diff options
Diffstat (limited to 'faceapi/lockfree.h')
| -rw-r--r-- | faceapi/lockfree.h | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/faceapi/lockfree.h b/faceapi/lockfree.h new file mode 100644 index 00000000..ce7d2a64 --- /dev/null +++ b/faceapi/lockfree.h @@ -0,0 +1,65 @@ +//lock free queue template class by Herb Sutter
+//Dr Dobbs Journal article http://www.drdobbs.com/cpp/210604448;jsessionid=OQGQPSMNL4X4XQE1GHPSKH4ATMY32JVN?pgno=1
+
+template <typename T> class LockFreeQueue
+{
+private:
+ struct Node
+ {
+ Node( T val ) : value(val), next(nullptr) { }
+ T value;
+ Node* next;
+ };
+
+ Node* first; // for producer only
+ Node* divider, last; // shared
+
+ //not working in VC2008
+ //atomic<Node*> divider, last; // shared
+
+public:
+ LockFreeQueue()
+ {
+ // add dummy separator
+ first = divider = last = new Node( T() );
+ }
+
+ ~LockFreeQueue()
+ {
+ while( first != nullptr )
+ {
+ // release the list
+ Node* tmp = first;
+ first = tmp->next;
+ delete tmp;
+ }
+ }
+
+ void Produce( const T& t )
+ {
+ last->next = new Node(t); // add the new item
+ last = last->next; // publish it
+
+ while( first != divider )
+ {
+ // trim unused nodes
+ Node* tmp = first;
+ first = first->next;
+ delete tmp;
+ }
+ }
+
+ bool Consume( T& result )
+ {
+ if( divider != last )
+ {
+ // if queue is nonempty
+ result = divider->next->value; // copy it back
+ divider = divider->next; // publish that we took it
+ return true; // and report success
+ }
+
+ return false; // else report empty
+ }
+};
+
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