1 files changed, 629 insertions, 0 deletions
diff --git a/src/rocksdb/db/merge_test.cc b/src/rocksdb/db/merge_test.cc
new file mode 100644
index 000000000..0d373d41e
--- /dev/null
+++ b/src/rocksdb/db/merge_test.cc
@@ -0,0 +1,629 @@
+//  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 <assert.h>
+
+#include <iostream>
+#include <memory>
+
+#include "db/db_impl/db_impl.h"
+#include "db/dbformat.h"
+#include "db/write_batch_internal.h"
+#include "port/stack_trace.h"
+#include "rocksdb/cache.h"
+#include "rocksdb/comparator.h"
+#include "rocksdb/db.h"
+#include "rocksdb/env.h"
+#include "rocksdb/merge_operator.h"
+#include "rocksdb/utilities/db_ttl.h"
+#include "test_util/testharness.h"
+#include "util/coding.h"
+#include "utilities/merge_operators.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+bool use_compression;
+
+class MergeTest : public testing::Test {};
+
+size_t num_merge_operator_calls;
+void resetNumMergeOperatorCalls() { num_merge_operator_calls = 0; }
+
+size_t num_partial_merge_calls;
+void resetNumPartialMergeCalls() { num_partial_merge_calls = 0; }
+
+class CountMergeOperator : public AssociativeMergeOperator {
+ public:
+  CountMergeOperator() {
+    mergeOperator_ = MergeOperators::CreateUInt64AddOperator();
+  }
+
+  bool Merge(const Slice& key, const Slice* existing_value, const Slice& value,
+             std::string* new_value, Logger* logger) const override {
+    assert(new_value->empty());
+    ++num_merge_operator_calls;
+    if (existing_value == nullptr) {
+      new_value->assign(value.data(), value.size());
+      return true;
+    }
+
+    return mergeOperator_->PartialMerge(key, *existing_value, value, new_value,
+                                        logger);
+  }
+
+  bool PartialMergeMulti(const Slice& key,
+                         const std::deque<Slice>& operand_list,
+                         std::string* new_value,
+                         Logger* logger) const override {
+    assert(new_value->empty());
+    ++num_partial_merge_calls;
+    return mergeOperator_->PartialMergeMulti(key, operand_list, new_value,
+                                             logger);
+  }
+
+  const char* Name() const override { return "UInt64AddOperator"; }
+
+ private:
+  std::shared_ptr<MergeOperator> mergeOperator_;
+};
+
+class EnvMergeTest : public EnvWrapper {
+ public:
+  EnvMergeTest() : EnvWrapper(Env::Default()) {}
+  static const char* kClassName() { return "MergeEnv"; }
+  const char* Name() const override { return kClassName(); }
+  //  ~EnvMergeTest() override {}
+
+  uint64_t NowNanos() override {
+    ++now_nanos_count_;
+    return target()->NowNanos();
+  }
+
+  static uint64_t now_nanos_count_;
+
+  static std::unique_ptr<EnvMergeTest> singleton_;
+
+  static EnvMergeTest* GetInstance() {
+    if (nullptr == singleton_) singleton_.reset(new EnvMergeTest);
+    return singleton_.get();
+  }
+};
+
+uint64_t EnvMergeTest::now_nanos_count_{0};
+std::unique_ptr<EnvMergeTest> EnvMergeTest::singleton_;
+
+std::shared_ptr<DB> OpenDb(const std::string& dbname, const bool ttl = false,
+                           const size_t max_successive_merges = 0) {
+  DB* db;
+  Options options;
+  options.create_if_missing = true;
+  options.merge_operator = std::make_shared<CountMergeOperator>();
+  options.max_successive_merges = max_successive_merges;
+  options.env = EnvMergeTest::GetInstance();
+  EXPECT_OK(DestroyDB(dbname, Options()));
+  Status s;
+// DBWithTTL is not supported in ROCKSDB_LITE
+#ifndef ROCKSDB_LITE
+  if (ttl) {
+    DBWithTTL* db_with_ttl;
+    s = DBWithTTL::Open(options, dbname, &db_with_ttl);
+    db = db_with_ttl;
+  } else {
+    s = DB::Open(options, dbname, &db);
+  }
+#else
+  assert(!ttl);
+  s = DB::Open(options, dbname, &db);
+#endif  // !ROCKSDB_LITE
+  EXPECT_OK(s);
+  assert(s.ok());
+  // Allowed to call NowNanos during DB creation (in GenerateRawUniqueId() for
+  // session ID)
+  EnvMergeTest::now_nanos_count_ = 0;
+  return std::shared_ptr<DB>(db);
+}
+
+// Imagine we are maintaining a set of uint64 counters.
