* The returned spliterator effectively allows to slice a segment into disjoint sub-segments, which can then * be processed in parallel by multiple threads (if the access mode {@link #ACQUIRE} is set). @@ -320,6 +321,10 @@ * buffer. The segment starts relative to the buffer's position (inclusive) * and ends relative to the buffer's limit (exclusive). *
+ * The segment will feature all access modes, unless the given + * buffer is {@linkplain ByteBuffer#isReadOnly() read-only} in which case the segment will + * not feature the {@link #WRITE} access mode. + *
* The resulting memory segment keeps a reference to the backing buffer, to ensure it remains reachable * for the life-time of the segment. * @@ -334,7 +339,7 @@ * Creates a new array memory segment that models the memory associated with a given heap-allocated byte array. *
* The resulting memory segment keeps a reference to the backing array, to ensure it remains reachable - * for the life-time of the segment. + * for the life-time of the segment. The segment will feature all access modes. * * @param arr the primitive array backing the array memory segment. * @return a new array memory segment. @@ -347,7 +352,7 @@ * Creates a new array memory segment that models the memory associated with a given heap-allocated char array. *
* The resulting memory segment keeps a reference to the backing array, to ensure it remains reachable - * for the life-time of the segment. + * for the life-time of the segment. The segment will feature all access modes. * * @param arr the primitive array backing the array memory segment. * @return a new array memory segment. @@ -360,7 +365,7 @@ * Creates a new array memory segment that models the memory associated with a given heap-allocated short array. *
* The resulting memory segment keeps a reference to the backing array, to ensure it remains reachable - * for the life-time of the segment. + * for the life-time of the segment. The segment will feature all access modes. * * @param arr the primitive array backing the array memory segment. * @return a new array memory segment. @@ -373,7 +378,7 @@ * Creates a new array memory segment that models the memory associated with a given heap-allocated int array. *
* The resulting memory segment keeps a reference to the backing array, to ensure it remains reachable - * for the life-time of the segment. + * for the life-time of the segment. The segment will feature all access modes. * * @param arr the primitive array backing the array memory segment. * @return a new array memory segment. @@ -386,7 +391,7 @@ * Creates a new array memory segment that models the memory associated with a given heap-allocated float array. *
* The resulting memory segment keeps a reference to the backing array, to ensure it remains reachable - * for the life-time of the segment. + * for the life-time of the segment. The segment will feature all access modes. * * @param arr the primitive array backing the array memory segment. * @return a new array memory segment. @@ -399,7 +404,7 @@ * Creates a new array memory segment that models the memory associated with a given heap-allocated long array. *
* The resulting memory segment keeps a reference to the backing array, to ensure it remains reachable - * for the life-time of the segment. + * for the life-time of the segment. The segment will feature all access modes. * * @param arr the primitive array backing the array memory segment. * @return a new array memory segment. @@ -412,7 +417,7 @@ * Creates a new array memory segment that models the memory associated with a given heap-allocated double array. *
* The resulting memory segment keeps a reference to the backing array, to ensure it remains reachable - * for the life-time of the segment. + * for the life-time of the segment. The segment will feature all access modes. * * @param arr the primitive array backing the array memory segment. * @return a new array memory segment. @@ -463,6 +468,10 @@ /** * Creates a new mapped memory segment that models a memory-mapped region of a file from a given path. + *
