Fix bugs in WAL trash file handling (#5520)

Summary:
1. Cleanup WAL trash files on open
2. Don't apply deletion rate limit if WAL dir is different from db dir
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5520

Test Plan: Add new unit tests and make check

Differential Revision: D16096750

Pulled By: anand1976

fbshipit-source-id: 6f07858ad864b754b711db416f0389c45ede599b

HISTORY.md

@@ -14,6 +14,7 @@
 * The semantics of the per-block-type block read counts in the performance context now match those of the generic block_read_count.
 * Add C bindings for secondary instance, i.e. DBImplSecondary.
 * db_bench adds a "benchmark" stats_history, which prints out the whole stats history.
+* Rate limited deletion of WALs is only enabled if DBOptions::wal_dir is not set, or explicitly set to db_name passed to DB::Open and DBOptions::db_paths is empty, or same as db_paths[0].path
 
 ### New Features
 * Add an option `snap_refresh_nanos` (default to 0.1s) to periodically refresh the snapshot list in compaction jobs. Assign to 0 to disable the feature.
@@ -40,6 +41,7 @@
 * Fix ingested file and directory not being fsync.
 * Return TryAgain status in place of Corruption when new tail is not visible to TransactionLogIterator.
 * Fix a bug caused by secondary not skipping the beginning of new MANIFEST.
+* On DB open, delete WAL trash files left behind in wal_dir
 
 ## 6.2.0 (4/30/2019)
 ### New Features

db/db_impl/db_impl.cc

@@ -3137,6 +3137,7 @@ Status DestroyDB(const std::string& dbname, const Options& options,
   ImmutableDBOptions soptions(SanitizeOptions(dbname, options));
   Env* env = soptions.env;
   std::vector<std::string> filenames;
+  bool wal_in_db_path = IsWalDirSameAsDBPath(&soptions);
 
   // Reset the logger because it holds a handle to the
   // log file and prevents cleanup and directory removal
@@ -3159,7 +3160,9 @@ Status DestroyDB(const std::string& dbname, const Options& options,
         if (type == kMetaDatabase) {
           del = DestroyDB(path_to_delete, options);
         } else if (type == kTableFile || type == kLogFile) {
-          del = DeleteDBFile(&soptions, path_to_delete, dbname);
+          del =
+              DeleteDBFile(&soptions, path_to_delete, dbname,
+                           /*force_bg=*/false, /*force_fg=*/!wal_in_db_path);
         } else {
           del = env->DeleteFile(path_to_delete);
         }
@@ -3193,7 +3196,8 @@ Status DestroyDB(const std::string& dbname, const Options& options,
           if (ParseFileName(fname, &number, &type) &&
               type == kTableFile) {  // Lock file will be deleted at end
             std::string table_path = path + "/" + fname;
-            Status del = DeleteDBFile(&soptions, table_path, dbname);
+            Status del = DeleteDBFile(&soptions, table_path, dbname,
+                                      /*force_bg=*/false, /*force_fg=*/false);
             if (result.ok() && !del.ok()) {
               result = del;
             }
@@ -3220,7 +3224,8 @@ Status DestroyDB(const std::string& dbname, const Options& options,
       for (const auto& file : archiveFiles) {
         if (ParseFileName(file, &number, &type) && type == kLogFile) {
           Status del =
-              DeleteDBFile(&soptions, archivedir + "/" + file, archivedir);
+              DeleteDBFile(&soptions, archivedir + "/" + file, archivedir,
+                           /*force_bg=*/false, /*force_fg=*/!wal_in_db_path);
           if (result.ok() && !del.ok()) {
             result = del;
           }
@@ -3235,7 +3240,8 @@ Status DestroyDB(const std::string& dbname, const Options& options,
         if (ParseFileName(file, &number, &type) && type == kLogFile) {
           Status del =
               DeleteDBFile(&soptions, LogFileName(soptions.wal_dir, number),
-                           soptions.wal_dir);
+                           soptions.wal_dir, /*force_bg=*/false,
+                           /*force_fg=*/!wal_in_db_path);
           if (result.ok() && !del.ok()) {
             result = del;
           }

db/db_impl/db_impl.h

@@ -1893,6 +1893,8 @@ class DBImpl : public DB {
   // results sequentially. Flush results of memtables with lower IDs get
   // installed to MANIFEST first.
   InstrumentedCondVar atomic_flush_install_cv_;
+
+  bool wal_in_db_path_;
 };
 
