taklwu commented on code in PR #11245:
URL: https://github.com/apache/ozone/pull/11245#discussion_r4065223839
##########
hadoop-ozone/ozonefs-common/src/main/java/org/apache/hadoop/fs/ozone/OzoneFSInputStream.java:
##########
@@ -211,4 +225,101 @@ public void readFully(long position, ByteBuffer buf)
throws IOException {
}
}
}
+
+ /**
+ * Byte-array positioned read. Tries the native stateless {@link
ExtendedInputStream#readFully}
+ * path first (via a zero-copy {@link ByteBuffer#wrap}). Falls back to a
synchronized
+ * seek-read-restore using byte-array {@link #read(byte[], int, int)} so
that the fallback
+ * works for any {@link Seekable} stream, not just those that also implement
+ * {@link org.apache.hadoop.fs.ByteBufferReadable}.
+ * <p>
+ * {@link FSInputStream} synchronizes its inherited implementation on {@code
this}, a different
+ * monitor from {@code positionedReadLock}; without this override the two
APIs can interleave.
+ */
+ @Override
+ public int read(long position, byte[] buffer, int offset, int length) throws
IOException {
+ // Validate before touching ByteBuffer so that null throws IAE (not NPE)
and
+ // negative position propagates as EOFException rather than being
swallowed.
+ validatePositionedReadArgs(position, buffer, offset, length);
+ if (length == 0) {
+ return 0;
+ }
+ if (inputStream instanceof ExtendedInputStream) {
+ final ByteBuffer buf = ByteBuffer.wrap(buffer, offset, length);
+ try {
+ if (((ExtendedInputStream) inputStream).readFully(position, buf)) {
+ final int bytesRead = length - buf.remaining();
+ // readFullyStateless can return true with bytesRead==0 for
pos==length.
+ // Convert that to -1 to comply with PositionedReadable contract.
+ if (bytesRead == 0) {
+ return -1;
+ }
+ if (statistics != null) {
+ statistics.incrementBytesRead(bytesRead);
+ }
Review Comment:
let me add it as well.
##########
hadoop-ozone/ozonefs-common/src/main/java/org/apache/hadoop/fs/ozone/OzoneFSInputStream.java:
##########
@@ -211,4 +225,101 @@ public void readFully(long position, ByteBuffer buf)
throws IOException {
}
}
}
+
+ /**
+ * Byte-array positioned read. Tries the native stateless {@link
ExtendedInputStream#readFully}
+ * path first (via a zero-copy {@link ByteBuffer#wrap}). Falls back to a
synchronized
+ * seek-read-restore using byte-array {@link #read(byte[], int, int)} so
that the fallback
+ * works for any {@link Seekable} stream, not just those that also implement
+ * {@link org.apache.hadoop.fs.ByteBufferReadable}.
+ * <p>
+ * {@link FSInputStream} synchronizes its inherited implementation on {@code
this}, a different
+ * monitor from {@code positionedReadLock}; without this override the two
APIs can interleave.
+ */
+ @Override
+ public int read(long position, byte[] buffer, int offset, int length) throws
IOException {
Review Comment:
I mentioned that in the comment that if the the inner input stream is not
child class of `ExtendedInputStream`, we will cannot use `ByteBuffer.wrap`
because not all Seekable streams also implement `ByteBufferReadable`, and the
casting may fail line#201 with `((ByteBufferReadable) inputStream).read(buf);` .
but if you think we only support `ByteBufferReadable` , then we can reuse
those existing method.
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