taklwu commented on code in PR #11102:
URL: https://github.com/apache/ozone/pull/11102#discussion_r3867022870
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hadoop-hdds/client/src/main/java/org/apache/hadoop/hdds/scm/storage/ChunkInputStream.java:
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@@ -429,6 +429,108 @@ protected void readChunkDataIntoBuffers(ChunkInfo
readChunkInfo)
allocated = true;
}
+ /**
+ * Whether this chunk stream can serve positioned reads without holding a
+ * lock. A plain chunk read is a self-contained RPC, so concurrent callers
+ * reading different ranges do not interfere. Overridden by
+ * {@link LocalChunkInputStream}, which reads from a shared {@link
+ * java.nio.channels.FileChannel} and therefore must serialize.
+ */
+ boolean supportsConcurrentPositionedRead() {
+ return true;
+ }
+
+ /**
+ * Stateless positioned read of up to {@code dst.remaining()} bytes starting
+ * at {@code chunkRelativePosition} within this chunk. Unlike the buffered
+ * {@link #read} path, this does not read or mutate any of the instance's
+ * buffer/position state ({@code buffers}, {@code chunkPosition},
+ * {@code bufferOffsetWrtChunkData}, ...), so it is safe to call concurrently
+ * from multiple threads sharing the same stream.
+ *
+ * @param chunkRelativePosition start offset within this chunk
+ * @param dst destination buffer
+ * @return number of bytes copied into {@code dst}, or {@link #EOF} at EOF
+ */
+ int readPositioned(long chunkRelativePosition, ByteBuffer dst)
+ throws IOException {
+ if (supportsConcurrentPositionedRead()) {
+ return doPositionedRead(chunkRelativePosition, dst);
+ }
+ // Local (short-circuit) reads share a FileChannel cursor; serialize them.
+ synchronized (this) {
Review Comment:
yup, you're right about the positional FileChannel, I made the change and
please review again.
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