[Misc] Replace /*! with /**. (#4823)

* replace

* blabla

* balbla

* blabla
Co-authored-by: Steve <ubuntu@ip-172-31-34-29.ap-northeast-1.compute.internal>

src/graph/unit_graph.cc

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file graph/unit_graph.cc
  * @brief UnitGraph graph implementation
@@ -161,17 +161,17 @@ class UnitGraph::COO : public BaseHeteroGraph {
   }
 
 
-  /*! @brief Pin the adj_: COOMatrix of the COO graph. */
+  /** @brief Pin the adj_: COOMatrix of the COO graph. */
   void PinMemory_() {
     adj_.PinMemory_();
   }
 
-  /*! @brief Unpin the adj_: COOMatrix of the COO graph. */
+  /** @brief Unpin the adj_: COOMatrix of the COO graph. */
   void UnpinMemory_() {
     adj_.UnpinMemory_();
   }
 
-  /*! @brief Record stream for the adj_: COOMatrix of the COO graph. */
+  /** @brief Record stream for the adj_: COOMatrix of the COO graph. */
   void RecordStream(DGLStreamHandle stream) override {
     adj_.RecordStream(stream);
   }
@@ -432,7 +432,7 @@ class UnitGraph::COO : public BaseHeteroGraph {
     return adj_;
   }
 
-  /*!
+  /**
    * @brief Determines whether the graph is "hypersparse", i.e. having significantly more
    * nodes than edges.
    */
@@ -457,7 +457,7 @@ class UnitGraph::COO : public BaseHeteroGraph {
  private:
   friend class Serializer;
 
-  /*! @brief internal adjacency matrix. Data array is empty */
+  /** @brief internal adjacency matrix. Data array is empty */
   aten::COOMatrix adj_;
 };
 
@@ -467,7 +467,7 @@ class UnitGraph::COO : public BaseHeteroGraph {
 //
 //////////////////////////////////////////////////////////
 
-/*! @brief CSR graph */
+/** @brief CSR graph */
 class UnitGraph::CSR : public BaseHeteroGraph {
  public:
   CSR(GraphPtr metagraph, int64_t num_src, int64_t num_dst,
@@ -571,17 +571,17 @@ class UnitGraph::CSR : public BaseHeteroGraph {
     }
   }
 
-  /*! @brief Pin the adj_: CSRMatrix of the CSR graph. */
+  /** @brief Pin the adj_: CSRMatrix of the CSR graph. */
   void PinMemory_() {
     adj_.PinMemory_();
   }
 
-  /*! @brief Unpin the adj_: CSRMatrix of the CSR graph. */
+  /** @brief Unpin the adj_: CSRMatrix of the CSR graph. */
   void UnpinMemory_() {
     adj_.UnpinMemory_();
   }
 
-  /*! @brief Record stream for the adj_: CSRMatrix of the CSR graph. */
+  /** @brief Record stream for the adj_: CSRMatrix of the CSR graph. */
   void RecordStream(DGLStreamHandle stream) override {
     adj_.RecordStream(stream);
   }
@@ -851,7 +851,7 @@ class UnitGraph::CSR : public BaseHeteroGraph {
  private:
   friend class Serializer;
 
-  /*! @brief internal adjacency matrix. Data array stores edge ids */
+  /** @brief internal adjacency matrix. Data array stores edge ids */
   aten::CSRMatrix adj_;
 };
 
@@ -1433,7 +1433,7 @@ UnitGraph::CSRPtr UnitGraph::GetInCSR(bool inplace) const {
   return ret;
 }
 
-/* !\brief Return out csr. If not exist, transpose the other one.*/
+/** @brief Return out csr. If not exist, transpose the other one.*/
 UnitGraph::CSRPtr UnitGraph::GetOutCSR(bool inplace) const {
   if (inplace)
     if (!(formats_ & CSR_CODE))
@@ -1469,7 +1469,7 @@ UnitGraph::CSRPtr UnitGraph::GetOutCSR(bool inplace) const {
   return ret;
 }
 
-/* !\brief Return coo. If not exist, create from csr.*/
+/** @brief Return coo. If not exist, create from csr.*/
 UnitGraph::COOPtr UnitGraph::GetCOO(bool inplace) const {
   if (inplace)
     if (!(formats_ & COO_CODE))

src/graph/unit_graph.h

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file graph/unit_graph.h
  * @brief UnitGraph graph
@@ -26,7 +26,7 @@ class HeteroGraph;
 class UnitGraph;
 typedef std::shared_ptr<UnitGraph> UnitGraphPtr;
 
