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The MongoDB Java Driver uber-artifact, containing mongodb-driver, mongodb-driver-core, and bson

There is a newer version: 3.12.14

/*
 * Copyright 2008-present MongoDB, Inc.
 *
 * 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.mongodb.internal.connection;

import com.github.luben.zstd.Zstd;
import com.github.luben.zstd.ZstdInputStream;
import com.mongodb.MongoInternalException;
import org.bson.ByteBuf;
import org.bson.io.BsonOutput;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

class ZstdCompressor extends Compressor {
    @Override
    public String getName() {
        return "zstd";
    }

    @Override
    public byte getId() {
        return 3;
    }

    @Override
    public void compress(final List source, final BsonOutput target) {
        int uncompressedSize = getUncompressedSize(source);

        byte[] singleByteArraySource = new byte[uncompressedSize];
        copy(source, singleByteArraySource);

        try {
            byte[] out = new byte[(int) Zstd.compressBound(uncompressedSize)];
            int compressedSize = (int) Zstd.compress(out, singleByteArraySource, Zstd.maxCompressionLevel());
            target.writeBytes(out, 0, compressedSize);
        } catch (RuntimeException e) {
            throw new MongoInternalException("Unexpected RuntimeException", e);
        }
    }

    private int getUncompressedSize(final List source) {
        int uncompressedSize = 0;
        for (ByteBuf cur : source) {
            uncompressedSize += cur.remaining();
        }
        return uncompressedSize;
    }

    private void copy(final List source, final byte[] in) {
        int offset = 0;
        for (ByteBuf cur : source) {
            int remaining = cur.remaining();
            cur.get(in, offset, remaining);
            offset += remaining;
        }
    }

    @Override
    InputStream getInputStream(final InputStream source) throws IOException {
        return new ZstdInputStream(source);
    }
}