SERVER-66210 Indicate when pass targets cause BatchedDeleteStage completion

4 files changed, 46 insertions, 3 deletions

diff --git a/src/mongo/db/exec/batched_delete_stage.cpp b/src/mongo/db/exec/batched_delete_stage.cpp
index 79a12600418..32f5bfe5d99 100644
--- a/src/mongo/db/exec/batched_delete_stage.cpp
+++ b/src/mongo/db/exec/batched_delete_stage.cpp
@@ -185,6 +185,19 @@ bool BatchedDeleteStage::isEOF() {
     return _stagedDeletesBuffer.empty() && _passStagingComplete;
 }
 
+std::unique_ptr<PlanStageStats> BatchedDeleteStage::getStats() {
+    _commonStats.isEOF = isEOF();
+    std::unique_ptr<PlanStageStats> stats =
+        std::make_unique<PlanStageStats>(_commonStats, stageType());
+    stats->specific = std::make_unique<BatchedDeleteStats>(_specificStats);
+    stats->children.emplace_back(child()->getStats());
+    return stats;
+}
+
+const SpecificStats* BatchedDeleteStage::getSpecificStats() const {
+    return &_specificStats;
+}
+
 PlanStage::StageState BatchedDeleteStage::doWork(WorkingSetID* out) {
     WorkingSetID idToReturn = WorkingSet::INVALID_ID;
     PlanStage::StageState planStageState = PlanStage::NEED_TIME;
@@ -213,7 +226,16 @@ PlanStage::StageState BatchedDeleteStage::doWork(WorkingSetID* out) {
         _stagedDeletesWatermarkBytes = 0;
         planStageState = _deleteBatch(&idToReturn);
 
-        _passStagingComplete = _passStagingComplete || _passTargetMet();
+        if (!_passStagingComplete) {
+            tassert(6621000, "Expected staging to be permitted", !_specificStats.passTargetMet);
+
+            // Staging hasn't yielded PlanStage::IS_EOF.
+            //
+            // Indicate whether the operation should reach completion due to a pass target.
+            _specificStats.passTargetMet = _passTargetMet();
+        }
+
+        _passStagingComplete = _passStagingComplete || _specificStats.passTargetMet;
         _commitStagedDeletes = _passStagingComplete || !_stagedDeletesBuffer.empty();
     }
 
diff --git a/src/mongo/db/exec/batched_delete_stage.h b/src/mongo/db/exec/batched_delete_stage.h
index 89e99a5e6db..0dee55290c0 100644
--- a/src/mongo/db/exec/batched_delete_stage.h
+++ b/src/mongo/db/exec/batched_delete_stage.h
@@ -118,6 +118,10 @@ public:
     // Returns true when no more work can be done (there are no more deletes to commit).
     bool isEOF() final;
 
+    std::unique_ptr<PlanStageStats> getStats() final;
+
+    const SpecificStats* getSpecificStats() const final;
+
     StageState doWork(WorkingSetID* out);
 
     StageType stageType() const final {
@@ -148,6 +152,8 @@ private:
     PlanStage::StageState _prepareToRetryDrainAfterWCE(
         WorkingSetID* out, const std::set<WorkingSetID>& recordsThatNoLongerMatch);
 
+    BatchedDeleteStats _specificStats;
+
     // Returns true if one or more of the batch targets are met and it is time to delete the batch.
     bool _batchTargetMet();
 
diff --git a/src/mongo/db/exec/delete_stage.h b/src/mongo/db/exec/delete_stage.h
index 244c8fb7c16..ef2b12624b8 100644
--- a/src/mongo/db/exec/delete_stage.h
+++ b/src/mongo/db/exec/delete_stage.h
@@ -128,9 +128,9 @@ public:
         return STAGE_DELETE;
     }
 
-    std::unique_ptr<PlanStageStats> getStats() final;
+    std::unique_ptr<PlanStageStats> getStats();
 
-    const SpecificStats* getSpecificStats() const final;
+    const SpecificStats* getSpecificStats() const;
 
 protected:
     void doSaveStateRequiresCollection() final {
diff --git a/src/mongo/db/exec/plan_stats.h b/src/mongo/db/exec/plan_stats.h
index 36014955c0d..6032654c63e 100644
--- a/src/mongo/db/exec/plan_stats.h
+++ b/src/mongo/db/exec/plan_stats.h
@@ -421,6 +421,21 @@ struct DeleteStats : public SpecificStats {
     size_t docsDeleted = 0u;
 };
 
+struct BatchedDeleteStats : public DeleteStats {
+    BatchedDeleteStats() = default;
+
+    // Unlike a standard multi:true delete, BatchedDeleteStage can complete with PlanStage::IS_EOF
+    // before deleting all the documents that match the query, if a 'BatchedDeleteStagePassParams'
+    // target is met.
+    //
+    // True indicates the operation reaches completion because a pass target is met.
+    //
+    // False indicates either (1) the operation hasn't reached completion or (2) the operation
+    // removed all the documents that matched the criteria to reach completion - this is always the
+    // case with the default BatchedDeleteStagePassParams.
+    bool passTargetMet = false;
+};
+
 struct DistinctScanStats : public SpecificStats {
     std::unique_ptr<SpecificStats> clone() const final {
         auto specific = std::make_unique<DistinctScanStats>(*this);