FailureFunction.java example

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presto-master
/*
 * 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.
 */
package com.facebook.presto.operator.scalar;

import com.facebook.presto.client.FailureInfo;
import com.facebook.presto.spi.PrestoException;
import com.facebook.presto.spi.StandardErrorCode;
import com.facebook.presto.spi.function.Description;
import com.facebook.presto.spi.function.ScalarFunction;
import com.facebook.presto.spi.function.SqlType;
import com.facebook.presto.spi.type.StandardTypes;
import io.airlift.json.JsonCodec;
import io.airlift.slice.Slice;

public final class FailureFunction
{
    private static final JsonCodec<FailureInfo> JSON_CODEC = JsonCodec.jsonCodec(FailureInfo.class);

    private FailureFunction() {}

    // We shouldn't be using UNKNOWN as an explicit type. This will be fixed when we fix type inference
    @Description("Decodes json to an exception and throws it")
    @ScalarFunction(hidden = true)
    @SqlType("unknown")
    public static void fail(@SqlType(StandardTypes.JSON) Slice failureInfoSlice)
    {
        FailureInfo failureInfo = JSON_CODEC.fromJson(failureInfoSlice.getBytes());
        // wrap the failure in a new exception to append the current stack trace
        throw new PrestoException(StandardErrorCode.GENERIC_USER_ERROR, failureInfo.toException());
    }
}