+// Each counter has a distinct name. And we would like
+// to support four high level operations:
+// set, add, get and remove
+// This is a quick implementation without a Merge operation.
+class Counters {
+ protected:
+  std::shared_ptr<DB> db_;
+
+  WriteOptions put_option_;
+  ReadOptions get_option_;
+  WriteOptions delete_option_;
+
+  uint64_t default_;
+
+ public:
+  explicit Counters(std::shared_ptr<DB> db, uint64_t defaultCount = 0)
+      : db_(db),
+        put_option_(),
+        get_option_(),
+        delete_option_(),
+        default_(defaultCount) {
+    assert(db_);
+  }
+
+  virtual ~Counters() {}
+
+  // public interface of Counters.
+  // All four functions return false
+  // if the underlying level db operation failed.
+
+  // mapped to a levedb Put
+  bool set(const std::string& key, uint64_t value) {
+    // just treat the internal rep of int64 as the string
+    char buf[sizeof(value)];
+    EncodeFixed64(buf, value);
+    Slice slice(buf, sizeof(value));
+    auto s = db_->Put(put_option_, key, slice);
+
+    if (s.ok()) {
+      return true;
+    } else {
+      std::cerr << s.ToString() << std::endl;
+      return false;
+    }
+  }
+
+  // mapped to a rocksdb Delete
+  bool remove(const std::string& key) {
+    auto s = db_->Delete(delete_option_, key);
+
+    if (s.ok()) {
+      return true;
+    } else {
+      std::cerr << s.ToString() << std::endl;
+      return false;
+    }
+  }
+
+  // mapped to a rocksdb Get
+  bool get(const std::string& key, uint64_t* value) {
+    std::string str;
+    auto s = db_->Get(get_option_, key, &str);
+
+    if (s.IsNotFound()) {
+      // return default value if not found;
+      *value = default_;
+      return true;
+    } else if (s.ok()) {
+      // deserialization
+      if (str.size() != sizeof(uint64_t)) {
+        std::cerr << "value corruption\n";
+        return false;
+      }
+      *value = DecodeFixed64(&str[0]);
+      return true;
+    } else {
+      std::cerr << s.ToString() << std::endl;
+      return false;
+    }
+  }
+
+  // 'add' is implemented as get -> modify -> set
+  // An alternative is a single merge operation, see MergeBasedCounters
+  virtual bool add(const std::string& key, uint64_t value) {
+    uint64_t base = default_;
+    return get(key, &base) && set(key, base + value);
+  }
+
+  // convenience functions for testing
+  void assert_set(const std::string& key, uint64_t value) {
+    assert(set(key, value));
+  }
+
+  void assert_remove(const std::string& key) { assert(remove(key)); }
+
+  uint64_t assert_get(const std::string& key) {
+    uint64_t value = default_;
+    int result = get(key, &value);
+    assert(result);
+    if (result == 0) exit(1);  // Disable unused variable warning.
+    return value;
+  }
+
+  void assert_add(const std::string& key, uint64_t value) {
+    int result = add(key, value);
+    assert(result);
+    if (result == 0) exit(1);  // Disable unused variable warning.
