- Implement first draft of quicksort in Python

- Extend test to have a set of processes (now lacks
significative output)
- Extend FCFS policy to do something useful
- FIXME : segfaults on sortQueue()
- FIXME : needs implementation for SchedulableQueue.swap()


git-svn-id: svn://svn.gna.org/svn/sgpemv2/trunk@389 3ecf2c5c-341e-0410-92b4-d18e462d057c

src/backend/policy.hh

@@ -44,7 +44,7 @@ namespace sgpem
 	  virtual ~Policy();
 	  
 	  virtual void			configure() = 0;
-	  virtual void 			sort_queue(sgpem::Scheduler::event) const = 0;
+	  virtual void 			sort_queue(Scheduler::event) const = 0;
 	  int		  	        get_id() const;
 	  virtual Glib::ustring 	get_description() const = 0;
 	  virtual bool 			is_pre_emptive() const = 0;

src/backend/pyloader/Policy.py

@@ -1,22 +1,11 @@
 from Abstract import *
-
-## @brief this function implements a quicksort in place
-# using the SchedulableQueue methods
+                
+## @brief This is the abstract class a user-defined policy
+# should inherit from
 #
-# The compare parameter should be a user defined function
-# name returning either True or False, defined like:
-# @code
-# def compare(SchedulableA,SchedulableB):
-#     return SchedulableA.someProperty() < SchedulableB.someProperty()
-# @endcode
-#
-# @param queue The SchedulableQueue to be sorted in place
-# @param cmp The binary function to use to compare elements
-# @returns None
-def sort(queue, cmp):
-    pass
-    
-
+# This class also exposes the method sort, which can be
+# used to easily sort the queue of ready process with a
+# given compare function
 class Policy:
     ## @var Avoid instantiation of an abstract class
     __metaclass__ = Metaclass
@@ -26,3 +15,58 @@ class Policy:
     is_preemptive = AbstractMethod('is_preemptive')
     get_time_slice = AbstractMethod('get_time_slice')
     
+    ## @brief this function implements a quicksort in place
+    # using the SchedulableQueue methods
+    #
+    # The compare parameter should be a user defined function
+    # name returning either True or False, defined like:
+    # @code
+    # def compare(SchedulableA,SchedulableB):
+    #     return SchedulableA.someProperty() < SchedulableB.someProperty()
+    # @endcode
+    #
+    # @param queue The SchedulableQueue to be sorted in place
+    # @param cmpf The binary function to use to compare elements
+    # @returns None
+    def sort(queue, cmpf):
+        __recursive_qsort_(queue, 0, queue.size()-1, cmpf)
+
+    ## @brief Recursive (private) call to perform quicksort on a
+    # queue
+    #
+    # @param queue The queue to sort
+    # @param a The initial element position of the slice
+    # @param b The final element position of the slice
+    # @param cmpf The user-defined compare function to employ
+    # @returns None
+    def __recursive_qsort_(queue, a, b, cmpf):
+        if(b>a):
+            pivot = __partition_(queue, a, b, cmpf)
+            __recursive_qsort_(queue, a, pivot-1, cmpf)
+            __recursive_qsort_(queue, pivot+1, b, cmpf)
+        
+    ## @brief Recursive (private) call to partition a slice of the queue
+    #
+    # This private function (the name mangling should work)
+    # naively sorts a partition of queue in place using just
+    # its methods.
+    #
+    # Feel the love.
+    #
+    # @param queue The SchedulableQueue to sort
+    # @param a The partition starting element position in the queue
+    # @param b The partition ending element position in the queue
+    # @param cmpf The binary function to use for comparing two elements
+    # @return The new pivot index
+    def __partition_(queue, a, b, cmpf):
+        # takes pivot element:
+        right = queue.get_item_at(b)
+        i = a
+        for j in range(a,b-1):
+            if cmpf(queue.get_item_at(j), right):
+                # the C++ code should do nothing if i == j:
+                queue.swap(i,j)
+                i = i+1
+        # puts pivot in place
+        queue.swap(i,b)
+        return i

src/backend/pyloader/python_policy_manager.cc

@@ -50,7 +50,7 @@ Policy&
 PythonPolicyManager::get_policy()
 {
   // FIXME : assumes that _python_policy is always != NULL!
-  return *_python_policy;
+    return *_python_policy;
 }
 
 void
@@ -76,7 +76,5 @@ PythonPolicyManager::init()
 
   // FIXME : Hardcoded policy name
   char* policy_name = "fcfs";
-  PythonPolicy policy(policy_name);
-  policy.configure();
-  std::cout << policy.get_time_slice() << std::endl;
+  _python_policy = std::auto_ptr<PythonPolicy>(new PythonPolicy(policy_name));
 }

src/backend/sgpem.i

@@ -126,11 +126,7 @@ namespace sgpem {
     class SchedulableList 
     {
     public:
-	sgpem::SchedulableStatus* top();
-	sgpem::SchedulableStatus* bottom();
-	bool insert_at(const uint&, const uint&);
 	uint size() const;
-	SchedulableStatus* get_item_at(const uint&);
 	const SchedulableStatus* get_item_at(const uint&) const;
 	void swap(unsigned int positionA, unsigned int positionB) throw();