RocksDBOptionsParser::Parse()'s `ignore_unknown_options` argument only ingores options from higher version.

Summary:
RocksDB should always be able to parse an option file generated using the same or lower version. Unknown option should only happen if it is from a higher version. Change the behavior of RocksDBOptionsParser::Parse()'s behavior with ignore_unknown_options=true so that unknown option from a lower or the same version will never be skipped.
Closes https://github.com/facebook/rocksdb/pull/3527

Differential Revision: D7048851

Pulled By: siying

fbshipit-source-id: e261caea12f6515611a4a29f39acf2b619df2361

HISTORY.md

@@ -5,6 +5,7 @@
 * Add `include_end` option to make the range end exclusive when `include_end == false` in `DeleteFilesInRange()`.
 * Add `CompactRangeOptions::allow_write_stall`, which makes `CompactRange` start working immediately, even if it causes user writes to stall. The default value is false, meaning we add delay to `CompactRange` calls until stalling can be avoided when possible. Note this delay is not present in previous RocksDB versions.
 * Creating checkpoint with empty directory now returns `Status::InvalidArgument`; previously, it returned `Status::IOError`.
+* RocksDBOptionsParser::Parse()'s `ignore_unknown_options` argument will only be effective if the option file shows it is generated using a higher version of RocksDB than the current version.
 
 ### New Features
 * Improve the performance of iterators doing long range scans by using readahead.

options/options_parser.cc

@@ -268,6 +268,16 @@ Status RocksDBOptionsParser::Parse(const std::string& file_name, Env* env,
       if (!s.ok()) {
         return s;
       }
+
+      // If the option file is not generated by a higher minor version,
+      // there shouldn't be any unknown option.
+      if (ignore_unknown_options && section == kOptionSectionVersion) {
+        if (db_version[0] < ROCKSDB_MAJOR || (db_version[0] == ROCKSDB_MAJOR &&
+                                              db_version[1] <= ROCKSDB_MINOR)) {
+          ignore_unknown_options = false;
+        }
+      }
+
       s = ParseSection(&section, &title, &argument, line, line_num);
       if (!s.ok()) {
         return s;

options/options_test.cc

@@ -1216,18 +1216,53 @@ TEST_F(OptionsParserTest, DuplicateCFOptions) {
 }
 
 TEST_F(OptionsParserTest, IgnoreUnknownOptions) {
+  for (int case_id = 0; case_id < 5; case_id++) {
     DBOptions db_opt;
     db_opt.max_open_files = 12345;
     db_opt.max_background_flushes = 301;
     db_opt.max_total_wal_size = 1024;
     ColumnFamilyOptions cf_opt;
 
+    std::string version_string;
+    bool should_ignore = true;
+    if (case_id == 0) {
+      // same version
+      should_ignore = false;
+      version_string =
+          ToString(ROCKSDB_MAJOR) + "." + ToString(ROCKSDB_MINOR) + ".0";
+    } else if (case_id == 1) {
+      // higher minor version
+      should_ignore = true;
+      version_string =
+          ToString(ROCKSDB_MAJOR) + "." + ToString(ROCKSDB_MINOR + 1) + ".0";
+    } else if (case_id == 2) {
+      // higher major version.
+      should_ignore = true;
+      version_string = ToString(ROCKSDB_MAJOR + 1) + ".0.0";
+    } else if (case_id == 3) {
+      // lower minor version
+#if ROCKSDB_MINOR == 0
+      continue;
+#else
+      version_string =
+          ToString(ROCKSDB_MAJOR) + "." + ToString(ROCKSDB_MINOR - 1) + ".0";
+      should_ignore = false;
+#endif
+    } else {
+      // lower major version
+      should_ignore = false;
+      version_string =
+          ToString(ROCKSDB_MAJOR - 1) + "." + ToString(ROCKSDB_MINOR) + ".0";
+    }
+
     std::string options_file_content =
         "# This is a testing option string.\n"
         "# Currently we only support \"#\" styled comment.\n"
         "\n"
         "[Version]\n"
-      "  rocksdb_version=3.14.0\n"
+        "  rocksdb_version=" +
+        version_string +
+        "\n"
         "  options_file_version=1\n"
         "[DBOptions]\n"
         "  max_open_files=12345\n"
@@ -1242,11 +1277,18 @@ TEST_F(OptionsParserTest, IgnoreUnknownOptions) {
         "  # if a section is blank, we will use the default\n";
 
     const std::string kTestFileName = "test-rocksdb-options.ini";
+    env_->DeleteFile(kTestFileName);
     env_->WriteToNewFile(kTestFileName, options_file_content);
     RocksDBOptionsParser parser;
     ASSERT_NOK(parser.Parse(kTestFileName, env_.get()));
+    if (should_ignore) {
       ASSERT_OK(parser.Parse(kTestFileName, env_.get(),
                              true /* ignore_unknown_options */));
+    } else {
+      ASSERT_NOK(parser.Parse(kTestFileName, env_.get(),
+                              true /* ignore_unknown_options */));
+    }
+  }
 }
 
 TEST_F(OptionsParserTest, ParseVersion) {