support heterogenous fanout type

cpp/include/cugraph/sampling_functions.hpp

@@ -42,6 +42,8 @@ enum class prior_sources_behavior_t { DEFAULT = 0, CARRY_OVER, EXCLUDE };
 
 /**
  * @brief Uniform Neighborhood Sampling.
+ * 
+ * @deprecated This API will be deleted, use neighbor_sample instead
  *
  * This function traverses from a set of starting vertices, traversing outgoing edges and
  * randomly selects from these outgoing neighbors to extract a subgraph.
@@ -139,6 +141,8 @@ uniform_neighbor_sample(
 
 /**
  * @brief Biased Neighborhood Sampling.
+ * 
+ * @deprecated This API will be deleted, use neighbor_sample instead
  *
  * This function traverses from a set of starting vertices, traversing outgoing edges and
  * randomly selects (with edge biases) from these outgoing neighbors to extract a subgraph.
@@ -240,6 +244,121 @@ biased_neighbor_sample(
  bool dedupe_sources = false,
  bool do_expensive_check = false);
 
+
+/**
+ * @brief Neighborhood Sampling.
+ *
+ * This function traverses from a set of starting vertices, traversing outgoing edges and
+ * randomly selects (with edge biases or not) from these outgoing neighbors to extract a subgraph.
+ * When branching out to select outgoing neighbors, either fan_out or heterogeneous_fan_out must
+ * be provided but not both.
+ *
+ * Output from this function is a tuple of vectors (src, dst, weight, edge_id, edge_type, hop,
+ * label, offsets), identifying the randomly selected edges. src is the source vertex, dst is the
+ * destination vertex, weight (optional) is the edge weight, edge_id (optional) identifies the edge
+ * id, edge_type (optional) identifies the edge type, hop identifies which hop the edge was
+ * encountered in. The label output (optional) identifes the vertex label. The offsets array
+ * (optional) will be described below and is dependent upon the input parameters.
+ *
+ * If @p starting_vertex_labels is not specified then no organization is applied to the output, the
+ * label and offsets values in the return set will be std::nullopt.
+ *
+ * If @p starting_vertex_labels is specified and @p label_to_output_comm_rank is not specified then
+ * the label output has values. This will also result in the output being sorted by vertex label.
+ * The offsets array in the return will be a CSR-style offsets array to identify the beginning of
+ * each label range in the data. `labels.size() == (offsets.size() - 1)`.
+ *
+ * If @p starting_vertex_labels is specified and @p label_to_output_comm_rank is specified then the
+ * label output has values. This will also result in the output being sorted by vertex label. The
+ * offsets array in the return will be a CSR-style offsets array to identify the beginning of each
+ * label range in the data. `labels.size() == (offsets.size() - 1)`. Additionally, the data will
+ * be shuffled so that all data with a particular label will be on the specified rank.
+ *
+ * @tparam vertex_t Type of vertex identifiers. Needs to be an integral type.
+ * @tparam edge_t Type of edge identifiers. Needs to be an integral type.
+ * @tparam weight_t Type of edge weights. Needs to be a floating point type.
+ * @tparam edge_type_t Type of edge type. Needs to be an integral type.
+ * @tparam label_t Type of label. Needs to be an integral type.
+ * @tparam store_transposed Flag indicating whether sources (if false) or destinations (if
+ * true) are major indices
+ * @tparam multi_gpu Flag indicating whether template instantiation should target single-GPU (false)
+ * @param handle RAFT handle object to encapsulate resources (e.g. CUDA stream, communicator, and
+ * handles to various CUDA libraries) to run graph algorithms.
+ * * @param rng_state A pre-initialized raft::RngState object for generating random numbers
+ * @param graph_view Graph View object to generate NBR Sampling on.
+ * @param edge_weight_view Optional view object holding edge weights for @p graph_view.
+ * @param edge_id_view Optional view object holding edge ids for @p graph_view.
+ * @param edge_type_view Optional view object holding edge types for @p graph_view.
+ * @param edge_bias_view Optional view object holding edge biases (to be used in biased sampling) for @p
+ * graph_view. Bias values should be non-negative and the sum of edge bias values from any vertex
+ * should not exceed std::numeric_limits<bias_t>::max(). 0 bias value indicates that the
