netty-incubator-buffer-api/src/main/java/io/netty/buffer/api/WritableComponent.java
Chris Vest 95709828bf Add a ByteBuffer based implementation of Buffer
Motivation:
We need a new implementation of our new API that supports Java 11, since that is what Netty 5 will most likely baseline on.
We also need an implementation that does not rely on Unsafe.
This leaves us with ByteBuffer as the underlying currency of memory.

Modification:
- Add a NioBuffer implementation and associated supporting classes.
- The entry-point for this is a new MemoryManagers API, which is used to pick the implementation and provide the on-/off-heap MemoryManager implementations.
- Add a mechanism to configure/override which MemoryManagers implementation to use.
- The MemoryManagers implementations are service-loadable, so new ones can be discovered at runtime.
- The existing MemorySegment based implementation also get a MemoryManagers implementation.
- Expand the BufferTest to include all combinations of all implementations. We now run 360.000 tests in BufferTest.
- Some common infrastructure, like ArcDrop, is moved to its own package.
- Add a module-info.java to control the service loading, and the visibility in the various packages.
- Some pom.xml file updates to support our now module based project.

Result:
We have an implementation that should work on Java 11, but we currently don't build or test on 11.
More work needs to happen before that is a reality.
2021-03-18 15:18:22 +01:00

75 lines
2.6 KiB
Java

/*
* Copyright 2020 The Netty Project
*
* The Netty Project 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:
*
* https://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.netty.buffer.api;
import java.nio.ByteBuffer;
/**
* A view onto the buffer component being processed in a given iteration of
* {@link Buffer#forEachWritable(int, WritableComponentProcessor)}.
*/
public interface WritableComponent {
/**
* Check if this component is backed by a cached byte array than can be accessed cheaply.
*
* @return {@code true} if {@link #writableArray()} is a cheap operation, otherwise {@code false}.
*/
boolean hasWritableArray();
/**
* Get a byte array of the contents of this component.
*
* @return A byte array of the contents of this component.
* @throws UnsupportedOperationException if {@link #hasWritableArray()} returns {@code false}.
* @see #writableArrayOffset()
* @see #writableArrayLength()
*/
byte[] writableArray();
/**
* An offset into the {@link #writableArray()} where this component starts.
*
* @return An offset into {@link #writableArray()}.
* @throws UnsupportedOperationException if {@link #hasWritableArray()} returns {@code false}.
*/
int writableArrayOffset();
/**
* The number of bytes in the {@link #writableArray()} that belong to this component.
*
* @return The number of bytes, from the {@link #writableArrayOffset()} into the {@link #writableArray()},
* that belong to this component.
* @throws UnsupportedOperationException if {@link #hasWritableArray()} returns {@code false}.
*/
int writableArrayLength();
/**
* Give the native memory address backing this buffer, or return 0 if this buffer has no native memory address.
*
* @return The native memory address, if any, otherwise 0.
*/
long writableNativeAddress();
/**
* Get a {@link ByteBuffer} instance for this memory component, which can be used for modifying the buffer
* contents.
*
* @return A new {@link ByteBuffer}, with its own position and limit, for this memory component.
*/
ByteBuffer writableBuffer();
}