From 5bdf0534bc53eafdad8ee3c992e1ac7b97564ddf Mon Sep 17 00:00:00 2001
From: ChunjiangZhu <chunjiang.zhu@uconn.edu>
Date: Mon, 28 Oct 2019 12:42:46 -0400
Subject: [PATCH] fix bug

---
 .../include/method/small_world_rand.h         |  1 +
 .../src/method/small_world_rand.cc            | 84 ++++++++++++++++++-
 2 files changed, 83 insertions(+), 2 deletions(-)

diff --git a/similarity_search/include/method/small_world_rand.h b/similarity_search/include/method/small_world_rand.h
index f8fc350..9e3ebee 100644
--- a/similarity_search/include/method/small_world_rand.h
+++ b/similarity_search/include/method/small_world_rand.h
@@ -302,6 +302,7 @@ class SmallWorldRand : public Index<dist_t> {
   void SearchOld(KNNQuery<dist_t>* query) const;
   void SearchV1Merge(KNNQuery<dist_t>* query) const;
 
+  void SearchOld(RangeQuery<dist_t>* query) const;
   void SearchV1Merge(RangeQuery<dist_t>* query) const;
 
   void UpdateNextNodeId(size_t newNextNodeId);
diff --git a/similarity_search/src/method/small_world_rand.cc b/similarity_search/src/method/small_world_rand.cc
index 32aa605..4498f99 100644
--- a/similarity_search/src/method/small_world_rand.cc
+++ b/similarity_search/src/method/small_world_rand.cc
@@ -601,8 +601,8 @@ void SmallWorldRand<dist_t>::addCriticalSection(MSWNode *newElement){
 template <typename dist_t>
 void SmallWorldRand<dist_t>::Search(RangeQuery<dist_t>* query, IdType) const {
 //  throw runtime_error("Range search is not supported!");
-    if (searchAlgoType_ == kV1Merge) { std::cerr << "call SearchV1Merge" << endl; SearchV1Merge(query);}
-//  else SearchOld(query);
+    if (searchAlgoType_ == kV1Merge) SearchV1Merge(query);
+    else SearchOld(query);
 }
 
 template <typename dist_t>
@@ -909,6 +909,86 @@ void SmallWorldRand<dist_t>::SearchOld(KNNQuery<dist_t>* query) const {
   }
 }
 
+template <typename dist_t>
+void SmallWorldRand<dist_t>::SearchOld(RangeQuery<dist_t>* query) const {
+
+  if (ElList_.empty()) return;
+  CHECK_MSG(efSearch_ > 0, "efSearch should be > 0");
+/*
+ * The trick of using large dense bitsets instead of unordered_set was
+ * borrowed from Wei Dong's kgraph: https://github.com/aaalgo/kgraph
+ *
+ * This trick works really well even in a multi-threaded mode. Indeed, the amount
+ * of allocated memory is small. For example, if one has 8M entries, the size of
+ * the bitmap is merely 1 MB. Furthermore, setting 1MB of entries to zero via memset would take only
+ * a fraction of millisecond.
+ */
+  vector<bool>                        visitedBitset(NextNodeId_);
+
+  MSWNode* provider = pEntryPoint_;
+  CHECK_MSG(provider != nullptr, "Bug: there is not entry point set!")
+
+  priority_queue <dist_t>                          closestDistQueue; //The set of all elements which distance was calculated
+  priority_queue <EvaluatedMSWNodeReverse<dist_t>> candidateQueue; //the set of elements which we can use to evaluate
+
+  const Object* currObj = provider->getData();
+  dist_t d = query->DistanceObjLeft(currObj);
+  query->CheckAndAddToResult(d, currObj); // This should be done before the object goes to the queue: otherwise it will not be compared to the query at all!
+
+  EvaluatedMSWNodeReverse<dist_t> ev(d, provider);
+  candidateQueue.push(ev);
+  closestDistQueue.emplace(d);
+
+  IdType nodeId = provider->getId();
+  CHECK_MSG(nodeId < NextNodeId_, "Bug: nodeId (" + ConvertToString(nodeId) +  ") > NextNodeId_ (" +ConvertToString(NextNodeId_) + ")");
+  visitedBitset[nodeId] = true;
+
+  while(!candidateQueue.empty()){
+
+    auto iter = candidateQueue.top(); // This one was already compared to the query
+    const EvaluatedMSWNodeReverse<dist_t>& currEv = iter;
+
+    // Did we reach a local minimum?
+    if (currEv.getDistance() > closestDistQueue.top()) {
+      break;
+    }
+
+    for (MSWNode* neighbor : (currEv.getMSWNode())->getAllFriends()) {
+      _mm_prefetch(reinterpret_cast<const char*>(const_cast<const Object*>(neighbor->getData())), _MM_HINT_T0);
+    }
+    for (MSWNode* neighbor : (currEv.getMSWNode())->getAllFriends()) {
+      _mm_prefetch(const_cast<const char*>(neighbor->getData()->data()), _MM_HINT_T0);
+    }
+
+    const vector<MSWNode*>& neighbor = (currEv.getMSWNode())->getAllFriends();
+
+    // Can't access curEv anymore! The reference would become invalid
+    candidateQueue.pop();
+
+    //calculate distance to each neighbor
+    for (auto iter = neighbor.begin(); iter != neighbor.end(); ++iter){
+      nodeId = (*iter)->getId();
+      CHECK_MSG(nodeId < NextNodeId_, "Bug: nodeId (" + ConvertToString(nodeId) +  ") > NextNodeId_ (" +ConvertToString(NextNodeId_));
+      if (!visitedBitset[nodeId]) {
+        currObj = (*iter)->getData();
+        d = query->DistanceObjLeft(currObj);
+        visitedBitset[nodeId] = true;
+
+        if (closestDistQueue.size() < efSearch_ || d < closestDistQueue.top()) {
+          closestDistQueue.emplace(d);
+          if (closestDistQueue.size() > efSearch_) {
+            closestDistQueue.pop();
+          }
+
+          candidateQueue.emplace(d, *iter);
+        }
+
+        query->CheckAndAddToResult(d, currObj);
+      }
+    }
+  }
+}
+
 template <typename dist_t>
 void SmallWorldRand<dist_t>::SaveIndex(const string &location) {
   CHECK_MSG(!changedAfterCreateIndex_,