 extern Options SanitizeOptions(const std::string& db, const Options& src);

db/db_impl/db_impl_files.cc

@@ -258,7 +258,8 @@ void DBImpl::DeleteObsoleteFileImpl(int job_id, const std::string& fname,
   Status file_deletion_status;
   if (type == kTableFile || type == kLogFile) {
     file_deletion_status =
-        DeleteDBFile(&immutable_db_options_, fname, path_to_sync);
+        DeleteDBFile(&immutable_db_options_, fname, path_to_sync,
+                     /*force_bg=*/false, /*force_fg=*/!wal_in_db_path_);
   } else {
     file_deletion_status = env_->DeleteFile(fname);
   }

db/db_impl/db_impl_open.cc

@@ -122,6 +122,25 @@ DBOptions SanitizeOptions(const std::string& dbname, const DBOptions& src) {
   }
 
 #ifndef ROCKSDB_LITE
+  ImmutableDBOptions immutable_db_options(result);
+  if (!IsWalDirSameAsDBPath(&immutable_db_options)) {
+    // Either the WAL dir and db_paths[0]/db_name are not the same, or we
+    // cannot tell for sure. In either case, assume they're different and
+    // explicitly cleanup the trash log files (bypass DeleteScheduler)
+    // Do this first so even if we end up calling
+    // DeleteScheduler::CleanupDirectory on the same dir later, it will be
+    // safe
+    std::vector<std::string> filenames;
+    result.env->GetChildren(result.wal_dir, &filenames);
+    for (std::string& filename : filenames) {
+      if (filename.find(".log.trash",
+                  filename.length() - std::string(".log.trash").length()) !=
+                  std::string::npos) {
+        std::string trash_file = result.wal_dir + "/" + filename;
+        result.env->DeleteFile(trash_file);
+      }
+    }
+  }
   // When the DB is stopped, it's possible that there are some .trash files that
   // were not deleted yet, when we open the DB we will find these .trash files
   // and schedule them to be deleted (or delete immediately if SstFileManager
@@ -1294,6 +1313,10 @@ Status DBImpl::Open(const DBOptions& db_options, const std::string& dbname,
     delete impl;
     return s;
   }
+
+  impl->wal_in_db_path_ =
+      IsWalDirSameAsDBPath(&impl->immutable_db_options_);
+
   impl->mutex_.Lock();
   // Handles create_if_missing, error_if_exists
   s = impl->Recover(column_families);

db/db_sst_test.cc

@@ -470,6 +470,111 @@ TEST_F(DBSSTTest, RateLimitedWALDelete) {
   rocksdb::SyncPoint::GetInstance()->DisableProcessing();
 }
 
