From d9e4d82eb846637063c32fc8e32b337aff208f33 Mon Sep 17 00:00:00 2001
From: Sean Tao <sean.tao@10gen.com>
Date: Fri, 13 Jul 2018 16:28:03 -0400
Subject: SERVER-21167 Top keeps state about operations against non-existent
 collections

---
 src/mongo/db/stats/top.cpp | 8 +++++---
 src/mongo/db/stats/top.h   | 2 +-
 2 files changed, 6 insertions(+), 4 deletions(-)

(limited to 'src/mongo/db/stats')

diff --git a/src/mongo/db/stats/top.cpp b/src/mongo/db/stats/top.cpp
index 45680f7db15..155f122fef5 100644
--- a/src/mongo/db/stats/top.cpp
+++ b/src/mongo/db/stats/top.cpp
@@ -85,8 +85,9 @@ void Top::record(OperationContext* opCtx,
     auto hashedNs = UsageMap::HashedKey(ns);
     stdx::lock_guard<SimpleMutex> lk(_lock);
 
-    if ((command || logicalOp == LogicalOp::opQuery) && ns == _lastDropped) {
-        _lastDropped = "";
+    if ((command || logicalOp == LogicalOp::opQuery) &&
+        _collDropNs.find(ns.toString()) != _collDropNs.end()) {
+        _collDropNs.erase(ns.toString());
         return;
     }
 
@@ -142,10 +143,11 @@ void Top::_record(OperationContext* opCtx,
 void Top::collectionDropped(StringData ns, bool databaseDropped) {
     stdx::lock_guard<SimpleMutex> lk(_lock);
     _usage.erase(ns);
+
     if (!databaseDropped) {
         // If a collection drop occurred, there will be a subsequent call to record for this
         // collection namespace which must be ignored. This does not apply to a database drop.
-        _lastDropped = ns.toString();
+        _collDropNs.insert(ns.toString());
     }
 }
 
diff --git a/src/mongo/db/stats/top.h b/src/mongo/db/stats/top.h
index ccd4ac5e13f..6dc2cf7f8a3 100644
--- a/src/mongo/db/stats/top.h
+++ b/src/mongo/db/stats/top.h
@@ -143,7 +143,7 @@ private:
     mutable SimpleMutex _lock;
     OperationLatencyHistogram _globalHistogramStats;
     UsageMap _usage;
-    std::string _lastDropped;
+    std::set<std::string> _collDropNs;
 };
 
 }  // namespace mongo
-- 
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