Added a new fault injection test.

This test is intended to ensure leveldb properly detects and recovers from
faults - specifically unwritten file data lost as a result of a system reset.

Makefile

@@ -49,6 +49,7 @@ TESTS = \
 	db_test \
 	dbformat_test \
 	env_test \
+	fault_injection_test \
 	filename_test \
 	filter_block_test \
 	hash_test \
@@ -155,6 +156,9 @@ dbformat_test: db/dbformat_test.o $(LIBOBJECTS) $(TESTHARNESS)
 env_test: util/env_test.o $(LIBOBJECTS) $(TESTHARNESS)
 	$(CXX) $(LDFLAGS) util/env_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
 
+fault_injection_test: db/fault_injection_test.o $(LIBOBJECTS) $(TESTHARNESS)
+	$(CXX) $(LDFLAGS) db/fault_injection_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
+
 filename_test: db/filename_test.o $(LIBOBJECTS) $(TESTHARNESS)
 	$(CXX) $(LDFLAGS) db/filename_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS)
 

db/fault_injection_test.cc

@@ -0,0 +1,542 @@
+// Copyright 2014 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+// This test uses a custom Env to keep track of the state of a filesystem as of
+// the last "sync". It then checks for data loss errors by purposely dropping
+// file data (or entire files) not protected by a "sync".
+
+#include "leveldb/db.h"
+
+#include <map>
+#include <set>
+#include "db/db_impl.h"
+#include "db/filename.h"
+#include "db/log_format.h"
+#include "db/version_set.h"
+#include "leveldb/cache.h"
+#include "leveldb/env.h"
+#include "leveldb/table.h"
+#include "leveldb/write_batch.h"
+#include "util/logging.h"
+#include "util/mutexlock.h"
+#include "util/testharness.h"
+#include "util/testutil.h"
+
+namespace leveldb {
+
+static const int kValueSize = 1000;
+static const int kMaxNumValues = 2000;
+static const size_t kNumIterations = 3;
+
+class FaultInjectionTestEnv;
+
+namespace {
+
+// Assume a filename, and not a directory name like "/foo/bar/"
+static std::string GetDirName(const std::string filename) {
+  size_t found = filename.find_last_of("/\\");
+  if (found == std::string::npos) {
+    return "";
+  } else {
+    return filename.substr(0, found);
+  }
+}
+
+Status SyncDir(const std::string& dir) {
+  // As this is a test it isn't required to *actually* sync this directory.
+  return Status::OK();
+}
+
+// A basic file truncation function suitable for this test.
+Status Truncate(const std::string& filename, uint64_t length) {
+  leveldb::Env* env = leveldb::Env::Default();
+
+  SequentialFile* orig_file;
+  Status s = env->NewSequentialFile(filename, &orig_file);
+  if (!s.ok())
+    return s;
+
+  char* scratch = new char[length];
+  leveldb::Slice result;
+  s = orig_file->Read(length, &result, scratch);
+  delete orig_file;
+  if (s.ok()) {
+    std::string tmp_name = GetDirName(filename) + "/truncate.tmp";
+    WritableFile* tmp_file;
+    s = env->NewWritableFile(tmp_name, &tmp_file);
+    if (s.ok()) {
+      s = tmp_file->Append(result);
+      delete tmp_file;
+      if (s.ok()) {
+        s = env->RenameFile(tmp_name, filename);
+      } else {
+        env->DeleteFile(tmp_name);
+      }
+    }
+  }
+
+  delete[] scratch;
+
+  return s;
+}
+
+struct FileState {
+  std::string filename_;
+  ssize_t pos_;
+  ssize_t pos_at_last_sync_;
+  ssize_t pos_at_last_flush_;
+
+  FileState(const std::string& filename)
+      : filename_(filename),
+        pos_(-1),
+        pos_at_last_sync_(-1),
+        pos_at_last_flush_(-1) { }
+
+  FileState() : pos_(-1), pos_at_last_sync_(-1), pos_at_last_flush_(-1) {}
+
+  bool IsFullySynced() const { return pos_ <= 0 || pos_ == pos_at_last_sync_; }
+
+  Status DropUnsyncedData() const;
+};
+
+}  // anonymous namespace
+
+// A wrapper around WritableFile which informs another Env whenever this file
+// is written to or sync'ed.
