From ffda7fcc04f926821ccd87dbe7cd7a51ad5f13a7 Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Thu, 11 Mar 2021 14:02:21 -0500
Subject: [PATCH] simpler interfaces

---
 examples/plugins/morse2plugin.cpp | 32 ++++++++++++++++---------------
 src/lammpsplugin.h                |  4 ++--
 src/plugin.cpp                    | 27 +++++++++++++++++++-------
 src/plugin.h                      |  5 +++--
 4 files changed, 42 insertions(+), 26 deletions(-)

diff --git a/examples/plugins/morse2plugin.cpp b/examples/plugins/morse2plugin.cpp
index d7290edfb0..cfb6689cae 100644
--- a/examples/plugins/morse2plugin.cpp
+++ b/examples/plugins/morse2plugin.cpp
@@ -22,21 +22,23 @@ static Pair *morse2ompcreator(LAMMPS *lmp)
 }
 
 static lammpsplugin_t plugin;
-extern "C" void lammpsplugin_init(void *lmp, void *handle, lammpsplugin_regfunc register_plugin)
+extern "C" void lammpsplugin_init(void *lmp, void *handle, void *regfunc)
 {
-    memset(&plugin,0,sizeof(lammpsplugin_t));
-    plugin.version = LAMMPS_VERSION;
-    plugin.style   = "pair";
-    plugin.name    = "morse2";
-    plugin.info    = "Morse2 variant pair style v1.0";
-    plugin.author  = "Axel Kohlmeyer (akohlmey@gmail.com)";
-    plugin.creator = (lammpsplugin_factory *) &morse2creator;
-    plugin.handle  = handle;
-    register_plugin(&plugin,lmp);
+  // register plain morse2 pair style
+  lammpsplugin_regfunc register_plugin = (lammpsplugin_regfunc) regfunc;
+  memset(&plugin,0,sizeof(lammpsplugin_t));
+  plugin.version = LAMMPS_VERSION;
+  plugin.style   = "pair";
+  plugin.name    = "morse2";
+  plugin.info    = "Morse2 variant pair style v1.0";
+  plugin.author  = "Axel Kohlmeyer (akohlmey@gmail.com)";
+  plugin.creator = (lammpsplugin_factory *) &morse2creator;
+  plugin.handle  = handle;
+  register_plugin(&plugin,lmp);
 
-    plugin.style   = "pair";
-    plugin.name    = "morse2/omp";
-    plugin.info    = "Morse2 variant pair style for OpenMP v1.0";
-    plugin.creator = (lammpsplugin_factory *) &morse2ompcreator;
-    register_plugin(&plugin,lmp);
+  // also register morse2/omp pair style. only need to update changed fields
+  plugin.name    = "morse2/omp";
+  plugin.info    = "Morse2 variant pair style for OpenMP v1.0";
+  plugin.creator = (lammpsplugin_factory *) &morse2ompcreator;
+  register_plugin(&plugin,lmp);
 }
diff --git a/src/lammpsplugin.h b/src/lammpsplugin.h
index 6cdf67e09b..34a0b60811 100644
--- a/src/lammpsplugin.h
+++ b/src/lammpsplugin.h
@@ -31,12 +31,12 @@ extern "C" {
   } lammpsplugin_t;
 
   typedef void (*lammpsplugin_regfunc)(lammpsplugin_t *, void *);
-  typedef void (*lammpsplugin_initfunc)(void *, void *, lammpsplugin_regfunc);
+  typedef void (*lammpsplugin_initfunc)(void *, void *, void *);
 
   // prototype for initializer function required
   // to load a plugin; uses C bindings
 
-  void lammpsplugin_init(void *, void *, lammpsplugin_regfunc);
+  void lammpsplugin_init(void *, void *, void *);
 }
 
 #endif
diff --git a/src/plugin.cpp b/src/plugin.cpp
index f81c453afb..e978d90059 100644
--- a/src/plugin.cpp
+++ b/src/plugin.cpp
@@ -18,6 +18,7 @@
 #include "lammps.h"
 #include "modify.h"
 
+#include <map>
 #include <vector>
 
 #ifdef _WIN32
@@ -28,14 +29,20 @@
 
 namespace LAMMPS_NS
 {
+  // store list of plugin information data for loaded styles
   static std::vector<lammpsplugin_t> pluginlist;
+  // map of dso handles 
+  static std::map<void *, int> dso_refcounter;
 
-  void plugin_load(const char *file, void *ptr)
+  // load DSO and call included registration function
+  void plugin_load(const char *file, LAMMPS *lmp)
   {
-    LAMMPS *lmp = (LAMMPS *)ptr;
 #if defined(WIN32)
     utils::logmesg(lmp,"Loading of plugins not supported on Windows yet\n");
 #else
+
+    // open DSO from given path
+    
     void *dso = dlopen(file,RTLD_NOW|RTLD_GLOBAL);
     if (dso == nullptr) {
       utils::logmesg(lmp,fmt::format("Loading of plugin from file {} failed: "
@@ -43,17 +50,23 @@ namespace LAMMPS_NS
       return;
     }
 
+    // look up lammpsplugin_init() function in DSO. must have C bindings.
+
     void *initfunc = dlsym(dso,"lammpsplugin_init");
     if (initfunc == nullptr) {
       dlclose(dso);
       utils::logmesg(lmp,fmt::format("Symbol lookup failure in file {}\n",file));
       return;
     }
-    ((lammpsplugin_initfunc)(initfunc))(ptr,dso,&plugin_register);
-//    dlclose(dso);
+
+    // call initializer function loaded from DSO and pass pointer to LAMMPS instance,
+    // the DSO handle (for reference counting) and plugin registration function pointer
+
+    ((lammpsplugin_initfunc)(initfunc))((void *)lmp, dso, (void *)&plugin_register);
 #endif
   }
 
+  // register new style from plugin with LAMMPS
   void plugin_register(lammpsplugin_t *plugin, void *ptr)
   {
     LAMMPS *lmp = (LAMMPS *)ptr;
@@ -99,10 +112,10 @@ namespace LAMMPS_NS
     }
     return -1;
   }
-  
-  void plugin_unload(const char *style, const char *name, void *ptr)
+
+  // remove plugin from given style table
+  void plugin_unload(const char *style, const char *name, LAMMPS *lmp)
   {
-    LAMMPS *lmp = (LAMMPS *)ptr;
     std::string pstyle = style;
     if (pstyle == "pair") {
       auto found = lmp->force->pair_map->find(name);
diff --git a/src/plugin.h b/src/plugin.h
index 546ab2a644..051382ac27 100644
--- a/src/plugin.h
+++ b/src/plugin.h
@@ -18,12 +18,13 @@
 
 namespace LAMMPS_NS
 {
-  void plugin_load(const char *, void *);
+  class LAMMPS;
+  void plugin_load(const char *, LAMMPS *);
   void plugin_register(lammpsplugin_t *, void *);
   int plugin_get_num_plugins();
   const lammpsplugin_t *plugin_info(int);
   int plugin_find(const char *, const char *);
-  void plugin_unload(const char *, const char *, void *);
+  void plugin_unload(const char *, const char *, LAMMPS *);
 }
 
 #endif