-/*!
+/**
  * @brief UnitGraph graph
  *
  * UnitGraph graph is a special type of heterograph which
@@ -164,7 +164,7 @@ class UnitGraph : public BaseHeteroGraph {
       const std::vector<IdArray>& eids, bool preserve_nodes = false) const override;
 
   // creators
-  /*! @brief Create a graph with no edges */
+  /** @brief Create a graph with no edges */
   static HeteroGraphPtr Empty(
       int64_t num_vtypes, int64_t num_src, int64_t num_dst,
       DGLDataType dtype, DGLContext ctx) {
@@ -173,7 +173,7 @@ class UnitGraph : public BaseHeteroGraph {
     return CreateFromCOO(num_vtypes, num_src, num_dst, row, col);
   }
 
-  /*! @brief Create a graph from COO arrays */
+  /** @brief Create a graph from COO arrays */
   static HeteroGraphPtr CreateFromCOO(
       int64_t num_vtypes, int64_t num_src, int64_t num_dst,
       IdArray row, IdArray col, bool row_sorted = false,
@@ -183,7 +183,7 @@ class UnitGraph : public BaseHeteroGraph {
       int64_t num_vtypes, const aten::COOMatrix& mat,
       dgl_format_code_t formats = ALL_CODE);
 
-  /*! @brief Create a graph from (out) CSR arrays */
+  /** @brief Create a graph from (out) CSR arrays */
   static HeteroGraphPtr CreateFromCSR(
       int64_t num_vtypes, int64_t num_src, int64_t num_dst,
       IdArray indptr, IdArray indices, IdArray edge_ids,
@@ -193,7 +193,7 @@ class UnitGraph : public BaseHeteroGraph {
       int64_t num_vtypes, const aten::CSRMatrix& mat,
       dgl_format_code_t formats = ALL_CODE);
 
-  /*! @brief Create a graph from (in) CSC arrays */
+  /** @brief Create a graph from (in) CSC arrays */
   static HeteroGraphPtr CreateFromCSC(
       int64_t num_vtypes, int64_t num_src, int64_t num_dst,
       IdArray indptr, IdArray indices, IdArray edge_ids,
@@ -203,13 +203,13 @@ class UnitGraph : public BaseHeteroGraph {
       int64_t num_vtypes, const aten::CSRMatrix& mat,
       dgl_format_code_t formats = ALL_CODE);
 
-  /*! @brief Convert the graph to use the given number of bits for storage */
+  /** @brief Convert the graph to use the given number of bits for storage */
   static HeteroGraphPtr AsNumBits(HeteroGraphPtr g, uint8_t bits);
 
-  /*! @brief Copy the data to another context */
+  /** @brief Copy the data to another context */
   static HeteroGraphPtr CopyTo(HeteroGraphPtr g, const DGLContext &ctx);
 
-  /*!
+  /**
   * @brief Pin the in_csr_, out_scr_ and coo_ of the current graph.
   * @note The graph will be pinned inplace. Behavior depends on the current context,
   *       kDGLCPU: will be pinned;
@@ -219,7 +219,7 @@ class UnitGraph : public BaseHeteroGraph {
   */
   void PinMemory_() override;
 
-  /*!
+  /**
   * @brief Unpin the in_csr_, out_scr_ and coo_ of the current graph.
   * @note The graph will be unpinned inplace. Behavior depends on the current context,
   *       IsPinned: will be unpinned;
@@ -228,13 +228,13 @@ class UnitGraph : public BaseHeteroGraph {
   */
   void UnpinMemory_();
 
-  /*!
+  /**
    * @brief Record stream for this graph.
    * @param stream The stream that is using the graph
    */
   void RecordStream(DGLStreamHandle stream) override;
 
-  /*! 
+  /** 
    * @brief Create in-edge CSR format of the unit graph.
    * @param inplace if true and the in-edge CSR format does not exist, the created
    *                format will be cached in this object unless the format is restricted.
@@ -242,7 +242,7 @@ class UnitGraph : public BaseHeteroGraph {
    */
   CSRPtr GetInCSR(bool inplace = true) const;
 
-  /*! 
+  /** 
    * @brief Create out-edge CSR format of the unit graph.
    * @param inplace if true and the out-edge CSR format does not exist, the created
    *                format will be cached in this object unless the format is restricted.
@@ -250,7 +250,7 @@ class UnitGraph : public BaseHeteroGraph {
    */
   CSRPtr GetOutCSR(bool inplace = true) const;
 
