SERVER-25694 Eliminate race in PlanExecutor cleanup.

Ensures that a collection lock is held in at least MODE_IS while
deregistering a PlanExecutor from the cursor manager. Introduces new
PlanExecutor::dispose() and ClientCursor::dispose() methods that must be
called before destruction of those classes, and ensures they are called
before destruction. These calls will thread an OperationContext all the
way through to DocumentSource::dispose() for each stage in a Pipeline,
which will give DocumentSourceCursor a chance to acquire locks and
deregister its PlanExecutor if necessary.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/mongo/db/query/plan_yield_policy.cpp b/src/mongo/db/query/plan_yield_policy.cpp
index f315daec285..b7a8f0225ea 100644
--- a/src/mongo/db/query/plan_yield_policy.cpp
+++ b/src/mongo/db/query/plan_yield_policy.cpp
@@ -59,7 +59,7 @@ PlanYieldPolicy::PlanYieldPolicy(PlanExecutor::YieldPolicy policy, ClockSource*
       _planYielding(nullptr) {}
 
 bool PlanYieldPolicy::shouldYield() {
-    if (!allowedToYield())
+    if (!canAutoYield())
         return false;
     invariant(!_planYielding->getOpCtx()->lockState()->inAWriteUnitOfWork());
     if (_forceYield)
@@ -73,7 +73,7 @@ void PlanYieldPolicy::resetTimer() {
 
 bool PlanYieldPolicy::yield(RecordFetcher* fetcher) {
     invariant(_planYielding);
-    invariant(allowedToYield());
+    invariant(canAutoYield());
 
     // After we finish yielding (or in any early return), call resetTimer() to prevent yielding
     // again right away. We delay the resetTimer() call so that the clock doesn't start ticking