traverser: add partial cancellation functionality

Problem: Fluxion issue
flux-framework#1151 and flux-core
issue flux-framework/flux-core#4312
identified the need for partial release of resources. The current
functionality need is to release all resources managed by a single
broker rank. In the future support for releasing arbitrary subgraphs
will be needed for cloud and converged use cases.

Modify the rem_* traverser functions to take a modification type and
type_to_count unordered_map. Add logic in the recursive job
modification calls to distinguish between a full and partial job
cancellation and issue corresponding planner interface calls, handling
errors as needed.

resource/traversers/dfu.cpp

@@ -391,6 +391,24 @@ int dfu_traverser_t::remove (int64_t jobid)
     return detail::dfu_impl_t::remove (root, jobid);
 }
 
+int dfu_traverser_t::remove (const std::string &R_to_cancel,
+                    std::shared_ptr<resource_reader_base_t> &reader,
+                    int64_t jobid, bool &full_cancel)
+{
+    const subsystem_t &dom = get_match_cb ()->dom_subsystem ();
+    if (!get_graph () || !get_graph_db ()
+        || get_graph_db ()->metadata.roots.find (dom)
+           == get_graph_db ()->metadata.roots.end ()
+        || !get_match_cb ()) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    vtx_t root = get_graph_db ()->metadata.roots.at (dom);
+    return detail::dfu_impl_t::remove (root, R_to_cancel, reader, jobid,
+                                       full_cancel);
+}
+
 int dfu_traverser_t::mark (const std::string &root_path, 
                            resource_pool_t::status_t status)
 {

resource/traversers/dfu.hpp

@@ -164,6 +164,22 @@ class dfu_traverser_t : protected detail::dfu_impl_t
      */
     int remove (int64_t jobid);
 
+    /*! Remove the allocation/reservation referred to by jobid and update
+     *  the resource state.
+     *
+     *  \param R_to_cancel   deallocation string such as written in JGF.
+     *  \param reader        reader object that deserialize str to update the
+     *                       graph
+     *  \param jobid         job id.
+     *  \param full_cancel   bool indicating if the partial cancel cancelled all
+     *                       job resources
+     *  \return              0 on success; -1 on error.
+     *                       EINVAL: graph, roots or match callback not set.
+     */
+    int remove (const std::string &to_cancel,
+                std::shared_ptr<resource_reader_base_t> &reader,
+                int64_t jobid, bool &full_cancel);
+
     /*! Mark the resource status up|down|etc starting at subtree_root.
      *
      *  \param root_path     path to the root of the subtree to update.

resource/traversers/dfu_impl.hpp

@@ -292,6 +292,21 @@ class dfu_impl_t {
      */
     int remove (vtx_t root, int64_t jobid);
 
+    /*! Remove the allocation/reservation referred to by jobid and update
+     *  the resource state.
+     *
+     *  \param root      root resource vertex.
+     *  \param to_cancel deallocation string such as written in JGF.
+     *  \param reader    reader object that deserialize str to update the graph
+     *  \param jobid     job id.
+     *  \param full_cancel   bool indicating if the partial cancel cancelled all
+     *                       job resources
+     *  \return          0 on success; -1 on error.
+     */
+    int remove (vtx_t root, const std::string &to_cancel,
+                std::shared_ptr<resource_reader_base_t> &reader,
+                int64_t jobid, bool &full_cancel);
+
     /*! Update the resource status to up|down|etc starting at subtree_root.
      *
      *  \param root_path     path to the root of the subtree to update.
@@ -474,14 +489,19 @@ class dfu_impl_t {
                  unsigned int needs, bool excl, const jobmeta_t &jobmeta,
                  bool full, std::map<std::string, int64_t> &to_parent,
                  bool emit_shadow);
-
-    int rem_txfilter (vtx_t u, int64_t jobid, bool &stop);
-    int rem_agfilter (vtx_t u, int64_t jobid, const std::string &s);
-    int rem_idata (vtx_t u, int64_t jobid, const std::string &s, bool &stop);
-    int rem_plan (vtx_t u, int64_t jobid);
-    int rem_upv (vtx_t u, int64_t jobid);
-    int rem_dfv (vtx_t u, int64_t jobid);
-    int rem_exv (int64_t jobid);
+    bool rem_tag (vtx_t u, int64_t jobid);
+    int rem_exclusive_filter (vtx_t u, int64_t jobid,
+                              const modify_data_t &mod_data);
+    int mod_agfilter (vtx_t u, int64_t jobid, const std::string &s,
+                      const modify_data_t &mod_data, bool &stop);
+    int mod_idata (vtx_t u, int64_t jobid, const std::string &s,
+                   const modify_data_t &mod_data, bool &stop);
+    int mod_plan (vtx_t u, int64_t jobid, modify_data_t &mod_data);
+    int mod_upv (vtx_t u, int64_t jobid, const modify_data_t &mod_data);
+    int mod_dfv (vtx_t u, int64_t jobid, modify_data_t &mod_data);
+    int mod_exv (int64_t jobid, const modify_data_t &mod_data);
+    int cancel_vertex (vtx_t vtx, modify_data_t &mod_data,
+                       int64_t jobid);
 
 
     /************************************************************************