+  }
+};
+
+// Implement 'add' directly with the new Merge operation
+class MergeBasedCounters : public Counters {
+ private:
+  WriteOptions merge_option_;  // for merge
+
+ public:
+  explicit MergeBasedCounters(std::shared_ptr<DB> db, uint64_t defaultCount = 0)
+      : Counters(db, defaultCount), merge_option_() {}
+
+  // mapped to a rocksdb Merge operation
+  bool add(const std::string& key, uint64_t value) override {
+    char encoded[sizeof(uint64_t)];
+    EncodeFixed64(encoded, value);
+    Slice slice(encoded, sizeof(uint64_t));
+    auto s = db_->Merge(merge_option_, key, slice);
+
+    if (s.ok()) {
+      return true;
+    } else {
+      std::cerr << s.ToString() << std::endl;
+      return false;
+    }
+  }
+};
+
+void dumpDb(DB* db) {
+  auto it = std::unique_ptr<Iterator>(db->NewIterator(ReadOptions()));
+  for (it->SeekToFirst(); it->Valid(); it->Next()) {
+    // uint64_t value = DecodeFixed64(it->value().data());
+    // std::cout << it->key().ToString() << ": " << value << std::endl;
+  }
+  assert(it->status().ok());  // Check for any errors found during the scan
+}
+
+void testCounters(Counters& counters, DB* db, bool test_compaction) {
+  FlushOptions o;
+  o.wait = true;
+
+  counters.assert_set("a", 1);
+
+  if (test_compaction) {
+    ASSERT_OK(db->Flush(o));
+  }
+
+  ASSERT_EQ(counters.assert_get("a"), 1);
+
+  counters.assert_remove("b");
+
+  // defaut value is 0 if non-existent
+  ASSERT_EQ(counters.assert_get("b"), 0);
+
+  counters.assert_add("a", 2);
+
+  if (test_compaction) {
+    ASSERT_OK(db->Flush(o));
+  }
+
+  // 1+2 = 3
+  ASSERT_EQ(counters.assert_get("a"), 3);
+
+  dumpDb(db);
+
+  // 1+...+49 = ?
+  uint64_t sum = 0;
+  for (int i = 1; i < 50; i++) {
+    counters.assert_add("b", i);
+    sum += i;
+  }
+  ASSERT_EQ(counters.assert_get("b"), sum);
+
+  dumpDb(db);
+
+  if (test_compaction) {
+    ASSERT_OK(db->Flush(o));
+
+    ASSERT_OK(db->CompactRange(CompactRangeOptions(), nullptr, nullptr));
+
+    dumpDb(db);
+
+    ASSERT_EQ(counters.assert_get("a"), 3);
+    ASSERT_EQ(counters.assert_get("b"), sum);
+  }
+}
+
+void testCountersWithFlushAndCompaction(Counters& counters, DB* db) {
+  ASSERT_OK(db->Put({}, "1", "1"));
+  ASSERT_OK(db->Flush(FlushOptions()));
+
+  std::atomic<int> cnt{0};
+  const auto get_thread_id = [&cnt]() {
+    thread_local int thread_id{cnt++};
+    return thread_id;
+  };
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->ClearAllCallBacks();
+  SyncPoint::GetInstance()->SetCallBack(
+      "VersionSet::LogAndApply:BeforeWriterWaiting", [&](void* /*arg*/) {
+        int thread_id = get_thread_id();
+        if (1 == thread_id) {
+          TEST_SYNC_POINT(
+              "testCountersWithFlushAndCompaction::bg_compact_thread:0");
+        } else if (2 == thread_id) {
+          TEST_SYNC_POINT(
+              "testCountersWithFlushAndCompaction::bg_flush_thread:0");
+        }
+      });
+  SyncPoint::GetInstance()->SetCallBack(
+      "VersionSet::LogAndApply:WriteManifest", [&](void* /*arg*/) {
+        int thread_id = get_thread_id();
+        if (0 == thread_id) {
+          TEST_SYNC_POINT(
+              "testCountersWithFlushAndCompaction::set_options_thread:0");
+          TEST_SYNC_POINT(
+              "testCountersWithFlushAndCompaction::set_options_thread:1");
+        }
