Add a unit test to Ignorable manfiest record (#4964)

Summary:
https://github.com/facebook/rocksdb/pull/4960 introduced ignorable manfiest
record. Adding a test to it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4964

Differential Revision: D14012667

Pulled By: siying

fbshipit-source-id: e5f10ecc68dec2716e178d44f0fe2b76c3d857ef

db/version_edit.h

@@ -229,6 +229,10 @@ class VersionEdit {
 
   uint64_t log_number() { return log_number_; }
 
+  bool has_next_file_number() const { return has_next_file_number_; }
+
+  uint64_t next_file_number() const { return next_file_number_; }
+
   // Add the specified file at the specified number.
   // REQUIRES: This version has not been saved (see VersionSet::SaveTo)
   // REQUIRES: "smallest" and "largest" are smallest and largest keys in file

db/version_edit_test.cc

@@ -8,6 +8,7 @@
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 
 #include "db/version_edit.h"
+#include "util/coding.h"
 #include "util/sync_point.h"
 #include "util/testharness.h"
 
@@ -197,6 +198,47 @@ TEST_F(VersionEditTest, AtomicGroupTest) {
   TestEncodeDecode(edit);
 }
 
+TEST_F(VersionEditTest, IgnorableField) {
+  VersionEdit ve;
+  std::string encoded;
+
+  // Size of ignorable field is too large
+  PutVarint32Varint64(&encoded, 2 /* kLogNumber */, 66);
+  // This is a customized ignorable tag
+  PutVarint32Varint64(&encoded,
+                      0x2710 /* A field with kTagSafeIgnoreMask set */,
+                      5 /* fieldlength 5 */);
+  encoded += "abc";  // Only fills 3 bytes,
+  ASSERT_NOK(ve.DecodeFrom(encoded));
+
+  encoded.clear();
+  // Error when seeing unidentified tag that is not ignorable
+  PutVarint32Varint64(&encoded, 2 /* kLogNumber */, 66);
+  // This is a customized ignorable tag
+  PutVarint32Varint64(&encoded, 666 /* A field with kTagSafeIgnoreMask unset */,
+                      3 /* fieldlength 3 */);
+  encoded += "abc";  //  Fill 3 bytes
+  PutVarint32Varint64(&encoded, 3 /* next file number */, 88);
+  ASSERT_NOK(ve.DecodeFrom(encoded));
+
+  // Safely ignore an identified but safely ignorable entry
+  encoded.clear();
+  PutVarint32Varint64(&encoded, 2 /* kLogNumber */, 66);
+  // This is a customized ignorable tag
+  PutVarint32Varint64(&encoded,
+                      0x2710 /* A field with kTagSafeIgnoreMask set */,
+                      3 /* fieldlength 3 */);
+  encoded += "abc";  //  Fill 3 bytes
+  PutVarint32Varint64(&encoded, 3 /* kNextFileNumber */, 88);
+
+  ASSERT_OK(ve.DecodeFrom(encoded));
+
+  ASSERT_TRUE(ve.has_log_number());
+  ASSERT_TRUE(ve.has_next_file_number());
+  ASSERT_EQ(66, ve.log_number());
+  ASSERT_EQ(88, ve.next_file_number());
+}
+
 }  // namespace rocksdb
 
 int main(int argc, char** argv) {