+class TestWritableFile : public WritableFile {
+ public:
+  TestWritableFile(const std::string& fname,
+                   WritableFile* f,
+                   FaultInjectionTestEnv* env);
+  virtual ~TestWritableFile();
+  virtual Status Append(const Slice& data);
+  virtual Status Close();
+  virtual Status Flush();
+  virtual Status Sync();
+
+ private:
+  FileState state_;
+  WritableFile* target_;
+  bool writable_file_opened_;
+  FaultInjectionTestEnv* env_;
+
+  Status SyncParent();
+};
+
+class FaultInjectionTestEnv : public EnvWrapper {
+ public:
+  FaultInjectionTestEnv() : EnvWrapper(Env::Default()), filesystem_active_(true) {}
+  virtual ~FaultInjectionTestEnv() { }
+  virtual Status NewWritableFile(const std::string& fname,
+                                 WritableFile** result);
+  virtual Status DeleteFile(const std::string& f);
+  virtual Status RenameFile(const std::string& s, const std::string& t);
+
+  void WritableFileClosed(const FileState& state);
+  Status DropUnsyncedFileData();
+  Status DeleteFilesCreatedAfterLastDirSync();
+  void DirWasSynced();
+  bool IsFileCreatedSinceLastDirSync(const std::string& filename);
+  void ResetState();
+  void UntrackFile(const std::string& f);
+  // Setting the filesystem to inactive is the test equivalent to simulating a
+  // system reset. Setting to inactive will freeze our saved filesystem state so
+  // that it will stop being recorded. It can then be reset back to the state at
+  // the time of the reset.
+  bool IsFilesystemActive() const { return filesystem_active_; }
+  void SetFilesystemActive(bool active) { filesystem_active_ = active; }
+
+ private:
+  port::Mutex mutex_;
+  std::map<std::string, FileState> db_file_state_;
+  std::set<std::string> new_files_since_last_dir_sync_;
+  bool filesystem_active_;  // Record flushes, syncs, writes
+};
+
+TestWritableFile::TestWritableFile(const std::string& fname,
+                                   WritableFile* f,
+                                   FaultInjectionTestEnv* env)
+    : state_(fname),
+      target_(f),
+      writable_file_opened_(true),
+      env_(env) {
+  assert(f != NULL);
+  state_.pos_ = 0;
+}
+
+TestWritableFile::~TestWritableFile() {
+  if (writable_file_opened_) {
+    Close();
+  }
+  delete target_;
+}
+
+Status TestWritableFile::Append(const Slice& data) {
+  Status s = target_->Append(data);
+  if (s.ok() && env_->IsFilesystemActive()) {
+    state_.pos_ += data.size();
+  }
+  return s;
+}
+
+Status TestWritableFile::Close() {
+  writable_file_opened_ = false;
+  Status s = target_->Close();
+  if (s.ok()) {
+    env_->WritableFileClosed(state_);
+  }
+  return s;
+}
+
+Status TestWritableFile::Flush() {
+  Status s = target_->Flush();
+  if (s.ok() && env_->IsFilesystemActive()) {
+    state_.pos_at_last_flush_ = state_.pos_;
+  }
+  return s;
+}
+
+Status TestWritableFile::SyncParent() {
+  Status s = SyncDir(GetDirName(state_.filename_));
+  if (s.ok()) {
+    env_->DirWasSynced();
+  }
+  return s;
+}
+
+Status TestWritableFile::Sync() {
+  if (!env_->IsFilesystemActive()) {
+    return Status::OK();
+  }
+  // Ensure new files referred to by the manifest are in the filesystem.
