db_write_test.cc

//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).

#include <atomic>
#include <fstream>
#include <memory>
#include <thread>
#include <vector>

#include "db/db_test_util.h"
#include "db/write_batch_internal.h"
#include "db/write_thread.h"
#include "port/port.h"
#include "port/stack_trace.h"
#include "test_util/sync_point.h"
#include "util/random.h"
#include "util/string_util.h"
#include "utilities/fault_injection_env.h"

namespace ROCKSDB_NAMESPACE {

// Test variations of WriteImpl.
class DBWriteTest : public DBTestBase, public testing::WithParamInterface<int> {
 public:
  DBWriteTest() : DBTestBase("/db_write_test") {}

  Options GetOptions() { return DBTestBase::GetOptions(GetParam()); }

  void Open() { DBTestBase::Reopen(GetOptions()); }
};

// It is invalid to do sync write while disabling WAL.
TEST_P(DBWriteTest, SyncAndDisableWAL) {
  WriteOptions write_options;
  write_options.sync = true;
  write_options.disableWAL = true;
  ASSERT_TRUE(dbfull()->Put(write_options, "foo", "bar").IsInvalidArgument());
  WriteBatch batch;
  ASSERT_OK(batch.Put("foo", "bar"));
  ASSERT_TRUE(dbfull()->Write(write_options, &batch).IsInvalidArgument());
}

TEST_P(DBWriteTest, WriteThreadHangOnWriteStall) {
  Options options = GetOptions();
  options.level0_stop_writes_trigger = options.level0_slowdown_writes_trigger = 4;
  std::vector<port::Thread> threads;
  std::atomic<int> thread_num(0);
  port::Mutex mutex;
  port::CondVar cv(&mutex);

  Reopen(options);

  std::function<void()> write_slowdown_func = [&]() {
    int a = thread_num.fetch_add(1);
    std::string key = "foo" + std::to_string(a);
    WriteOptions wo;
    wo.no_slowdown = false;
    dbfull()->Put(wo, key, "bar");
  };
  std::function<void()> write_no_slowdown_func = [&]() {
    int a = thread_num.fetch_add(1);
    std::string key = "foo" + std::to_string(a);
    WriteOptions wo;
    wo.no_slowdown = true;
    dbfull()->Put(wo, key, "bar");
  };
  std::function<void(void *)> unblock_main_thread_func = [&](void *) {
    mutex.Lock();
    cv.SignalAll();
    mutex.Unlock();
  };

  // Create 3 L0 files and schedule 4th without waiting
  Put("foo" + std::to_string(thread_num.fetch_add(1)), "bar");
  Flush();
  Put("foo" + std::to_string(thread_num.fetch_add(1)), "bar");
  Flush();
  Put("foo" + std::to_string(thread_num.fetch_add(1)), "bar");
  Flush();
  Put("foo" + std::to_string(thread_num.fetch_add(1)), "bar");

  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
      "WriteThread::JoinBatchGroup:Start", unblock_main_thread_func);
  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->LoadDependency(
      {{"DBWriteTest::WriteThreadHangOnWriteStall:1",
        "DBImpl::BackgroundCallFlush:start"},
       {"DBWriteTest::WriteThreadHangOnWriteStall:2",
        "DBImpl::WriteImpl:BeforeLeaderEnters"},
       // Make compaction start wait for the write stall to be detected and
       // implemented by a write group leader
       {"DBWriteTest::WriteThreadHangOnWriteStall:3",
        "BackgroundCallCompaction:0"}});
  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing();

  // Schedule creation of 4th L0 file without waiting. This will seal the
  // memtable and then wait for a sync point before writing the file. We need
  // to do it this way because SwitchMemtable() needs to enter the
  // write_thread
  FlushOptions fopt;
  fopt.wait = false;
  dbfull()->Flush(fopt);

  // Create a mix of slowdown/no_slowdown write threads
  mutex.Lock();
  // First leader
  threads.emplace_back(write_slowdown_func);
  cv.Wait();
  // Second leader. Will stall writes
  threads.emplace_back(write_slowdown_func);
  cv.Wait();
  threads.emplace_back(write_no_slowdown_func);
  cv.Wait();
  threads.emplace_back(write_slowdown_func);
  cv.Wait();
  threads.emplace_back(write_no_slowdown_func);
  cv.Wait();
  threads.emplace_back(write_slowdown_func);
  cv.Wait();
  mutex.Unlock();