+      });
+  SyncPoint::GetInstance()->SetCallBack(
+      "VersionSet::LogAndApply:WakeUpAndDone", [&](void* arg) {
+        auto* mutex = reinterpret_cast<InstrumentedMutex*>(arg);
+        mutex->AssertHeld();
+        int thread_id = get_thread_id();
+        ASSERT_EQ(2, thread_id);
+        mutex->Unlock();
+        TEST_SYNC_POINT(
+            "testCountersWithFlushAndCompaction::bg_flush_thread:1");
+        TEST_SYNC_POINT(
+            "testCountersWithFlushAndCompaction::bg_flush_thread:2");
+        mutex->Lock();
+      });
+  SyncPoint::GetInstance()->LoadDependency({
+      {"testCountersWithFlushAndCompaction::set_options_thread:0",
+       "testCountersWithCompactionAndFlush:BeforeCompact"},
+      {"testCountersWithFlushAndCompaction::bg_compact_thread:0",
+       "testCountersWithFlushAndCompaction:BeforeIncCounters"},
+      {"testCountersWithFlushAndCompaction::bg_flush_thread:0",
+       "testCountersWithFlushAndCompaction::set_options_thread:1"},
+      {"testCountersWithFlushAndCompaction::bg_flush_thread:1",
+       "testCountersWithFlushAndCompaction:BeforeVerification"},
+      {"testCountersWithFlushAndCompaction:AfterGet",
+       "testCountersWithFlushAndCompaction::bg_flush_thread:2"},
+  });
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  port::Thread set_options_thread([&]() {
+    ASSERT_OK(reinterpret_cast<DBImpl*>(db)->SetOptions(
+        {{"disable_auto_compactions", "false"}}));
+  });
+  TEST_SYNC_POINT("testCountersWithCompactionAndFlush:BeforeCompact");
+  port::Thread compact_thread([&]() {
+    ASSERT_OK(reinterpret_cast<DBImpl*>(db)->CompactRange(
+        CompactRangeOptions(), db->DefaultColumnFamily(), nullptr, nullptr));
+  });
+
+  TEST_SYNC_POINT("testCountersWithFlushAndCompaction:BeforeIncCounters");
+  counters.add("test-key", 1);
+
+  FlushOptions flush_opts;
+  flush_opts.wait = false;
+  ASSERT_OK(db->Flush(flush_opts));
+
+  TEST_SYNC_POINT("testCountersWithFlushAndCompaction:BeforeVerification");
+  std::string expected;
+  PutFixed64(&expected, 1);
+  std::string actual;
+  Status s = db->Get(ReadOptions(), "test-key", &actual);
+  TEST_SYNC_POINT("testCountersWithFlushAndCompaction:AfterGet");
+  set_options_thread.join();
+  compact_thread.join();
+  ASSERT_OK(s);
+  ASSERT_EQ(expected, actual);
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->ClearAllCallBacks();
+}
+
+void testSuccessiveMerge(Counters& counters, size_t max_num_merges,
+                         size_t num_merges) {
+  counters.assert_remove("z");
+  uint64_t sum = 0;
+
+  for (size_t i = 1; i <= num_merges; ++i) {
+    resetNumMergeOperatorCalls();
+    counters.assert_add("z", i);
+    sum += i;
+
+    if (i % (max_num_merges + 1) == 0) {
+      ASSERT_EQ(num_merge_operator_calls, max_num_merges + 1);
+    } else {
+      ASSERT_EQ(num_merge_operator_calls, 0);
+    }
+
+    resetNumMergeOperatorCalls();
+    ASSERT_EQ(counters.assert_get("z"), sum);
+    ASSERT_EQ(num_merge_operator_calls, i % (max_num_merges + 1));
+  }
+}
+
+void testPartialMerge(Counters* counters, DB* db, size_t max_merge,
+                      size_t min_merge, size_t count) {
+  FlushOptions o;
+  o.wait = true;
+
+  // Test case 1: partial merge should be called when the number of merge
+  //              operands exceeds the threshold.
