feat(stream): add support of XPENDING command

src/commands/cmd_stream.cc

@@ -28,6 +28,7 @@
 #include "error_constants.h"
 #include "event_util.h"
 #include "server/server.h"
+#include "status.h"
 #include "time_util.h"
 #include "types/redis_stream.h"
 
@@ -814,6 +815,98 @@ class CommandXInfo : public Commander {
   }
 };
 
+class CommandXPending : public Commander {
+ public:
+  Status Parse(const std::vector<std::string> &args) override {
+    CommandParser parser(args, 1);
+    stream_name_ = GET_OR_RET(parser.TakeStr());
+    group_name_ = GET_OR_RET(parser.TakeStr());
+    if (parser.EatEqICase("idle")) {
+      options_.idle_time = GET_OR_RET(parser.TakeInt<uint64_t>());
+      options_.with_time = true;
+    }
+
+    if (parser.Good()) {
+      std::string start_id, end_id;
+      start_id = GET_OR_RET(parser.TakeStr());
+      end_id = GET_OR_RET(parser.TakeStr());
+      if (start_id != "-") {
+        auto s = ParseStreamEntryID(start_id, &options_.start_id);
+        if (!s.IsOK()) {
+          return s;
+        }
+      }
+
+      if (end_id != "+") {
+        auto s = ParseStreamEntryID(start_id, &options_.end_id);
+        if (!s.IsOK()) {
+          return s;
+        }
+      }
+
+      options_.count = GET_OR_RET(parser.TakeInt<uint64_t>());
+      options_.with_count = true;
+      if (parser.Good()) {
+        options_.consumer = GET_OR_RET(parser.TakeStr());
+        options_.with_consumer = true;
+      }
+    }
+    return Status::OK();
+  }
+
+  Status Execute(Server *srv, Connection *conn, std::string *output) override {
+    redis::Stream stream_db(srv->storage, conn->GetNamespace());
+    std::vector<std::pair<std::string, int>> pending_infos;
+    StreamGetPendingEntryResult results;
+    options_.stream_name = stream_name_;
+    options_.group_name = group_name_;
+    std::vector<StreamGetExtPendingEntryResult> ext_results;
+    auto s = stream_db.GetPendingEntries(options_, results, ext_results);
+    if (!s.ok()) {
+      return {Status::RedisExecErr, s.ToString()};
+    }
+    if (options_.with_count) {
+      return SendExtResults(conn, output, ext_results);
+    }
+    return SendResults(conn, output, results);
+  }
+
+  static Status SendResults(Connection *conn, std::string *output, StreamGetPendingEntryResult &results) {
+    output->append(redis::MultiLen(3 + results.consumer_infos.size()));
+    output->append(redis::Integer(results.pending_number));
+    output->append(redis::BulkString(results.smallest_id.ToString()));
+    output->append(redis::BulkString(results.greatest_id.ToString()));
+    for (const auto &entry : results.consumer_infos) {
+      output->append(redis::MultiLen(1));
+      output->append(redis::MultiLen(2));
+      output->append(redis::BulkString(entry.first));
+      output->append(redis::BulkString(std::to_string(entry.second)));
+    }
+
+    return Status::OK();
+  }
+
+  static Status SendExtResults(Connection *conn, std::string *output,
+                               std::vector<StreamGetExtPendingEntryResult> &ext_results) {
+    output->append(redis::MultiLen(ext_results.size()));
+    for (const auto &entry : ext_results) {
+      output->append(redis::MultiLen(4));
+      output->append(redis::BulkString(entry.id.ToString()));
+      output->append(redis::BulkString(entry.consumer_name));
+      output->append(redis::Integer(entry.delivered_time));
+      output->append(redis::Integer(entry.delivered_count));
+    }
+
+    return Status::OK();
+  }
+
+ private:
+  std::string group_name_;
+  std::string stream_name_;
+  std::string consumer_name_;
+  StreamPendingOptions options_;
+};
+
 class CommandXRange : public Commander {
  public:
   Status Parse(const std::vector<std::string> &args) override {
@@ -1744,6 +1837,7 @@ REDIS_REGISTER_COMMANDS(MakeCmdAttr<CommandXAck>("xack", -4, "write no-dbsize-ch
                         MakeCmdAttr<CommandXGroup>("xgroup", -4, "write", 2, 2, 1),
                         MakeCmdAttr<CommandXLen>("xlen", -2, "read-only", 1, 1, 1),
                         MakeCmdAttr<CommandXInfo>("xinfo", -2, "read-only", 0, 0, 0),
+                        MakeCmdAttr<CommandXPending>("xpending", -3, "read-only", 1, 1, 1),
                         MakeCmdAttr<CommandXRange>("xrange", -4, "read-only", 1, 1, 1),
                         MakeCmdAttr<CommandXRevRange>("xrevrange", -2, "read-only", 1, 1, 1),
                         MakeCmdAttr<CommandXRead>("xread", -4, "read-only", 0, 0, 0),

src/types/redis_stream.cc

@@ -1707,4 +1707,90 @@ rocksdb::Status Stream::SetId(const Slice &stream_name, const StreamEntryID &las
   return storage_->Write(storage_->DefaultWriteOptions(), batch->GetWriteBatch());
 }
 