-  /*!
+  /**
    * @brief Create COO format of the unit graph.
    * @param inplace if true and the COO format does not exist, the created
    *                format will be cached in this object unless the format is restricted.
@@ -258,20 +258,20 @@ class UnitGraph : public BaseHeteroGraph {
    */
   COOPtr GetCOO(bool inplace = true) const;
 
-  /*! @return Return the COO matrix form */
+  /** @return Return the COO matrix form */
   aten::COOMatrix GetCOOMatrix(dgl_type_t etype) const override;
 
-  /*! @return Return the in-edge CSC in the matrix form */
+  /** @return Return the in-edge CSC in the matrix form */
   aten::CSRMatrix GetCSCMatrix(dgl_type_t etype) const override;
 
-  /*! @return Return the out-edge CSR in the matrix form */
+  /** @return Return the out-edge CSR in the matrix form */
   aten::CSRMatrix GetCSRMatrix(dgl_type_t etype) const override;
 
   SparseFormat SelectFormat(dgl_type_t etype, dgl_format_code_t preferred_formats) const override {
     return SelectFormat(preferred_formats);
   }
 
-  /*!
+  /**
    * @brief Return the graph in the given format. Perform format conversion if the
    * requested format does not exist.
    *
@@ -285,19 +285,19 @@ class UnitGraph : public BaseHeteroGraph {
 
   HeteroGraphPtr GetGraphInFormat(dgl_format_code_t formats) const override;
 
-  /*! @return Load UnitGraph from stream, using CSRMatrix*/
+  /** @return Load UnitGraph from stream, using CSRMatrix*/
   bool Load(dmlc::Stream* fs);
 
-  /*! @return Save UnitGraph to stream, using CSRMatrix */
+  /** @return Save UnitGraph to stream, using CSRMatrix */
   void Save(dmlc::Stream* fs) const;
 
-  /*! @brief Creat a LineGraph of self */
+  /** @brief Creat a LineGraph of self */
   HeteroGraphPtr LineGraph(bool backtracking) const;
 
-  /*! @return the reversed graph */
+  /** @return the reversed graph */
   UnitGraphPtr Reverse() const;
 
-  /*! @return the simpled (no-multi-edge) graph
+  /** @return the simpled (no-multi-edge) graph
    *          the count recording the number of duplicated edges from the original graph.
    *          the edge mapping from the edge IDs of original graph to those of the
    *          returned graph.
@@ -319,7 +319,7 @@ class UnitGraph : public BaseHeteroGraph {
   // private empty constructor
   UnitGraph() {}
 
-  /*!
+  /**
    * @brief constructor
    * @param metagraph metagraph
    * @param in_csr in edge csr
@@ -329,7 +329,7 @@ class UnitGraph : public BaseHeteroGraph {
   UnitGraph(GraphPtr metagraph, CSRPtr in_csr, CSRPtr out_csr, COOPtr coo,
             dgl_format_code_t formats = ALL_CODE);
 
-  /*!
+  /**
    * @brief constructor
    * @param num_vtypes number of vertex types (1 or 2)
    * @param metagraph metagraph
@@ -350,10 +350,10 @@ class UnitGraph : public BaseHeteroGraph {
       bool has_coo,
       dgl_format_code_t formats = ALL_CODE);
 
-  /*! @return Return any existing format. */
+  /** @return Return any existing format. */
   HeteroGraphPtr GetAny() const;
 
-  /*!
+  /**
    * @brief Determine which format to use with a preference.
    *
    * If the storage of unit graph is "locked", i.e. no conversion is allowed, then
@@ -364,24 +364,24 @@ class UnitGraph : public BaseHeteroGraph {
    */
   SparseFormat SelectFormat(dgl_format_code_t preferred_formats) const;
 
-  /*! @return Whether the graph is hypersparse */
+  /** @return Whether the graph is hypersparse */
   bool IsHypersparse() const;
 
   GraphPtr AsImmutableGraph() const override;
 
   // Graph stored in different format. We use an on-demand strategy: the format is
   // only materialized if the operation that suitable for it is invoked.
-  /*! @brief CSR graph that stores reverse edges */
+  /** @brief CSR graph that stores reverse edges */
   CSRPtr in_csr_;
-  /*! @brief CSR representation */
+  /** @brief CSR representation */
   CSRPtr out_csr_;
-  /*! @brief COO representation */
+  /** @brief COO representation */
   COOPtr coo_;
-  /*!
+  /**
    * @brief Storage format restriction.
    */
   dgl_format_code_t formats_;
-  /*! @brief which streams have recorded the graph */
+  /** @brief which streams have recorded the graph */
   std::vector<DGLStreamHandle> recorded_streams;
 };
 

src/partition/cuda/partition_op.cu

-/*!
+/**
  *  Copyright (c) 2021 by Contributors
  * @file ndarray_partition.h
  * @brief Operations on partition implemented in CUDA.

