SERVER-37726 Add the ability for the CollectionIndexBuildsTracker to wait until the requested index build is finished

2 files changed, 37 insertions, 8 deletions

diff --git a/src/mongo/db/collection_index_builds_tracker.cpp b/src/mongo/db/collection_index_builds_tracker.cpp
index 677aa17fa3a..2c81c638d62 100644
--- a/src/mongo/db/collection_index_builds_tracker.cpp
+++ b/src/mongo/db/collection_index_builds_tracker.cpp
@@ -68,9 +68,7 @@ void CollectionIndexBuildsTracker::removeIndexBuild(
         _buildStateByIndexName.erase(indexName);
     }
 
-    if (_buildStateByBuildUUID.empty()) {
-        _noIndexBuildsRemainCondVar.notify_all();
-    }
+    _indexBuildFinishedCondVar.notify_all();
 }
 
 std::shared_ptr<ReplIndexBuildState> CollectionIndexBuildsTracker::getIndexBuildState(
@@ -88,6 +86,14 @@ bool CollectionIndexBuildsTracker::hasIndexBuildState(WithLock, StringData index
     return true;
 }
 
+std::vector<UUID> CollectionIndexBuildsTracker::getIndexBuildUUIDs(WithLock) const {
+    std::vector<UUID> buildUUIDs;
+    for (const auto& state : _buildStateByBuildUUID) {
+        buildUUIDs.push_back(state.first);
+    }
+    return buildUUIDs;
+}
+
 void CollectionIndexBuildsTracker::runOperationOnAllBuilds(
     WithLock lk,
     IndexBuildsManager* indexBuildsManager,
@@ -106,7 +112,7 @@ int CollectionIndexBuildsTracker::getNumberOfIndexBuilds(WithLock) const {
 }
 
 void CollectionIndexBuildsTracker::waitUntilNoIndexBuildsRemain(stdx::unique_lock<Latch>& lk) {
-    _noIndexBuildsRemainCondVar.wait(lk, [&] {
+    _indexBuildFinishedCondVar.wait(lk, [&] {
         if (_buildStateByBuildUUID.empty()) {
             return true;
         }
@@ -122,4 +128,16 @@ void CollectionIndexBuildsTracker::waitUntilNoIndexBuildsRemain(stdx::unique_loc
     });
 }
 
+void CollectionIndexBuildsTracker::waitUntilIndexBuildFinished(stdx::unique_lock<Latch>& lk,
+                                                               const UUID& buildUUID) {
+    log() << "Waiting until index build with UUID " << buildUUID << " is finished";
+
+    _indexBuildFinishedCondVar.wait(lk, [&] {
+        if (_buildStateByBuildUUID.find(buildUUID) == _buildStateByBuildUUID.end()) {
+            return true;
+        }
+        return false;
+    });
+}
+
 }  // namespace mongo
diff --git a/src/mongo/db/collection_index_builds_tracker.h b/src/mongo/db/collection_index_builds_tracker.h
index 81c25fe73d3..234e6ccfcb5 100644
--- a/src/mongo/db/collection_index_builds_tracker.h
+++ b/src/mongo/db/collection_index_builds_tracker.h
@@ -49,7 +49,9 @@ class IndexBuildsManager;
  * The owner of a CollectionIndexBuildsTracker instance must instantiate a mutex to use along with
  * the data structure to ensure it remains consistent across single or multiple function accesses.
  *
- * This is intended to only be used by the IndexBuildsCoordinator class.
+ * This is intended to only be used by the IndexBuildsCoordinator class. Functions expecting a lock
+ * to be passed in as a parameter require an already locked IndexBuildsCoordinator::_mutex in this
+ * case.
  */
 class CollectionIndexBuildsTracker {
     CollectionIndexBuildsTracker(const CollectionIndexBuildsTracker&) = delete;
@@ -73,6 +75,8 @@ public:
 
     bool hasIndexBuildState(WithLock, StringData indexName) const;
 
+    std::vector<UUID> getIndexBuildUUIDs(WithLock) const;
+
     /**
      * Runs the provided function operation on all this collection's index builds
      *
@@ -98,15 +102,22 @@ public:
      */
     void waitUntilNoIndexBuildsRemain(stdx::unique_lock<Latch>& lk);
 
+    /**
+     * Returns when the index build with the given build UUID is no longer active. When the build
+     * UUID does not correspond to an active index build, returns immediately.
+     */
+    void waitUntilIndexBuildFinished(stdx::unique_lock<Latch>& lk, const UUID& buildUUID);
+
 private:
     // Maps of index build states on the collection, by build UUID and index name.
     stdx::unordered_map<UUID, std::shared_ptr<ReplIndexBuildState>, UUID::Hash>
         _buildStateByBuildUUID;
     stdx::unordered_map<std::string, std::shared_ptr<ReplIndexBuildState>> _buildStateByIndexName;
 
-    // Condition variable that is signaled when there are no active index builds remaining on the
-    // collection.
-    stdx::condition_variable _noIndexBuildsRemainCondVar;
+    // Condition variable that is signaled when an index build has finished on the collection. The
+    // accompanying mutex for this condition variable comes from the owner managing this class
+    // instance.
+    stdx::condition_variable _indexBuildFinishedCondVar;
 };
 
 }  // namespace mongo