+ * corresponding edge can never be selected. passing std::nullopt as the edge biases will result in
+ * uniform sampling.
+ * @param starting_vertices Device span of starting vertex IDs for the sampling.
+ * In a multi-gpu context the starting vertices should be local to this GPU.
+ * @param starting_vertex_labels Optional device span of labels associted with each starting vertex
+ * for the sampling.
+ * @param label_to_output_comm_rank Optional tuple of device spans mapping label to a particular
+ * output rank. Element 0 of the tuple identifes the label, Element 1 of the tuple identifies the
+ * output rank. The label span must be sorted in ascending order.
+ * @param fan_out Host span defining branching out (fan-out) degree per source vertex for each
+ * level. When fan_out is provided, the sampling method uses the same fanout value for each type.
+ * @param heterogeneous_fan_out Tuple of host spans defining branching out (fan-out) degree per
+ * source vertex for each level in CSR style format. The first element of the tuple is the offset
+ * array per edge type id and the second element correspond to the fanout values.
+ * When heterogeneous_fan_out is provided, different fan_out values can be used for each edge type.
+ * The fan-out offsets size must be proportional to the number of edge types and fan_out values.
+ * @param return_hops boolean flag specifying if the hop information should be returned. 
+ * @param prior_sources_behavior Enum type defining how to handle prior sources, (defaults to
+ * DEFAULT)
+ * @param dedupe_sources boolean flag, if true then if a vertex v appears as a destination in hop X
+ * multiple times with the same label, it will only be passed once (for each label) as a source
+ * for the next hop. Default is false.
+ * @param with_replacement boolean flag specifying if random sampling is done with replacement
+ * (true); or, without replacement (false); default = true;
+ * @param do_expensive_check A flag to run expensive checks for input arguments (if set to `true`).
+ * @return tuple device vectors (vertex_t source_vertex, vertex_t destination_vertex,
+ * optional weight_t weight, optional edge_t edge id, optional edge_type_t edge type,
+ * optional int32_t hop, optional label_t label, optional size_t offsets)
+ */
+// FIXME: Add flag for bias=True/False
+template <typename vertex_t,
+ typename edge_t,
+ typename weight_t,
+ typename edge_type_t,
+ typename bias_t,
+ typename label_t,
+ bool store_transposed,
+ bool multi_gpu>
+std::tuple<rmm::device_uvector<vertex_t>,
+ rmm::device_uvector<vertex_t>,
+ std::optional<rmm::device_uvector<weight_t>>,
+ std::optional<rmm::device_uvector<edge_t>>,
+ std::optional<rmm::device_uvector<edge_type_t>>,
+ std::optional<rmm::device_uvector<int32_t>>,
+ std::optional<rmm::device_uvector<label_t>>,
+ std::optional<rmm::device_uvector<size_t>>>
+neighbor_sample(
+ raft::handle_t const& handle,
+ raft::random::RngState& rng_state,
+ graph_view_t<vertex_t, edge_t, store_transposed, multi_gpu> const& graph_view,
+ std::optional<edge_property_view_t<edge_t, weight_t const*>> edge_weight_view,
+ std::optional<edge_property_view_t<edge_t, edge_t const*>> edge_id_view,
+ std::optional<edge_property_view_t<edge_t, edge_type_t const*>> edge_type_view,
+ std::optional<edge_property_view_t<edge_t, bias_t const*>> edge_bias_view,
+ raft::device_span<vertex_t const> starting_vertices,
+ std::optional<raft::device_span<label_t const>> starting_vertex_labels,
+ std::optional<std::tuple<raft::device_span<label_t const>, raft::device_span<int32_t const>>>
+ label_to_output_comm_rank,
+ std::optional<raft::host_span<int32_t const>> fan_out,
+ std::optional<std::tuple<raft::host_span<int32_t const>, raft::host_span<int32_t const>>>
+ heterogeneous_fan_out,
+ bool return_hops,
+ bool with_replacement = true,
+ prior_sources_behavior_t prior_sources_behavior = prior_sources_behavior_t::DEFAULT,
+ bool dedupe_sources = false,
+ bool do_expensive_check = false);
+
 /*
  * @brief renumber sampled edge list and compress to the (D)CSR|(D)CSC format.
  *

cpp/include/cugraph_c/sampling_algorithms.h

@@ -319,8 +319,59 @@ void cugraph_sampling_set_dedupe_sources(cugraph_sampling_options_t* options, bo
  */
 void cugraph_sampling_options_free(cugraph_sampling_options_t* options);
 