  TEST_SYNC_POINT("DBWriteTest::WriteThreadHangOnWriteStall:1");
  dbfull()->TEST_WaitForFlushMemTable(nullptr);
  // This would have triggered a write stall. Unblock the write group leader
  TEST_SYNC_POINT("DBWriteTest::WriteThreadHangOnWriteStall:2");
  // The leader is going to create missing newer links. When the leader finishes,
  // the next leader is going to delay writes and fail writers with no_slowdown

  TEST_SYNC_POINT("DBWriteTest::WriteThreadHangOnWriteStall:3");
  for (auto& t : threads) {
    t.join();
  }
}

TEST_P(DBWriteTest, IOErrorOnWALWritePropagateToWriteThreadFollower) {
  constexpr int kNumThreads = 5;
  std::unique_ptr<FaultInjectionTestEnv> mock_env(
      new FaultInjectionTestEnv(Env::Default()));
  Options options = GetOptions();
  options.env = mock_env.get();
  Reopen(options);
  std::atomic<int> ready_count{0};
  std::atomic<int> leader_count{0};
  std::vector<port::Thread> threads;
  mock_env->SetFilesystemActive(false);

  // Wait until all threads linked to write threads, to make sure
  // all threads join the same batch group.
  SyncPoint::GetInstance()->SetCallBack(
      "WriteThread::JoinBatchGroup:Wait", [&](void* arg) {
        ready_count++;
        auto* w = reinterpret_cast<WriteThread::Writer*>(arg);
        if (w->state == WriteThread::STATE_GROUP_LEADER) {
          leader_count++;
          while (ready_count < kNumThreads) {
            // busy waiting
          }
        }
      });
  SyncPoint::GetInstance()->EnableProcessing();
  for (int i = 0; i < kNumThreads; i++) {
    threads.push_back(port::Thread(
        [&](int index) {
          // All threads should fail.
          auto res = Put("key" + ToString(index), "value");
          if (options.manual_wal_flush) {
            ASSERT_TRUE(res.ok());
            // we should see fs error when we do the flush

            // TSAN reports a false alarm for lock-order-inversion but Open and
            // FlushWAL are not run concurrently. Disabling this until TSAN is
            // fixed.
            // res = dbfull()->FlushWAL(false);
            // ASSERT_FALSE(res.ok());
          } else {
            ASSERT_FALSE(res.ok());
          }
        },
        i));
  }
  for (int i = 0; i < kNumThreads; i++) {
    threads[i].join();
  }
  ASSERT_EQ(1, leader_count);
  // Close before mock_env destruct.
  Close();
}

TEST_P(DBWriteTest, ManualWalFlushInEffect) {
  Options options = GetOptions();
  Reopen(options);
  // try the 1st WAL created during open
  ASSERT_TRUE(Put("key" + ToString(0), "value").ok());
  ASSERT_TRUE(options.manual_wal_flush != dbfull()->TEST_WALBufferIsEmpty());
  ASSERT_TRUE(dbfull()->FlushWAL(false).ok());
  ASSERT_TRUE(dbfull()->TEST_WALBufferIsEmpty());
  // try the 2nd wal created during SwitchWAL
  dbfull()->TEST_SwitchWAL();
  ASSERT_TRUE(Put("key" + ToString(0), "value").ok());
  ASSERT_TRUE(options.manual_wal_flush != dbfull()->TEST_WALBufferIsEmpty());
  ASSERT_TRUE(dbfull()->FlushWAL(false).ok());
  ASSERT_TRUE(dbfull()->TEST_WALBufferIsEmpty());
}

TEST_P(DBWriteTest, IOErrorOnWALWriteTriggersReadOnlyMode) {
  std::unique_ptr<FaultInjectionTestEnv> mock_env(
      new FaultInjectionTestEnv(Env::Default()));
  Options options = GetOptions();
  options.env = mock_env.get();
  Reopen(options);
  for (int i = 0; i < 2; i++) {
    // Forcibly fail WAL write for the first Put only. Subsequent Puts should
    // fail due to read-only mode
    mock_env->SetFilesystemActive(i != 0);
    auto res = Put("key" + ToString(i), "value");
    // TSAN reports a false alarm for lock-order-inversion but Open and
    // FlushWAL are not run concurrently. Disabling this until TSAN is
    // fixed.
    /*
    if (options.manual_wal_flush && i == 0) {
      // even with manual_wal_flush the 2nd Put should return error because of
      // the read-only mode
      ASSERT_TRUE(res.ok());
      // we should see fs error when we do the flush
      res = dbfull()->FlushWAL(false);
    }
    */
    if (!options.manual_wal_flush) {
      ASSERT_FALSE(res.ok());
    }
  }
  // Close before mock_env destruct.
  Close();
}