+  Status s = target_->Sync();
+  if (s.ok()) {
+    state_.pos_at_last_sync_ = state_.pos_;
+  }
+  if (env_->IsFileCreatedSinceLastDirSync(state_.filename_)) {
+    Status ps = SyncParent();
+    if (s.ok() && !ps.ok()) {
+      s = ps;
+    }
+  }
+  return s;
+}
+
+Status FaultInjectionTestEnv::NewWritableFile(const std::string& fname,
+                                              WritableFile** result) {
+  WritableFile* actual_writable_file;
+  Status s = target()->NewWritableFile(fname, &actual_writable_file);
+  if (s.ok()) {
+    *result = new TestWritableFile(fname, actual_writable_file, this);
+    // WritableFile doesn't append to files, so if the same file is opened again
+    // then it will be truncated - so forget our saved state.
+    UntrackFile(fname);
+    MutexLock l(&mutex_);
+    new_files_since_last_dir_sync_.insert(fname);
+  }
+  return s;
+}
+
+Status FaultInjectionTestEnv::DropUnsyncedFileData() {
+  Status s;
+  MutexLock l(&mutex_);
+  for (std::map<std::string, FileState>::const_iterator it =
+           db_file_state_.begin();
+       s.ok() && it != db_file_state_.end(); ++it) {
+    const FileState& state = it->second;
+    if (!state.IsFullySynced()) {
+      s = state.DropUnsyncedData();
+    }
+  }
+  return s;
+}
+
+void FaultInjectionTestEnv::DirWasSynced() {
+  MutexLock l(&mutex_);
+  new_files_since_last_dir_sync_.clear();
+}
+
+bool FaultInjectionTestEnv::IsFileCreatedSinceLastDirSync(
+    const std::string& filename) {
+  MutexLock l(&mutex_);
+  return new_files_since_last_dir_sync_.find(filename) !=
+         new_files_since_last_dir_sync_.end();
+}
+
+void FaultInjectionTestEnv::UntrackFile(const std::string& f) {
+  MutexLock l(&mutex_);
+  db_file_state_.erase(f);
+  new_files_since_last_dir_sync_.erase(f);
+}
+
+Status FaultInjectionTestEnv::DeleteFile(const std::string& f) {
+  Status s = EnvWrapper::DeleteFile(f);
+  ASSERT_OK(s);
+  if (s.ok()) {
+    UntrackFile(f);
+  }
+  return s;
+}
+
+Status FaultInjectionTestEnv::RenameFile(const std::string& s,
+                                         const std::string& t) {
+  Status ret = EnvWrapper::RenameFile(s, t);
+
+  if (ret.ok()) {
+    MutexLock l(&mutex_);
+    if (db_file_state_.find(s) != db_file_state_.end()) {
+      db_file_state_[t] = db_file_state_[s];
+      db_file_state_.erase(s);
+    }
+
+    if (new_files_since_last_dir_sync_.erase(s) != 0) {
+      assert(new_files_since_last_dir_sync_.find(t) ==
+             new_files_since_last_dir_sync_.end());
+      new_files_since_last_dir_sync_.insert(t);
+    }
+  }
+
+  return ret;
+}
+
+void FaultInjectionTestEnv::ResetState() {
+  MutexLock l(&mutex_);
+  db_file_state_.clear();
+  new_files_since_last_dir_sync_.clear();
+  SetFilesystemActive(true);
+}
+
+Status FaultInjectionTestEnv::DeleteFilesCreatedAfterLastDirSync() {
+  // Because DeleteFile access this container make a copy to avoid deadlock
+  mutex_.Lock();
+  std::set<std::string> new_files(new_files_since_last_dir_sync_.begin(),
+                                  new_files_since_last_dir_sync_.end());
+  mutex_.Unlock();
+  Status s;
