PC sampling client: using raw pointers (#902)

* PC sampling client: using raw pointers to prevent premature destruction of buffers

* PCS client: freeing buffer_ids

[ROCm/rocprofiler-sdk commit: b0c41827c3]

projects/rocprofiler-sdk/samples/pc_sampling/client.cpp

@@ -69,6 +69,9 @@ tool_init(rocprofiler_client_finalize_t fini_func, void* /*tool_data*/)
 {
     client_fini_func = fini_func;
 
+    // Initialize necessary data structures
+    pcs::init();
+
     client::pcs::find_all_gpu_agents_supporting_pc_sampling();
 
     if(client::pcs::gpu_agents.empty())
@@ -86,6 +89,8 @@ tool_init(rocprofiler_client_finalize_t fini_func, void* /*tool_data*/)
 
     ROCPROFILER_CHECK(rocprofiler_create_context(&client_ctx));
 
+    auto* buff_ids_vec = pcs::get_pc_sampling_buffer_ids();
+
     for(auto& gpu_agent : pcs::gpu_agents)
     {
         // creating a buffer that will hold pc sampling information
@@ -108,7 +113,7 @@ tool_init(rocprofiler_client_finalize_t fini_func, void* /*tool_data*/)
 
         ROCPROFILER_CHECK(rocprofiler_assign_callback_thread(buffer_id, client_agent_thread));
 
-        client::pcs::buffer_ids.emplace_back(buffer_id);
+        buff_ids_vec->emplace_back(buffer_id);
     }
 
     int valid_ctx = 0;
@@ -138,12 +143,12 @@ tool_fini(void* /*tool_data*/)
         assert(state == 0);
 
         // No need to stop the context, since it has been stopped implicitly by the rocprofiler-SDK.
-        for(size_t i = 0; i < client::pcs::buffer_ids.size(); i++)
+        for(auto buff_id : *pcs::get_pc_sampling_buffer_ids())
         {
             // Flush the buffer explicitly
-            ROCPROFILER_CHECK(rocprofiler_flush_buffer(client::pcs::buffer_ids.at(i)));
+            ROCPROFILER_CHECK(rocprofiler_flush_buffer(buff_id));
             // Destroying the buffer
-            rocprofiler_status_t status = rocprofiler_destroy_buffer(client::pcs::buffer_ids.at(i));
+            rocprofiler_status_t status = rocprofiler_destroy_buffer(buff_id);
             if(status == ROCPROFILER_STATUS_ERROR_BUFFER_BUSY)
             {
                 *utils::get_output_stream()
@@ -155,6 +160,9 @@ tool_fini(void* /*tool_data*/)
             }
         }
     }
+
+    // deallocation
+    pcs::fini();
 }
 
 }  // namespace

projects/rocprofiler-sdk/samples/pc_sampling/pcs.cpp

@@ -40,8 +40,40 @@ namespace client
 {
 namespace pcs
 {
-tool_agent_info_vec_t                gpu_agents;
-std::vector<rocprofiler_buffer_id_t> buffer_ids;
+// TODO: Since this is used only within the `tool_init`,
+// we are safe using static constructor.
+// It would be nice to make this consistent with the `buffer_ids`.
+tool_agent_info_vec_t gpu_agents;
+// The reason for using raw pointers is the following.
+// Sometimes, statically created objects of the client::pcs
+// namespace might be freed prior to the `tool_fini`,
+// meaning `buffer_ids` become unusable inside `tool_fini`.
+// Instead, use raw pointers to control objects deallocation time.
+// TODO: The approach with exporting raw pointers outside of the
+// `pcs` namespace is a temporary solution.
+// Instead, it would be better to encapsulate `buffer_ids` inside the
+// `pcs` namespace and export functions for registering/flushing/destroying buffers.
+pc_sampling_buffer_id_vec_t* buffer_ids = nullptr;
+
+void
+init()
+{
+    buffer_ids = new pc_sampling_buffer_id_vec_t();
+}
+
+void
+fini()
+{
+    // Clear the data
+    buffer_ids->clear();
+    delete buffer_ids;
+}
+
+pc_sampling_buffer_id_vec_t*
+get_pc_sampling_buffer_ids()
+{
+    return buffer_ids;
+}
 
 rocprofiler_status_t
 find_all_gpu_agents_supporting_pc_sampling_impl(rocprofiler_agent_version_t version,

projects/rocprofiler-sdk/samples/pc_sampling/pcs.hpp

@@ -35,8 +35,9 @@ constexpr size_t BUFFER_SIZE_BYTES = 8192;
 constexpr size_t WATERMARK         = (BUFFER_SIZE_BYTES / 4);
 
 struct tool_agent_info;
-using avail_configs_vec_t   = std::vector<rocprofiler_pc_sampling_configuration_t>;
-using tool_agent_info_vec_t = std::vector<std::unique_ptr<tool_agent_info>>;
+using avail_configs_vec_t         = std::vector<rocprofiler_pc_sampling_configuration_t>;
+using tool_agent_info_vec_t       = std::vector<std::unique_ptr<tool_agent_info>>;
+using pc_sampling_buffer_id_vec_t = std::vector<rocprofiler_buffer_id_t>;
 
 struct tool_agent_info
 {
@@ -50,8 +51,18 @@ struct tool_agent_info
 // meaning we were not able to enable PC sampling service.
 // Check the `tool_init` for more information.
 extern tool_agent_info_vec_t gpu_agents;
+
+// Must be called first (prior to any other function from this namespace)
+void
+init();
+
+// Must be called at the end of the `tool_fini`
+void
+fini();
+
 // Ids of the buffers used as containers for PC sampling records
-extern std::vector<rocprofiler_buffer_id_t> buffer_ids;
+pc_sampling_buffer_id_vec_t*
+get_pc_sampling_buffer_ids();
 
 void
 find_all_gpu_agents_supporting_pc_sampling();