+rocksdb::Status Stream::GetPendingEntries(StreamPendingOptions &options, StreamGetPendingEntryResult &pending_infos,
+                                          std::vector<StreamGetExtPendingEntryResult> &ext_results) {
+  const std::string &stream_name = options.stream_name;
+  const std::string &group_name = options.group_name;
+  std::string ns_key = AppendNamespacePrefix(stream_name);
+
+  StreamMetadata metadata(false);
+  rocksdb::Status s = GetMetadata(GetOptions{}, ns_key, &metadata);
+  if (!s.ok()) {
+    return s.IsNotFound() ? rocksdb::Status::OK() : s;
+  }
+
+  std::string group_key = internalKeyFromGroupName(ns_key, metadata, group_name);
+  std::string get_group_value;
+  s = storage_->Get(rocksdb::ReadOptions(), stream_cf_handle_, group_key, &get_group_value);
+  if (!s.ok()) {
+    return s.IsNotFound() ? rocksdb::Status::OK() : s;
+  }
+
+  std::string prefix_key = internalPelKeyFromGroupAndEntryId(ns_key, metadata, group_name, options.start_id);
+  std::string end_key = internalPelKeyFromGroupAndEntryId(ns_key, metadata, group_name, options.end_id);
+
+  rocksdb::ReadOptions read_options = storage_->DefaultScanOptions();
+  LatestSnapShot ss(storage_);
+  read_options.snapshot = ss.GetSnapShot();
+  rocksdb::Slice upper_bound(end_key);
+  read_options.iterate_upper_bound = &upper_bound;
+  rocksdb::Slice lower_bound(prefix_key);
+  read_options.iterate_lower_bound = &lower_bound;
+
+  auto iter = util::UniqueIterator(storage_, read_options, stream_cf_handle_);
+  std::unordered_set<std::string> consumer_names;
+  StreamEntryID smallest_id{StreamEntryID::Maximum()};
+  StreamEntryID greatest_id{StreamEntryID::Minimum()};
+  uint64_t count = 0;
+  for (iter->SeekToLast(); iter->Valid(); iter->Prev()) {
+    if (identifySubkeyType(iter->key()) == StreamSubkeyType::StreamPelEntry) {
+      if (options.with_count && options.count <= count) {
+        break;
+      }
+      std::string tmp_group_name;
+      StreamEntryID entry_id = groupAndEntryIdFromPelInternalKey(iter->key(), tmp_group_name);
+      if (tmp_group_name != group_name) continue;
+
+      if (smallest_id > entry_id) {
+        smallest_id = entry_id;
+      }
+      if (greatest_id < entry_id) {
+        greatest_id = entry_id;
+      }
+      StreamPelEntry pel_entry = decodeStreamPelEntryValue(iter->value().ToString());
+      const std::string &consumer_name = pel_entry.consumer_name;
+
+      if (options.with_consumer && options.consumer != consumer_name) {
+        continue;
+      }
+
+      ext_results.push_back({entry_id, consumer_name, pel_entry.last_delivery_time_ms, pel_entry.last_delivery_count});
+
+      if (options.with_count) {
+        continue;
+      }
+      std::string consumer_key = internalKeyFromConsumerName(ns_key, metadata, group_name, consumer_name);
+      std::string get_consumer_value;
+      s = storage_->Get(rocksdb::ReadOptions(), stream_cf_handle_, consumer_key, &get_consumer_value);
+      if (!s.ok() && !s.IsNotFound()) {
+        return s;
+      }
+      if (s.IsNotFound()) {
+        return rocksdb::Status::OK();
+      }
+
+      StreamConsumerMetadata consumer_metadata = decodeStreamConsumerMetadataValue(get_consumer_value);
+      if (consumer_names.find(consumer_name) == consumer_names.end()) {
+        consumer_names.insert(consumer_name);
+        pending_infos.consumer_infos.emplace_back(consumer_name, consumer_metadata.pending_number);
+      }
+      count++;
+    }
+  }
+  pending_infos.greatest_id = greatest_id;
+  pending_infos.smallest_id = smallest_id;
+  pending_infos.pending_number = count;
+  return rocksdb::Status::OK();
+}
+
 }  // namespace redis

src/types/redis_stream.h

@@ -63,6 +63,8 @@ class Stream : public SubKeyScanner {
                                std::vector<std::pair<std::string, StreamConsumerGroupMetadata>> &group_metadata);
   rocksdb::Status GetConsumerInfo(const Slice &stream_name, const std::string &group_name,
                                   std::vector<std::pair<std::string, StreamConsumerMetadata>> &consumer_metadata);
+  rocksdb::Status GetPendingEntries(StreamPendingOptions &options, StreamGetPendingEntryResult &pending_infos,
+                                    std::vector<StreamGetExtPendingEntryResult> &ext_results);
   rocksdb::Status Range(const Slice &stream_name, const StreamRangeOptions &options, std::vector<StreamEntry> *entries);
   rocksdb::Status RangeWithPending(const Slice &stream_name, StreamRangeOptions &options,
                                    std::vector<StreamEntry> *entries, std::string &group_name,

src/types/redis_stream_base.h

@@ -239,6 +239,36 @@ struct StreamAutoClaimResult {
   std::vector<std::string> deleted_ids;
 };
 