+  uint64_t tmp_sum = 0;
+  resetNumPartialMergeCalls();
+  for (size_t i = 1; i <= count; i++) {
+    counters->assert_add("b", i);
+    tmp_sum += i;
+  }
+  ASSERT_OK(db->Flush(o));
+  ASSERT_OK(db->CompactRange(CompactRangeOptions(), nullptr, nullptr));
+  ASSERT_EQ(tmp_sum, counters->assert_get("b"));
+  if (count > max_merge) {
+    // in this case, FullMerge should be called instead.
+    ASSERT_EQ(num_partial_merge_calls, 0U);
+  } else {
+    // if count >= min_merge, then partial merge should be called once.
+    ASSERT_EQ((count >= min_merge), (num_partial_merge_calls == 1));
+  }
+
+  // Test case 2: partial merge should not be called when a put is found.
+  resetNumPartialMergeCalls();
+  tmp_sum = 0;
+  ASSERT_OK(db->Put(ROCKSDB_NAMESPACE::WriteOptions(), "c", "10"));
+  for (size_t i = 1; i <= count; i++) {
+    counters->assert_add("c", i);
+    tmp_sum += i;
+  }
+  ASSERT_OK(db->Flush(o));
+  ASSERT_OK(db->CompactRange(CompactRangeOptions(), nullptr, nullptr));
+  ASSERT_EQ(tmp_sum, counters->assert_get("c"));
+  ASSERT_EQ(num_partial_merge_calls, 0U);
+  // NowNanos was previously called in MergeHelper::FilterMerge(), which
+  // harmed performance.
+  ASSERT_EQ(EnvMergeTest::now_nanos_count_, 0U);
+}
+
+void testSingleBatchSuccessiveMerge(DB* db, size_t max_num_merges,
+                                    size_t num_merges) {
+  ASSERT_GT(num_merges, max_num_merges);
+
+  Slice key("BatchSuccessiveMerge");
+  uint64_t merge_value = 1;
+  char buf[sizeof(merge_value)];
+  EncodeFixed64(buf, merge_value);
+  Slice merge_value_slice(buf, sizeof(merge_value));
+
+  // Create the batch
+  WriteBatch batch;
+  for (size_t i = 0; i < num_merges; ++i) {
+    ASSERT_OK(batch.Merge(key, merge_value_slice));
+  }
+
+  // Apply to memtable and count the number of merges
+  resetNumMergeOperatorCalls();
+  ASSERT_OK(db->Write(WriteOptions(), &batch));
+  ASSERT_EQ(
+      num_merge_operator_calls,
+      static_cast<size_t>(num_merges - (num_merges % (max_num_merges + 1))));
+
+  // Get the value
+  resetNumMergeOperatorCalls();
+  std::string get_value_str;
+  ASSERT_OK(db->Get(ReadOptions(), key, &get_value_str));
+  assert(get_value_str.size() == sizeof(uint64_t));
+  uint64_t get_value = DecodeFixed64(&get_value_str[0]);
+  ASSERT_EQ(get_value, num_merges * merge_value);
+  ASSERT_EQ(num_merge_operator_calls,
+            static_cast<size_t>((num_merges % (max_num_merges + 1))));
+}
+
+void runTest(const std::string& dbname, const bool use_ttl = false) {
+  {
+    auto db = OpenDb(dbname, use_ttl);
+
+    {
+      Counters counters(db, 0);
+      testCounters(counters, db.get(), true);
+    }
+
+    {
+      MergeBasedCounters counters(db, 0);
+      testCounters(counters, db.get(), use_compression);
+    }
+  }
+
+  ASSERT_OK(DestroyDB(dbname, Options()));
+
+  {
+    size_t max_merge = 5;
+    auto db = OpenDb(dbname, use_ttl, max_merge);
+    MergeBasedCounters counters(db, 0);
+    testCounters(counters, db.get(), use_compression);
+    testSuccessiveMerge(counters, max_merge, max_merge * 2);
+    testSingleBatchSuccessiveMerge(db.get(), 5, 7);
+    ASSERT_OK(db->Close());
+    ASSERT_OK(DestroyDB(dbname, Options()));
+  }
+
+  {
+    size_t max_merge = 100;
+    // Min merge is hard-coded to 2.
