[Misc] Polish metapath_randomwalk.h (#5471)

Co-authored-by: Ubuntu <ubuntu@ip-172-31-28-63.ap-northeast-1.compute.internal>

src/graph/sampling/randomwalks/metapath_randomwalk.h

@@ -2,7 +2,7 @@
  *  Copyright (c) 2018 by Contributors
  * @file graph/sampler/generic_randomwalk_cpu.h
  * @brief DGL sampler - templated implementation definition of random walks on
- * CPU
+ *     CPU.
  */
 
 #ifndef DGL_GRAPH_SAMPLING_RANDOMWALKS_METAPATH_RANDOMWALK_H_
@@ -30,10 +30,6 @@ namespace impl {
 
 namespace {
 
-// bool WhetherToTerminate(
-//     IdxType *node_ids_generated_so_far,
-//     dgl_id_t last_node_id_generated,
-//     int64_t number_of_nodes_generated_so_far)
 template <typename IdxType>
 using TerminatePredicate = std::function<bool(IdxType *, dgl_id_t, int64_t)>;
 
@@ -78,9 +74,9 @@ std::tuple<dgl_id_t, dgl_id_t, bool> MetapathRandomWalkStep(
   const int64_t size = offsets[curr + 1] - offsets[curr];
   if (size == 0) return std::make_tuple(-1, -1, true);
 
-  // Use a reference to the original array instead of copying
-  // This avoids updating the ref counts atomically from different threads
-  // and avoids cache ping-ponging in the tight loop
+  // Use a reference to the original array instead of copying. This avoids
+  // updating the ref counts atomically from different threads and avoids cache
+  // ping-ponging in the tight loop.
   const FloatArray &prob_etype = prob[etype];
   IdxType idx = 0;
   if (IsNullArray(prob_etype)) {
@@ -115,9 +111,8 @@ std::tuple<dgl_id_t, dgl_id_t, bool> MetapathRandomWalkStep(
  * @param edges_by_type Vector of results from \c GetAdj() by edge type.
  * @param metapath_data Edge types of given metapath.
  * @param prob Transition probability per edge type, for this special case this
- * will be a NullArray
- * @param terminate Predicate for terminating the current
- * random walk path.
+ *     will be a NullArray.
+ * @param terminate Predicate for terminating the current random walk path.
  *
  * @return A pair of ID of next successor (-1 if not exist), as well as whether
  *     to terminate. \note This function is called only if all the probability
@@ -162,8 +157,8 @@ std::tuple<dgl_id_t, dgl_id_t, bool> MetapathRandomWalkStepUniform(
  *     first edge type in the metapath.
  * @param metapath A 1D array of edge types representing the metapath.
  * @param prob A vector of 1D float arrays, indicating the transition
- * probability of each edge by edge type.  An empty float array assumes uniform
- * transition.
+ *     probability of each edge by edge type.  An empty float array assumes
+ *     uniform transition.
  * @param terminate Predicate for terminating a random walk path.
  * @return A 2D array of shape (len(seeds), len(metapath) + 1) with node IDs,
  *     and A 2D array of shape (len(seeds), len(metapath)) with edge IDs.