From: Sage Weil <sage@redhat.com>
Date: Tue, 29 Sep 2015 02:18:43 +0000 (-0400)
Subject: log_writer: conditionally adjust crc
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=19003513862bcd7bc1fe86f196025b4fb8f49ff2;p=rocksdb.git

log_writer: conditionally adjust crc
---

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));