TEST_P(DBWriteTest, IOErrorOnSwitchMemtable) {
  Random rnd(301);
  std::unique_ptr<FaultInjectionTestEnv> mock_env(
      new FaultInjectionTestEnv(Env::Default()));
  Options options = GetOptions();
  options.env = mock_env.get();
  options.writable_file_max_buffer_size = 4 * 1024 * 1024;
  options.write_buffer_size = 3 * 512 * 1024;
  options.wal_bytes_per_sync = 256 * 1024;
  options.manual_wal_flush = true;
  Reopen(options);
  mock_env->SetFilesystemActive(false, Status::IOError("Not active"));
  Status s;
  for (int i = 0; i < 4 * 512; ++i) {
    s = Put(Key(i), rnd.RandomString(1024));
    if (!s.ok()) {
      break;
    }
  }
  ASSERT_EQ(s.severity(), Status::Severity::kFatalError);

  mock_env->SetFilesystemActive(true);
  // Close before mock_env destruct.
  Close();
}

// Test that db->LockWAL() flushes the WAL after locking.
TEST_P(DBWriteTest, LockWalInEffect) {
  Options options = GetOptions();
  Reopen(options);
  // try the 1st WAL created during open
  ASSERT_OK(Put("key" + ToString(0), "value"));
  ASSERT_TRUE(options.manual_wal_flush != dbfull()->TEST_WALBufferIsEmpty());
  ASSERT_OK(dbfull()->LockWAL());
  ASSERT_TRUE(dbfull()->TEST_WALBufferIsEmpty(false));
  ASSERT_OK(dbfull()->UnlockWAL());
  // try the 2nd wal created during SwitchWAL
  dbfull()->TEST_SwitchWAL();
  ASSERT_OK(Put("key" + ToString(0), "value"));
  ASSERT_TRUE(options.manual_wal_flush != dbfull()->TEST_WALBufferIsEmpty());
  ASSERT_OK(dbfull()->LockWAL());
  ASSERT_TRUE(dbfull()->TEST_WALBufferIsEmpty(false));
  ASSERT_OK(dbfull()->UnlockWAL());
}

TEST_P(DBWriteTest, ConcurrentlyDisabledWAL) {
    Options options = GetOptions();
    options.statistics = ROCKSDB_NAMESPACE::CreateDBStatistics();
    options.statistics->set_stats_level(StatsLevel::kAll);
    Reopen(options);
    std::string wal_key_prefix = "WAL_KEY_";
    std::string no_wal_key_prefix = "K_";
    // 100 KB value each for NO-WAL operation
    std::string no_wal_value(1024 * 100, 'X');
    // 1B value each for WAL operation
    std::string wal_value = "0";
    std::thread threads[10];
    for (int t = 0; t < 10; t++) {
        threads[t] = std::thread([t, wal_key_prefix, wal_value, no_wal_key_prefix, no_wal_value, this] {
            for(int i = 0; i < 10; i++) {
              ROCKSDB_NAMESPACE::WriteOptions write_option_disable;
              write_option_disable.disableWAL = true;
              ROCKSDB_NAMESPACE::WriteOptions write_option_default;
              std::string no_wal_key = no_wal_key_prefix + std::to_string(t) +
                                       "_" + std::to_string(i);
              this->Put(no_wal_key, no_wal_value, write_option_disable);
              std::string wal_key =
                  wal_key_prefix + std::to_string(i) + "_" + std::to_string(i);
              this->Put(wal_key, wal_value, write_option_default);
              dbfull()->SyncWAL();
            }
            return 0;
        });
    }
    for (auto& t: threads) {
        t.join();
    }
    uint64_t bytes_num = options.statistics->getTickerCount(
        ROCKSDB_NAMESPACE::Tickers::WAL_FILE_BYTES);
    // written WAL size should less than 100KB (even included HEADER & FOOTER overhead)
    ASSERT_LE(bytes_num, 1024 * 100);
}

INSTANTIATE_TEST_CASE_P(DBWriteTestInstance, DBWriteTest,
                        testing::Values(DBTestBase::kDefault,
                                        DBTestBase::kConcurrentWALWrites,
                                        DBTestBase::kPipelinedWrite));

}  // namespace ROCKSDB_NAMESPACE

int main(int argc, char** argv) {
  ROCKSDB_NAMESPACE::port::InstallStackTraceHandler();
  ::testing::InitGoogleTest(&argc, argv);
  return RUN_ALL_TESTS();
}