src/partition/ndarray_partition.cc

-/*!
+/**
  *  Copyright (c) 2021 by Contributors
  * @file ndarray_partition.cc
  * @brief DGL utilities for working with the partitioned NDArrays

src/partition/ndarray_partition.h

-/*!
+/**
  *  Copyright (c) 2021 by Contributors
  * @file ndarray_partition.h
  * @brief DGL utilities for working with the partitioned NDArrays

src/partition/partition_op.h

-/*!
+/**
  *  Copyright (c) 2021 by Contributors
  * @file ndarray_partition.h
  * @brief DGL utilities for working with the partitioned NDArrays

src/random/cpu/choice.cc

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file random/choice.cc
  * @brief Non-uniform discrete sampling implementation

src/random/cpu/sample_utils.h

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file dgl/sample_utils.h
  * @brief Sampling utilities
@@ -20,12 +20,12 @@
 namespace dgl {
 namespace utils {
 
-/*! @brief Base sampler class */
+/** @brief Base sampler class */
 template <typename Idx>
 class BaseSampler {
  public:
   virtual ~BaseSampler() = default;
-  /*! @brief Draw one integer sample */
+  /** @brief Draw one integer sample */
   virtual Idx Draw() {
     LOG(INFO) << "Not implemented yet.";
     return 0;
@@ -37,7 +37,7 @@ class BaseSampler {
 // probability 0.  DType could be uint8 in this case, which will give incorrect arithmetic
 // results due to overflowing and/or integer division.
 
-/*
+/**
  * AliasSampler is used to sample elements from a given discrete categorical distribution.
  * Algorithm: Alias Method(https://en.wikipedia.org/wiki/Alias_method)
  * Sampler building complexity: O(n)
@@ -165,7 +165,7 @@ class AliasSampler: public BaseSampler<Idx> {
 };
 
 
-/*
+/**
  * CDFSampler is used to sample elements from a given discrete categorical distribution.
  * Algorithm: create a cumulative distribution function and conduct binary search for sampling.
  * Reference: https://github.com/numpy/numpy/blob/d37908/numpy/random/mtrand.pyx#L804
@@ -256,7 +256,7 @@ class CDFSampler: public BaseSampler<Idx> {
 };
 
 
-/*
+/**
  * TreeSampler is used to sample elements from a given discrete categorical distribution.
  * Algorithm: create a heap that stores accumulated likelihood of its leaf descendents.
  * Reference: https://blog.smola.org/post/1016514759

src/random/random.cc

-/*!
+/**
  *  Copyright (c) 2017 by Contributors
  * @file random.cc
  * @brief Random number generator interfaces

src/rpc/net_type.h

-/*!
+/**
  *  Copyright (c) 2022 by Contributors
  * @file net_type.h
  * @brief Base communicator for DGL distributed training.
@@ -14,21 +14,21 @@ namespace dgl {
 namespace rpc {
 
 struct RPCBase {
-  /*!
+  /**
    * @brief Finalize Receiver
    *
    * Finalize() is not thread-safe and only one thread can invoke this API.
    */
   virtual void Finalize() = 0;
 
-  /*!
+  /**
    * @brief Communicator type: 'socket', 'tensorpipe', etc
    */
   virtual const std::string &NetType() const = 0;
 };
 
 struct RPCSender : RPCBase {
-  /*!
+  /**
    * @brief Connect to a receiver.
    *
    * When there are multiple receivers to be connected, application will call
@@ -44,7 +44,7 @@ struct RPCSender : RPCBase {
    */
   virtual bool ConnectReceiver(const std::string &addr, int recv_id) = 0;
 
-  /*!
+  /**
    * @brief Finalize the action to connect to receivers. Make sure that either
    *        all connections are successfully established or connection fails.
    * @return True for success and False for fail
@@ -53,7 +53,7 @@ struct RPCSender : RPCBase {
    */
   virtual bool ConnectReceiverFinalize(const int max_try_times) { return true; }
 
