common/FastCDC: refactor scan into a helper

Signed-off-by: Sage Weil <sage@newdream.net>

diff --git a/src/common/FastCDC.cc b/src/common/FastCDC.cc
index 5fa8e0d985317050a719b5a1b3e975be48e74492..0836aa6468b64c6f2eccd93724e1b82c700be3c6 100644 (file)
--- a/src/common/FastCDC.cc
+++ b/src/common/FastCDC.cc
@@ -57,6 +57,22 @@ void FastCDC::_setup(int target, int size_window_bits)
   }
 }
 
+static inline bool _scan(
+  unsigned char *ptr, size_t& pos, size_t max, uint64_t mask, uint64_t& fp,
+  uint64_t *table)
+{
+  while (true) {
+    if ((fp & mask) == mask) {
+      return false;
+    }
+    if (pos >= max) {
+      return true;
+    }
+    fp = (fp << 1) ^ table[ptr[pos]];
+    ++pos;
+  }
+}
+
 void FastCDC::calc_chunks(
   bufferlist& bl,
   std::vector<std::pair<uint64_t, uint64_t>> *chunks)
@@ -85,29 +101,18 @@ void FastCDC::calc_chunks(
     }
 
     // find an end marker
-    // small
-    size_t max = std::min(len,
-                         cstart + (1 << (target_bits - TARGET_WINDOW_BITS)));
-    while ((fp & small_mask) != small_mask && pos < max) {
-      fp = (fp << 1) ^ table[ptr[pos]];
-      ++pos;
-    }
-    if (pos >= max) {
-      // target
-      max = std::min(len, cstart + (1 << (target_bits + TARGET_WINDOW_BITS)));
-      while ((fp & target_mask) != target_mask && pos < max) {
-       fp = (fp << 1) ^ table[ptr[pos]];
-       ++pos;
-      }
-      if (pos >= max) {
-       // large
-       max = std::min(len, cstart + (1 << max_bits));
-       while ((fp & large_mask) != large_mask && pos < max) {
-         fp = (fp << 1) ^ table[ptr[pos]];
-         ++pos;
-       }
-      }
-    }
+    if (_scan(ptr, pos,
+             std::min(len,
+                      cstart + (1 << (target_bits - TARGET_WINDOW_BITS))),
+             small_mask, fp, table) &&
+       _scan(ptr, pos,
+             std::min(len,
+                      cstart + (1 << (target_bits + TARGET_WINDOW_BITS))),
+             target_mask, fp, table) &&
+       _scan(ptr, pos,
+             std::min(len,
+                      cstart + (1 << max_bits)),
+             large_mask, fp, table)) ;
 
     chunks->push_back(std::pair<uint64_t,uint64_t>(cstart, pos - cstart));
   }