From 74e12dd17ac68b65dac49430499b9fa1bd64b845 Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Sat, 29 May 2010 01:25:14 +0200
Subject: [PATCH] factor advice holding buffer into separate Class

---
 src/lib/advice.hpp        | 75 ++++++++++++++++++++++++++++++---------
 src/lib/advice/advice.cpp | 21 ++++++++---
 src/lib/advice/index.hpp  |  6 ++--
 3 files changed, 78 insertions(+), 24 deletions(-)

diff --git a/src/lib/advice.hpp b/src/lib/advice.hpp
index 33cc3392e..7a33ceffa 100644
--- a/src/lib/advice.hpp
+++ b/src/lib/advice.hpp
@@ -116,13 +116,15 @@ namespace advice {
           pattern_ = binding.buildMatcher();
         }
       
-      void publishProvision();
+      void publishProvision (PointOfAdvice*);
       void discardSolutions ();
       void publishBindingChange();
       void publishRequestBindingChange();
       
-      void registrateRequest();
-      void deregistrateRequest();
+      void registerRequest();
+      void deregisterRequest();
+      
+      void* getBuffer(size_t);
       
     public:
       explicit
@@ -181,7 +183,6 @@ namespace advice {
   class Provision
     : public PointOfAdvice
     {
-      AD theAdvice_;
       
       
       /* == policy definitions == */    ////TODO: extract into policy classes
@@ -194,7 +195,6 @@ namespace advice {
       explicit
       Provision (Literal bindingSpec =0)
         : PointOfAdvice (Binding(bindingSpec).addTypeGuard<AD>())
-        , theAdvice_()
         { }
       
      ~Provision()
@@ -203,21 +203,13 @@ namespace advice {
         }
       
       
-      AD const&
-      getAdvice()  const
-        {
-          return theAdvice_;
-        }
-      
       void setAdvice (AD const& pieceOfAdvice)
         {
-          theAdvice_ = pieceOfAdvice;
-          publishProvision (); ///////////////////////////TODO how to propagate without specific typing?
+          publishProvision (storeCopy (pieceOfAdvice));
         }
       
       void retractAdvice()
         {
-          theAdvice_ = this->handleMissingSolution();
           discardSolutions ();
         }
       
@@ -227,8 +219,57 @@ namespace advice {
           setBindingPattern (Binding(topic).addTypeGuard<AD>());
           publishBindingChange();
         }
+      
+    private:
+      PointOfAdvice* storeCopy (AD const& advice_given);
     };
   
+  
+  /**
+   * Piece of Advice as incorporated into the AdviceSystem.
+   * This holder-object contains a copy of the advice data
+   * and is placed into the internal storage buffer; the
+   * advice index keeps a (type erased) pointer to serve
+   * any requests which happen to match the binding.
+   */
+  template<class AD>
+  class ActiveProvision
+    : public PointOfAdvice
+    {
+      AD theAdvice_;
+      
+    public:
+      AD const&
+      getAdvice()  const
+        {
+          return theAdvice_;
+        }
+      
+    protected:
+      ActiveProvision (PointOfAdvice const& refPoint, AD const& advice_given)
+        : PointOfAdvice(refPoint)
+        , theAdvice_(advice_given)
+        {
+          setSolution (this, this);
+        }
+      
+      friend class Provision<AD>;
+    };
+  
+    
+  /** function to copy advice into an internal buffer,
+      @return type erased pointer to the data holder created
+      @throw  error::External on allocation problems, plus anything
+              the advice data may throw during copy construction. */
+  template<class AD>
+  PointOfAdvice*
+  Provision<AD>::storeCopy (AD const& advice_given)
+    {
+      typedef ActiveProvision<AD> Holder;
+      return new(getBuffer(sizeof(Holder))) Holder (*this, advice_given);
+    }
+
+  
     
     
   
@@ -241,7 +282,7 @@ namespace advice {
   class Request
     : public PointOfAdvice
     {
-      typedef const Provision<AD> AdviceProvision;
+      typedef const ActiveProvision<AD> AdviceProvision;
       
       
       /* == policy definitions == */    ////TODO: extract into policy classes
@@ -254,12 +295,12 @@ namespace advice {
       Request (Literal bindingSpec =0)
         : PointOfAdvice (Binding(bindingSpec).addTypeGuard<AD>())
         {
-          registrateRequest();
+          registerRequest();
         }
       
      ~Request()
         {
-          deregistrateRequest();
+          deregisterRequest();
         }
       
       
diff --git a/src/lib/advice/advice.cpp b/src/lib/advice/advice.cpp
index 1ed7889fb..e7f729055 100644
--- a/src/lib/advice/advice.cpp
+++ b/src/lib/advice/advice.cpp
@@ -31,9 +31,22 @@ namespace advice {
 //  LUMIERA_ERROR_DEFINE (MISSING_INSTANCE, "Existing ID registration without associated instance");
 
   
-  /* ohlolololohaha */
+  /** allocate raw storage for a buffer holding the actual piece of advice.
+      We need to manage this internally, as the original advice::Provision
+      may go out of scope, while the advice information as such remains valid.
+      @note the special twist is the size of the buffer depending on the actual
+            advice type, which we need to erase for tracking all advice provisions
+            and advice requests through an generic index datastructure.
+      @todo rewrite to use Lumiera's block allocator / memory pool */
+  void*
+  PointOfAdvice::getBuffer(size_t)
+  {
+    UNIMPLEMENTED ("raw allocation and de-allocation of advice holding buffer");
+  }
+  
+  
   void
-  PointOfAdvice::publishProvision()
+  PointOfAdvice::publishProvision (PointOfAdvice*)
   {
     UNIMPLEMENTED ("change advice provision registration");
   }
@@ -61,14 +74,14 @@ namespace advice {
   
   
   void
-  PointOfAdvice::registrateRequest()
+  PointOfAdvice::registerRequest()
   {
     UNIMPLEMENTED ("registrate request with the index");
   }
   
   
   void
-  PointOfAdvice::deregistrateRequest()
+  PointOfAdvice::deregisterRequest()
   {
     UNIMPLEMENTED ("detach request from index");
   }
diff --git a/src/lib/advice/index.hpp b/src/lib/advice/index.hpp
index 31e2bf0ca..e15c308d0 100644
--- a/src/lib/advice/index.hpp
+++ b/src/lib/advice/index.hpp
@@ -392,9 +392,9 @@ namespace advice {
       void
       removeProvision (POA const& refEntry)
         {
-          HashVal oKey (hash_value(refEntry));
-          provisionEntries_[oKey].remove (refEntry);
-          requestEntries_[oKey].retract_all_solutions (refEntry, provisionEntries_[oKey]);
+          HashVal key (hash_value(refEntry));
+          provisionEntries_[key].remove (refEntry);
+          requestEntries_[key].retract_all_solutions (refEntry, provisionEntries_[key]);
         }