Add Iterator To Skiplist

Author: wingerted

demo/cpp_demo.cpp

@@ -26,6 +26,7 @@ int main(int argc, const char * argv[]) {
 
     Wolf<int, int> wolf_home("/Users/wingerted/test_shared_memory_dat", 10000000, true);
     wolf_home.Add(1, 1);
+    wolf_home.Find(2);
 
 
 //    // insert code here...

src/core/container/lockfree_skiplist.h

@@ -30,13 +30,15 @@ class LockFreeSkipList {
     struct Node;
     struct Ref;
 public:
+    class Iterator;
+
     LockFreeSkipList(ShmManager* shm_manager,
                      bool reset = false,
                      Comparator cmp = DefaultComparator<Key>());
 
     bool Add(Key key, Value value);
     bool Remove(Key key);
-    Value FindLessThan(Key key);
+    Iterator FindLessThan(Key key);
 
 private:
     int RandomHeight();
@@ -58,6 +60,34 @@ class LockFreeSkipList {
     LockFreeSkipList<Key, Value, Comparator>::Node* head_;
 };
 
+template<typename Key, typename Value, class Comparator>
+class LockFreeSkipList<Key, Value, Comparator>::Iterator {
+public:
+    Iterator(LockFreeSkipList<Key, Value, Comparator>* skiplist,
+             Node* node): skiplist_(skiplist), node_(node) {}
+
+    bool Valid() const {
+        return this->node_->GetRef(0)->load().mark_removed;
+    }
+
+    const Key& key() const {
+        return this->node_->key;
+    }
+
+    const Value& value() const {
+        return this->node_->value;
+    }
+
+    void Next() {
+        this->node_ = this->skiplist_->GetNodeByOffset(this->node_->GetRef(0)->load().next_offset);
+    }
+
+    private:
+    LockFreeSkipList<Key, Value, Comparator>* skiplist_;
+    Node* node_;
+};
+
+
 template<typename Key, typename Value, class Comparator>
 struct LockFreeSkipList<Key, Value, Comparator>::Ref {
     Ref() = default;
@@ -152,7 +182,8 @@ bool LockFreeSkipList<Key, Value, Comparator>::FindWindow(Key key,
 }
 
 template<typename Key, typename Value, class Comparator>
-Value LockFreeSkipList<Key, Value, Comparator>::FindLessThan(Key key) {
+//typename LockFreeSkipList<Key, Value, Comparator>::
+auto LockFreeSkipList<Key, Value, Comparator>::FindLessThan(Key key) -> Iterator {
     Node* pred = this->head_;
     for (int i=kMaxHeight-1; i>=0; --i) {
         Node* curr = this->GetNodeByOffset(pred->GetRef(i)->load().next_offset);
@@ -179,7 +210,7 @@ Value LockFreeSkipList<Key, Value, Comparator>::FindLessThan(Key key) {
         }
     }
 
-    return pred->value;
+    return Iterator(this, pred);
 }
 
 template<typename Key, typename Value, class Comparator>

src/wolf.h

@@ -48,9 +48,10 @@ class Wolf{
         }
     }
 
-//    void Find(const Data& data) {
-//        this->inner_data_->FindLessThan(data);
-//    }
+    bool Find(const Index& index) {
+        auto iter = this->inner_data_->FindLessThan(index);
+        return iter.Valid();
+    }
 
 private:
     const std::string index_path_;