+  std::set<std::string>::const_iterator it;
+  for (it = new_files.begin(); s.ok() && it != new_files.end(); ++it) {
+    s = DeleteFile(*it);
+  }
+  return s;
+}
+
+void FaultInjectionTestEnv::WritableFileClosed(const FileState& state) {
+  MutexLock l(&mutex_);
+  db_file_state_[state.filename_] = state;
+}
+
+Status FileState::DropUnsyncedData() const {
+  ssize_t sync_pos = pos_at_last_sync_ == -1 ? 0 : pos_at_last_sync_;
+  return Truncate(filename_, sync_pos);
+}
+
+class FaultInjectionTest {
+ public:
+  enum ExpectedVerifResult { VAL_EXPECT_NO_ERROR, VAL_EXPECT_ERROR };
+  enum ResetMethod { RESET_DROP_UNSYNCED_DATA, RESET_DELETE_UNSYNCED_FILES };
+
+  FaultInjectionTestEnv* env_;
+  std::string dbname_;
+  Cache* tiny_cache_;
+  Options options_;
+  DB* db_;
+
+  FaultInjectionTest() : env_(NULL), tiny_cache_(NULL), db_(NULL) { NewDB(); }
+
+  ~FaultInjectionTest() { ASSERT_OK(TearDown()); }
+
+  Status NewDB() {
+    assert(db_ == NULL);
+    assert(tiny_cache_ == NULL);
+    assert(env_ == NULL);
+
+    env_ = new FaultInjectionTestEnv();
+
+    options_ = Options();
+    options_.env = env_;
+    options_.paranoid_checks = true;
+
+    tiny_cache_ = NewLRUCache(100);
+    options_.block_cache = tiny_cache_;
+    dbname_ = test::TmpDir() + "/fault_test";
+
+    options_.create_if_missing = true;
+    Status s = OpenDB();
+    options_.create_if_missing = false;
+    return s;
+  }
+
+  Status SetUp() {
+    Status s = TearDown();
+    if (s.ok()) {
+      s = NewDB();
+    }
+    return s;
+  }
+
+  Status TearDown() {
+    CloseDB();
+
+    Status s = DestroyDB(dbname_, Options());
+
+    delete tiny_cache_;
+    tiny_cache_ = NULL;
+
+    delete env_;
+    env_ = NULL;
+
+    return s;
+  }
+
+  void Build(int start_idx, int num_vals) {
+    std::string key_space, value_space;
+    WriteBatch batch;
+    for (int i = start_idx; i < start_idx + num_vals; i++) {
+      Slice key = Key(i, &key_space);
+      batch.Clear();
+      batch.Put(key, Value(i, &value_space));
+      WriteOptions options;
+      ASSERT_OK(db_->Write(options, &batch));
+    }
+  }
+
+  Status ReadValue(int i, std::string* val) const {
+    std::string key_space, value_space;
+    Slice key = Key(i, &key_space);
+    Value(i, &value_space);
+    ReadOptions options;
+    return db_->Get(options, key, val);
+  }
+
+  Status Verify(int start_idx, int num_vals,
+                ExpectedVerifResult expected) const {
+    std::string val;
+    std::string value_space;
+    Status s;
+    for (int i = start_idx; i < start_idx + num_vals && s.ok(); i++) {
+      Value(i, &value_space);
+      s = ReadValue(i, &val);
+      if (expected == VAL_EXPECT_NO_ERROR) {
+        if (s.ok()) {
+          ASSERT_EQ(value_space, val);
+        }
+      } else if (s.ok()) {
+        fprintf(stderr, "Expected an error at %d, but was OK\n", i);
+        s = Status::IOError(dbname_, "Expected value error:");
+      } else {
+        s = Status::OK();  // An expected error
+      }
+    }
+    return s;
+  }
+
+  // Return the ith key
+  Slice Key(int i, std::string* storage) const {
+    char buf[100];
