saxenapranav commented on code in PR #6699:
URL: https://github.com/apache/hadoop/pull/6699#discussion_r1570043455


##########
hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/AbfsInputStream.java:
##########
@@ -376,32 +439,48 @@ private int readLastBlock(final byte[] b, final int off, 
final int len)
     // data need to be copied to user buffer from index bCursor,
     // AbfsInutStream buffer is going to contain data from last block start. In
     // that case bCursor will be set to fCursor - lastBlockStart
-    long lastBlockStart = max(0, contentLength - footerReadSize);
+    if (!fileStatusInformationPresent.get()) {
+      long lastBlockStart = max(0, (fCursor + len) - footerReadSize);
+      bCursor = (int) (fCursor - lastBlockStart);
+      return optimisedRead(b, off, len, lastBlockStart, min(fCursor + len, 
footerReadSize), true);
+    }
+    long lastBlockStart = max(0, getContentLength() - footerReadSize);
     bCursor = (int) (fCursor - lastBlockStart);
     // 0 if contentlength is < buffersize
-    long actualLenToRead = min(footerReadSize, contentLength);
-    return optimisedRead(b, off, len, lastBlockStart, actualLenToRead);
+    long actualLenToRead = min(footerReadSize, getContentLength());
+    return optimisedRead(b, off, len, lastBlockStart, actualLenToRead, false);
   }
 
   private int optimisedRead(final byte[] b, final int off, final int len,
-      final long readFrom, final long actualLen) throws IOException {
+      final long readFrom, final long actualLen,
+      final boolean isReadWithoutContentLengthInformation) throws IOException {
     fCursor = readFrom;
     int totalBytesRead = 0;
     int lastBytesRead = 0;
     try {
       buffer = new byte[bufferSize];
+      boolean fileStatusInformationPresentBeforeRead = 
fileStatusInformationPresent.get();
       for (int i = 0;
-           i < MAX_OPTIMIZED_READ_ATTEMPTS && fCursor < contentLength; i++) {
+           i < MAX_OPTIMIZED_READ_ATTEMPTS && 
(!fileStatusInformationPresent.get()
+               || fCursor < getContentLength()); i++) {
         lastBytesRead = readInternal(fCursor, buffer, limit,
             (int) actualLen - limit, true);
         if (lastBytesRead > 0) {
           totalBytesRead += lastBytesRead;
+          boolean shouldBreak = !fileStatusInformationPresentBeforeRead

Review Comment:
   In a non-lazily opened InputStream, the contentLength is available before 
opening the InputStream. In this case, the optimizedRead will always be done on 
the last part of the file.  
   In a lazily opened InputStream, the contentLength is not available before 
opening the InputStream. In this case, the optimizedRead may not be done on the 
last part of the file. If the optimizedRead is done on a non-last part of the 
file, the InputStream should read only the amount of data requested by 
optimizedRead, as the buffer supplied would be only of the size of the data 
requested by optimizedRead
   
   Added as a comment.



-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org

For queries about this service, please contact Infrastructure at:
us...@infra.apache.org


---------------------------------------------------------------------
To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: common-issues-h...@hadoop.apache.org

Reply via email to