+class DBWALTestWithParam
+    : public DBSSTTest,
+      public testing::WithParamInterface<std::tuple<std::string, bool>> {
+ public:
+  DBWALTestWithParam() {
+    wal_dir_ = std::get<0>(GetParam());
+    wal_dir_same_as_dbname_ = std::get<1>(GetParam());
+  }
+
+  std::string wal_dir_;
+  bool wal_dir_same_as_dbname_;
+};
+
+TEST_P(DBWALTestWithParam, WALTrashCleanupOnOpen) {
+  class MyEnv : public EnvWrapper {
+   public:
+    MyEnv(Env* t) : EnvWrapper(t), fake_log_delete(false) {}
+
+    Status DeleteFile(const std::string& fname) {
+      if (fname.find(".log.trash") != std::string::npos && fake_log_delete) {
+        return Status::OK();
+      }
+
+      return target()->DeleteFile(fname);
+    }
+
+    void set_fake_log_delete(bool fake) { fake_log_delete = fake; }
+
+   private:
+    bool fake_log_delete;
+  };
+
+  std::unique_ptr<MyEnv> env(new MyEnv(Env::Default()));
+  Destroy(last_options_);
+
+  env->set_fake_log_delete(true);
+
+  Options options = CurrentOptions();
+  options.disable_auto_compactions = true;
+  options.compression = kNoCompression;
+  options.env = env.get();
+  options.wal_dir = dbname_ + wal_dir_;
+
+  int64_t rate_bytes_per_sec = 1024 * 10;  // 10 Kbs / Sec
+  Status s;
+  options.sst_file_manager.reset(
+      NewSstFileManager(env_, nullptr, "", 0, false, &s, 0));
+  ASSERT_OK(s);
+  options.sst_file_manager->SetDeleteRateBytesPerSecond(rate_bytes_per_sec);
+  auto sfm = static_cast<SstFileManagerImpl*>(options.sst_file_manager.get());
+  sfm->delete_scheduler()->SetMaxTrashDBRatio(3.1);
+
+  ASSERT_OK(TryReopen(options));
+
+  // Create 4 files in L0
+  for (char v = 'a'; v <= 'd'; v++) {
+    ASSERT_OK(Put("Key2", DummyString(1024, v)));
+    ASSERT_OK(Put("Key3", DummyString(1024, v)));
+    ASSERT_OK(Put("Key4", DummyString(1024, v)));
+    ASSERT_OK(Put("Key1", DummyString(1024, v)));
+    ASSERT_OK(Put("Key4", DummyString(1024, v)));
+    ASSERT_OK(Flush());
+  }
+  // We created 4 sst files in L0
+  ASSERT_EQ("4", FilesPerLevel(0));
+
+  Close();
+
+  options.sst_file_manager.reset();
+  std::vector<std::string> filenames;
+  int trash_log_count = 0;
+  if (!wal_dir_same_as_dbname_) {
+    // Forcibly create some trash log files
+    std::unique_ptr<WritableFile> result;
+    env->NewWritableFile(options.wal_dir + "/1000.log.trash", &result,
+                         EnvOptions());
+    result.reset();
+  }
+  env->GetChildren(options.wal_dir, &filenames);
+  for (const std::string& fname : filenames) {
+    if (fname.find(".log.trash") != std::string::npos) {
+      trash_log_count++;
+    }
+  }
+  ASSERT_GE(trash_log_count, 1);
+
+  env->set_fake_log_delete(false);
+  ASSERT_OK(TryReopen(options));
+
+  filenames.clear();
+  trash_log_count = 0;
+  env->GetChildren(options.wal_dir, &filenames);
+  for (const std::string& fname : filenames) {
+    if (fname.find(".log.trash") != std::string::npos) {
+      trash_log_count++;
+    }
+  }
+  ASSERT_EQ(trash_log_count, 0);
+  Close();
+}
+
+INSTANTIATE_TEST_CASE_P(DBWALTestWithParam, DBWALTestWithParam,
+                        ::testing::Values(std::make_tuple("", true),
+                                          std::make_tuple("_wal_dir", false)));
+
 TEST_F(DBSSTTest, OpenDBWithExistingTrash) {
   Options options = CurrentOptions();
 

db/wal_manager.cc

@@ -187,7 +187,8 @@ void WalManager::PurgeObsoleteWALFiles() {
           continue;
         }
         if (now_seconds - file_m_time > db_options_.wal_ttl_seconds) {
-          s = DeleteDBFile(&db_options_, file_path, archival_dir, false);
+          s = DeleteDBFile(&db_options_, file_path, archival_dir, false,
+                           /*force_fg=*/!wal_in_db_path_);
           if (!s.ok()) {
             ROCKS_LOG_WARN(db_options_.info_log, "Can't delete file: %s: %s",
                            file_path.c_str(), s.ToString().c_str());
@@ -213,7 +214,8 @@ void WalManager::PurgeObsoleteWALFiles() {
             log_file_size = std::max(log_file_size, file_size);
             ++log_files_num;
           } else {
-            s = DeleteDBFile(&db_options_, file_path, archival_dir, false);
+            s = DeleteDBFile(&db_options_, file_path, archival_dir, false,
+                             /*force_fg=*/!wal_in_db_path_);
             if (!s.ok()) {
               ROCKS_LOG_WARN(db_options_.info_log,
                              "Unable to delete file: %s: %s", file_path.c_str(),
@@ -253,7 +255,8 @@ void WalManager::PurgeObsoleteWALFiles() {
   for (size_t i = 0; i < files_del_num; ++i) {
     std::string const file_path = archived_logs[i]->PathName();
     s = DeleteDBFile(&db_options_, db_options_.wal_dir + "/" + file_path,
-                     db_options_.wal_dir, false);
+                     db_options_.wal_dir, false,
+                     /*force_fg=*/!wal_in_db_path_);
     if (!s.ok()) {
       ROCKS_LOG_WARN(db_options_.info_log, "Unable to delete file: %s: %s",
                      file_path.c_str(), s.ToString().c_str());

db/wal_manager.h

@@ -18,6 +18,7 @@
 #include <memory>
 
 #include "db/version_set.h"
+#include "file/file_util.h"
 #include "options/db_options.h"
 #include "port/port.h"
 #include "rocksdb/env.h"
@@ -40,7 +41,8 @@ class WalManager {
         env_options_(env_options),
         env_(db_options.env),
         purge_wal_files_last_run_(0),
-        seq_per_batch_(seq_per_batch) {}
+        seq_per_batch_(seq_per_batch),
+        wal_in_db_path_(IsWalDirSameAsDBPath(&db_options)) {}
 