-  /*!
+  /**
    * @brief Send RPCMessage to specified Receiver.
    * @param msg data message
    * @param recv_id receiver's ID
@@ -62,7 +62,7 @@ struct RPCSender : RPCBase {
 };
 
 struct RPCReceiver : RPCBase {
-  /*!
+  /**
    * @brief Wait for all the Senders to connect
    * @param addr Networking address, e.g., 'tcp://127.0.0.1:50051', 'mpi://0'
    * @param num_sender total number of Senders
@@ -74,7 +74,7 @@ struct RPCReceiver : RPCBase {
   virtual bool Wait(
       const std::string &addr, int num_sender, bool blocking = true) = 0;
 
-  /*!
+  /**
    * @brief Recv RPCMessage from Sender. Actually removing data from queue.
    * @param msg pointer of RPCmessage
    * @param timeout The timeout value in milliseconds. If zero, wait

src/rpc/network/common.cc

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file common.cc
  * @brief This file provide basic facilities for string

src/rpc/network/common.h

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file common.h
  * @brief This file provide basic facilities for string

src/rpc/network/communicator.h

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file communicator.h
  * @brief Communicator for DGL distributed training.
@@ -16,7 +16,7 @@
 namespace dgl {
 namespace network {
 
-/*!
+/**
  * @brief Network Sender for DGL distributed training.
  *
  * Sender is an abstract class that defines a set of APIs for sending binary
@@ -27,7 +27,7 @@ namespace network {
  */
 class Sender : public rpc::RPCSender {
  public:
-  /*!
+  /**
    * @brief Sender constructor
    * @param queue_size size (bytes) of message queue.
    * @param max_thread_count size of thread pool. 0 for no limit
@@ -42,7 +42,7 @@ class Sender : public rpc::RPCSender {
 
   virtual ~Sender() {}
 
-  /*!
+  /**
    * @brief Send data to specified Receiver.
    * @param msg data message
    * @param recv_id receiver's ID
@@ -58,17 +58,17 @@ class Sender : public rpc::RPCSender {
   virtual STATUS Send(Message msg, int recv_id) = 0;
 
  protected:
-  /*!
+  /**
    * @brief Size of message queue
    */
   int64_t queue_size_;
-  /*!
+  /**
    * @brief Size of thread pool. 0 for no limit
    */
   int max_thread_count_;
 };
 
-/*!
+/**
  * @brief Network Receiver for DGL distributed training.
  *
  * Receiver is an abstract class that defines a set of APIs for receiving binary
@@ -79,7 +79,7 @@ class Sender : public rpc::RPCSender {
  */
 class Receiver : public rpc::RPCReceiver {
  public:
-  /*!
+  /**
    * @brief Receiver constructor
    * @param queue_size size of message queue.
    * @param max_thread_count size of thread pool. 0 for no limit
@@ -96,7 +96,7 @@ class Receiver : public rpc::RPCReceiver {
 
   virtual ~Receiver() {}
 
-  /*!
+  /**
    * @brief Recv data from Sender
    * @param msg pointer of data message
    * @param send_id which sender current msg comes from
@@ -110,7 +110,7 @@ class Receiver : public rpc::RPCReceiver {
    */
   virtual STATUS Recv(Message* msg, int* send_id, int timeout = 0) = 0;
 
-  /*!
+  /**
    * @brief Recv data from a specified Sender
    * @param msg pointer of data message
    * @param send_id sender's ID
@@ -125,11 +125,11 @@ class Receiver : public rpc::RPCReceiver {
   virtual STATUS RecvFrom(Message* msg, int send_id, int timeout = 0) = 0;
 
  protected:
-  /*!
+  /**
    * @brief Size of message queue
    */
   int64_t queue_size_;
-  /*!
+  /**
    * @brief Size of thread pool. 0 for no limit
    */
   int max_thread_count_;

src/rpc/network/msg_queue.cc

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file msg_queue.cc
  * @brief Message queue for DGL distributed training.

src/rpc/network/msg_queue.h

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file msg_queue.h
  * @brief Message queue for DGL distributed training.
@@ -22,7 +22,7 @@ namespace network {
 
 typedef int STATUS;
 
-/*!
+/**
  * @brief Status code of message queue
  */
 #define ADD_SUCCESS 3400     // Add message successfully
@@ -33,45 +33,45 @@ typedef int STATUS;
 #define REMOVE_SUCCESS 3405  // Remove message successfully
 #define QUEUE_EMPTY 3406     // Cannot remove when queue is empty
 
-/*!
+/**
  * @brief Message used by network communicator and message queue.
  */
 struct Message {
-  /*!
+  /**
    * @brief Constructor
    */
   Message() {}
 
-  /*!
+  /**
    * @brief Constructor
    */
   Message(char* data_ptr, int64_t data_size)
       : data(data_ptr), size(data_size) {}
 
