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8224974: Implement JEP 352

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Non-Volatile Mapped Byte Buffers

Reviewed-by: alanb, kvn, bpb, gromero, darcy, shade, bulasevich, dchuyko
This commit is contained in:
Andrew Dinn 2019-08-20 10:11:53 +01:00
parent db359f11b5
commit 047b8bfeb7
53 changed files with 1400 additions and 69 deletions
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57
src/java.base/share/classes/java/nio/MappedByteBuffer.java
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@ -78,18 +78,33 @@ public abstract class MappedByteBuffer
// operations if valid; null if the buffer is not mapped.
private final FileDescriptor fd;
// A flag true if this buffer is mapped against non-volatile
// memory using one of the extended FileChannel.MapMode modes,
// MapMode.READ_ONLY_SYNC or MapMode.READ_WRITE_SYNC and false if
// it is mapped using any of the other modes. This flag only
// determines the behavior of force operations.
private final boolean isSync;
// This should only be invoked by the DirectByteBuffer constructors
//
MappedByteBuffer(int mark, int pos, int lim, int cap, // package-private
FileDescriptor fd)
{
FileDescriptor fd, boolean isSync) {
super(mark, pos, lim, cap);
this.fd = fd;
this.isSync = isSync;
}
MappedByteBuffer(int mark, int pos, int lim, int cap, // package-private
boolean isSync) {
super(mark, pos, lim, cap);
this.fd = null;
this.isSync = isSync;
}
MappedByteBuffer(int mark, int pos, int lim, int cap) { // package-private
super(mark, pos, lim, cap);
this.fd = null;
this.isSync = false;
}
// Returns the distance (in bytes) of the buffer start from the
@ -146,6 +161,23 @@ public abstract class MappedByteBuffer
return address & ~(pageSize - 1);
}
/**
* Tells whether this buffer was mapped against a non-volatile
* memory device by passing one of the sync map modes {@link
* jdk.nio.mapmode.ExtendedMapMode#READ_ONLY_SYNC
* ExtendedMapModeMapMode#READ_ONLY_SYNC} or {@link
* jdk.nio.mapmode.ExtendedMapMode#READ_ONLY_SYNC
* ExtendedMapMode#READ_WRITE_SYNC} in the call to {@link
* java.nio.channels.FileChannel#map FileChannel.map} or was
* mapped by passing one of the other map modes.
*
* @return true if the file was mapped using one of the sync map
* modes, otherwise false.
*/
private boolean isSync() {
return isSync;
}
/**
* Tells whether or not this buffer's content is resident in physical
* memory.
@ -168,6 +200,10 @@ public abstract class MappedByteBuffer
if (fd == null) {
return true;
}
// a sync mapped buffer is always loaded
if (isSync()) {
return true;
}
if ((address == 0) || (capacity() == 0))
return true;
long offset = mappingOffset();
@ -192,6 +228,10 @@ public abstract class MappedByteBuffer
if (fd == null) {
return this;
}
// no need to load a sync mapped buffer
if (isSync()) {
return this;
}
if ((address == 0) || (capacity() == 0))
return this;
long offset = mappingOffset();
@ -247,6 +287,9 @@ public abstract class MappedByteBuffer
if (fd == null) {
return this;
}
if (isSync) {
return force(0, limit());
}
if ((address != 0) && (capacity() != 0)) {
long offset = mappingOffset();
force0(fd, mappingAddress(offset), mappingLength(offset));
@ -303,8 +346,14 @@ public abstract class MappedByteBuffer
if ((address != 0) && (limit() != 0)) {
// check inputs
Objects.checkFromIndexSize(index, length, limit());
long offset = mappingOffset(index);
force0(fd, mappingAddress(offset, index), mappingLength(offset, length));
if (isSync) {
// simply force writeback of associated cache lines
Unsafe.getUnsafe().writebackMemory(address + index, length);
} else {
// force writeback via file descriptor
long offset = mappingOffset(index);
force0(fd, mappingAddress(offset, index), mappingLength(offset, length));
}
}
return this;
}