io.prestosql.jdbc.$internal.okio.Source Maven / Gradle / Ivy
/*
* Copyright (C) 2014 Square, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.prestosql.jdbc.$internal.okio;
import java.io.Closeable;
import java.io.IOException;
/**
* Supplies a stream of bytes. Use this interface to read data from wherever
* it's located: from the network, storage, or a buffer in memory. Sources may
* be layered to transform supplied data, such as to decompress, decrypt, or
* remove protocol framing.
*
* Most applications shouldn't operate on a source directly, but rather on a
* {@link BufferedSource} which is both more efficient and more convenient. Use
* {@link Okio#buffer(Source)} to wrap any source with a buffer.
*
*
Sources are easy to test: just use a {@link Buffer} in your tests, and
* fill it with the data your application is to read.
*
*
Comparison with InputStream
* This interface is functionally equivalent to {@link java.io.InputStream}.
*
* {@code InputStream} requires multiple layers when consumed data is
* heterogeneous: a {@code DataInputStream} for primitive values, a {@code
* BufferedInputStream} for buffering, and {@code InputStreamReader} for
* strings. This class uses {@code BufferedSource} for all of the above.
*
*
Source avoids the impossible-to-implement {@linkplain
* java.io.InputStream#available available()} method. Instead callers specify
* how many bytes they {@link BufferedSource#require require}.
*
*
Source omits the unsafe-to-compose {@linkplain java.io.InputStream#mark
* mark and reset} state that's tracked by {@code InputStream}; instead, callers
* just buffer what they need.
*
*
When implementing a source, you don't need to worry about the {@linkplain
* java.io.InputStream#read single-byte read} method that is awkward to implement efficiently
* and returns one of 257 possible values.
*
*
And source has a stronger {@code skip} method: {@link BufferedSource#skip}
* won't return prematurely.
*
*
Interop with InputStream
* Use {@link Okio#source} to adapt an {@code InputStream} to a source. Use
* {@link BufferedSource#inputStream} to adapt a source to an {@code
* InputStream}.
*/
public interface Source extends Closeable {
/**
* Removes at least 1, and up to {@code byteCount} bytes from this and appends
* them to {@code sink}. Returns the number of bytes read, or -1 if this
* source is exhausted.
*/
long read(Buffer sink, long byteCount) throws IOException;
/** Returns the timeout for this source. */
Timeout timeout();
/**
* Closes this source and releases the resources held by this source. It is an
* error to read a closed source. It is safe to close a source more than once.
*/
@Override void close() throws IOException;
}