Get file attributes in bulk for VerifyBackup and CreateNewBackup

Summary:
For VerifyBackup(), backup files can be spread across "shared/",
"shared_checksum/", and "private/" subdirectories, so we have to
bulk get all three.

For CreateNewBackup(), we make two separate bulk calls: one for the
data files and one for WAL files.

There is also a new helper function, ExtendPathnameToSizeBytes(),
that translates the file attributes vector to a map. I decided to leave
GetChildrenFileAttributes()'s (from D53781) return type as vector to
keep it consistent with GetChildren().

Depends on D53781.

Test Plan:
verified relevant unit tests

  $ ./backupable_db_test

Reviewers: IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D53919

utilities/backupable/backupable_db.cc

@@ -117,6 +117,12 @@ class BackupEngineImpl : public BackupEngine {
  private:
   void DeleteChildren(const std::string& dir, uint32_t file_type_filter = 0);
 
+  // Extends the "result" map with pathname->size mappings for the contents of
+  // "dir". Pathnames are prefixed with "dir".
+  Status InsertPathnameToSizeBytes(
+      const std::string& dir,
+      std::unordered_map<std::string, uint64_t>* result);
+
   struct FileInfo {
     FileInfo(const std::string& fname, uint64_t sz, uint32_t checksum)
       : refs(0), filename(fname), size(sz), checksum_value(checksum) {}
@@ -179,8 +185,10 @@ class BackupEngineImpl : public BackupEngine {
       return files_;
     }
 
-    Status LoadFromFile(const std::string& backup_dir,
-                        bool use_size_in_file_name);
+    // @param abs_path_to_size Pre-fetched file sizes (bytes).
+    Status LoadFromFile(
+        const std::string& backup_dir, bool use_size_in_file_name,
+        const std::unordered_map<std::string, uint64_t>& abs_path_to_size);
     Status StoreToFile(bool sync);
 
     std::string GetInfoString() {
@@ -427,7 +435,7 @@ class BackupEngineImpl : public BackupEngine {
       std::vector<BackupAfterCopyOrCreateWorkItem>& backup_items_to_finish,
       BackupID backup_id, bool shared, const std::string& src_dir,
       const std::string& fname,  // starts with "/"
-      RateLimiter* rate_limiter, uint64_t size_limit = 0,
+      RateLimiter* rate_limiter, uint64_t size_bytes, uint64_t size_limit = 0,
       bool shared_checksum = false,
       std::function<void()> progress_callback = []() {},
       const std::string& contents = std::string());
@@ -573,10 +581,19 @@ Status BackupEngineImpl::Initialize() {
       return s;
     }
   } else {  // Load data from storage
+    std::unordered_map<std::string, uint64_t> abs_path_to_size;
+    for (const auto& rel_dir :
+         {GetSharedFileRel(), GetSharedFileWithChecksumRel()}) {
+      const auto abs_dir = GetAbsolutePath(rel_dir);
+      InsertPathnameToSizeBytes(abs_dir, &abs_path_to_size);
+    }
     // load the backups if any
     for (auto& backup : backups_) {
+      InsertPathnameToSizeBytes(
+          GetAbsolutePath(GetPrivateFileRel(backup.first)), &abs_path_to_size);
       Status s = backup.second->LoadFromFile(
-          options_.backup_dir, options_.use_file_size_in_file_name);
+          options_.backup_dir, options_.use_file_size_in_file_name,
+          abs_path_to_size);
       if (!s.ok()) {
         Log(options_.info_log, "Backup %u corrupted -- %s", backup.first,
             s.ToString().c_str());
@@ -685,6 +702,12 @@ Status BackupEngineImpl::CreateNewBackup(
   std::unordered_set<std::string> live_dst_paths;
   live_dst_paths.reserve(live_files.size() + live_wal_files.size());
 
+  // Pre-fetch sizes for data files
+  std::unordered_map<std::string, uint64_t> data_path_to_size;
+  if (s.ok()) {
+    s = InsertPathnameToSizeBytes(db->GetName(), &data_path_to_size);
+  }
+
   std::vector<BackupAfterCopyOrCreateWorkItem> backup_items_to_finish;
   // Add a CopyOrCreateWorkItem to the channel for each live file
   std::string manifest_fname, current_fname;
@@ -709,13 +732,19 @@ Status BackupEngineImpl::CreateNewBackup(
       manifest_fname = live_files[i];
     }
 
