Add support of the command ZDIFF and ZDIFFSTORE

src/commands/cmd_zset.cc

@@ -1419,6 +1419,99 @@ class CommandZRandMember : public Commander {
   bool no_parameters_ = true;
 };
 
+class CommandZDiff : public Commander {
+ public:
+  Status Parse(const std::vector<std::string> &args) override {
+    auto parse_result = ParseInt<int>(args[1], 10);
+    if (!parse_result) return {Status::RedisParseErr, errValueNotInteger};
+
+    numkeys_ = *parse_result;
+    if (numkeys_ > args.size() - 2) return {Status::RedisParseErr, errInvalidSyntax};
+
+    size_t j = 0;
+    while (j < numkeys_) {
+      keys_.emplace_back(args[j + 2]);
+      j++;
+    }
+
+    if (auto i = 2 + numkeys_; i < args.size()) {
+      if (util::ToLower(args[i]) == "withscores") {
+        with_scores_ = true;
+      }
+    }
+
+    return Commander::Parse(args);
+  }
+
+  Status Execute(Server *srv, Connection *conn, std::string *output) override {
+    redis::ZSet zset_db(srv->storage, conn->GetNamespace());
+
+    std::vector<MemberScore> members_with_scores;
+    auto s = zset_db.Diff(keys_, &members_with_scores);
+    if (!s.ok()) {
+      return {Status::RedisExecErr, s.ToString()};
+    }
+
+    output->append(redis::MultiLen(members_with_scores.size() * (with_scores_ ? 2 : 1)));
+    for (const auto &ms : members_with_scores) {
+      output->append(redis::BulkString(ms.member));
+      if (with_scores_) output->append(redis::BulkString(util::Float2String(ms.score)));
+    }
+
+    return Status::OK();
+  }
+
+  static CommandKeyRange Range(const std::vector<std::string> &args) {
+    int num_key = *ParseInt<int>(args[1], 10);
+    return {2, 2 + num_key, 1};
+  }
+
+ protected:
+  size_t numkeys_ = 0;
+  std::vector<rocksdb::Slice> keys_;
+  bool with_scores_ = false;
+};
+
+class CommandZDiffStore : public Commander {
+ public:
+  Status Parse(const std::vector<std::string> &args) override {
+    auto parse_result = ParseInt<int>(args[2], 10);
+    if (!parse_result) return {Status::RedisParseErr, errValueNotInteger};
+
+    numkeys_ = *parse_result;
+    if (numkeys_ > args.size() - 3) return {Status::RedisParseErr, errInvalidSyntax};
+
+    size_t j = 0;
+    while (j < numkeys_) {
+      keys_.emplace_back(args[j + 3]);
+      j++;
+    }
+
+    return Commander::Parse(args);
+  }
+
+  Status Execute(Server *srv, Connection *conn, std::string *output) override {
+    redis::ZSet zset_db(srv->storage, conn->GetNamespace());
+
+    uint64_t stored_count = 0;
+    auto s = zset_db.DiffStore(args_[1], keys_, &stored_count);
+    if (!s.ok()) {
+      return {Status::RedisExecErr, s.ToString()};
+    }
+    *output = redis::Integer(stored_count);
+    return Status::OK();
+  }
+
+  static CommandKeyRange Range(const std::vector<std::string> &args) {
+    int num_key = *ParseInt<int>(args[1], 10);
+    return {3, 2 + num_key, 1};
+  }
+
+ protected:
+  size_t numkeys_ = 0;
+  std::vector<rocksdb::Slice> keys_;
+};
+
 REDIS_REGISTER_COMMANDS(MakeCmdAttr<CommandZAdd>("zadd", -4, "write", 1, 1, 1),
                         MakeCmdAttr<CommandZCard>("zcard", 2, "read-only", 1, 1, 1),
                         MakeCmdAttr<CommandZCount>("zcount", 4, "read-only", 1, 1, 1),
@@ -1451,6 +1544,8 @@ REDIS_REGISTER_COMMANDS(MakeCmdAttr<CommandZAdd>("zadd", -4, "write", 1, 1, 1),
                         MakeCmdAttr<CommandZScan>("zscan", -3, "read-only", 1, 1, 1),
                         MakeCmdAttr<CommandZUnionStore>("zunionstore", -4, "write", CommandZUnionStore::Range),
                         MakeCmdAttr<CommandZUnion>("zunion", -3, "read-only", CommandZUnion::Range),
-                        MakeCmdAttr<CommandZRandMember>("zrandmember", -2, "read-only", 1, 1, 1))
+                        MakeCmdAttr<CommandZRandMember>("zrandmember", -2, "read-only", 1, 1, 1),
+                        MakeCmdAttr<CommandZDiff>("zdiff", -3, "read-only", CommandZDiff::Range),
+                        MakeCmdAttr<CommandZDiffStore>("zdiffstore", -3, "read-only", CommandZDiffStore::Range), )
 
 }  // namespace redis

src/types/redis_zset.cc

@@ -931,4 +931,42 @@ rocksdb::Status ZSet::RandMember(const Slice &user_key, int64_t command_count,
   return rocksdb::Status::OK();
 }
 