+    uint32_t min_merge = 2;
+    for (uint32_t count = min_merge - 1; count <= min_merge + 1; count++) {
+      auto db = OpenDb(dbname, use_ttl, max_merge);
+      MergeBasedCounters counters(db, 0);
+      testPartialMerge(&counters, db.get(), max_merge, min_merge, count);
+      ASSERT_OK(db->Close());
+      ASSERT_OK(DestroyDB(dbname, Options()));
+    }
+    {
+      auto db = OpenDb(dbname, use_ttl, max_merge);
+      MergeBasedCounters counters(db, 0);
+      testPartialMerge(&counters, db.get(), max_merge, min_merge,
+                       min_merge * 10);
+      ASSERT_OK(db->Close());
+      ASSERT_OK(DestroyDB(dbname, Options()));
+    }
+  }
+
+  {
+    {
+      auto db = OpenDb(dbname);
+      MergeBasedCounters counters(db, 0);
+      counters.add("test-key", 1);
+      counters.add("test-key", 1);
+      counters.add("test-key", 1);
+      ASSERT_OK(db->CompactRange(CompactRangeOptions(), nullptr, nullptr));
+    }
+
+    DB* reopen_db;
+    ASSERT_OK(DB::Open(Options(), dbname, &reopen_db));
+    std::string value;
+    ASSERT_NOK(reopen_db->Get(ReadOptions(), "test-key", &value));
+    delete reopen_db;
+    ASSERT_OK(DestroyDB(dbname, Options()));
+  }
+
+  /* Temporary remove this test
+  {
+    std::cout << "Test merge-operator not set after reopen (recovery case)\n";
+    {
+      auto db = OpenDb(dbname);
+      MergeBasedCounters counters(db, 0);
+      counters.add("test-key", 1);
+      counters.add("test-key", 1);
+      counters.add("test-key", 1);
+    }
+
+    DB* reopen_db;
+    ASSERT_TRUE(DB::Open(Options(), dbname, &reopen_db).IsInvalidArgument());
+  }
+  */
+}
+
+TEST_F(MergeTest, MergeDbTest) {
+  runTest(test::PerThreadDBPath("merge_testdb"));
+}
+
+#ifndef ROCKSDB_LITE
+TEST_F(MergeTest, MergeDbTtlTest) {
+  runTest(test::PerThreadDBPath("merge_testdbttl"),
+          true);  // Run test on TTL database
+}
+
+TEST_F(MergeTest, MergeWithCompactionAndFlush) {
+  const std::string dbname =
+      test::PerThreadDBPath("merge_with_compaction_and_flush");
+  {
+    auto db = OpenDb(dbname);
+    {
+      MergeBasedCounters counters(db, 0);
+      testCountersWithFlushAndCompaction(counters, db.get());
+    }
+  }
+  ASSERT_OK(DestroyDB(dbname, Options()));
+}
+#endif  // !ROCKSDB_LITE
+
+}  // namespace ROCKSDB_NAMESPACE
+
+int main(int argc, char** argv) {
+  ROCKSDB_NAMESPACE::use_compression = false;
+  if (argc > 1) {
+    ROCKSDB_NAMESPACE::use_compression = true;
+  }
+
+  ROCKSDB_NAMESPACE::port::InstallStackTraceHandler();
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}