From a73410882a69bb43757190d7910612f0e67e3c15 Mon Sep 17 00:00:00 2001
From: Hannes Kuchelmeister <hannes@kuchelmeister.org>
Date: Thu, 31 Dec 2020 14:45:56 +0100
Subject: [PATCH] implement optimistic list

---
 Assignment_2/OptimisticList.cpp | 129 ++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 Assignment_2/OptimisticList.cpp

diff --git a/Assignment_2/OptimisticList.cpp b/Assignment_2/OptimisticList.cpp
new file mode 100644
index 0000000..e73cea8
--- /dev/null
+++ b/Assignment_2/OptimisticList.cpp
@@ -0,0 +1,129 @@
+#include <bits/stdc++.h>
+
+#include"Node.cpp"
+
+class OptimisticSet {
+    protected:
+        Node* first;
+        bool validate(Node* p, Node* c);
+    public:
+        OptimisticSet();
+        bool add(int element);
+        bool rmv(int element);
+        bool ctn(int element);
+        
+};
+
+OptimisticSet::OptimisticSet(){
+    first = Node::Dummy(); // dummy node;
+    Node* last = Node::Dummy();
+    first->next = last;
+}
+
+bool OptimisticSet::add(int element) {
+    Node* p;
+    Node* c;
+    while (true) {
+        p = this->first;
+        c = p->next;
+        while(c->is_smaller_than(element)) {
+            p = c;
+            c = c->next;
+        }
+
+        p->lock();
+        c->lock();
+        
+        if(validate(p,c)) {
+            if (c->is_equal(element)) {
+                p->unlock();
+                c->unlock();
+                return false;
+            } else {
+                Node* n = new Node(element);
+                n->next = c;
+                p->next = n;
+                p->unlock();
+                c->unlock();
+                return true;
+            }
+        } else {
+            p->unlock();
+            c->unlock();
+        }
+    }
+}
+bool OptimisticSet::rmv(int element) {
+    Node* p;
+    Node* c;
+    while (true) {
+        p = this->first;
+        c = p->next;
+        while(c->is_smaller_than(element)) {
+            p = c;
+            c = c->next;
+        }
+
+        p->lock();
+        c->lock();
+        
+        if(validate(p,c)) {
+            if (c->is_equal(element)) {
+                p->next = c->next;
+
+                p->unlock();
+                c->unlock();
+                return true;
+            } else {
+                p->unlock();
+                c->unlock();
+                return false;
+            }
+        } else {
+            p->unlock();
+            c->unlock();
+        }
+    }
+}
+bool OptimisticSet::ctn(int element) {
+    Node* p;
+    Node* c;
+    while (true) {
+        p = this->first;
+        c = p->next;
+        while(c->is_smaller_than(element)) {
+            p = c;
+            c = c->next;
+        }
+
+        p->lock();
+        c->lock();
+        
+        if(validate(p,c)) {
+            if (c->is_equal(element)) {
+                p->unlock();
+                c->unlock();
+                return true;
+            } else {
+                p->unlock();
+                c->unlock();
+                return false;
+            }
+        } else {
+            p->unlock();
+            c->unlock();
+        }
+    }
+}
+
+bool OptimisticSet::validate(Node* p, Node* c) {
+    Node* n = this->first;
+    while (n->is_smaller_than(p)) {
+        n = n->next;
+    }
+    if ((n == p) && (p->next == c)) {
+        return true;
+    } else {
+        return false;
+    }
+}
\ No newline at end of file