nizhikov commented on code in PR #11518: URL: https://github.com/apache/ignite/pull/11518#discussion_r1836104321
########## modules/core/src/main/java/org/apache/ignite/internal/jdbc2/JdbcBinaryBuffer.java: ########## @@ -0,0 +1,449 @@ +/* + * 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.ignite.internal.jdbc2; + +import java.io.IOException; +import java.io.InputStream; +import java.io.OutputStream; +import java.util.Objects; +import org.apache.ignite.internal.util.typedef.internal.U; + +import static org.apache.ignite.internal.binary.streams.BinaryAbstractOutputStream.MAX_ARRAY_SIZE; + +/** + * Buffer storing the binary data. + * + * <p>Buffer can start working in read-only mode if created wrapping the existing byte array which + * can not be modified. Any write operation switches it lazily to the read-write mode. This allows + * to prevent the unnecessary data copying. + * + * <p>Data may be read via the InputStream API and modified via the OutputStream one. Changes done via + * OutputStream are visible via the InputStream even if InputStream is created before changes done. + * + * <p>InputStream and OutputStream created remain valid even if the underlying data storage changed from + * read-only to read-write. + * + * <p>Note however that implementation is not thread-safe. + */ +public class JdbcBinaryBuffer { + /** Byte array storing data. */ + private byte[] arr; + + /** Offset the data starts in the array. */ + private int off; + + /** The length of data. */ + private int len; + + /** Read only flag. */ + private boolean isReadOnly; + + /** Minimum buffer capacity. */ + public static final int MIN_CAP = 256; + + /** + * Create buffer which wraps the existing byte array and start working in the read-only mode. + * + * @param arr The byte array to be wrapped. + * @param off The offset to the first byte to be wrapped. + * @param len The length in bytes of the data to be wrapped. + */ + public static JdbcBinaryBuffer createReadOnly(byte[] arr, int off, int len) { + return new JdbcBinaryBuffer(arr, off, len, true); + } + + /** + * Create buffer which takes ownerhip of and wraps data in the existing byte array and + * starts working in the read-write mode. + * + * @param arr The byte array to be wrapped. + */ + public static JdbcBinaryBuffer createReadWrite(byte[] arr) { + return new JdbcBinaryBuffer(arr, 0, arr.length, false); + } + + /** + * Create empty buffer which starts working in the read-write mode. + */ + public static JdbcBinaryBuffer createReadWrite() { + return new JdbcBinaryBuffer(new byte[MIN_CAP], 0, 0, false); + } + + /** + * Private constructor. + * + * @param arr The byte array to be wrapped. + * @param off The offset to the first byte to be wrapped. + * @param len The length in bytes of the data to be wrapped. + * @param isReadOnly The read-only flag. + */ + private JdbcBinaryBuffer(byte[] arr, int off, int len, boolean isReadOnly) { + this.arr = arr; + this.off = off; + this.len = len; + this.isReadOnly = isReadOnly; + } + + /** + * Create shallow read-only copy of this buffer. + */ + public JdbcBinaryBuffer shallowCopy() { + return new JdbcBinaryBuffer(arr, off, len, true); + } + + /** + * Provide InputStream through which the data can be read starting from the + * begining. + * + * <p>Stream is not limited meaning that it would return any new data + * written to the buffer after stream creation. + * + * @return InputStream instance. + */ + public InputStream inputStream() { + return new BufferInputStream(); + } + + /** + * Get copy of the buffer data as byte array. + * + * @return Byte array containing buffer data. + */ + public byte[] bytes() { + byte[] bytes = new byte[len]; + + read(0, bytes, 0, len); + + return bytes; + } + + /** + * Provide OutputStream through which the data can be written to buffer starting from + * the (zero-based) {@code pos} position. + * + * @param pos The zero-based offset to the first byte to be written. Must not be negative + * or greater than total count of bytes in buffer. + * + * @return OutputStream instance. + */ + OutputStream outputStream(int pos) { + return new BufferOutputStream(pos); + } + + /** + * Provide InputStream through which the no more than {@code len} bytes can be read + * from buffer starting from the specified zero-based position {@code pos}. + * + * @param pos The zero-based offset to the first byte to be retrieved. Must not be negative + * or greater than total count of bytes in buffer. + * @param len The length in bytes of the data to be retrieved. Must not be negative. + * @return InputStream instance. + */ + InputStream inputStream(int pos, int len) { + return new BufferInputStream(pos, pos + len); + } + + /** + * Truncate data in this buffer to specified length. + * + * @param len New length. + */ + void truncate(int len) { + this.len = len; + + reallocate(Math.max(MIN_CAP, len)); Review Comment: Why we want to keep MIN_CAP size even if user ask to trunkcate data to `len`? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: notifications-unsubscr...@ignite.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
