cassandra.db.marshal.AbstractType; |
| import org.apache.cassandra.exceptions.InvalidRequestException; |
| import org.apache.cassandra.transport.ProtocolVersion; |
| |
| /** |
| * Function used internally to hold the pre-computed result of another function. |
| * <p> |
| * See {@link ScalarFunction#partialApplication(ProtocolVersion, List)} for why this is used. |
| * <p> |
| * Note : the function is cautious in keeping the protocol version used for the pre-computed value and to |
| * fallback to recomputation if the version we get when {@link #execute} is called. I don't think it's truly necessary |
| * though as I don't think we actually depend on the protocol version for values anymore (it's remnant of previous |
| * transitions). It's not a lot of code to be on safe side though until this is cleaned (assuming we do clean it). |
| */ |
| class PreComputedScalarFunction extends NativeScalarFunction implements PartialScalarFunction |
| { |
| private final ByteBuffer value; |
| private final ProtocolVersion valueVersion; |
| |
| private final ScalarFunction function; |
| private final List<ByteBuffer> parameters; |
| |
| PreComputedScalarFunction(AbstractType<?> returnType, |
| ByteBuffer value, |
| ProtocolVersion valueVersion, |
| ScalarFunction function, |
| List<ByteBuffer> parameters) |
| { |
| // Note that we never register those function, there are just used internally, so the name doesn't matter much |
| super("__constant__", returnType); |
| this.value = value; |
| this.valueVersion = valueVersion; |
| this.function = function; |
| this.parameters = parameters; |
| } |
| |
| @Override |
| public Function getFunction() |
| { |
| return function; |
| } |
| |
| @Override |
| public List<ByteBuffer> getPartialParameters() |
| { |
| return parameters; |
| } |
| |
| public ByteBuffer execute(ProtocolVersion protocolVersion, List<ByteBuffer> nothing) throws InvalidRequestException |
| { |
| if (protocolVersion == valueVersion) |
| return value; |
| |
| return function.execute(protocolVersion, parameters); |
| } |
| |
| public ScalarFunction partialApplication(ProtocolVersion protocolVersion, List<ByteBuffer> nothing) throws InvalidRequestException |
| { |
| return this; |
| } |
| } |