szetszwo commented on code in PR #9649:
URL: https://github.com/apache/ozone/pull/9649#discussion_r2789577171
##########
hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/impl/ChunkManagerDummyImpl.java:
##########
@@ -72,9 +125,26 @@ public ChunkBuffer readChunk(Container container, BlockID
blockID,
ChunkInfo info, DispatcherContext dispatcherContext)
throws StorageContainerException {
- limitReadSize(info.getLen());
Review Comment:
Let's keeping using `limitReadSize(..)`. It limits the len <=
OZONE_SCM_CHUNK_MAX_SIZE.
Then, we may create the backing file using the size OZONE_SCM_CHUNK_MAX_SIZE.
##########
hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/impl/ChunkManagerDummyImpl.java:
##########
@@ -40,6 +46,53 @@
*/
public class ChunkManagerDummyImpl implements ChunkManager {
+ private static final int DEFAULT_MAP_SIZE = 1 * 1024 * 1024; // 1MB
+
+ private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
+ private volatile MappedByteBuffer mapped;
+ private volatile int mappedSize;
+ private volatile Path backingFile;
+
+ private void ensureMapped(int minSize)
+ throws StorageContainerException {
+ if (mapped != null && mappedSize >= minSize) {
+ return;
+ }
+
+ lock.writeLock().lock();
+ try {
+ if (mapped != null && mappedSize >= minSize) {
+ return;
+ }
+
+ int newSize = Math.max(DEFAULT_MAP_SIZE, minSize);
+ if (backingFile == null) {
+ backingFile = Files.createTempFile("ozone-dummy-chunk-", ".bin");
+ backingFile.toFile().deleteOnExit();
+ }
+
+ try (FileChannel ch = FileChannel.open(backingFile,
+ StandardOpenOption.READ, StandardOpenOption.WRITE)) {
+ long currentSize = ch.size();
+ if (currentSize < newSize) {
+ ch.position(newSize - 1L);
Review Comment:
> ... A later attempt to write bytes at such a position will cause the file
to be grown to accommodate the new bytes; the values of any bytes between the
previous end-of-file and the newly-written bytes are unspecified.
From the [FileChannel
javadoc](https://docs.oracle.com/javase/8/docs/api/java/nio/channels/FileChannel.html#position-long-)
above, we should write zeros for the zero-filled buffer..
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