+/**
+ * @brief Opaque neighborhood sampling heterogeneous fanout type
+ */
+// FIXME: internal representation should be tuple instead of pairs - Make it more generic (tuple)
+// cugraph_device_tuple_t, host_device_tuple_t,
+// dictionary, key and array
+// translate dictionary to a tuple. Add to the draft PR the PLC layer.
+// Concatenate to build the 3 arrays from the PLC layer
+/// mimic
+typedef struct {
+ int32_t align_;
+} cugraph_sample_heterogeneous_fan_out_t;
+
+/**
+ * @brief Create heterogeneous fanout
+ *
+ * Input data will be stored in the heterogenous_fanout.
+ * 
+ * The fanout is going to be a CSR structure, the edge_type_offsets will define which range
+ * of the fanout array is associated with each edge type, the fanout will be the values of
+ * fanout for that hop/type. So for edge type k, fanout[edge_type_offsets[k]] will identify
+ * the fanout for hop 0 for edge type k. fanout[edge_type_offsets[k] +1] will identify the
+ * fanout for hop 1, etc. edge_type_offsets[k+1] will mark the beginning of the fanout
+ * array for type k+1 (and the end of the fanout array for type k.
+ *
+ * @param [in] handle Handle for accessing resources
+ * @param [in] graph Pointer to graph
+ * @param [in] edge_type_offsets Type erased array of edge type offsets
+ * @param [in] fanout Type erased array of fanout values
+ * @param [out] heterogeneous_fanout Opaque pointer to fanout_t
+ * @param [out] error Pointer to an error object storing details of any error. Will
+ * be populated if error code is not CUGRAPH_SUCCESS
+ * @return error code
+ */
+cugraph_error_code_t cugraph_create_heterogeneous_fan_out(
+ const cugraph_resource_handle_t* handle,
+ cugraph_graph_t* graph,
+ const cugraph_type_erased_host_array_view_t* edge_type_offsets,
+ const cugraph_type_erased_host_array_view_t* fanout,
+ cugraph_sample_heterogeneous_fan_out_t** heterogeneous_fanout,
+ cugraph_error_t** error);
+
+/**
+ * @brief Free edge type and fanout pairs
+ *
+ * @param [in] heterogeneous_fanout The edge type size and fanout values
+ */
+void cugraph_heterogeneous_fanout_free(cugraph_sample_heterogeneous_fan_out_t* heterogeneous_fanout);
+
 /**
  * @brief Uniform Neighborhood Sampling
+ * 
+ * @deprecated This API will be deleted, use cugraph_neighbor_sample instead
  *
  * Returns a sample of the neighborhood around specified start vertices. Optionally, each
  * start vertex can be associated with a label, allowing the caller to specify multiple batches
@@ -376,6 +427,8 @@ cugraph_error_code_t cugraph_uniform_neighbor_sample(
 
 /**
  * @brief Biased Neighborhood Sampling
+ * 
+ * @deprecated This API will be deleted, use cugraph_neighbor_sample instead
  *
  * Returns a sample of the neighborhood around specified start vertices. Optionally, each
  * start vertex can be associated with a label, allowing the caller to specify multiple batches
@@ -433,6 +486,74 @@ cugraph_error_code_t cugraph_biased_neighbor_sample(
  cugraph_sample_result_t** result,
  cugraph_error_t** error);
 
