org.apache.drill.exec.expr.fn.FunctionImplementationRegistry.java Source code

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Here is the source code for org.apache.drill.exec.expr.fn.FunctionImplementationRegistry.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.drill.exec.expr.fn;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.List;
import java.util.Set;
import java.util.concurrent.TimeUnit;

import org.apache.drill.common.config.DrillConfig;
import org.apache.drill.common.expression.FunctionCall;
import org.apache.drill.common.expression.fn.CastFunctions;
import org.apache.drill.common.types.TypeProtos;
import org.apache.drill.common.types.TypeProtos.MajorType;
import org.apache.drill.common.util.PathScanner;
import org.apache.drill.exec.ExecConstants;
import org.apache.drill.exec.planner.sql.DrillOperatorTable;
import org.apache.drill.exec.resolver.FunctionResolver;

import com.google.common.base.Stopwatch;
import com.google.common.collect.Lists;
import org.apache.drill.exec.server.options.OptionManager;

public class FunctionImplementationRegistry implements FunctionLookupContext {
    static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(FunctionImplementationRegistry.class);

    private DrillFunctionRegistry drillFuncRegistry;
    private List<PluggableFunctionRegistry> pluggableFuncRegistries = Lists.newArrayList();
    private OptionManager optionManager = null;

    public FunctionImplementationRegistry(DrillConfig config) {
        Stopwatch w = new Stopwatch().start();

        logger.debug("Generating function registry.");
        drillFuncRegistry = new DrillFunctionRegistry(config);

        Set<Class<? extends PluggableFunctionRegistry>> registryClasses = PathScanner.scanForImplementations(
                PluggableFunctionRegistry.class, config.getStringList(ExecConstants.FUNCTION_PACKAGES));

        for (Class<? extends PluggableFunctionRegistry> clazz : registryClasses) {
            for (Constructor<?> c : clazz.getConstructors()) {
                Class<?>[] params = c.getParameterTypes();
                if (params.length != 1 || params[0] != DrillConfig.class) {
                    logger.warn(
                            "Skipping PluggableFunctionRegistry constructor {} for class {} since it doesn't implement a "
                                    + "[constructor(DrillConfig)]",
                            c, clazz);
                    continue;
                }

                try {
                    PluggableFunctionRegistry registry = (PluggableFunctionRegistry) c.newInstance(config);
                    pluggableFuncRegistries.add(registry);
                } catch (InstantiationException | IllegalAccessException | IllegalArgumentException
                        | InvocationTargetException e) {
                    logger.warn("Unable to instantiate PluggableFunctionRegistry class '{}'. Skipping it.", clazz,
                            e);
                }

                break;
            }
        }
        logger.info("Function registry loaded.  {} functions loaded in {} ms.", drillFuncRegistry.size(),
                w.elapsed(TimeUnit.MILLISECONDS));
    }

    public FunctionImplementationRegistry(DrillConfig config, OptionManager optionManager) {
        this(config);
        this.optionManager = optionManager;
    }

    /**
     * Register functions in given operator table.
     * @param operatorTable
     */
    public void register(DrillOperatorTable operatorTable) {
        // Register Drill functions first and move to pluggable function registries.
        drillFuncRegistry.register(operatorTable);

        for (PluggableFunctionRegistry registry : pluggableFuncRegistries) {
            registry.register(operatorTable);
        }
    }

    /**
     * Using the given <code>functionResolver</code> find Drill function implementation for given
     * <code>functionCall</code>
     *
     * @param functionResolver
     * @param functionCall
     * @return
     */
    @Override
    public DrillFuncHolder findDrillFunction(FunctionResolver functionResolver, FunctionCall functionCall) {
        return functionResolver.getBestMatch(drillFuncRegistry.getMethods(functionReplacement(functionCall)),
                functionCall);
    }

    // Check if this Function Replacement is needed; if yes, return a new name. otherwise, return the original name
    private String functionReplacement(FunctionCall functionCall) {
        String funcName = functionCall.getName();
        if (optionManager != null && optionManager.getOption(ExecConstants.CAST_TO_NULLABLE_NUMERIC).bool_val
                && functionCall.args.size() > 0 && CastFunctions
                        .isReplacementNeeded(functionCall.args.get(0).getMajorType().getMinorType(), funcName)) {
            org.apache.drill.common.types.TypeProtos.DataMode dataMode = functionCall.args.get(0).getMajorType()
                    .getMode();
            funcName = CastFunctions.getReplacingCastFunction(funcName, dataMode);
        }

        return funcName;
    }

    /**
     * Find the Drill function implementation that matches the name, arg types and return type.
     * @param name
     * @param argTypes
     * @param returnType
     * @return
     */
    public DrillFuncHolder findExactMatchingDrillFunction(String name, List<MajorType> argTypes,
            MajorType returnType) {
        for (DrillFuncHolder h : drillFuncRegistry.getMethods(name)) {
            if (h.matches(returnType, argTypes)) {
                return h;
            }
        }

        return null;
    }

    /**
     * Find function implementation for given <code>functionCall</code> in non-Drill function registries such as Hive UDF
     * registry.
     *
     * Note: Order of searching is same as order of {@link org.apache.drill.exec.expr.fn.PluggableFunctionRegistry}
     * implementations found on classpath.
     *
     * @param functionCall
     * @return
     */
    @Override
    public AbstractFuncHolder findNonDrillFunction(FunctionCall functionCall) {
        for (PluggableFunctionRegistry registry : pluggableFuncRegistries) {
            AbstractFuncHolder h = registry.getFunction(functionCall);
            if (h != null) {
                return h;
            }
        }

        return null;
    }

    // Method to find if the output type of a drill function if of complex type
    public boolean isFunctionComplexOutput(String name) {
        List<DrillFuncHolder> methods = drillFuncRegistry.getMethods(name);
        for (DrillFuncHolder holder : methods) {
            if (holder.getReturnValue().isComplexWriter()) {
                return true;
            }
        }
        return false;
    }
}