+    auto data_path_to_size_iter =
+        data_path_to_size.find(db->GetName() + live_files[i]);
+    uint64_t size_bytes = data_path_to_size_iter == data_path_to_size.end()
+                              ? port::kMaxUint64
+                              : data_path_to_size_iter->second;
+
     // rules:
     // * if it's kTableFile, then it's shared
     // * if it's kDescriptorFile, limit the size to manifest_file_size
     s = AddBackupFileWorkItem(
         live_dst_paths, backup_items_to_finish, new_backup_id,
         options_.share_table_files && type == kTableFile, db->GetName(),
-        live_files[i], rate_limiter.get(),
+        live_files[i], rate_limiter.get(), size_bytes,
         (type == kDescriptorFile) ? manifest_file_size : 0,
         options_.share_files_with_checksum && type == kTableFile,
         progress_callback);
@@ -725,21 +754,37 @@ Status BackupEngineImpl::CreateNewBackup(
     s = AddBackupFileWorkItem(
         live_dst_paths, backup_items_to_finish, new_backup_id,
         false /* shared */, "" /* src_dir */, CurrentFileName(""),
-        rate_limiter.get(), 0 /* size_limit */, false /* shared_checksum */,
-        progress_callback, manifest_fname.substr(1) + "\n");
+        rate_limiter.get(), manifest_fname.size(), 0 /* size_limit */,
+        false /* shared_checksum */, progress_callback,
+        manifest_fname.substr(1) + "\n");
   }
+
+  // Pre-fetch sizes for WAL files
+  std::unordered_map<std::string, uint64_t> wal_path_to_size;
+  if (s.ok()) {
+    if (db->GetOptions().wal_dir != "") {
+      s = InsertPathnameToSizeBytes(db->GetOptions().wal_dir,
+                                    &wal_path_to_size);
+    } else {
+      wal_path_to_size = std::move(data_path_to_size);
+    }
+  }
+
   // Add a CopyOrCreateWorkItem to the channel for each WAL file
   for (size_t i = 0; s.ok() && i < live_wal_files.size(); ++i) {
+    auto wal_path_to_size_iter =
+        wal_path_to_size.find(live_wal_files[i]->PathName());
+    uint64_t size_bytes = wal_path_to_size_iter == wal_path_to_size.end()
+                              ? port::kMaxUint64
+                              : wal_path_to_size_iter->second;
     if (live_wal_files[i]->Type() == kAliveLogFile) {
       // we only care about live log files
       // copy the file into backup_dir/files/<new backup>/
-      s = AddBackupFileWorkItem(live_dst_paths,
-                                backup_items_to_finish,
-                                new_backup_id,
-                                false, /* not shared */
+      s = AddBackupFileWorkItem(live_dst_paths, backup_items_to_finish,
+                                new_backup_id, false, /* not shared */
                                 db->GetOptions().wal_dir,
                                 live_wal_files[i]->PathName(),
-                                rate_limiter.get());
+                                rate_limiter.get(), size_bytes);
     }
   }
 
@@ -1070,21 +1115,20 @@ Status BackupEngineImpl::VerifyBackup(BackupID backup_id) {
 
   Log(options_.info_log, "Verifying backup id %u\n", backup_id);
 
-  uint64_t size;
-  Status result;
-  std::string file_path;
+  std::unordered_map<std::string, uint64_t> curr_abs_path_to_size;
+  for (const auto& rel_dir : {GetPrivateFileRel(backup_id), GetSharedFileRel(),
+                              GetSharedFileWithChecksumRel()}) {
+    const auto abs_dir = GetAbsolutePath(rel_dir);
+    InsertPathnameToSizeBytes(abs_dir, &curr_abs_path_to_size);
+  }
+
   for (const auto& file_info : backup->GetFiles()) {
-    const std::string& file = file_info->filename;
-    file_path = GetAbsolutePath(file);
-    result = backup_env_->FileExists(file_path);
-    if (!result.ok()) {
-      return result;
+    const auto abs_path = GetAbsolutePath(file_info->filename);
+    if (curr_abs_path_to_size.find(abs_path) == curr_abs_path_to_size.end()) {
+      return Status::NotFound("File missing: " + abs_path);
     }
-    result = backup_env_->GetFileSize(file_path, &size);
-    if (!result.ok()) {
-      return result;
-    } else if (size != file_info->size) {
-      return Status::Corruption("File corrupted: " + file);
+    if (file_info->size != curr_abs_path_to_size[abs_path]) {
+      return Status::Corruption("File corrupted: " + abs_path);
     }
   }
   return Status::OK();
@@ -1219,30 +1263,29 @@ Status BackupEngineImpl::AddBackupFileWorkItem(
     std::unordered_set<std::string>& live_dst_paths,
     std::vector<BackupAfterCopyOrCreateWorkItem>& backup_items_to_finish,
     BackupID backup_id, bool shared, const std::string& src_dir,
-    const std::string& fname, RateLimiter* rate_limiter, uint64_t size_limit,
-    bool shared_checksum, std::function<void()> progress_callback,
-    const std::string& contents) {
+    const std::string& fname, RateLimiter* rate_limiter, uint64_t size_bytes,
+    uint64_t size_limit, bool shared_checksum,
+    std::function<void()> progress_callback, const std::string& contents) {
   assert(!fname.empty() && fname[0] == '/');
   assert(contents.empty() != src_dir.empty());
 
