org.apache.druid.indexing.overlord.setup.JavaScriptWorkerSelectStrategy.java Source code

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Here is the source code for org.apache.druid.indexing.overlord.setup.JavaScriptWorkerSelectStrategy.java

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/*
 * 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.druid.indexing.overlord.setup;

import com.fasterxml.jackson.annotation.JacksonInject;
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableMap;
import org.apache.druid.indexing.common.task.Task;
import org.apache.druid.indexing.overlord.ImmutableWorkerInfo;
import org.apache.druid.indexing.overlord.config.WorkerTaskRunnerConfig;
import org.apache.druid.js.JavaScriptConfig;

import javax.script.Compilable;
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class JavaScriptWorkerSelectStrategy implements WorkerSelectStrategy {
    public interface SelectorFunction {
        String apply(WorkerTaskRunnerConfig config, ImmutableMap<String, ImmutableWorkerInfo> zkWorkers, Task task);
    }

    private final String function;

    // This variable is lazily initialized to avoid unnecessary JavaScript compilation during JSON serde
    private SelectorFunction fnSelector;

    @JsonCreator
    public JavaScriptWorkerSelectStrategy(@JsonProperty("function") String fn,
            @JacksonInject JavaScriptConfig config) {
        Preconditions.checkNotNull(fn, "function must not be null");
        Preconditions.checkState(config.isEnabled(), "JavaScript is disabled");

        this.function = fn;
    }

    private SelectorFunction compileSelectorFunction() {
        final ScriptEngine engine = new ScriptEngineManager().getEngineByName("javascript");
        try {
            ((Compilable) engine).compile("var apply = " + function).eval();
            return ((Invocable) engine).getInterface(SelectorFunction.class);
        } catch (ScriptException e) {
            throw Throwables.propagate(e);
        }
    }

    @Override
    public ImmutableWorkerInfo findWorkerForTask(WorkerTaskRunnerConfig config,
            ImmutableMap<String, ImmutableWorkerInfo> zkWorkers, Task task) {
        fnSelector = fnSelector == null ? compileSelectorFunction() : fnSelector;
        String worker = fnSelector.apply(config, zkWorkers, task);
        return worker == null ? null : zkWorkers.get(worker);
    }

    @JsonProperty
    public String getFunction() {
        return function;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        JavaScriptWorkerSelectStrategy that = (JavaScriptWorkerSelectStrategy) o;

        if (function != null ? !function.equals(that.function) : that.function != null) {
            return false;
        }

        return true;
    }

    @Override
    public int hashCode() {
        return function.hashCode();
    }

    @Override
    public String toString() {
        return "JavaScriptWorkerSelectStrategy{" + "function='" + function + '\'' + '}';
    }
}