+ * The segment will feature all access modes, unless the given mapping mode + * is {@linkplain FileChannel.MapMode#READ_ONLY READ_ONLY}, in which case the segment will not feature + * the {@link #WRITE} access mode. * * @implNote When obtaining a mapped segment from a newly created file, the initialization state of the contents of the block * of mapped memory associated with the returned mapped memory segment is unspecified and should not be relied upon. @@ -482,7 +491,7 @@ /** * Creates a new native memory segment that models a newly allocated block of off-heap memory with given size and - * alignment constraint (in bytes). + * alignment constraint (in bytes). The segment will feature all access modes. * * @implNote The block of off-heap memory associated with the returned native memory segment is initialized to zero. * Moreover, a client is responsible to call the {@link MemorySegment#close()} on a native memory segment, @@ -512,7 +521,7 @@ * bounds, and can therefore be closed; closing such a segment can optionally result in calling an user-provided cleanup * action. This method can be very useful when interacting with custom native memory sources (e.g. custom allocators, * GPU memory, etc.), where an address to some underlying memory region is typically obtained from native code - * (often as a plain {@code long} value). + * (often as a plain {@code long} value). The segment will feature all access modes. *
* This method is restricted. Restricted method are unsafe, and, if used incorrectly, their use might crash
* the JVM crash or, worse, silently result in memory corruption. Thus, clients should refrain from depending on
--- old/src/jdk.incubator.foreign/share/classes/jdk/internal/foreign/MappedMemorySegmentImpl.java 2020-04-30 16:04:02.000000000 +0100
+++ new/src/jdk.incubator.foreign/share/classes/jdk/internal/foreign/MappedMemorySegmentImpl.java 2020-04-30 16:04:02.000000000 +0100
@@ -104,8 +104,12 @@
try (FileChannelImpl channelImpl = (FileChannelImpl)FileChannel.open(path, openOptions(mapMode))) {
UnmapperProxy unmapperProxy = channelImpl.mapInternal(mapMode, 0L, bytesSize);
MemoryScope scope = new MemoryScope(null, unmapperProxy::unmap);
+ int modes = defaultAccessModes(bytesSize);
+ if (mapMode == FileChannel.MapMode.READ_ONLY) {
+ modes &= ~WRITE;
+ }
return new MappedMemorySegmentImpl(unmapperProxy.address(), unmapperProxy, bytesSize,
- defaultAccessModes(bytesSize), Thread.currentThread(), scope);
+ modes, Thread.currentThread(), scope);
}
}
--- old/test/jdk/java/foreign/TestByteBuffer.java 2020-04-30 16:04:05.000000000 +0100
+++ new/test/jdk/java/foreign/TestByteBuffer.java 2020-04-30 16:04:05.000000000 +0100
@@ -78,7 +78,7 @@
import org.testng.SkipException;
import org.testng.annotations.*;
import sun.nio.ch.DirectBuffer;
-
+import static jdk.incubator.foreign.MemorySegment.*;
import static org.testng.Assert.*;
public class TestByteBuffer {
@@ -236,6 +236,21 @@
}
}
+ static final int ALL_ACCESS_MODES = READ | WRITE | CLOSE | ACQUIRE | HANDOFF;
+
+ @Test
+ public void testDefaultAccessModesMappedSegment() throws Throwable {
+ try (MappedMemorySegment segment = MemorySegment.mapFromPath(tempPath, 8, FileChannel.MapMode.READ_WRITE)) {
+ assertTrue(segment.hasAccessModes(ALL_ACCESS_MODES));
+ assertEquals(segment.accessModes(), ALL_ACCESS_MODES);
+ }
+
+ try (MappedMemorySegment segment = MemorySegment.mapFromPath(tempPath, 8, FileChannel.MapMode.READ_ONLY)) {
+ assertTrue(segment.hasAccessModes(ALL_ACCESS_MODES & ~WRITE));
+ assertEquals(segment.accessModes(), ALL_ACCESS_MODES& ~WRITE);
+ }
+ }
+
@Test
public void testMappedSegment() throws Throwable {
File f = new File("test2.out");
@@ -446,6 +461,21 @@
}
}
+ @Test
+ public void testDefaultAccessModesOfBuffer() {
+ ByteBuffer rwBuffer = ByteBuffer.wrap(new byte[4]);
+ try (MemorySegment segment = MemorySegment.ofByteBuffer(rwBuffer)) {
+ assertTrue(segment.hasAccessModes(ALL_ACCESS_MODES));
+ assertEquals(segment.accessModes(), ALL_ACCESS_MODES);
+ }
+
+ ByteBuffer roBuffer = rwBuffer.asReadOnlyBuffer();
+ try (MemorySegment segment = MemorySegment.ofByteBuffer(roBuffer)) {
+ assertTrue(segment.hasAccessModes(ALL_ACCESS_MODES & ~WRITE));
+ assertEquals(segment.accessModes(), ALL_ACCESS_MODES & ~WRITE);
+ }
+ }
+
@Test(dataProvider="bufferSources")
public void testBufferToSegment(ByteBuffer bb, Predicate