-  /*!
+  /**
    * @brief message data
    */
   char* data;
-  /*!
+  /**
    * @brief message size in bytes
    */
   int64_t size;
-  /*!
+  /**
    * @brief message receiver id
    */
   int receiver_id = -1;
-  /*!
+  /**
    * @brief user-defined deallocator, which can be nullptr
    */
   std::function<void(Message*)> deallocator = nullptr;
 };
 
-/*!
+/**
  * @brief Free memory buffer of message
  */
 inline void DefaultMessageDeleter(Message* msg) { delete[] msg->data; }
 
-/*!
+/**
  * @brief Message Queue for network communication.
  *
  * MessageQueue is FIFO queue that adopts producer/consumer model for data
@@ -89,7 +89,7 @@ inline void DefaultMessageDeleter(Message* msg) { delete[] msg->data; }
  */
 class MessageQueue {
  public:
-  /*!
+  /**
    * @brief MessageQueue constructor
    * @param queue_size size (bytes) of message queue
    * @param num_producers number of producers, use 1 by default
@@ -97,12 +97,12 @@ class MessageQueue {
   explicit MessageQueue(
       int64_t queue_size /* in bytes */, int num_producers = 1);
 
-  /*!
+  /**
    * @brief MessageQueue deconstructor
    */
   ~MessageQueue() {}
 
-  /*!
+  /**
    * @brief Add message to the queue
    * @param msg data message
    * @param is_blocking Blocking if cannot add, else return
@@ -110,7 +110,7 @@ class MessageQueue {
    */
   STATUS Add(Message msg, bool is_blocking = true);
 
-  /*!
+  /**
    * @brief Remove message from the queue
    * @param msg pointer of data msg
    * @param is_blocking Blocking if cannot remove, else return
@@ -118,64 +118,64 @@ class MessageQueue {
    */
   STATUS Remove(Message* msg, bool is_blocking = true);
 
-  /*!
+  /**
    * @brief Signal that producer producer_id will no longer produce anything
    * @param producer_id An integer uniquely to identify a producer thread
    */
   void SignalFinished(int producer_id);
 
-  /*!
+  /**
    * @return true if queue is empty.
    */
   bool Empty() const;
 
-  /*!
+  /**
    * @return true if queue is empty and all num_producers have signaled.
    */
   bool EmptyAndNoMoreAdd() const;
 
  protected:
-  /*!
+  /**
    * @brief message queue
    */
   std::queue<Message> queue_;
 
-  /*!
+  /**
    * @brief Size of the queue in bytes
    */
   int64_t queue_size_;
 
-  /*!
+  /**
    * @brief Free size of the queue
    */
   int64_t free_size_;
 
-  /*!
+  /**
    * @brief Used to check all producers will no longer produce anything
    */
   size_t num_producers_;
 
-  /*!
+  /**
    * @brief Store finished producer id
    */
   std::set<int /* producer_id */> finished_producers_;
 
-  /*!
+  /**
    * @brief Condition when consumer should wait
    */
   std::condition_variable cond_not_full_;
 
-  /*!
+  /**
    * @brief Condition when producer should wait
    */
   std::condition_variable cond_not_empty_;
 
-  /*!
+  /**
    * @brief Signal for exit wait
    */
   std::atomic<bool> exit_flag_{false};
 
-  /*!
+  /**
    * @brief Protect all above data and conditions
    */
   mutable std::mutex mutex_;

src/rpc/network/socket_communicator.cc

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file communicator.cc
  * @brief SocketCommunicator for DGL distributed training.

src/rpc/network/socket_communicator.h

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file communicator.h
  * @brief SocketCommunicator for DGL distributed training.
@@ -25,7 +25,7 @@ static constexpr int kTimeOut =
     10 * 60;  // 10 minutes (in seconds) for socket timeout
 static constexpr int kMaxConnection = 1024;  // maximal connection: 1024
 
-/*!
+/**
  * @breif Networking address
  */
 struct IPAddr {
@@ -33,14 +33,14 @@ struct IPAddr {
   int port;
 };
 
-/*!
+/**
  * @brief SocketSender for DGL distributed training.
  *
  * SocketSender is the communicator implemented by tcp socket.
  */
 class SocketSender : public Sender {
  public:
-  /*!
+  /**
    * @brief Sender constructor
    * @param queue_size size of message queue
    * @param max_thread_count size of thread pool. 0 for no limit
@@ -48,7 +48,7 @@ class SocketSender : public Sender {
   SocketSender(int64_t queue_size, int max_thread_count)
       : Sender(queue_size, max_thread_count) {}
 