   std::string dst_relative = fname.substr(1);
   std::string dst_relative_tmp;
   Status s;
-  uint64_t size;
   uint32_t checksum_value = 0;
 
   if (shared && shared_checksum) {
     // add checksum and file length to the file name
     s = CalculateChecksum(src_dir + fname, db_env_, size_limit,
                           &checksum_value);
-    if (s.ok()) {
-      s = db_env_->GetFileSize(src_dir + fname, &size);
-    }
     if (!s.ok()) {
       return s;
     }
-    dst_relative = GetSharedFileWithChecksum(dst_relative, checksum_value,
-                                             size);
+    if (size_bytes == port::kMaxUint64) {
+      return Status::NotFound("File missing: " + src_dir + fname);
+    }
+    dst_relative =
+        GetSharedFileWithChecksum(dst_relative, checksum_value, size_bytes);
     dst_relative_tmp = GetSharedFileWithChecksumRel(dst_relative, true);
     dst_relative = GetSharedFileWithChecksumRel(dst_relative, false);
   } else if (shared) {
@@ -1282,7 +1325,7 @@ Status BackupEngineImpl::AddBackupFileWorkItem(
     if (shared_checksum) {
       Log(options_.info_log,
           "%s already present, with checksum %u and size %" PRIu64,
-          fname.c_str(), checksum_value, size);
+          fname.c_str(), checksum_value, size_bytes);
     } else if (backuped_file_infos_.find(dst_relative) ==
                backuped_file_infos_.end() && !same_path) {
       // file already exists, but it's not referenced by any backup. overwrite
@@ -1295,7 +1338,6 @@ Status BackupEngineImpl::AddBackupFileWorkItem(
       backup_env_->DeleteFile(dst_path);
     } else {
       // the file is present and referenced by a backup
-      db_env_->GetFileSize(src_dir + fname, &size);  // Ignore error
       Log(options_.info_log, "%s already present, calculate checksum",
           fname.c_str());
       s = CalculateChecksum(src_dir + fname, db_env_, size_limit,
@@ -1324,7 +1366,7 @@ Status BackupEngineImpl::AddBackupFileWorkItem(
     backup_items_to_finish.push_back(std::move(after_copy_or_create_work_item));
     CopyOrCreateResult result;
     result.status = s;
-    result.size = size;
+    result.size = size_bytes;
     result.checksum_value = checksum_value;
     promise_result.set_value(std::move(result));
   }
@@ -1390,6 +1432,22 @@ void BackupEngineImpl::DeleteChildren(const std::string& dir,
   }
 }
 
+Status BackupEngineImpl::InsertPathnameToSizeBytes(
+    const std::string& dir, std::unordered_map<std::string, uint64_t>* result) {
+  assert(result != nullptr);
+  std::vector<Env::FileAttributes> files_attrs;
+  Status status = backup_env_->GetChildrenFileAttributes(dir, &files_attrs);
+  if (!status.ok()) {
+    return status;
+  }
+  const bool slash_needed = dir.empty() || dir.back() != '/';
+  for (const auto& file_attrs : files_attrs) {
+    result->emplace(dir + (slash_needed ? "/" : "") + file_attrs.name,
+                    file_attrs.size_bytes);
+  }
+  return Status::OK();
+}
+
 Status BackupEngineImpl::GarbageCollect() {
   assert(!read_only_);
   Log(options_.info_log, "Starting garbage collection");
@@ -1561,8 +1619,9 @@ bool TEST_GetFileSizeFromBackupFileName(const std::string full_name,
 // <file1> <crc32(literal string)> <crc32_value>
 // <file2> <crc32(literal string)> <crc32_value>
 // ...
-Status BackupEngineImpl::BackupMeta::LoadFromFile(const std::string& backup_dir,
-                                                  bool use_size_in_file_name) {
+Status BackupEngineImpl::BackupMeta::LoadFromFile(
+    const std::string& backup_dir, bool use_size_in_file_name,
+    const std::unordered_map<std::string, uint64_t>& abs_path_to_size) {
   assert(Empty());
   Status s;
   unique_ptr<SequentialFile> backup_meta_file;
@@ -1606,9 +1665,11 @@ Status BackupEngineImpl::BackupMeta::LoadFromFile(const std::string& backup_dir,
     } else {
       if (!use_size_in_file_name ||
           !GetFileSizeFromBackupFileName(filename, &size)) {
-        s = env_->GetFileSize(backup_dir + "/" + filename, &size);
-        if (!s.ok()) {
-          return s;
+        std::string abs_path = backup_dir + "/" + filename;
+        try {
+          size = abs_path_to_size.at(abs_path);
+        } catch (std::out_of_range& e) {
+          return Status::NotFound("Size missing for pathname: " + abs_path);
         }
       }
     }