+/**
+ * @brief Neighborhood Sampling
+ *
+ * Returns a sample of the neighborhood around specified start vertices with edge biases or not.
+ * Optionally, each start vertex can be associated with a label, allowing the caller to specify
+ * multiple batches of sampling requests in the same function call - which should improve GPU
+ * utilization.
+ *
+ * If label is NULL then all start vertices will be considered part of the same batch and the
+ * return value will not have a label column.
+ *
+ * @param [in] handle Handle for accessing resources
+ * * @param [in,out] rng_state State of the random number generator, updated with each call
+ * @param [in] graph Pointer to graph. NOTE: Graph might be modified if the storage
+ * needs to be transposed
+ * @param [in] edge_biases Device array of edge biases to use for sampling. If NULL
+ * use the edge weight as the bias. If set to NULL, edges will be sampled uniformly.
+ * @param [in] start_vertices Device array of start vertices for the sampling
+ * @param [in] start_vertex_labels Device array of start vertex labels for the sampling. The
+ * labels associated with each start vertex will be included in the output associated with results
+ * that were derived from that start vertex. We only support label of type INT32. If label is
+ * NULL, the return data will not be labeled.
+ * @param [in] label_list Device array of the labels included in @p start_vertex_labels. If
+ * @p label_to_comm_rank is not specified this parameter is ignored. If specified, label_list
+ * must be sorted in ascending order.
+ * @param [in] label_to_comm_rank Device array identifying which comm rank the output for a
+ * particular label should be shuffled in the output. If not specifed the data is not organized in
+ * output. If specified then the all data from @p label_list[i] will be shuffled to rank @p. This
+ * cannot be specified unless @p start_vertex_labels is also specified
+ * label_to_comm_rank[i]. If not specified then the output data will not be shuffled between ranks.
+ * @param [in] label_offsets Device array of the offsets for each label in the seed list. This
+ * parameter is only used with the retain_seeds option.
+ * @param [in] fanout Host array defining the fan out at each step in the sampling algorithm.
+ * We only support fanout values of type INT32
+ * @param [in] heterogeneous_fanout Tuple of host arrays defining the fan out at each step in the
+ * sampling algorithm. in CSR style format. The first element of the tuple is the offset array per
+ * edge type id and the second element correspond to the fanout values.
+ * We only support type INT32 for both the offsets and the fanout values array.
+ * @param [in] sampling_options
+ * Opaque pointer defining the sampling options.
+ * @param [in] is_biased
+ * A flag specifying whether to run biased neighborhood sampling
+ * (if set to true) or uniform neighbor sampling.
+ * @param [in] do_expensive_check
+ * A flag to run expensive checks for input arguments (if set to true)
+ * @param [out] result Output from the uniform_neighbor_sample call
+ * @param [out] error Pointer to an error object storing details of any error. Will
+ * be populated if error code is not CUGRAPH_SUCCESS
+ * @return error code
+ */
+cugraph_error_code_t cugraph_neighbor_sample(
+ const cugraph_resource_handle_t* handle,
+ cugraph_rng_state_t* rng_state,
+ cugraph_graph_t* graph,
+ const cugraph_edge_property_view_t* edge_biases,
+ const cugraph_type_erased_device_array_view_t* start_vertices,
+ const cugraph_type_erased_device_array_view_t* start_vertex_labels,
+ const cugraph_type_erased_device_array_view_t* label_list,
+ const cugraph_type_erased_device_array_view_t* label_to_comm_rank,
+ const cugraph_type_erased_device_array_view_t* label_offsets,
+ const cugraph_type_erased_host_array_view_t* fan_out,
+ const cugraph_sample_heterogeneous_fan_out_t* heterogeneous_fanout,
+ const cugraph_sampling_options_t* options,
+ bool_t is_biased,
+ bool_t do_expensive_check,
+ cugraph_sample_result_t** result,
+ cugraph_error_t** error);
+
 /**
  * @deprecated This call should be replaced with cugraph_sample_result_get_majors
  * @brief Get the source vertices from the sampling algorithm result
@@ -667,6 +788,7 @@ cugraph_error_code_t cugraph_test_uniform_neighborhood_sample_result_create(
  * not CUGRAPH_SUCCESS
  * @return error code
  */
+
 cugraph_error_code_t cugraph_select_random_vertices(const cugraph_resource_handle_t* handle,
  const cugraph_graph_t* graph,
  cugraph_rng_state_t* rng_state,

cpp/src/c_api/array.hpp

@@ -125,6 +125,27 @@ struct cugraph_type_erased_host_array_t {
  std::copy(vec.begin(), vec.end(), reinterpret_cast<T*>(data_.get()));
  }
 
+ cugraph_type_erased_host_array_t(cugraph_type_erased_host_array_view_t const* view_p)
+ : data_(std::make_unique<std::byte[]>(view_p->num_bytes_)),
+ size_(view_p->size_),
+ num_bytes_(view_p->num_bytes_),
+ type_(view_p->type_)
+ {
+ std::copy(view_p->data_, view_p->data_ + num_bytes_, data_.get());
+ }
+
+ template <typename T>
+ T* as_type()
+ {
+ return reinterpret_cast<T*>(data_.get());
+ }
+
+ template <typename T>
+ T const* as_type() const
+ {
+ return reinterpret_cast<T const*>(data_.get());
+ }
+
  auto view()
  {
  return new cugraph_type_erased_host_array_view_t{data_.get(), size_, num_bytes_, type_};

cpp/src/c_api/graph_functions.cpp

@@ -84,7 +84,7 @@ struct create_vertex_pairs_functor : public cugraph::c_api::abstract_functor {
  std::nullopt,
  std::nullopt);
  }
-
+ // FIXME: use std::tuple (template) instead.
  result_ = new cugraph::c_api::cugraph_vertex_pairs_t{
  new cugraph::c_api::cugraph_type_erased_device_array_t(first_copy, graph_->vertex_type_),
  new cugraph::c_api::cugraph_type_erased_device_array_t(second_copy, graph_->vertex_type_)};