[content-sensitive-splitter] Add Max size to chunking code.

In order to avoid very large chunks which are less likely to deduplicate
well, cap the chunks at 8 times the window_size.

src/content_sensitive_splitter.rs

@@ -136,6 +136,7 @@ impl ContentSensitiveSplitter {
         let mut offset = 0;
         let mut remainder = self.unconsumed_len as usize;
         let min_size = self.window_size as usize / 4;
+        let max_size = self.window_size as usize * 8;
         let ws = self.window_size as usize;
 
         if remainder < min_size {
@@ -160,12 +161,16 @@ impl ContentSensitiveSplitter {
                     break;
                 }
             }
-            if let Some(boundary) = self.hasher.next_match(&data[offset..], self.mask_l) {
+            let len_l = max_size - remainder;
+            let end = std::cmp::min(data.len(), offset + len_l);
+            if let Some(boundary) = self.hasher.next_match(&data[offset..end], self.mask_l) {
                 consumes.push(remainder + boundary);
                 offset += boundary + min_size;
                 remainder = min_size;
             } else {
-                break;
+                consumes.push(end - offset + remainder);
+                offset = end + min_size;
+                remainder = min_size;
             }
         }