Add cluster_info API for PBSPro job adapter

lib/ood_core/job/adapters/pbspro.rb

@@ -1,4 +1,5 @@
 require "time"
+require "json"
 require "ood_core/refinements/hash_extensions"
 require "ood_core/job/adapters/helper"
 
@@ -85,6 +86,50 @@ def initialize(host: nil, submit_host: "", strict_host_checking: true, pbs_exec:
             @bin_overrides        = bin_overrides
           end
 
+          # Get a ClusterInfo object containing information about the given cluster
+          # @return [ClusterInfo] object containing cluster details
+          def get_cluster_info
+            args = ["-a", "-F", "json"]
+            stdout = call("pbsnodes", *args)
+            node_info = JSON.parse(stdout)
+
+            # Initialize cluster info values
+            total_nodes     = 0
+            allocated_nodes = 0
+            total_cpus      = 0
+            allocated_cpus  = 0
+            total_gpus      = 0
+            allocated_gpus  = 0 
+
+            nodes = node_info.fetch('nodes', {})
+
+            nodes.each do |_node_name, node|
+              total_nodes += 1
+              resources_avail = node.fetch('resources_available', {})
+              total_cpus += get_node_resource(resources_avail, 'ncpus')
+              total_gpus += get_node_resource(resources_avail, 'ngpus')
+
+              # Resources assigned (currently allocated to jobs)
+              resources_assigned = node.fetch('resources_assigned', {})
+              ncpus_assigned     = get_node_resource(resources_assigned, 'ncpus')
+              ngpus_assigned     = get_node_resource(resources_assigned, 'ngpus')
+
+              allocated_cpus += ncpus_assigned
+              allocated_gpus += ngpus_assigned
+
+              # A node is allocated if at least one CPU has been assigned to a job
+              allocated_nodes += 1 if ncpus_assigned > 0
+            end
+
+            ClusterInfo.new(active_nodes: allocated_nodes,
+                            total_nodes: total_nodes,
+                            active_processors: allocated_cpus,
+                            total_processors: total_cpus,
+                            active_gpus: allocated_gpus,
+                            total_gpus: total_gpus
+            )
+          end
+
           # Get a list of hashes detailing each of the jobs on the batch server
           # @example Status info for all jobs
           #   my_batch.get_jobs
@@ -174,6 +219,13 @@ def submit_string(str, args: [], chdir: nil)
           end
 
           private
+            # Get a resource value from a node's resources hash, returning 0 if the
+            # resource is not present
+            def get_node_resource(resources, key)
+             val = resources.fetch(key, 0)
+             val.to_i
+            end
+
             # Call a forked PBS Pro command for a given batch server
             def call(cmd, *args, env: {}, stdin: "", chdir: nil)
               cmd = cmd.to_s
@@ -299,6 +351,10 @@ def submit(script, after: [], afterok: [], afternotok: [], afterany: [])
           raise JobAdapterError, e.message
         end
 
+        def cluster_info
+          @pbspro.get_cluster_info
+        end
+
         # Retrieve info for all jobs from the resource manager
         # @raise [JobAdapterError] if something goes wrong getting job info
         # @return [Array<Info>] information describing submitted jobs