Algorithm improvements, free_unreachable_objects() added.

[SVN r16894]

sp_debug_hooks.cpp

@@ -14,11 +14,12 @@
 #if defined(BOOST_ENABLE_SP_DEBUG_HOOKS)
 
 #include <boost/assert.hpp>
-#include <boost/detail/shared_count.hpp>
+#include <boost/shared_ptr.hpp>
 #include <boost/detail/lightweight_mutex.hpp>
 #include <new>
 #include <cstdlib>
 #include <map>
+#include <deque>
 #include <iostream>
 
 int const m = 2; // m * sizeof(int) must be aligned appropriately
@@ -113,7 +114,7 @@ void * operator new[](size_t n, nothrow_t const &) throw()
 
 // cycle detection
 
-typedef std::map< void *, std::pair<void *, size_t> > map_type;
+typedef std::map< void const *, std::pair<void *, size_t> > map_type;
 
 static map_type & get_map()
 {
@@ -151,7 +152,9 @@ namespace
 // assume 4 byte alignment for pointers when scanning
 size_t const pointer_align = 4;
 
-static void scan_and_count(void const * area, size_t size, map_type const & m, std::map<void const *, long> & m2)
+typedef std::map<void const *, long> map2_type;
+
+static void scan_and_count(void const * area, size_t size, map_type const & m, map2_type & m2)
 {
     unsigned char const * p = static_cast<unsigned char const *>(area);
 
@@ -166,79 +169,132 @@ static void scan_and_count(void const * area, size_t size, map_type const & m, s
     }
 }
 
-static bool scan_and_mark(void const * area, size_t size, map_type const & m, std::map<void const *, long> & m2)
+typedef std::deque<void const *> open_type;
+
+static void scan_and_mark(void const * area, size_t size, map2_type & m2, open_type & open)
 {
-    bool updated = false;
     unsigned char const * p = static_cast<unsigned char const *>(area);
 
     for(size_t n = 0; n + sizeof(shared_ptr_layout) <= size; p += pointer_align, n += pointer_align)
     {
         shared_ptr_layout const * q = reinterpret_cast<shared_ptr_layout const *>(p);
 
-        if(q->pn.id == boost::detail::shared_count_id && q->pn.pi != 0 && m.count(q->pn.pi) != 0)
+        if(q->pn.id == boost::detail::shared_count_id && q->pn.pi != 0 && m2.count(q->pn.pi) != 0)
         {
-            // mark as reachable
+            open.push_back(q->pn.pi);
-
+            m2.erase(q->pn.pi);
-            if(m2[q->pn.pi] != 0)
-            {
-                updated = true;
-                m2[q->pn.pi] = 0;
-            }
         }
     }
-
-    return updated;
 }
 
-void report_unreachable_objects()
+static void find_unreachable_objects(map_type const & m, map2_type & m2)
 {
-    std::map<void const *, long> m2;
-
-    mutex_type::scoped_lock lock(get_mutex());
-
-    map_type & m = get_map();
-
     // scan objects for shared_ptr members, compute internal counts
 
-    for(map_type::iterator i = m.begin(); i != m.end(); ++i)
     {
-        boost::detail::counted_base const * p = static_cast<boost::detail::counted_base *>(i->first);
+        for(map_type::const_iterator i = m.begin(); i != m.end(); ++i)
+        {
+            boost::detail::counted_base const * p = static_cast<boost::detail::counted_base const *>(i->first);
 
-        BOOST_ASSERT(p->use_count() != 0); // there should be no inactive counts in the map
+            BOOST_ASSERT(p->use_count() != 0); // there should be no inactive counts in the map
 
-        scan_and_count(i->second.first, i->second.second, m, m2);
+            scan_and_count(i->second.first, i->second.second, m, m2);
+        }
     }
 
     // mark reachable objects
 
-    bool updated;
-
-    do
     {
-        updated = false;
+        open_type open;
 
-        for(map_type::iterator i = m.begin(); i != m.end(); ++i)
+        for(map2_type::iterator i = m2.begin(); i != m2.end(); ++i)
         {
-            boost::detail::counted_base const * p = static_cast<boost::detail::counted_base *>(i->first);
+            boost::detail::counted_base const * p = static_cast<boost::detail::counted_base const *>(i->first);
-
+            if(p->use_count() != i->second) open.push_back(p);
-            if(p->use_count() != m2[p] && scan_and_mark(i->second.first, i->second.second, m, m2))
-            {
-                updated = true;
-            }
         }
 
-    } while(updated);
+        for(open_type::iterator j = open.begin(); j != open.end(); ++j)
-
-    // report unreachable objects
-
-    for(map_type::iterator i = m.begin(); i != m.end(); ++i)
-    {
-        boost::detail::counted_base const * p = static_cast<boost::detail::counted_base *>(i->first);
-
-        if(p->use_count() == m2[p])
         {
-            std::cerr << "Unreachable object at " << i->second.first << ", " << i->second.second << " bytes long.\n";
+            m2.erase(*j);
         }
+
+        while(!open.empty())
+        {
+            void const * p = open.front();
+            open.pop_front();
+
+            map_type::const_iterator i = m.find(p);
+            BOOST_ASSERT(i != m.end());
+
+            scan_and_mark(i->second.first, i->second.second, m2, open);
+        }
+    }
+
+    // m2 now contains the unreachable objects
+}
+
+void report_unreachable_objects(bool verbose)
+{
+    map2_type m2;
+
+    mutex_type::scoped_lock lock(get_mutex());
+
+    map_type const & m = get_map();
+
+    find_unreachable_objects(m, m2);
+
+    if(verbose)
+    {
+        for(map2_type::iterator j = m2.begin(); j != m2.end(); ++j)
+        {
+            map_type::const_iterator i = m.find(j->first);
+            BOOST_ASSERT(i != m.end());
+//            std::cerr << "Unreachable object at " << i->second.first << ", " << i->second.second << " bytes long.\n";
+        }
+    }
+
+    if(verbose || !m2.empty())
+    {
+        std::cerr << m2.size() << " unreachable objects.\n";
+    }
+}
+
+typedef std::deque< boost::shared_ptr<X> > free_list_type;
+
+static void scan_and_free(void * area, size_t size, map2_type const & m2, free_list_type & free)
+{
+    unsigned char * p = static_cast<unsigned char *>(area);
+
+    for(size_t n = 0; n + sizeof(shared_ptr_layout) <= size; p += pointer_align, n += pointer_align)
+    {
+        shared_ptr_layout * q = reinterpret_cast<shared_ptr_layout *>(p);
+
+        if(q->pn.id == boost::detail::shared_count_id && q->pn.pi != 0 && m2.count(q->pn.pi) != 0 && q->px != 0)
+        {
+            boost::shared_ptr<X> * ppx = reinterpret_cast< boost::shared_ptr<X> * >(p);
+            free.push_back(*ppx);
+            ppx->reset();
+        }
+    }
+}
+
+void free_unreachable_objects()
+{
+    map2_type m2;
+
+    mutex_type::scoped_lock lock(get_mutex());
+
+    map_type const & m = get_map();
+
+    find_unreachable_objects(m, m2);
+
+    free_list_type free;
+
+    for(map2_type::iterator j = m2.begin(); j != m2.end(); ++j)
+    {
+        map_type::const_iterator i = m.find(j->first);
+        BOOST_ASSERT(i != m.end());
+        scan_and_free(i->second.first, i->second.second, m2, free);
     }
 }