-  /*!
+  /**
    * @brief Connect to a receiver.
    *
    * When there are multiple receivers to be connected, application will call
@@ -64,7 +64,7 @@ class SocketSender : public Sender {
    */
   bool ConnectReceiver(const std::string& addr, int recv_id) override;
 
-  /*!
+  /**
    * @brief Finalize the action to connect to receivers. Make sure that either
    *        all connections are successfully established or connection fails.
    * @return True for success and False for fail
@@ -73,19 +73,19 @@ class SocketSender : public Sender {
    */
   bool ConnectReceiverFinalize(const int max_try_times) override;
 
-  /*!
+  /**
    * @brief Send RPCMessage to specified Receiver.
    * @param msg data message
    * @param recv_id receiver's ID
    */
   void Send(const rpc::RPCMessage& msg, int recv_id) override;
 
-  /*!
+  /**
    * @brief Finalize TPSender
    */
   void Finalize() override;
 
-  /*!
+  /**
    * @brief Communicator type: 'socket'
    */
   const std::string& NetType() const override {
@@ -93,7 +93,7 @@ class SocketSender : public Sender {
     return net_type;
   }
 
-  /*!
+  /**
    * @brief Send data to specified Receiver. Actually pushing message to message
    * queue.
    * @param msg data message.
@@ -110,29 +110,29 @@ class SocketSender : public Sender {
   STATUS Send(Message msg, int recv_id) override;
 
  private:
-  /*!
+  /**
    * @brief socket for each connection of receiver
    */
   std::vector<
       std::unordered_map<int /* receiver ID */, std::shared_ptr<TCPSocket>>>
       sockets_;
 
-  /*!
+  /**
    * @brief receivers' address
    */
   std::unordered_map<int /* receiver ID */, IPAddr> receiver_addrs_;
 
-  /*!
+  /**
    * @brief message queue for each thread
    */
   std::vector<std::shared_ptr<MessageQueue>> msg_queue_;
 
-  /*!
+  /**
    * @brief Independent thread
    */
   std::vector<std::shared_ptr<std::thread>> threads_;
 
-  /*!
+  /**
    * @brief Send-loop for each thread
    * @param sockets TCPSockets for current thread
    * @param queue message_queue for current thread
@@ -147,14 +147,14 @@ class SocketSender : public Sender {
       std::shared_ptr<MessageQueue> queue);
 };
 
-/*!
+/**
  * @brief SocketReceiver for DGL distributed training.
  *
  * SocketReceiver is the communicator implemented by tcp socket.
  */
 class SocketReceiver : public Receiver {
  public:
-  /*!
+  /**
    * @brief Receiver constructor
    * @param queue_size size of message queue.
    * @param max_thread_count size of thread pool. 0 for no limit
@@ -162,7 +162,7 @@ class SocketReceiver : public Receiver {
   SocketReceiver(int64_t queue_size, int max_thread_count)
       : Receiver(queue_size, max_thread_count) {}
 
-  /*!
+  /**
    * @brief Wait for all the Senders to connect
    * @param addr Networking address, e.g., 'tcp://127.0.0.1:50051', 'mpi://0'
    * @param num_sender total number of Senders
@@ -174,7 +174,7 @@ class SocketReceiver : public Receiver {
   bool Wait(
       const std::string& addr, int num_sender, bool blocking = true) override;
 
-  /*!
+  /**
    * @brief Recv RPCMessage from Sender. Actually removing data from queue.
    * @param msg pointer of RPCmessage
    * @param timeout The timeout value in milliseconds. If zero, wait
@@ -183,7 +183,7 @@ class SocketReceiver : public Receiver {
    */
   rpc::RPCStatus Recv(rpc::RPCMessage* msg, int timeout) override;
 
-  /*!
+  /**
    * @brief Recv data from Sender. Actually removing data from msg_queue.
    * @param msg pointer of data message
    * @param send_id which sender current msg comes from
@@ -197,7 +197,7 @@ class SocketReceiver : public Receiver {
    */
   STATUS Recv(Message* msg, int* send_id, int timeout = 0) override;
 
-  /*!
+  /**
    * @brief Recv data from a specified Sender. Actually removing data from
    * msg_queue.
    * @param msg pointer of data message.
@@ -212,14 +212,14 @@ class SocketReceiver : public Receiver {
    */
   STATUS RecvFrom(Message* msg, int send_id, int timeout = 0) override;
 
