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#include <climits>
#include "ace/RB_Tree.h"
/*
Much of this is credited to "Efficient Distrubuted Deadlock
Avoidance with Liveness Guarentees" by Sanchez, Sipma, and Manna,
EMSOFT 2006
*/
struct AnnotationNode {
AnnotationNode()
:count(0), size(0), larger(0), larger_me(0), larger_left(INT_MAX), larger_right(INT_MAX)
{
}
int count; //number of processes with this annotation
int size; //total number of processes in subtree including this node
int larger; //minimum of larger_left, larger_me, and, larger_right
int larger_me;
int larger_left;
int larger_right;
};
class Live_P_Tree : public ACE_RB_Tree<int, AnnotationNode, ACE_Equal_To<int>, ACE_Thread_Mutex> {
public:
Live_P_Tree(int maxThreads);
virtual ~Live_P_Tree();
int bind(const int& ext_id);
int unbind (const int &ext_id);
int calc_max() const;
protected:
void RB_rotate_right(ACE_RB_Tree_Node<int, AnnotationNode> *x);
void RB_rotate_left(ACE_RB_Tree_Node<int, AnnotationNode> *x);
private:
void recalculate_augmentation(ACE_RB_Tree_Node<int, AnnotationNode>* nodePtr);
void recalculate_augmentation_up(ACE_RB_Tree_Node<int, AnnotationNode>* x);
int calc_max_i(ACE_RB_Tree_Node<int, AnnotationNode>* nodePtr, int extra) const;
static int MIN(int a, int b) { return (a<b)?a:b; }
static int MIN_THREE(int a, int b, int c) {
return (a<b)?MIN(a,c):MIN(b,c);
}
int T_;
};
ACE_INLINE
Live_P_Tree::Live_P_Tree(int maxThreads)
:ACE_RB_Tree(),
T_(maxThreads) {
}
ACE_INLINE
Live_P_Tree::~Live_P_Tree() {
}
ACE_INLINE
int
Live_P_Tree::bind(const int& ext_id)
{
ACE_RB_Tree_Node<int, AnnotationNode>* entry = 0;
int returnVal = -1; //return error unless we return
//something else from the parent unbind
RB_SearchResult result = LEFT;
entry = find_node (ext_id, result);
// If there is a matching node, don't add a new one, just mod the existing one
if (entry && result == EXACT) {
entry->item().count++;
} else {
returnVal = ACE_RB_Tree::bind(ext_id, AnnotationNode(), entry);
}
recalculate_augmentation_up(entry);
return returnVal;
}
void
Live_P_Tree::RB_rotate_right (ACE_RB_Tree_Node<int, AnnotationNode> *x)
{
ACE_RB_Tree::RB_rotate_right(x);
recalculate_augmentation_up(x);
}
void
Live_P_Tree::RB_rotate_left (ACE_RB_Tree_Node<int, AnnotationNode> *x)
{
ACE_RB_Tree::RB_rotate_left(x);
recalculate_augmentation_up(x);
}
ACE_INLINE
int
Live_P_Tree::unbind(const int& ext_id)
{
ACE_RB_Tree_Node<int, AnnotationNode>* entry = 0;
RB_SearchResult result = LEFT;
int returnVal = -1; //return error unless we return
//something else from the parent unbind
entry = find_node (ext_id, result);
// If there is a matching node, don't add a new one, just mod the existing one
if (entry && result == EXACT) {
if (--(entry->item().count) == 0) {
entry = entry->parent();
returnVal = ACE_RB_Tree::unbind(ext_id);
}
} else {
//exception? probably bad if we try to unbind something not in the tree
}
if (entry) {
recalculate_augmentation_up(entry);
}
return returnVal;
}
ACE_INLINE void
Live_P_Tree::recalculate_augmentation(ACE_RB_Tree_Node<int, AnnotationNode>* nodePtr) {
AnnotationNode& node = nodePtr->item();
AnnotationNode& left = nodePtr->left() ? AnnotationNode() : nodePtr->left()->item();
AnnotationNode& right = nodePtr->right() ? AnnotationNode() : nodePtr->right()->item();
// (1) size
node.size = left.size + right.size + node.count;
// (2) larger_me
node.larger_me = T_ - (node.count + right.size + nodePtr->key());
// (3) larger_right
node.larger_right = right.larger;
// (4) larger_left
node.larger_left = left.larger - (right.size + node.count);
//(5) larger
node.larger = MIN_THREE(node.larger_me, node.larger_left, node.larger_right);
}
ACE_INLINE void
Live_P_Tree::recalculate_augmentation_up(ACE_RB_Tree_Node<int, AnnotationNode>* x) {
while (x) {
recalculate_augmentation(x);
x = x->parent();
}
}
ACE_INLINE int
Live_P_Tree::calc_max() const {
//note: need to add get_root method to RB_Tree
return calc_max_i(get_root(), 0);
}
ACE_INLINE int
Live_P_Tree::calc_max_i(ACE_RB_Tree_Node<int, AnnotationNode>* nodePtr, int extra) const {
AnnotationNode& n = nodePtr->item();
if ( n.larger_left - extra==0) {
return calc_max_i(nodePtr->left(), extra + nodePtr->right()->item().size + n.count); }
else if (n.larger_me - extra==0) { return (nodePtr->key()); }
else if (n.larger_right - extra==0) { return calc_max_i(nodePtr->right(), extra); }
else { return T_; }
}
template <typename AnnotationId>
ACE_INLINE
Live_P_Strategy<AnnotationId>::Live_P_Strategy(int maxThreads)
:DA_Strategy_Base(maxThreads),
min_illegal_is_computed_(false),
min_illegal_(0)
{
}
template <typename AnnotationId>
ACE_INLINE
Live_P_Strategy<AnnotationId>::~Live_P_Strategy()
{
}
template <typename AnnotationId>
ACE_INLINE
bool
Live_P_Strategy<AnnotationId>::is_deadlock_potential(AnnotationId handle)
{
int annotation = get_annotation(handle);
computation_mutex_.acquire();
if (!min_illegal_is_computed_)
{
if (tree_pimpl_->current_size() > 1)
{
min_illegal_ = tree_pimpl_->calc_max();
}
min_illegal_is_computed_ = true;
}
computation_mutex_.release();
return annotation >= min_illegal_;
}
template <typename AnnotationId>
ACE_INLINE
void
Live_P_Strategy<AnnotationId>::grant(AnnotationId handle)
{
int annotation = get_annotation(handle);
//since the state of the tree is involved in calculation
//of max, we must aquire the lock before changing the
//structure of the tree
computation_mutex_.acquire();
tree_pimpl_->bind(annotation);
min_illegal_is_computed_ = false;
computation_mutex_.release();
}
template <typename AnnotationId>
ACE_INLINE
void
Live_P_Strategy<AnnotationId>::release(AnnotationId handle)
{
//since the state of the tree is involved in calculation
//of max, we must aquire the lock before changing the
//structure of the tree
computation_mutex_.acquire();
min_illegal_is_computed_ = false;
int annotation = get_annotation(handle);
tree_pimpl_->unbind(annotation);
computation_mutex_.release();
}
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