From 00a75d7c99e87f543a4e0a4390732bb2eaa286fe Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Sat, 10 Oct 2020 00:57:54 -0700
Subject: [PATCH] Hadoop: fix reading file tail

---
 .../java/seaweedfs/client/SeaweedRead.java    | 22 ++++++++++++-------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/other/java/client/src/main/java/seaweedfs/client/SeaweedRead.java b/other/java/client/src/main/java/seaweedfs/client/SeaweedRead.java
index 7e5c5cb88..cc8befb7a 100644
--- a/other/java/client/src/main/java/seaweedfs/client/SeaweedRead.java
+++ b/other/java/client/src/main/java/seaweedfs/client/SeaweedRead.java
@@ -40,7 +40,7 @@ public class SeaweedRead {
 
         //TODO parallel this
         long readCount = 0;
-        int startOffset = bufferOffset;
+        long startOffset = position;
         for (ChunkView chunkView : chunkViews) {
 
             if (startOffset < chunkView.logicOffset) {
@@ -57,7 +57,7 @@ public class SeaweedRead {
                 return 0;
             }
 
-            int len = readChunkView(position, buffer, startOffset, chunkView, locations);
+            int len = readChunkView(startOffset, buffer, bufferOffset + readCount, chunkView, locations);
 
             LOG.debug("read [{},{}) {} size {}", startOffset, startOffset + len, chunkView.fileId, chunkView.size);
 
@@ -66,7 +66,7 @@ public class SeaweedRead {
 
         }
 
-        long limit = Math.min(bufferLength, fileSize);
+        long limit = Math.min(bufferOffset + bufferLength, fileSize);
 
         if (startOffset < limit) {
             long gap = limit - startOffset;
@@ -78,7 +78,7 @@ public class SeaweedRead {
         return readCount;
     }
 
-    private static int readChunkView(long position, byte[] buffer, int startOffset, ChunkView chunkView, FilerProto.Locations locations) throws IOException {
+    private static int readChunkView(long startOffset, byte[] buffer, long bufOffset, ChunkView chunkView, FilerProto.Locations locations) throws IOException {
 
         byte[] chunkData = chunkCache.getChunk(chunkView.fileId);
 
@@ -88,9 +88,9 @@ public class SeaweedRead {
         }
 
         int len = (int) chunkView.size;
-        LOG.debug("readChunkView fid:{} chunkData.length:{} chunkView.offset:{} buffer.length:{} startOffset:{} len:{}",
-                chunkView.fileId, chunkData.length, chunkView.offset, buffer.length, startOffset, len);
-        System.arraycopy(chunkData, startOffset - (int) (chunkView.logicOffset - chunkView.offset), buffer, startOffset, len);
+        LOG.debug("readChunkView fid:{} chunkData.length:{} chunkView[{};{}) buf[{},{})/{} startOffset:{}",
+                chunkView.fileId, chunkData.length, chunkView.offset, chunkView.offset+chunkView.size, bufOffset, bufOffset+len, buffer.length, startOffset);
+        System.arraycopy(chunkData, (int) (startOffset - chunkView.logicOffset + chunkView.offset), buffer, (int)bufOffset, len);
 
         return len;
     }
@@ -98,7 +98,8 @@ public class SeaweedRead {
     public static byte[] doFetchFullChunkData(ChunkView chunkView, FilerProto.Locations locations) throws IOException {
 
         byte[] data = null;
-        for (long waitTime = 230L; waitTime < 20 * 1000; waitTime += waitTime / 2) {
+        IOException lastException = null;
+        for (long waitTime = 1000L; waitTime < 10 * 1000; waitTime += waitTime / 2) {
             for (FilerProto.Location location : locations.getLocationsList()) {
                 String url = String.format("http://%s/%s", location.getUrl(), chunkView.fileId);
                 try {
@@ -106,6 +107,7 @@ public class SeaweedRead {
                     break;
                 } catch (IOException ioe) {
                     LOG.debug("doFetchFullChunkData {} :{}", url, ioe);
+                    lastException = ioe;
                 }
             }
             if (data != null) {
@@ -117,6 +119,10 @@ public class SeaweedRead {
             }
         }
 
+        if (data == null) {
+            throw lastException;
+        }
+
         LOG.debug("doFetchFullChunkData fid:{} chunkData.length:{}", chunkView.fileId, data.length);
 
         return data;