utilities/backupable/backupable_db_test.cc

@@ -232,6 +232,23 @@ class TestEnv : public EnvWrapper {
     return EnvWrapper::GetChildren(dir, r);
   }
 
+  // Some test cases do not actually create the test files (e.g., see
+  // DummyDB::live_files_) - for those cases, we mock those files' attributes
+  // so CreateNewBackup() can get their attributes.
+  void SetFilenamesForMockedAttrs(const std::vector<std::string>& filenames) {
+    filenames_for_mocked_attrs_ = filenames;
+  }
+  Status GetChildrenFileAttributes(
+      const std::string& dir, std::vector<Env::FileAttributes>* r) override {
+    if (filenames_for_mocked_attrs_.size() > 0) {
+      for (const auto& filename : filenames_for_mocked_attrs_) {
+        r->push_back({dir + filename, 10 /* size_bytes */});
+      }
+      return Status::OK();
+    }
+    return EnvWrapper::GetChildrenFileAttributes(dir, r);
+  }
+
   void SetCreateDirIfMissingFailure(bool fail) {
     create_dir_if_missing_failure_ = fail;
   }
@@ -255,6 +272,7 @@ class TestEnv : public EnvWrapper {
   port::Mutex mutex_;
   bool dummy_sequential_file_ = false;
   std::vector<std::string> written_files_;
+  std::vector<std::string> filenames_for_mocked_attrs_;
   uint64_t limit_written_files_ = 1000000;
   uint64_t limit_delete_files_ = 1000000;
 
@@ -780,6 +798,7 @@ TEST_F(BackupableDBTest, NoDoubleCopy) {
   dummy_db_->live_files_ = { "/00010.sst", "/00011.sst",
                              "/CURRENT",   "/MANIFEST-01" };
   dummy_db_->wal_files_ = {{"/00011.log", true}, {"/00012.log", false}};
+  test_backup_env_->SetFilenamesForMockedAttrs(dummy_db_->live_files_);
   ASSERT_OK(backup_engine_->CreateNewBackup(db_.get(), false));
   std::vector<std::string> should_have_written = {
       "/shared/00010.sst.tmp",    "/shared/00011.sst.tmp",
@@ -796,6 +815,7 @@ TEST_F(BackupableDBTest, NoDoubleCopy) {
   dummy_db_->live_files_ = { "/00010.sst", "/00015.sst",
                              "/CURRENT",   "/MANIFEST-01" };
   dummy_db_->wal_files_ = {{"/00011.log", true}, {"/00012.log", false}};
+  test_backup_env_->SetFilenamesForMockedAttrs(dummy_db_->live_files_);
   ASSERT_OK(backup_engine_->CreateNewBackup(db_.get(), false));
   // should not open 00010.sst - it's already there
   should_have_written = {
@@ -846,6 +866,7 @@ TEST_F(BackupableDBTest, DifferentEnvs) {
   dummy_db_->live_files_ = { "/00010.sst", "/00011.sst",
                              "/CURRENT",   "/MANIFEST-01" };
   dummy_db_->wal_files_ = {{"/00011.log", true}, {"/00012.log", false}};
+  test_backup_env_->SetFilenamesForMockedAttrs(dummy_db_->live_files_);
   ASSERT_OK(backup_engine_->CreateNewBackup(db_.get(), false));
 
   CloseDBAndBackupEngine();
@@ -857,6 +878,7 @@ TEST_F(BackupableDBTest, DifferentEnvs) {
   CloseDBAndBackupEngine();
   DestroyDB(dbname_, Options());
 
+  test_backup_env_->SetFilenamesForMockedAttrs({});
   AssertBackupConsistency(0, 0, 100, 500);
 }