-  /*!
+  /**
    * @brief Finalize SocketReceiver
    *
    * Finalize() is not thread-safe and only one thread can invoke this API.
    */
   void Finalize() override;
 
-  /*!
+  /**
    * @brief Communicator type: 'socket'
    */
   const std::string& NetType() const override {
@@ -233,24 +233,24 @@ class SocketReceiver : public Receiver {
     int64_t received_bytes = 0;
     char* buffer = nullptr;
   };
-  /*!
+  /**
    * @brief number of sender
    */
   int num_sender_;
 
-  /*!
+  /**
    * @brief server socket for listening connections
    */
   TCPSocket* server_socket_;
 
-  /*!
+  /**
    * @brief socket for each client connections
    */
   std::vector<std::unordered_map<
       int /* Sender (virutal) ID */, std::shared_ptr<TCPSocket>>>
       sockets_;
 
-  /*!
+  /**
    * @brief Message queue for each socket connection
    */
   std::unordered_map<
@@ -258,18 +258,18 @@ class SocketReceiver : public Receiver {
       msg_queue_;
   std::unordered_map<int, std::shared_ptr<MessageQueue>>::iterator mq_iter_;
 
-  /*!
+  /**
    * @brief Independent thead
    */
   std::vector<std::shared_ptr<std::thread>> threads_;
 
-  /*!
+  /**
    * @brief queue_sem_ semphore to indicate number of messages in multiple
    * message queues to prevent busy wait of Recv
    */
   runtime::Semaphore queue_sem_;
 
-  /*!
+  /**
    * @brief Recv-loop for each thread
    * @param sockets client sockets of current thread
    * @param queue message queues of current thread

src/rpc/network/socket_pool.cc

-/*!
+/**
  *  Copyright (c) 2021 by Contributors
  * @file socket_pool.cc
  * @brief Socket pool of nonblocking sockets for DGL distributed training.

src/rpc/network/socket_pool.h

-/*!
+/**
  *  Copyright (c) 2021 by Contributors
  * @file socket_pool.h
  * @brief Socket pool of nonblocking sockets for DGL distributed training.
@@ -15,7 +15,7 @@ namespace network {
 
 class TCPSocket;
 
-/*!
+/**
  * @brief SocketPool maintains a group of nonblocking sockets, and can provide
  * active sockets.
  * Currently SocketPool is based on epoll, a scalable I/O event notification
@@ -23,20 +23,20 @@ class TCPSocket;
  */
 class SocketPool {
  public:
-  /*!
+  /**
    * @brief socket mode read/receive
    */
   static const int READ = 1;
-  /*!
+  /**
    * @brief socket mode write/send
    */
   static const int WRITE = 2;
-  /*!
+  /**
    * @brief SocketPool constructor
    */
   SocketPool();
 
-  /*!
+  /**
    * @brief Add a socket to SocketPool
    * @param socket tcp socket to add
    * @param socket_id receiver/sender id of the socket
@@ -45,19 +45,19 @@ class SocketPool {
   void AddSocket(
       std::shared_ptr<TCPSocket> socket, int socket_id, int events = READ);
 
-  /*!
+  /**
    * @brief Remove socket from SocketPool
    * @param socket tcp socket to remove
    * @return number of remaing sockets in the pool
    */
   size_t RemoveSocket(std::shared_ptr<TCPSocket> socket);
 
-  /*!
+  /**
    * @brief SocketPool destructor
    */
   ~SocketPool();
 
-  /*!
+  /**
    * @brief Get current active socket. This is a blocking method
    * @param socket_id output parameter of the socket_id of active socket
    * @return active TCPSocket
@@ -65,27 +65,27 @@ class SocketPool {
   std::shared_ptr<TCPSocket> GetActiveSocket(int* socket_id);
 
  private:
-  /*!
+  /**
    * @brief Wait for event notification
    */
   void Wait();
 
-  /*!
+  /**
    * @brief map from fd to TCPSocket
    */
   std::unordered_map<int, std::shared_ptr<TCPSocket>> tcp_sockets_;
 
-  /*!
+  /**
    * @brief map from fd to socket_id
    */
   std::unordered_map<int, int> socket_ids_;
 
-  /*!
+  /**
    * @brief fd for epoll base
    */
   int epfd_;
 
-  /*!
+  /**
    * @brief queue for current active fds
    */
   std::queue<int> pending_fds_;

src/rpc/network/tcp_socket.cc

-/*!
+/**
  *  Copyright (c) 2019 by Contributors
  * @file tcp_socket.cc
  * @brief TCP socket for DGL distributed training.