Ported RewindManager to use LinkedObjectPool class.

src/common/LinkedObjectPool.hxx

@@ -25,8 +25,8 @@
  * A fixed-size object-pool based doubly-linked list that makes use of
  * multiple STL lists, to reduce frequent (de)allocations.
  *
- * This structure acts like a queue (adds to end, removes from beginning),
- * but also allows for removal at any location in the queue.
+ * This structure can be used as either a stack or queue, but also allows
+ * for removal at any location in the list.
  *
  * There are two internal lists; one stores active nodes, and the other
  * stores pool nodes that have been 'deleted' from the active list (note
@@ -61,9 +61,29 @@ class LinkedObjectPool
     }
 
     /**
-     * Add a new node at the end of the active list, and return a reference to
-     * that node. The reference may then be modified; ie, you're able to change
-     * the data located at that node.
+     * Return a reference to the element at the first node in the active list.
+     */
+    T& first() { return myList.front(); }
+
+    /**
+     * Return a reference to the element at the last node in the active list.
+     */
+    T& last() { return myList.back(); }
+
+    /**
+     * Add a new node at beginning of the active list, and return a reference
+     * to that nodes' data. The reference may then be modified; ie, you're
+     * able to change the data located at that node.
+     */
+    T& addFirst() {
+      myList.splice(myList.begin(), myPool, myPool.begin());
+      return myList.front();
+    }
+
+    /**
+     * Add a new node at the end of the active list, and return a reference
+     * to that nodes' data. The reference may then be modified; ie, you're
+     * able to change the data located at that node.
      */
     T& addLast() {
       myList.splice(myList.end(), myPool, myPool.begin());
@@ -71,13 +91,22 @@ class LinkedObjectPool
     }
 
     /**
-     * Return a reference to the element at the first node.
-     * The reference may not be modified.
+     * Remove the first node of the active list.
      */
-    const T& first() const { return myList.front(); }
+    void removeFirst() {
+      myPool.splice(myPool.end(), myList, myList.begin());
+    }
 
     /**
-     * Remove a single element at position of the iterator +- the offset.
+     * Remove the last node of the active list.
+     */
+    void removeLast() {
+      myPool.splice(myPool.end(), myList, std::prev(myList.end(), 1));
+    }
+
+    /**
+     * Convenience method to remove a single element from the active list at
+     * position of the iterator +- the offset.
      */
     void remove(const_iter i, Int32 offset = 0) {
       myPool.splice(myPool.end(), myList,
@@ -85,37 +114,38 @@ class LinkedObjectPool
     }
 
     /**
-     * Remove a single element by index, offset from the beginning of the list.
-     * (ie, '0' means first element, '1' is second, and so on).
+     * Convenience method to remove a single element from the active list by
+     * index, offset from the beginning of the list. (ie, '0' means first
+     * element, '1' is second, and so on).
      */
     void remove(uInt32 index) {
       myPool.splice(myPool.end(), myList, std::next(myList.begin(), index));
     }
 
-    /**
-     * Convenience method to remove the first element in the list.
-     */
-    void removeFirst() {
-      myPool.splice(myPool.end(), myList, myList.begin());
-    }
-
     /**
      * Convenience method to remove a range of elements from 'index' to the
-     * end of the list.
+     * end of the active list.
      */
     void removeLast(uInt32 index) {
       myPool.splice(myPool.end(), myList, std::next(myList.begin(), index), myList.end());
     }
 
+    /**
+     * Erase entire contents of active list.
+     */
+    void clear() {
+      myPool.splice(myPool.end(), myList, myList.begin(), myList.end());
+    }
+
     /** Access the list with iterators, just as you would a normal C++ STL list */
     iter begin() { return myList.begin(); }
     iter end()   { return myList.end();   }
     const_iter begin() const { return myList.cbegin(); }
     const_iter end() const   { return myList.cend();   }
 
-    uInt32 size() const { return myList.size();      }
-    bool empty() const  { return size() == 0;        }
-    bool full() const   { return size() >= CAPACITY; }
+    uInt32 size() const { return myList.size();             }
+    bool empty() const  { return myList.size() == 0;        }
+    bool full() const   { return myList.size() >= CAPACITY; }
 
   private:
     std::list<T> myList, myPool;

src/common/RewindManager.cxx

@@ -32,16 +32,16 @@ RewindManager::RewindManager(OSystem& system, StateManager& statemgr)
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool RewindManager::addState(const string& message)
 {
-  RewindPtr state = make_unique<RewindState>();  // TODO: get this from object pool
-  Serializer& s = state->data;
+  if(myStateList.full())
+    myStateList.removeLast();  // remove the oldest state file
+
+  RewindState& state = myStateList.addFirst();
+  Serializer& s = state.data;
 
   s.reset();  // rewind Serializer internal buffers
   if(myStateManager.saveState(s) && myOSystem.console().tia().saveDisplay(s))
   {
-    state->message = "Rewind " + message;
-
-    // Add to the list  TODO: should check against current size
-    myStateList.emplace_front(std::move(state));
+    state.message = "Rewind " + message;
     return true;
   }
   return false;
@@ -50,18 +50,18 @@ bool RewindManager::addState(const string& message)
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool RewindManager::rewindState()
 {
-  if(myStateList.size() > 0)
+  if(!myStateList.empty())
   {
-    RewindPtr state = std::move(myStateList.front());
-    myStateList.pop_front();  // TODO: add 'state' to object pool
-    Serializer& s = state->data;
+    RewindState& state = myStateList.first();
+    Serializer& s = state.data;
 
     s.reset();  // rewind Serializer internal buffers
     myStateManager.loadState(s);
     myOSystem.console().tia().loadDisplay(s);
 
     // Show message indicating the rewind state
-    myOSystem.frameBuffer().showMessage(state->message);
+    myOSystem.frameBuffer().showMessage(state.message);
+    myStateList.removeFirst();
 
     return true;
   }

src/common/RewindManager.hxx

@@ -21,17 +21,12 @@
 class OSystem;
 class StateManager;
 
-#include <list>
+#include "LinkedObjectPool.hxx"
 #include "bspf.hxx"
 
 /**
   This class is used to save (and later 'rewind') system save states.
 
-  TODO: This will eventually be converted to use object pools
-        Currently, it uses a C++ doubly-linked list as a stack, with
-        add/remove happening at the front of the list
-        Also, the additions are currently unbounded
-
   @author  Stephen Anthony
 */
 class RewindManager
@@ -54,12 +49,12 @@ class RewindManager
     */
     bool rewindState();
 
-    bool empty() const { return myStateList.size() == 0; }
+    bool empty() const { return myStateList.empty(); }
     void clear() { myStateList.clear(); }
 
   private:
     // Maximum number of states to save
-    static constexpr uInt32 MAX_SIZE = 100;  // FIXME: use this
+    static constexpr uInt32 MAX_SIZE = 100;
 
     OSystem& myOSystem;
     StateManager& myStateManager;
@@ -67,10 +62,13 @@ class RewindManager
     struct RewindState {
       Serializer data;
       string message;
+
+      // We do nothing on object instantiation or copy
+      RewindState() { }
+      RewindState(const RewindState&) { }
     };
 
-    using RewindPtr = unique_ptr<RewindState>;
-    std::list<RewindPtr> myStateList;
+    Common::LinkedObjectPool<RewindState, MAX_SIZE> myStateList;
 
   private:
     // Following constructors and assignment operators not supported