+struct StreamPendingOptions {
+  uint64_t idle_time = 0;
+  bool with_time = false;
+
+  StreamEntryID start_id{StreamEntryID::Minimum()};
+  StreamEntryID end_id{StreamEntryID::Maximum()};
+
+  uint64_t count;
+  bool with_count = false;
+  bool with_consumer = false;
+
+  std::string consumer;
+  std::string stream_name;
+  std::string group_name;
+};
+
+struct StreamGetPendingEntryResult {
+  uint64_t pending_number;
+  StreamEntryID smallest_id;
+  StreamEntryID greatest_id;
+  std::vector<std::pair<std::string, int>> consumer_infos;
+};
+
+struct StreamGetExtPendingEntryResult {
+  StreamEntryID id;
+  std::string consumer_name;
+  uint64_t delivered_time;
+  uint64_t delivered_count;
+};
+
 Status IncrementStreamEntryID(StreamEntryID *id);
 Status ParseStreamEntryID(const std::string &input, StreamEntryID *id);
 StatusOr<std::unique_ptr<NextStreamEntryIDGenerationStrategy>> ParseNextStreamEntryIDStrategy(const std::string &input);

tests/gocase/unit/type/stream/stream_test.go

@@ -1904,6 +1904,82 @@ func TestStreamOffset(t *testing.T) {
 		require.Error(t, cmd.Err())
 		require.Equal(t, "ERR COUNT must be > 0", cmd.Err().Error())
 	})
+
+	t.Run("XPending with different kinds of commands", func(t *testing.T) {
+		streamName := "mystream"
+		groupName := "mygroup"
+		require.NoError(t, rdb.Del(ctx, streamName).Err())
+		r, err := rdb.XAck(ctx, streamName, groupName, "0-0").Result()
+		require.NoError(t, err)
+		require.Equal(t, int64(0), r)
+		require.NoError(t, rdb.XAdd(ctx, &redis.XAddArgs{
+			Stream: streamName,
+			ID:     "1-0",
+			Values: []string{"field1", "data1"},
+		}).Err())
+		require.NoError(t, rdb.XGroupCreate(ctx, streamName, groupName, "0").Err())
+		consumerName := "myconsumer"
+		err = rdb.XReadGroup(ctx, &redis.XReadGroupArgs{
+			Group:    groupName,
+			Consumer: consumerName,
+			Streams:  []string{streamName, ">"},
+			Count:    1,
+			NoAck:    false,
+		}).Err()
+		require.NoError(t, err)
+
+		r1, err1 := rdb.XPending(ctx, streamName, groupName).Result()
+		require.NoError(t, err1)
+
+		require.Equal(t, &redis.XPending{
+			Count:     1,
+			Lower:     "1-0",
+			Higher:    "1-0",
+			Consumers: map[string]int64{"myconsumer": 1},
+		}, r1)
+
+		require.NoError(t, rdb.XAdd(ctx, &redis.XAddArgs{
+			Stream: streamName,
+			ID:     "2-0",
+			Values: []string{"field1", "data1"},
+		}).Err())
+
+		require.NoError(t, rdb.XAdd(ctx, &redis.XAddArgs{
+			Stream: streamName,
+			ID:     "2-2",
+			Values: []string{"field1", "data1"},
+		}).Err())
+
+		require.NoError(t, rdb.XReadGroup(ctx, &redis.XReadGroupArgs{
+			Group:    groupName,
+			Consumer: consumerName,
+			Streams:  []string{streamName, ">"},
+			Count:    2,
+			NoAck:    false,
+		}).Err())
+
+		r1, err1 = rdb.XPending(ctx, streamName, groupName).Result()
+		require.NoError(t, err1)
+
+		require.Equal(t, &redis.XPending{
+			Count:     3,
+			Lower:     "1-0",
+			Higher:    "2-2",
+			Consumers: map[string]int64{"myconsumer": 3},
+		}, r1)
+
+		require.NoError(t, rdb.XAck(ctx, streamName, groupName, "2-0").Err())
+
+		r1, err1 = rdb.XPending(ctx, streamName, groupName).Result()
+		require.NoError(t, err1)
+
+		require.Equal(t, &redis.XPending{
+			Count:     2,
+			Lower:     "1-0",
+			Higher:    "2-2",
+			Consumers: map[string]int64{"myconsumer": 2},
+		}, r1)
+	})
 }
 
 func parseStreamEntryID(id string) (ts int64, seqNum int64) {