Fix a few bugs in best-efforts recovery (#6824)

Summary:
1. Update column_family_memtables_ to point to latest column_family_set in
   version_set after recovery.
2. Normalize file paths passed by application so that directories end with '/'
   or '\\'.
3. In addition to missing files, corrupted files are also ignored in
   best-efforts recovery.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6824

Test Plan: COMPILE_WITH_ASAN=1 make check

Reviewed By: anand1976

Differential Revision: D21463905

Pulled By: riversand963

fbshipit-source-id: c48db8843cc93c8c1c7139c474b64e6f775307d2

HISTORY.md

@@ -7,6 +7,8 @@
 * Fix consistency checking error swallowing in some cases when options.force_consistency_checks = true.
 * Fix possible false NotFound status from batched MultiGet using index type kHashSearch.
 * Fix corruption caused by enabling delete triggered compaction (NewCompactOnDeletionCollectorFactory) in universal compaction mode, along with parallel compactions. The bug can result in two parallel compactions picking the same input files, resulting in the DB resurrecting older and deleted versions of some keys.
+* Fix a use-after-free bug in best-efforts recovery. column_family_memtables_ needs to point to valid ColumnFamilySet.
+* Let best-efforts recovery ignore corrupted files during table loading.
 
 ### Public API Change
 * Flush(..., column_family) may return Status::ColumnFamilyDropped() instead of Status::InvalidArgument() if column_family is dropped while processing the flush request.

db/db_basic_test.cc

@@ -1840,11 +1840,16 @@ TEST_F(DBBasicTest, RecoverWithMissingFiles) {
     ASSERT_OK(Flush(static_cast<int>(cf)));
   }
 
-  // Delete files
+  // Delete and corrupt files
   for (size_t i = 0; i < all_cf_names.size(); ++i) {
     std::vector<std::string>& files = listener->GetFiles(all_cf_names[i]);
     ASSERT_EQ(3, files.size());
-    for (int j = static_cast<int>(files.size() - 1); j >= static_cast<int>(i);
+    std::string corrupted_data;
+    ASSERT_OK(ReadFileToString(env_, files[files.size() - 1], &corrupted_data));
+    ASSERT_OK(WriteStringToFile(
+        env_, corrupted_data.substr(0, corrupted_data.size() - 2),
+        files[files.size() - 1], /*should_sync=*/true));
+    for (int j = static_cast<int>(files.size() - 2); j >= static_cast<int>(i);
          --j) {
       ASSERT_OK(env_->DeleteFile(files[j]));
     }
@@ -1876,6 +1881,32 @@ TEST_F(DBBasicTest, RecoverWithMissingFiles) {
   }
 }
 
+TEST_F(DBBasicTest, BestEffortsRecoveryTryMultipleManifests) {
+  Options options = CurrentOptions();
+  options.env = env_;
+  DestroyAndReopen(options);
+  ASSERT_OK(Put("foo", "value0"));
+  ASSERT_OK(Flush());
+  Close();
+  {
+    // Hack by adding a new MANIFEST with high file number
+    std::string garbage(10, '\0');
+    ASSERT_OK(WriteStringToFile(env_, garbage, dbname_ + "/MANIFEST-001000",
+                                /*should_sync=*/true));
+  }
+  {
+    // Hack by adding a corrupted SST not referenced by any MANIFEST
+    std::string garbage(10, '\0');
+    ASSERT_OK(WriteStringToFile(env_, garbage, dbname_ + "/001001.sst",
+                                /*should_sync=*/true));
+  }
+
+  options.best_efforts_recovery = true;
+
+  Reopen(options);
+  ASSERT_OK(Put("bar", "value"));
+}
+
 TEST_F(DBBasicTest, RecoverWithNoCurrentFile) {
   Options options = CurrentOptions();
   options.env = env_;

db/db_impl/db_impl_files.cc

@@ -686,13 +686,15 @@ uint64_t PrecomputeMinLogNumberToKeep(
 Status DBImpl::FinishBestEffortsRecovery() {
   mutex_.AssertHeld();
   std::vector<std::string> paths;
-  paths.push_back(dbname_);
+  paths.push_back(NormalizePath(dbname_ + std::string(1, kFilePathSeparator)));
   for (const auto& db_path : immutable_db_options_.db_paths) {
-    paths.push_back(db_path.path);
+    paths.push_back(
+        NormalizePath(db_path.path + std::string(1, kFilePathSeparator)));
   }
   for (const auto* cfd : *versions_->GetColumnFamilySet()) {
     for (const auto& cf_path : cfd->ioptions()->cf_paths) {
-      paths.push_back(cf_path.path);
+      paths.push_back(
+          NormalizePath(cf_path.path + std::string(1, kFilePathSeparator)));
     }
   }
   // Dedup paths
@@ -711,7 +713,8 @@ Status DBImpl::FinishBestEffortsRecovery() {
       if (!ParseFileName(fname, &number, &type)) {
         continue;
       }
-      const std::string normalized_fpath = NormalizePath(path + fname);
+      // path ends with '/' or '\\'
+      const std::string normalized_fpath = path + fname;
       largest_file_number = std::max(largest_file_number, number);
       if (type == kTableFile && number >= next_file_number &&
           files_to_delete.find(normalized_fpath) == files_to_delete.end()) {

db/db_impl/db_impl_open.cc

@@ -425,6 +425,9 @@ Status DBImpl::Recover(
     s = versions_->TryRecover(column_families, read_only, &db_id_,
                               &missing_table_file);
     if (s.ok()) {
+      // TryRecover may delete previous column_family_set_.
+      column_family_memtables_.reset(
+          new ColumnFamilyMemTablesImpl(versions_->GetColumnFamilySet()));
       s = FinishBestEffortsRecovery();
     }
   }

db/version_edit_handler.cc

@@ -415,7 +415,8 @@ Status VersionEditHandler::LoadTables(ColumnFamilyData* cfd,
       version_set_->db_options_->max_file_opening_threads,
       prefetch_index_and_filter_in_cache, is_initial_load,
       cfd->GetLatestMutableCFOptions()->prefix_extractor.get());
-  if (s.IsPathNotFound() && no_error_if_table_files_missing_) {
+  if ((s.IsPathNotFound() || s.IsCorruption()) &&
+      no_error_if_table_files_missing_) {
     s = Status::OK();
   }
   if (!s.ok() && !version_set_->db_options_->paranoid_checks) {
@@ -546,7 +547,7 @@ Status VersionEditHandlerPointInTime::MaybeCreateVersion(
     const std::string fpath =
         MakeTableFileName(cfd->ioptions()->cf_paths[0].path, file_num);
     s = version_set_->VerifyFileMetadata(fpath, meta);
-    if (s.IsPathNotFound() || s.IsNotFound()) {
+    if (s.IsPathNotFound() || s.IsNotFound() || s.IsCorruption()) {
       missing_files.insert(file_num);
       s = Status::OK();
     }