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8221397: Support implementation-defined Map Modes

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Allow implementation-defined extensions to FileChannel MapMode enum

Reviewed-by: alanb
This commit is contained in:
Andrew Dinn 2019-04-09 16:21:20 +01:00
parent 4a477cabd8
commit 1c7d214f53
2 changed files with 27 additions and 13 deletions
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35
src/java.base/share/classes/java/nio/channels/FileChannel.java
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@ -791,7 +791,7 @@ public abstract class FileChannel
// -- Memory-mapped buffers -- // -- Memory-mapped buffers --
/** /**
* A typesafe enumeration for file-mapping modes. * A file-mapping mode.
* *
* @since 1.4 * @since 1.4
* *
@ -819,6 +819,12 @@ public abstract class FileChannel
private final String name; private final String name;
/**
* Constructs an instance of this class. This constructor may be used
* by code in java.base to create file mapping modes beyond the file
* mapping modes defined here.
* @param name the name of the map mode
*/
private MapMode(String name) { private MapMode(String name) {
this.name = name; this.name = name;
} }
@ -837,8 +843,8 @@ public abstract class FileChannel
/** /**
* Maps a region of this channel's file directly into memory. * Maps a region of this channel's file directly into memory.
* *
* <p> A region of a file may be mapped into memory in one of three modes: * <p> The {@code mode} parameter specifies how the region of the file is
* </p> * mapped and may be one of the following modes:
* *
* <ul> * <ul>
* *
@ -859,6 +865,8 @@ public abstract class FileChannel
* *
* </ul> * </ul>
* *
* <p> An implementation may support additional map modes.
*
* <p> For a read-only mapping, this channel must have been opened for * <p> For a read-only mapping, this channel must have been opened for
* reading; for a read/write or private mapping, this channel must have * reading; for a read/write or private mapping, this channel must have
* been opened for both reading and writing. * been opened for both reading and writing.
@ -892,7 +900,8 @@ public abstract class FileChannel
* MapMode#READ_WRITE READ_WRITE}, or {@link MapMode#PRIVATE * MapMode#READ_WRITE READ_WRITE}, or {@link MapMode#PRIVATE
* PRIVATE} defined in the {@link MapMode} class, according to * PRIVATE} defined in the {@link MapMode} class, according to
* whether the file is to be mapped read-only, read/write, or * whether the file is to be mapped read-only, read/write, or
* privately (copy-on-write), respectively * privately (copy-on-write), respectively, or an implementation
* specific map mode
* *
* @param position * @param position
* The position within the file at which the mapped region * The position within the file at which the mapped region
@ -905,25 +914,29 @@ public abstract class FileChannel
* @return The mapped byte buffer * @return The mapped byte buffer
* *
* @throws NonReadableChannelException * @throws NonReadableChannelException
* If the {@code mode} is {@link MapMode#READ_ONLY READ_ONLY} but * If the {@code mode} is {@link MapMode#READ_ONLY READ_ONLY} or
* this channel was not opened for reading * an implementation specific map mode requiring read access
* but this channel was not opened for reading
* *
* @throws NonWritableChannelException * @throws NonWritableChannelException
* If the {@code mode} is {@link MapMode#READ_WRITE READ_WRITE} or * If the {@code mode} is {@link MapMode#READ_WRITE READ_WRITE}.
* {@link MapMode#PRIVATE PRIVATE} but this channel was not opened * {@link MapMode#PRIVATE PRIVATE} or an implementation specific
* for both reading and writing * map mode requiring write access but this channel was not
* opened for both reading and writing
* *
* @throws IllegalArgumentException * @throws IllegalArgumentException
* If the preconditions on the parameters do not hold * If the preconditions on the parameters do not hold
* *
* @throws UnsupportedOperationException
* If an unsupported map mode is specified
*
* @throws IOException * @throws IOException
* If some other I/O error occurs * If some other I/O error occurs
* *
* @see java.nio.channels.FileChannel.MapMode * @see java.nio.channels.FileChannel.MapMode
* @see java.nio.MappedByteBuffer * @see java.nio.MappedByteBuffer
*/ */
public abstract MappedByteBuffer map(MapMode mode, public abstract MappedByteBuffer map(MapMode mode, long position, long size)
long position, long size)
throws IOException; throws IOException;

5
src/java.base/share/classes/sun/nio/ch/FileChannelImpl.java
View File

@ -940,14 +940,15 @@ public class FileChannelImpl
if (size > Integer.MAX_VALUE) if (size > Integer.MAX_VALUE)
throw new IllegalArgumentException("Size exceeds Integer.MAX_VALUE"); throw new IllegalArgumentException("Size exceeds Integer.MAX_VALUE");
int imode = -1; int imode;
if (mode == MapMode.READ_ONLY) if (mode == MapMode.READ_ONLY)
imode = MAP_RO; imode = MAP_RO;
else if (mode == MapMode.READ_WRITE) else if (mode == MapMode.READ_WRITE)
imode = MAP_RW; imode = MAP_RW;
else if (mode == MapMode.PRIVATE) else if (mode == MapMode.PRIVATE)
imode = MAP_PV; imode = MAP_PV;
assert (imode >= 0); else
throw new UnsupportedOperationException();
if ((mode != MapMode.READ_ONLY) && !writable) if ((mode != MapMode.READ_ONLY) && !writable)
throw new NonWritableChannelException(); throw new NonWritableChannelException();
if (!readable) if (!readable)