   Status GetSortedWalFiles(VectorLogPtr& files);
 
@@ -97,6 +99,8 @@ class WalManager {
 
   bool seq_per_batch_;
 
+  bool wal_in_db_path_;
+
   // obsolete files will be deleted every this seconds if ttl deletion is
   // enabled and archive size_limit is disabled.
   static const uint64_t kDefaultIntervalToDeleteObsoleteWAL = 600;

file/file_util.cc

@@ -88,12 +88,12 @@ Status CreateFile(Env* env, const std::string& destination,
 }
 
 Status DeleteDBFile(const ImmutableDBOptions* db_options,
-                     const std::string& fname, const std::string& dir_to_sync,
+                    const std::string& fname, const std::string& dir_to_sync,
-                     const bool force_bg) {
+                    const bool force_bg, const bool force_fg) {
 #ifndef ROCKSDB_LITE
   SstFileManagerImpl* sfm =
       static_cast<SstFileManagerImpl*>(db_options->sst_file_manager.get());
-  if (sfm) {
+  if (sfm && !force_fg) {
     return sfm->ScheduleFileDeletion(fname, dir_to_sync, force_bg);
   } else {
     return db_options->env->DeleteFile(fname);
@@ -101,10 +101,21 @@ Status DeleteDBFile(const ImmutableDBOptions* db_options,
 #else
   (void)dir_to_sync;
   (void)force_bg;
+  (void)force_fg;
   // SstFileManager is not supported in ROCKSDB_LITE
   // Delete file immediately
   return db_options->env->DeleteFile(fname);
 #endif
 }
 
+bool IsWalDirSameAsDBPath(const ImmutableDBOptions* db_options) {
+  bool same = false;
+  Status s = db_options->env->AreFilesSame(db_options->wal_dir,
+                                           db_options->db_paths[0].path, &same);
+  if (s.IsNotSupported()) {
+    same = db_options->wal_dir == db_options->db_paths[0].path;
+  }
+  return same;
+}
+
 }  // namespace rocksdb

file/file_util.h

@@ -24,7 +24,9 @@ extern Status CreateFile(Env* env, const std::string& destination,
 
 extern Status DeleteDBFile(const ImmutableDBOptions* db_options,
                            const std::string& fname,
-                           const std::string& path_to_sync,
+                           const std::string& path_to_sync, const bool force_bg,
-                           const bool force_bg = false);
+                           const bool force_fg);
+
+extern bool IsWalDirSameAsDBPath(const ImmutableDBOptions* db_options);
 
 }  // namespace rocksdb

utilities/blob_db/blob_db_impl.cc

@@ -1758,7 +1758,8 @@ std::pair<bool, int64_t> BlobDBImpl::DeleteObsoleteFiles(bool aborted) {
 
     blob_files_.erase(bfile->BlobFileNumber());
     Status s = DeleteDBFile(&(db_impl_->immutable_db_options()),
-                             bfile->PathName(), blob_dir_, true);
+                            bfile->PathName(), blob_dir_, true,
+                            /*force_fg=*/false);
     if (!s.ok()) {
       ROCKS_LOG_ERROR(db_options_.info_log,
                       "File failed to be deleted as obsolete %s",
@@ -1848,7 +1849,8 @@ Status DestroyBlobDB(const std::string& dbname, const Options& options,
     uint64_t number;
     FileType type;
     if (ParseFileName(f, &number, &type) && type == kBlobFile) {
-      Status del = DeleteDBFile(&soptions, blobdir + "/" + f, blobdir, true);
+      Status del = DeleteDBFile(&soptions, blobdir + "/" + f, blobdir, true,
+                                /*force_fg=*/false);
       if (status.ok() && !del.ok()) {
         status = del;
       }