Add support for nosync thrust exec policy

cpp/include/raft/core/resource/resource_types.hpp

@@ -42,6 +42,7 @@ enum resource_type {
   STREAM_VIEW,             // view of a cuda stream or a placeholder in
                            // CUDA-free builds
   THRUST_POLICY,           // thrust execution policy
+  THRUST_NOSYNC_POLICY,    // thrust nosync execution policy
   WORKSPACE_RESOURCE,      // rmm device memory resource
   CUBLASLT_HANDLE,         // cublasLt handle
   CUSTOM,                  // runtime-shared default-constructible resource

cpp/include/raft/core/resource/thrust_nosync_policy.hpp

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2024, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#pragma once
+
+#include <raft/core/resource/cuda_stream.hpp>
+#include <raft/core/resource/resource_types.hpp>
+#include <raft/core/resources.hpp>
+
+#include <rmm/exec_policy.hpp>
+namespace raft::resource {
+class thrust_nosync_policy_resource : public resource {
+ public:
+  thrust_nosync_policy_resource(rmm::cuda_stream_view stream_view)
+    : thrust_nosync_policy_(std::make_unique<rmm::exec_policy_nosync>(stream_view))
+  {
+  }
+  void* get_resource() override { return thrust_nosync_policy_.get(); }
+
+  ~thrust_nosync_policy_resource() override {}
+
+ private:
+  std::unique_ptr<rmm::exec_policy_nosync> thrust_nosync_policy_;
+};
+
+/**
+ * Factory that knows how to construct a
+ * specific raft::resource to populate
+ * the res_t.
+ */
+class thrust_nosync_policy_resource_factory : public resource_factory {
+ public:
+  thrust_nosync_policy_resource_factory(rmm::cuda_stream_view stream_view)
+    : stream_view_(stream_view)
+  {
+  }
+  resource_type get_resource_type() override { return resource_type::THRUST_NOSYNC_POLICY; }
+  resource* make_resource() override { return new thrust_nosync_policy_resource(stream_view_); }
+
+ private:
+  rmm::cuda_stream_view stream_view_;
+};
+
+/**
+ * @defgroup resource_thrust_nosync_policy Thrust nosync policy resource functions
+ * @{
+ */
+
+/**
+ * Load a thrust nosync policy from a res (and populate it on the res if needed).
+ * @param res raft res object for managing resources
+ * @return thrust execution policy nosync
+ */
+inline rmm::exec_policy_nosync& get_thrust_nosync_policy(resources const& res)
+{
+  if (!res.has_resource_factory(resource_type::THRUST_NOSYNC_POLICY)) {
+    rmm::cuda_stream_view stream = get_cuda_stream(res);
+    res.add_resource_factory(std::make_shared<thrust_nosync_policy_resource_factory>(stream));
+  }
+  return *res.get_resource<rmm::exec_policy_nosync>(resource_type::THRUST_NOSYNC_POLICY);
+};
+
+/**
+ * @}
+ */
+
+}  // namespace raft::resource