Include checksums in CorruptBlockException when relevant (#1291)

This additional metadata is somewhat valuable in the context of troubleshooting. Recently, we had an issue where the checksum itself was not (over)written and so it was stored as 0. In many cases, this won't be helpful, but since it is cheap and could be helpful, I propose adding some additional metadata when checksums don't match.
datastax · Sep 19, 2024 · 5ea584d · 5ea584d
1 parent b7def63
commit 5ea584d
Show file tree

Hide file tree

Showing 3 changed files with 26 additions and 8 deletions.
diff --git a/src/java/org/apache/cassandra/io/compress/CompressedSequentialWriter.java b/src/java/org/apache/cassandra/io/compress/CompressedSequentialWriter.java
@@ -310,8 +310,10 @@ private synchronized void doResetAndTruncate(DataPosition mark)
             crcCheckBuffer.clear();
             readChannel.read(crcCheckBuffer);
             crcCheckBuffer.flip();
-            if (crcCheckBuffer.getInt() != (int) checksum.getValue())
-                throw new CorruptBlockException(getFile().toString(), chunkOffset, chunkSize);
+            int storedChecksum = crcCheckBuffer.getInt();
+            int computedChecksum = (int) checksum.getValue();
+            if (storedChecksum != computedChecksum)
+                throw new CorruptBlockException(getFile().toString(), chunkOffset, chunkSize, storedChecksum, computedChecksum);
         }
         catch (CorruptBlockException e)
         {

diff --git a/src/java/org/apache/cassandra/io/compress/CorruptBlockException.java b/src/java/org/apache/cassandra/io/compress/CorruptBlockException.java
@@ -40,4 +40,16 @@ public CorruptBlockException(String filePath, long offset, int length, Throwable
     {
         super(String.format("(%s): corruption detected, chunk at %d of length %d.", filePath, offset, length), cause);
     }
+
+    public CorruptBlockException(String filePath, CompressionMetadata.Chunk chunk, int storedChecksum, int calculatedChecksum)
+    {
+        this(filePath, chunk.offset, chunk.length, storedChecksum, calculatedChecksum);
+    }
+
+    public CorruptBlockException(String filePath, long offset, int length, int storedChecksum, int calculatedChecksum)
+    {
+        super(String.format("(%s): corruption detected, chunk at %d of length %d has mismatched checksums. Expected %d, but calculated %d",
+                            filePath, offset, length, storedChecksum, calculatedChecksum));
+    }
+
 }
diff --git a/src/java/org/apache/cassandra/io/util/CompressedChunkReader.java b/src/java/org/apache/cassandra/io/util/CompressedChunkReader.java
@@ -138,8 +138,9 @@ public void readChunk(long position, ByteBuffer uncompressed)
                         int checksum = (int) ChecksumType.CRC32.of(compressed);
 
                         compressed.limit(length);
-                        if (compressed.getInt() != checksum)
-                            throw new CorruptBlockException(channel.filePath(), chunk);
+                        int storedChecksum = compressed.getInt();
+                        if (storedChecksum != checksum)
+                            throw new CorruptBlockException(channel.filePath(), chunk, storedChecksum, checksum);
 
                         compressed.position(0).limit(chunk.length);
                     }
@@ -166,9 +167,11 @@ public void readChunk(long position, ByteBuffer uncompressed)
 
                         ByteBuffer scratch = bufferHolder.getBuffer(Integer.BYTES);
 
-                        if (channel.read(scratch, chunkOffset + chunk.length) != Integer.BYTES
-                                || scratch.getInt(0) != checksum)
+                        if (channel.read(scratch, chunkOffset + chunk.length) != Integer.BYTES)
                             throw new CorruptBlockException(channel.filePath(), chunk);
+                        int storedChecksum = scratch.getInt(0);
+                        if (storedChecksum != checksum)
+                            throw new CorruptBlockException(channel.filePath(), chunk, storedChecksum, checksum);
                     }
                 }
                 uncompressed.flip();
@@ -231,8 +234,9 @@ public void readChunk(long position, ByteBuffer uncompressed)
                         int checksum = (int) ChecksumType.CRC32.of(compressedChunk);
 
                         compressedChunk.limit(compressedChunk.capacity());
-                        if (compressedChunk.getInt() != checksum)
-                            throw new CorruptBlockException(channel.filePath(), chunk);
+                        int storedChecksum = compressedChunk.getInt();
+                        if (storedChecksum != checksum)
+                            throw new CorruptBlockException(channel.filePath(), chunk, storedChecksum, checksum);
 
                         compressedChunk.position(chunkOffsetInSegment).limit(chunkOffsetInSegment + chunk.length);
                     }