Add a context-level query capability.

Augment the PaRSEC context API with query capabilities, allowing users
to find the number of processes, cores and other information from a
PaRSEC context.

Signed-off-by: George Bosilca <bosilca@icl.utk.edu>

parsec/parsec.c

@@ -2759,3 +2759,50 @@ void parsec_set_my_execution_stream(parsec_execution_stream_t *es)
 {
     PARSEC_TLS_SET_SPECIFIC(parsec_tls_execution_stream, es);
 }
+
+
+/**
+ * Query the number of devices of the requested type available in the
+ * PaRSEC context.
+ */
+int parsec_context_query(parsec_context_t *context, parsec_context_query_cmd_t cmd, ...)
+{
+    parsec_device_module_t* dev;
+    va_list args;
+    va_start(args, cmd);
+
+    switch(cmd) {
+        case PARSEC_CONTEXT_QUERY_NODES:
+            switch (parsec_communication_engine_up) {
+                case 0: return 0;  /* context not ready for distributed runs, and lacking datatype chandling capabilities */
+                case 1: return 1;  /* single node runs, but the context has datatype management capabilties */
+                case 2: return -1; /* we are in a distributed run, but the MPI engine is not yet ready, so the nb_nodes might not be accurate */
+                case 3: return context->nb_nodes;
+            }
+            return PARSEC_ERROR;
+
+        case PARSEC_CONTEXT_QUERY_RANK:
+            return context->my_rank;
+
+        case PARSEC_CONTEXT_QUERY_DEVICES:
+            int device_type = va_arg(args, int), count = 0;
+            for( uint32_t i = 0; i < parsec_nb_devices; i++ ) {
+                dev = parsec_mca_device_get(i);
+                if( dev->type & device_type ) count++;
+            }
+            return count;
+
+        case PARSEC_CONTEXT_QUERY_CORES:
+            int nb_total_comp_threads = 0;
+            for (int idx = 0; idx < context->nb_vp; idx++) {
+                nb_total_comp_threads += context->virtual_processes[idx]->nb_cores;
+            }
+            return nb_total_comp_threads;
+
+        case PARSEC_CONTEXT_QUERY_ACTIVE_TASKPOOLS:
+            return context->active_taskpools;
+        /* no default */
+    }
+    return PARSEC_ERR_NOT_SUPPORTED;  /* unknown command */
+}
+

parsec/runtime.h

@@ -286,6 +286,33 @@ int parsec_context_add_taskpool( parsec_context_t* context, parsec_taskpool_t* t
  */
 int parsec_context_remove_taskpool( parsec_taskpool_t* tp );
 
+/**
+ * Query PaRSEC context capabilities.
+ */
+
+typedef enum parsec_context_query_cmd_e {
+    PARSEC_CONTEXT_QUERY_NODES,
+    PARSEC_CONTEXT_QUERY_RANK,
+    PARSEC_CONTEXT_QUERY_DEVICES,
+    PARSEC_CONTEXT_QUERY_CORES,
+    PARSEC_CONTEXT_QUERY_ACTIVE_TASKPOOLS
+} parsec_context_query_cmd_t;
+
+/**
+ * @brief Query PaRSEC context's properties.
+ *
+ * @details
+ * Query properties of the runtime, such as number of devices of a certain type
+ * or number of cores available to the context.
+ *
+ * @param[in] context the PaRSEC context
+ * @param[in] device_type the type of device the query is about
+ * @return a negative number if the PaRSEC context has not yet properly been
+ * initialized (and as such the query does not yet makes sense), or the number
+ * of available devices of the requested type.
+ */
+int parsec_context_query(parsec_context_t* context, parsec_context_query_cmd_t device_type, ... );
+
 /**
  * @brief Start taskpool that were enqueued into the PaRSEC context
  *