From 19003513862bcd7bc1fe86f196025b4fb8f49ff2 Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@redhat.com>
Date: Mon, 28 Sep 2015 22:18:43 -0400
Subject: [PATCH] log_writer: conditionally adjust crc

---
 db/log_writer.cc | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/db/log_writer.cc b/db/log_writer.cc
index eeb0844f..aba862c1 100644
--- a/db/log_writer.cc
+++ b/db/log_writer.cc
@@ -93,8 +93,14 @@ Status Writer::EmitPhysicalRecord(RecordType t, const char* ptr, size_t n) {
 
   // Compute the crc of the record type and the payload.
   uint32_t crc = crc32c::Extend(type_crc_[t], ptr, n);
-  crc = crc32c::Mask(crc);                 // Adjust for storage
-  EncodeFixed32(buf, crc);
+  if (db_options_->recycle_log_files) {
+    uint32_t final_crc = crc ^ log_number_;              // XOR in log numb
+    final_crc = crc32c::Mask(final_crc);                 // Adjust for storage
+    EncodeFixed32(buf, final_crc);
+  } else {
+    crc = crc32c::Mask(crc);                 // Adjust for storage
+    EncodeFixed32(buf, crc);
+  }
 
   // Write the header and the payload
   Status s = dest_->Append(Slice(buf, kHeaderSize));
-- 
2.47.3