+rocksdb::Status ZSet::Diff(const std::vector<Slice> &keys, MemberScores *members) {
+  members->clear();
+  MemberScores source_member_scores;
+  RangeScoreSpec spec;
+  uint64_t size = 0;
+  auto s = RangeByScore(keys[0], spec, &source_member_scores, &size);
+  if (!s.ok()) return s;
+
+  if (size == 0) {
+    return rocksdb::Status::OK();
+  }
+
+  std::map<std::string, bool> exclude_members;
+  MemberScores target_member_scores;
+  for (size_t i = 1; i < keys.size(); i++) {
+    uint64_t size = 0;
+    s = RangeByScore(keys[i], spec, &target_member_scores, &size);
+    if (!s.ok()) return s;
+    for (const auto &member_score : target_member_scores) {
+      exclude_members[member_score.member] = true;
+    }
+  }
+  for (const auto &member_score : source_member_scores) {
+    if (exclude_members.find(member_score.member) == exclude_members.end()) {
+      members->push_back(member_score);
+    }
+  }
+  return rocksdb::Status::OK();
+}
+
+rocksdb::Status ZSet::DiffStore(const Slice &dst, const std::vector<Slice> &keys, uint64_t *stored_count) {
+  MemberScores mscores;
+  auto s = Diff(keys, &mscores);
+  if (!s.ok()) return s;
+  *stored_count = mscores.size();
+  return Overwrite(dst, mscores);
+}
+
 }  // namespace redis

src/types/redis_zset.h

@@ -116,6 +116,8 @@ class ZSet : public SubKeyScanner {
                              AggregateMethod aggregate_method, uint64_t *saved_cnt);
   rocksdb::Status Union(const std::vector<KeyWeight> &keys_weights, AggregateMethod aggregate_method,
                         std::vector<MemberScore> *members);
+  rocksdb::Status Diff(const std::vector<Slice> &keys, MemberScores *members);
+  rocksdb::Status DiffStore(const Slice &dst, const std::vector<Slice> &keys, uint64_t *stored_count);
   rocksdb::Status MGet(const Slice &user_key, const std::vector<Slice> &members, std::map<std::string, double> *scores);
   rocksdb::Status GetMetadata(const Slice &ns_key, ZSetMetadata *metadata);
 

tests/cppunit/types/zset_test.cc

@@ -535,3 +535,81 @@ TEST_F(RedisZSetTest, RandMember) {
   auto s = zset_->Del(key_);
   EXPECT_TRUE(s.ok());
 }
+
+TEST_F(RedisZSetTest, Diff) {
+  uint64_t ret = 0;
+
+  std::string k1 = "key1";
+  std::vector<MemberScore> k1_mscores = {{"a", -100.1}, {"b", -100.1}, {"c", 0}, {"d", 1.234}};
+
+  std::string k2 = "key2";
+  std::vector<MemberScore> k2_mscores = {{"c", -150.1}};
+
+  std::string k3 = "key3";
+  std::vector<MemberScore> k3_mscores = {{"a", -1000.1}, {"c", -100.1}, {"e", 8000.9}};
+
+  auto s = zset_->Add(k1, ZAddFlags::Default(), &k1_mscores, &ret);
+  EXPECT_EQ(ret, 4);
+  zset_->Add(k2, ZAddFlags::Default(), &k2_mscores, &ret);
+  EXPECT_EQ(ret, 1);
+  zset_->Add(k3, ZAddFlags::Default(), &k3_mscores, &ret);
+  EXPECT_EQ(ret, 3);
+
+  std::vector<MemberScore> mscores;
+  zset_->Diff({k1, k2, k3}, &mscores);
+
+  EXPECT_EQ(2, mscores.size());
+  std::vector<MemberScore> expected_mscores = {{"b", -100.1}, {"d", 1.234}};
+  int index = 0;
+  for (const auto &mscore : expected_mscores) {
+    EXPECT_EQ(mscore.member, mscores[index].member);
+    EXPECT_EQ(mscore.score, mscores[index].score);
+    index++;
+  }
+
+  s = zset_->Del(k1);
+  EXPECT_TRUE(s.ok());
+  s = zset_->Del(k2);
+  EXPECT_TRUE(s.ok());
+  s = zset_->Del(k3);
+  EXPECT_TRUE(s.ok());
+}
+
+TEST_F(RedisZSetTest, DiffStore) {
+  uint64_t ret = 0;
+
+  std::string k1 = "key1";
+  std::vector<MemberScore> k1_mscores = {{"a", -100.1}, {"b", -100.1}, {"c", 0}, {"d", 1.234}};
+
+  std::string k2 = "key2";
+  std::vector<MemberScore> k2_mscores = {{"c", -150.1}};
+
+  auto s = zset_->Add(k1, ZAddFlags::Default(), &k1_mscores, &ret);
+  EXPECT_EQ(ret, 4);
+  zset_->Add(k2, ZAddFlags::Default(), &k2_mscores, &ret);
+  EXPECT_EQ(ret, 1);
+
+  uint64_t stored_count = 0;
+  zset_->DiffStore("zsetdiff", {k1, k2}, &stored_count);
+  EXPECT_EQ(stored_count, 3);
+
+  RangeScoreSpec spec;
+  std::vector<MemberScore> mscores;
+  zset_->RangeByScore("zsetdiff", spec, &mscores, nullptr);
+  EXPECT_EQ(mscores.size(), 3);
+
+  std::vector<MemberScore> expected_mscores = {{"a", -100.1}, {"b", -100.1}, {"d", 1.234}};
+  int index = 0;
+  for (const auto &mscore : expected_mscores) {
+    EXPECT_EQ(mscore.member, mscores[index].member);
+    EXPECT_EQ(mscore.score, mscores[index].score);
+    index++;
+  }
+
+  s = zset_->Del(k1);
+  EXPECT_TRUE(s.ok());
+  s = zset_->Del(k2);
+  EXPECT_TRUE(s.ok());
+  s = zset_->Del("zsetdiff");
+  EXPECT_TRUE(s.ok());
+}