+    snprintf(buf, sizeof(buf), "%016d", i);
+    storage->assign(buf, strlen(buf));
+    return Slice(*storage);
+  }
+
+  // Return the value to associate with the specified key
+  Slice Value(int k, std::string* storage) const {
+    Random r(k);
+    return test::RandomString(&r, kValueSize, storage);
+  }
+
+  Status OpenDB() {
+    delete db_;
+    db_ = NULL;
+    env_->ResetState();
+    return DB::Open(options_, dbname_, &db_);
+  }
+
+  void CloseDB() {
+    delete db_;
+    db_ = NULL;
+  }
+
+  void DeleteAllData() {
+    Iterator* iter = db_->NewIterator(ReadOptions());
+    WriteOptions options;
+    for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
+      ASSERT_OK(db_->Delete(WriteOptions(), iter->key()));
+    }
+
+    delete iter;
+  }
+
+  void ResetDBState(ResetMethod reset_method) {
+    switch (reset_method) {
+      case RESET_DROP_UNSYNCED_DATA:
+        ASSERT_OK(env_->DropUnsyncedFileData());
+        break;
+      case RESET_DELETE_UNSYNCED_FILES:
+        ASSERT_OK(env_->DeleteFilesCreatedAfterLastDirSync());
+        break;
+      default:
+        assert(false);
+    }
+  }
+
+  void PartialCompactTestPreFault(int num_pre_sync, int num_post_sync) {
+    DeleteAllData();
+    Build(0, num_pre_sync);
+    db_->CompactRange(NULL, NULL);
+    Build(num_pre_sync, num_post_sync);
+  }
+
+  void PartialCompactTestReopenWithFault(ResetMethod reset_method,
+                                         int num_pre_sync,
+                                         int num_post_sync) {
+    env_->SetFilesystemActive(false);
+    CloseDB();
+    ResetDBState(reset_method);
+    ASSERT_OK(OpenDB());
+    ASSERT_OK(Verify(0, num_pre_sync, FaultInjectionTest::VAL_EXPECT_NO_ERROR));
+    ASSERT_OK(Verify(num_pre_sync, num_post_sync, FaultInjectionTest::VAL_EXPECT_ERROR));
+  }
+
+  void NoWriteTestPreFault() {
+  }
+
+  void NoWriteTestReopenWithFault(ResetMethod reset_method) {
+    CloseDB();
+    ResetDBState(reset_method);
+    ASSERT_OK(OpenDB());
+  }
+};
+
+TEST(FaultInjectionTest, FaultTest) {
+  Random rnd(0);
+  ASSERT_OK(SetUp());
+  for (size_t idx = 0; idx < kNumIterations; idx++) {
+    int num_pre_sync = rnd.Uniform(kMaxNumValues);
+    int num_post_sync = rnd.Uniform(kMaxNumValues);
+
+    PartialCompactTestPreFault(num_pre_sync, num_post_sync);
+    PartialCompactTestReopenWithFault(RESET_DROP_UNSYNCED_DATA,
+                                      num_pre_sync,
+                                      num_post_sync);
+
+    NoWriteTestPreFault();
+    NoWriteTestReopenWithFault(RESET_DROP_UNSYNCED_DATA);
+
+    PartialCompactTestPreFault(num_pre_sync, num_post_sync);
+    // No new files created so we expect all values since no files will be
+    // dropped.
+    PartialCompactTestReopenWithFault(RESET_DELETE_UNSYNCED_FILES,
+                                      num_pre_sync + num_post_sync,
+                                      0);
+
+    NoWriteTestPreFault();
+    NoWriteTestReopenWithFault(RESET_DELETE_UNSYNCED_FILES);
+  }
+}
+
+}  // namespace leveldb
+
+int main(int argc, char** argv) {
+  return leveldb::test::RunAllTests();
+}