readers: infer node id from hostname suffix

Problem: the JGF writer supplies the ID of nodes based on the
hostname suffix (assuming it exists), which determines which nodes
are matched first under policies like high and low. However, the
JGF reader could just as easily supply the ID itself, thereby
reducing the size of JGF.

Make the reader supply the ID instead of the writer.

resource/readers/resource_reader_jgf.cpp

@@ -17,6 +17,7 @@ extern "C" {
 #include <map>
 #include <unordered_set>
 #include <unistd.h>
+#include <regex>
 #include <jansson.h>
 #include "resource/readers/resource_reader_jgf.hpp"
 #include "resource/store/resource_graph_store.hpp"
@@ -353,8 +354,25 @@ int resource_reader_jgf_t::apply_defaults (fetch_helper_t &f, const char *name)
             return -1;
         }
     }
-    if (f.id == -1)
+    if (f.id == -1) {
         f.id = f.uniq_id;
+        // for nodes, see if there is an integer suffix on the hostname and use it if so
+        if (f.type == std::string{"node"} && name != NULL) {
+            std::string sname{name};
+            std::regex nodesuffix ("(\\d+$)");
+            std::smatch r;
+            if (std::regex_search (sname, r, nodesuffix)) {
+                try {
+                    f.id = std::stoll (r.str (0));
+                } catch (std::invalid_argument const &ex) {
+                    m_err_msg += __FUNCTION__;
+                    m_err_msg += ": could not extract ID from hostname ";
+                    m_err_msg += sname;
+                    return -1;
+                }
+            }
+        }
+    }
     if (f.exclusive == -1)
         f.exclusive = 0;
     if (f.size == -1)

src/python/fluxion/resourcegraph/V1.py

@@ -7,7 +7,6 @@
 #
 # SPDX-License-Identifier: LGPL-3.0
 ##############################################################
-import re
 
 from flux.idset import IDset
 from flux.hostlist import Hostlist
@@ -125,13 +124,6 @@ def _contains_any(self, prop_str, charset):
                 return True
         return False
 
-    def _extract_id_from_hn(self, hostName):
-        postfix = re.findall(r"(\d+$)", hostName)
-        rc = self._uniqId
-        if len(postfix) == 1:
-            rc = int(postfix[0])
-        return rc
-
     def _encode_child(self, ppid, path, rank, resType, i):
         vtx = FluxionResourcePoolV1(
             self._uniqId, resType, iden=i, rank=rank, path=f"{path}/{resType}{i}"
@@ -146,7 +138,6 @@ def _encode_rank(self, ppid, path, rank, children, hostname, properties):
             "node",
             name=hostname,
             rank=rank,
-            iden=self._extract_id_from_hn(hostname),
             properties=properties,
             path=path,
         )