1 files changed, 27 insertions, 2 deletions
diff --git a/src/mongo/db/sorter/sorter.h b/src/mongo/db/sorter/sorter.h
index aed12ffdfe2..440da3b54c3 100644
--- a/src/mongo/db/sorter/sorter.h
+++ b/src/mongo/db/sorter/sorter.h
@@ -40,6 +40,7 @@
 #include <vector>
 
 #include "mongo/bson/util/builder.h"
+#include "mongo/platform/atomic_word.h"
 #include "mongo/util/bufreader.h"
 
 /**
@@ -91,6 +92,14 @@
 namespace mongo {
 
 /**
+ * For collecting file usage metrics.
+ */
+struct SorterFileStats {
+    AtomicWord<long long> opened;
+    AtomicWord<long long> closed;
+};
+
+/**
  * Runtime options that control the Sorter's behavior
  */
 struct SortOptions {
@@ -108,7 +117,14 @@ struct SortOptions {
     // extSortAllowed is true.
     std::string tempDir;
 
-    SortOptions() : limit(0), maxMemoryUsageBytes(64 * 1024 * 1024), extSortAllowed(false) {}
+    // If set, allows us to observe Sorter file handle usage.
+    SorterFileStats* sorterFileStats;
+
+    SortOptions()
+        : limit(0),
+          maxMemoryUsageBytes(64 * 1024 * 1024),
+          extSortAllowed(false),
+          sorterFileStats(nullptr) {}
 
     // Fluent API to support expressions like SortOptions().Limit(1000).ExtSortAllowed(true)
 
@@ -131,6 +147,11 @@ struct SortOptions {
         tempDir = newTempDir;
         return *this;
     }
+
+    SortOptions& FileStats(SorterFileStats* newSorterFileStats) {
+        sorterFileStats = newSorterFileStats;
+        return *this;
+    }
 };
 
 /**
@@ -219,7 +240,8 @@ public:
      */
     class File {
     public:
-        File(std::string path) : _path(std::move(path)) {
+        File(std::string path, SorterFileStats* stats = nullptr)
+            : _path(std::move(path)), _stats(stats) {
             invariant(!_path.empty());
         }
 
@@ -266,6 +288,9 @@ public:
 
         // Whether to keep the on-disk file even after this in-memory object has been destructed.
         bool _keep = false;
+
+        // If set, this points to an external metrics holder for tracking file open/close activity.
+        SorterFileStats* _stats;
     };
 
     explicit Sorter(const SortOptions& opts);