From 7532d2cd7f0711306e101c2ecf22003a10d5e144 Mon Sep 17 00:00:00 2001
From: WrinklyNinja <wrinklyninja1@gmail.com>
Date: Wed, 14 Aug 2013 13:41:14 +0100
Subject: [PATCH] Issue #41. Overlaps can no longer cause cycle-forming edges.

Also fixed plugins with the same size not being detected. Not sure about
how the edge formation changes affect the sorting validity, haven't
checked yet.
---
 src/backend/graph.cpp  | 24 ++++++++++++++++++++++--
 src/backend/graph.h    |  2 ++
 src/backend/metadata.h |  8 ++++++++
 src/gui/main.cpp       | 15 ++++++++-------
 4 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/src/backend/graph.cpp b/src/backend/graph.cpp
index 7b40e1c9..f5333805 100644
--- a/src/backend/graph.cpp
+++ b/src/backend/graph.cpp
@@ -26,6 +26,7 @@
 
 #include <boost/algorithm/string.hpp>
 #include <boost/log/trivial.hpp>
+#include <boost/graph/breadth_first_search.hpp>
 
 using namespace std;
 
@@ -244,8 +245,8 @@ namespace boss {
             if (overlapIt != overlapMap.end()) {
                 for (vector<string>::const_iterator it=overlapIt->second.begin(), itend=overlapIt->second.end(); it != itend; ++it) {
                     if (boss::GetVertexByName(graph, *it, parentVertex) &&
-                        !boost::edge(*vit, parentVertex, graph).second &&
-                        !boost::edge(parentVertex, *vit, graph).second) {  //No edge going the other way, OK to add this edge.
+                        !boost::edge(parentVertex, *vit, graph).second &&
+                        !EdgeCreatesCycle(graph, parentVertex, *vit)) {  //No edge going the other way, OK to add this edge.
 
                         BOOST_LOG_TRIVIAL(trace) << "Adding edge from \"" << graph[parentVertex]->Name() << "\" to \"" << graph[*vit]->Name() << "\".";
 
@@ -263,4 +264,23 @@ namespace boss {
             boost::remove_edge(*it, graph);
         }
     }
+
+    bool EdgeCreatesCycle(PluginGraph& graph, vertex_t u, vertex_t v) {
+        //A cycle is created when adding the edge (u,v) if there already exists a path from v to u, so check for that using a breadth-first search.
+
+        //Breadth-first search requires an index map, which std::list-based VertexList graphs don't have, so one needs to be built separately.
+
+        map<vertex_t, size_t> index_map;
+        boost::associative_property_map< map<vertex_t, size_t> > v_index_map(index_map);
+        size_t i=0;
+        BGL_FORALL_VERTICES(v, graph, PluginGraph)
+            put(v_index_map, v, i++);
+
+        map<vertex_t, vertex_t> predecessor_map;
+        boost::associative_property_map< map<vertex_t, vertex_t> > v_predecessor_map(predecessor_map);
+
+        boost::breadth_first_search(graph, v, visitor(boost::make_bfs_visitor(boost::record_predecessors(v_predecessor_map, boost::on_tree_edge()))).vertex_index_map(v_index_map));
+
+        return predecessor_map.find(u) != predecessor_map.end();
+    }
 }
diff --git a/src/backend/graph.h b/src/backend/graph.h
index 4c7e97e7..cfa1821f 100644
--- a/src/backend/graph.h
+++ b/src/backend/graph.h
@@ -71,6 +71,8 @@ namespace boss {
     void AddOverlapEdges(PluginGraph& graph, const boost::unordered_map< std::string, std::vector<std::string> >& overlapMap);
 
     void ClearEdges(PluginGraph& graph);
+
+    bool EdgeCreatesCycle(PluginGraph& graph, vertex_t u, vertex_t v);
 }
 
 #endif
diff --git a/src/backend/metadata.h b/src/backend/metadata.h
index dc4bd47d..86d1c353 100644
--- a/src/backend/metadata.h
+++ b/src/backend/metadata.h
@@ -203,6 +203,14 @@ namespace boss {
         size_t numOverrideRecords;
     };
 
+    struct plugin_hash : std::unary_function<Plugin, size_t> {
+        inline size_t operator () (const Plugin& p) const {
+            size_t seed = 0;
+            boost::hash_combine(seed, p.Name());
+            return seed;
+        }
+    };
+
     bool operator == (const File& lhs, const Plugin& rhs);
 
     bool operator == (const Plugin& lhs, const File& rhs);
diff --git a/src/gui/main.cpp b/src/gui/main.cpp
index c6825448..0d4c21ae 100644
--- a/src/gui/main.cpp
+++ b/src/gui/main.cpp
@@ -466,28 +466,29 @@ void Launcher::OnSortPlugins(wxCommandEvent& event) {
 
     //First calculate the mean plugin size. Store it temporarily in a map to reduce filesystem lookups and file size recalculation.
     size_t meanFileSize = 0;
-    boost::unordered_map<size_t, boss::Plugin> tempMap;
+    boost::unordered_map<boss::Plugin, size_t, plugin_hash> tempMap;
     for (fs::directory_iterator it(_game.DataPath()); it != fs::directory_iterator(); ++it) {
         if (fs::is_regular_file(it->status()) && IsPlugin(it->path().string())) {
+
             size_t fileSize = fs::file_size(it->path());
             meanFileSize += fileSize;
 
-            tempMap.emplace(fileSize, boss::Plugin(it->path().filename().string()));
+            tempMap.emplace(boss::Plugin(it->path().filename().string()), fileSize);
         }
     }
     meanFileSize /= tempMap.size();
 
     //Now load plugins.
     plugin_list_loader pll(plugins, _game);
-    for (boost::unordered_map<size_t, boss::Plugin>::const_iterator it=tempMap.begin(), endit=tempMap.end(); it != endit; ++it) {
+    for (boost::unordered_map<boss::Plugin, size_t, plugin_hash>::const_iterator it=tempMap.begin(), endit=tempMap.end(); it != endit; ++it) {
 
-        BOOST_LOG_TRIVIAL(trace) << "Found plugin: " << it->second.Name();
+        BOOST_LOG_TRIVIAL(trace) << "Found plugin: " << it->first.Name();
 
-        plugins.push_back(it->second);
+        plugins.push_back(it->first);
 
-        if (it->first > meanFileSize) {
+        if (it->second > meanFileSize) {
             plugin_loader pl(plugins.back(), _game);
-            pll.skipPlugins.insert(it->second.Name());
+            pll.skipPlugins.insert(it->first.Name());
             group.create_thread(pl);
         }