101 lines
4.1 KiB
Java
101 lines
4.1 KiB
Java
/*
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* Copyright 2020 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.buffer.api;
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import java.nio.ByteBuffer;
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/**
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* A view onto the buffer component being processed in a given iteration of
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* {@link Buffer#forEachReadable(int, ReadableComponentProcessor)}.
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*/
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public interface ReadableComponent {
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/**
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* Check if this component is backed by a cached byte array than can be accessed cheaply.
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* <p>
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* <strong>Note</strong> that regardless of what this method returns, the array should not be used to modify the
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* contents of this buffer component.
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*
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* @return {@code true} if {@link #readableArray()} is a cheap operation, otherwise {@code false}.
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*/
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boolean hasReadableArray();
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/**
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* Get a byte array of the contents of this component.
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* <p>
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* <strong>Note</strong> that the array is meant to be read-only. It may either be a direct reference to the
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* concrete array instance that is backing this component, or it is a fresh copy. Writing to the array may produce
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* undefined behaviour.
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*
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* @return A byte array of the contents of this component.
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* @throws UnsupportedOperationException if {@link #hasReadableArray()} returns {@code false}.
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* @see #readableArrayOffset()
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* @see #readableArrayLength()
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*/
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byte[] readableArray();
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/**
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* An offset into the {@link #readableArray()} where this component starts.
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*
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* @return An offset into {@link #readableArray()}.
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* @throws UnsupportedOperationException if {@link #hasReadableArray()} returns {@code false}.
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*/
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int readableArrayOffset();
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/**
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* The number of bytes in the {@link #readableArray()} that belong to this component.
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*
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* @return The number of bytes, from the {@link #readableArrayOffset()} into the {@link #readableArray()},
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* that belong to this component.
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* @throws UnsupportedOperationException if {@link #hasReadableArray()} returns {@code false}.
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*/
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int readableArrayLength();
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/**
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* Give the native memory address backing this buffer, or return 0 if this buffer has no native memory address.
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* <p>
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* <strong>Note</strong> that the address should not be used for writing to the buffer memory, and doing so may
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* produce undefined behaviour.
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*
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* @return The native memory address, if any, otherwise 0.
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*/
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long readableNativeAddress();
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/**
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* Get a {@link ByteBuffer} instance for this memory component.
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* <p>
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* <strong>Note</strong> that the {@link ByteBuffer} is read-only, to prevent write accesses to the memory,
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* when the buffer component is obtained through {@link Buffer#forEachReadable(int, ReadableComponentProcessor)}.
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*
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* @return A new {@link ByteBuffer}, with its own position and limit, for this memory component.
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*/
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ByteBuffer readableBuffer();
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/**
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* Open a cursor to iterate the readable bytes of this component.
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* Any offsets internal to the component are not modified by the cursor.
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* <p>
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* Care should be taken to ensure that the buffers lifetime extends beyond the cursor and the iteration, and that
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* the internal offsets of the component (such as {@link Buffer#readerOffset()} and {@link Buffer#writerOffset()})
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* are not modified while the iteration takes place. Otherwise unpredictable behaviour might result.
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*
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* @return A {@link ByteCursor} for iterating the readable bytes of this buffer.
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* @see Buffer#openCursor()
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*/
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ByteCursor openCursor();
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// todo for Unsafe-based impl, DBB.attachment needs to keep underlying memory alive
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}
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