src/java.base/share/classes/jdk/internal/access/JavaNioAccess.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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package jdk.internal.access;

import jdk.internal.access.foreign.MappedMemoryUtilsProxy;
import jdk.internal.access.foreign.UnmapperProxy;
import jdk.internal.foreign.AbstractMemorySegmentImpl;
import jdk.internal.foreign.MemorySessionImpl;
import jdk.internal.misc.VM.BufferPool;

import java.lang.foreign.MemorySegment;
import java.nio.Buffer;
import java.nio.ByteBuffer;

public interface JavaNioAccess {

    /**
     * Used by {@code jdk.internal.misc.VM}.
     */
    BufferPool getDirectBufferPool();

    /**
     * Constructs a direct ByteBuffer referring to the block of memory starting
     * at the given memory address and extending {@code cap} bytes.
     * The {@code ob} parameter is an arbitrary object that is attached
     * to the resulting buffer.
     * Used by {@code jdk.internal.foreignMemorySegmentImpl}.
     */
    ByteBuffer newDirectByteBuffer(long addr, int cap, Object obj, MemorySegment segment);

    /**
     * Constructs a mapped ByteBuffer referring to the block of memory starting
     * at the given memory address and extending {@code cap} bytes.
     * The {@code ob} parameter is an arbitrary object that is attached
     * to the resulting buffer. The {@code sync} and {@code fd} parameters of the mapped
     * buffer are derived from the {@code UnmapperProxy}.
     * Used by {@code jdk.internal.foreignMemorySegmentImpl}.
     */
    ByteBuffer newMappedByteBuffer(UnmapperProxy unmapperProxy, long addr, int cap, Object obj, MemorySegment segment);

    /**
     * Constructs an heap ByteBuffer with given backing array, offset, capacity and segment.
     * Used by {@code jdk.internal.foreignMemorySegmentImpl}.
     */
    ByteBuffer newHeapByteBuffer(byte[] hb, int offset, int capacity, MemorySegment segment);

    /**
     * Used by {@code sun.nio.ch.Util}.
     */
    ByteBuffer newDirectByteBuffer(long addr, int cap);

    /**
     * Used by {@code jdk.internal.foreign.Utils}.
     */
    Object getBufferBase(Buffer bb);

    /**
     * Used by {@code jdk.internal.foreign.Utils}.
     */
    long getBufferAddress(Buffer buffer);

    /**
     * Used by {@code jdk.internal.foreign.Utils}.
     */
    UnmapperProxy unmapper(Buffer buffer);

    /**
     * Used by {@code jdk.internal.foreign.AbstractMemorySegmentImpl} and byte buffer var handle views.
     */
    MemorySegment bufferSegment(Buffer buffer);

    /**
     * Used by operations to make a buffer's session non-closeable
     * (for the duration of the operation) by acquiring the session.
     * {@snippet lang = java:
     * acquireSession(buffer);
     * try {
     *     performOperation(buffer);
     * } finally {
     *     releaseSession(buffer);
     * }
     *}
     *
     * @see #releaseSession(Buffer)
     */
    void acquireSession(Buffer buffer);

    void releaseSession(Buffer buffer);

    boolean isThreadConfined(Buffer buffer);

    boolean hasSession(Buffer buffer);

    /**
     * Used by {@code jdk.internal.foreign.MappedMemorySegmentImpl}.
     */
    MappedMemoryUtilsProxy mappedMemoryUtils();

    /**
     * Used by {@code jdk.internal.foreign.NativeMemorySegmentImpl}.
     */
    void reserveMemory(long size, long cap);

    /**
     * Used by {@code jdk.internal.foreign.NativeMemorySegmentImpl}.
     */
    void unreserveMemory(long size, long cap);

    /**
     * Used by {@code jdk.internal.foreign.NativeMemorySegmentImpl}.
     */
    int pageSize();

    int scaleShifts(Buffer buffer);

    AbstractMemorySegmentImpl heapSegment(Buffer buffer,
                                          Object base,
                                          long offset,
                                          long length,
                                          boolean readOnly,
                                          MemorySessionImpl bufferScope);

}