io.trino.util.CompilerUtils Maven / Gradle / Ivy

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/*
 * 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 io.trino.util;

import io.airlift.bytecode.ClassDefinition;
import io.airlift.bytecode.DynamicClassLoader;
import io.airlift.bytecode.ParameterizedType;
import io.airlift.log.Logger;

import java.lang.invoke.MethodHandle;
import java.time.Instant;
import java.time.format.DateTimeFormatter;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.atomic.AtomicLong;

import static io.airlift.bytecode.BytecodeUtils.toJavaIdentifierString;
import static io.airlift.bytecode.ClassGenerator.classGenerator;
import static io.airlift.bytecode.ParameterizedType.typeFromJavaClassName;
import static java.time.ZoneOffset.UTC;

public final class CompilerUtils
{
    private static final Logger log = Logger.get(CompilerUtils.class);

    private static final AtomicLong CLASS_ID = new AtomicLong();
    private static final DateTimeFormatter TIMESTAMP_FORMAT = DateTimeFormatter.ofPattern("yyyyMMdd_HHmmss");
    private static final String PACKAGE_PREFIX = "io.trino.$gen.";
    // Maximum symbol table entry allowed by the JVM class file format
    private static final int MAX_SYMBOL_TABLE_ENTRY_LENGTH = 65535;
    // Leave enough of a buffer between the maximum generated class name length and the symbol table limit
    // so that method handles and other symbols that embed the class name can be encoded without failing
    private static final int MAX_CLASS_NAME_LENGTH = MAX_SYMBOL_TABLE_ENTRY_LENGTH - 8192;

    private CompilerUtils() {}

    public static ParameterizedType makeClassName(String baseName, Optional suffix)
    {
        String classNameSuffix = suffix.orElseGet(() -> Instant.now().atZone(UTC).format(TIMESTAMP_FORMAT));
        String classUniqueId = String.valueOf(CLASS_ID.incrementAndGet());

        int addedNameLength = PACKAGE_PREFIX.length() +
                2 + // underscores
                classNameSuffix.length() +
                classUniqueId.length();

        // truncate the baseName to ensure that we don't exceed the bytecode limit on class names, while also ensuring
        // the class suffix and unique ID are fully preserved to avoid conflicts with other generated class names
        if (baseName.length() + addedNameLength > MAX_CLASS_NAME_LENGTH) {
            baseName = baseName.substring(0, MAX_CLASS_NAME_LENGTH - addedNameLength);
        }

        String className = baseName + "_" + classNameSuffix + "_" + classUniqueId;
        return typeFromJavaClassName(PACKAGE_PREFIX + toJavaIdentifierString(className));
    }

    public static ParameterizedType makeClassName(String baseName)
    {
        return makeClassName(baseName, Optional.empty());
    }

    public static  Class defineClass(ClassDefinition classDefinition, Class superType, Map callSiteBindings, ClassLoader parentClassLoader)
    {
        return defineClass(classDefinition, superType, new DynamicClassLoader(parentClassLoader, callSiteBindings));
    }

    public static  Class defineClass(ClassDefinition classDefinition, Class superType, DynamicClassLoader classLoader)
    {
        log.debug("Defining class: %s", classDefinition.getName());
        return classGenerator(classLoader).defineClass(classDefinition, superType);
    }
}