swift-actor-no-priorities.patch

diff --git a/stdlib/public/Concurrency/Actor.cpp b/stdlib/public/Concurrency/Actor.cpp
index e210fbb534b..bc2799e27a0 100644
--- a/stdlib/public/Concurrency/Actor.cpp
+++ b/stdlib/public/Concurrency/Actor.cpp
@@ -1052,6 +1052,12 @@ static JobRef getNextJobInQueue(Job *job) {
 static void setNextJobInQueue(Job *job, JobRef next) {
   *reinterpret_cast<JobRef*>(job->SchedulerPrivate) = next;
 }
+static Job* getLastJobInQueue(Job *job) {
+  return *reinterpret_cast<Job**>(job->SchedulerPrivate + 1);
+}
+static void setLastJobInQueue(Job *job, Job *last) {
+  *reinterpret_cast<Job**>(job->SchedulerPrivate + 1) = last;
+}
 
 namespace {
 
@@ -1062,6 +1068,12 @@ struct JobQueueTraits {
   static void setNext(Job *job, Job *next) {
     setNextJobInQueue(job, JobRef::getPreprocessed(next));
   }
+  static Job *getLast(Job *job) {
+    return getLastJobInQueue(job);
+  }
+  static void setLast(Job *job, Job *last) {
+    setLastJobInQueue(job, last);
+  }
   static int compare(Job *lhs, Job *rhs) {
     return descendingPriorityOrder(lhs->getPriority(), rhs->getPriority());
   }
@@ -1089,8 +1101,10 @@ preprocessQueue(JobRef unprocessedStart, JobRef unprocessedEnd, Job *existingPro
   assert(unprocessedStart.getAsJob() != unprocessedEnd.getAsJob());
 
   // Build up a list of jobs we need to preprocess
-  using ListMerger = swift::ListMerger<Job*, JobQueueTraits>;
-  ListMerger jobsToProcess;
+  // using ListMerger = swift::ListMerger<Job*, JobQueueTraits>;
+  // ListMerger jobsToProcess;
+  Job *newFirst = NULL;
+  Job *newLast = NULL;
 
   // Get just the prefix list of unprocessed jobs
   auto current = unprocessedStart;
@@ -1100,16 +1114,26 @@ preprocessQueue(JobRef unprocessedStart, JobRef unprocessedEnd, Job *existingPro
     auto job = current.getAsJob();
     current = getNextJobInQueue(job);
 
-    jobsToProcess.insertAtFront(job);
+    // jobsToProcess.insertAtFront(job);
+    JobQueueTraits::setNext(job, newFirst);
+    newFirst = job;
+    if (!newLast) {
+      newLast = job;
+    }
   }
 
   // Finish processing the unprocessed jobs
-  Job *newProcessedJobs = jobsToProcess.release();
-  assert(newProcessedJobs);
-
-  ListMerger mergedList(existingProcessedJobsToMergeInto);
-  mergedList.merge(newProcessedJobs);
-  return mergedList.release();
+  // Job *newProcessedJobs = jobsToProcess.release();
+  // assert(newProcessedJobs);
+  assert(newFirst);
+
+  // ListMerger mergedList(existingProcessedJobsToMergeInto);
+  // mergedList.merge(newProcessedJobs);
+  // return mergedList.release();
+  Job *existingLast = JobQueueTraits::getLast(existingProcessedJobsToMergeInto);
+  JobQueueTraits::setNext(existingLast, newFirst);
+  JobQueueTraits::setLast(existingProcessedJobsToMergeInto, newLast);
+  return existingProcessedJobsToMergeInto;
 }
 
 // Called with the actor drain lock held.
@@ -1129,8 +1153,10 @@ preprocessQueue(JobRef start) {
   // There exist some jobs which haven't been preprocessed
 
   // Build up a list of jobs we need to preprocess
-  using ListMerger = swift::ListMerger<Job*, JobQueueTraits>;
-  ListMerger jobsToProcess;
+  // using ListMerger = swift::ListMerger<Job*, JobQueueTraits>;
+  // ListMerger jobsToProcess;
+  Job *newFirst = NULL;
+  Job *newLast = NULL;
 
   Job *wellFormedListStart = NULL;
 
@@ -1148,23 +1174,34 @@ preprocessQueue(JobRef start) {
     auto job = current.getAsJob();
     current = getNextJobInQueue(job);
 
-    jobsToProcess.insertAtFront(job);
+    // jobsToProcess.insertAtFront(job);
+    JobQueueTraits::setNext(job, newFirst);
+    newFirst = job;
+    if (!newLast) {
+      newLast = job;
+    }
   }
 
   // Finish processing the unprocessed jobs
-  auto processedJobHead = jobsToProcess.release();
-  assert(processedJobHead);
+  // auto processedJobHead = jobsToProcess.release();
+  // assert(processedJobHead);
+  assert(newFirst);
 
   Job *firstJob = NULL;
   if (wellFormedListStart) {
     // Merge it with already known well formed list if we have one.
-    ListMerger mergedList(wellFormedListStart);
-    mergedList.merge(processedJobHead);
-    firstJob = mergedList.release();
+    // ListMerger mergedList(wellFormedListStart);
+    // mergedList.merge(processedJobHead);
+    // firstJob = mergedList.release();
+    firstJob = wellFormedListStart;
+    Job *existingLast = JobQueueTraits::getLast(firstJob);
+    JobQueueTraits::setNext(existingLast, newFirst);
   } else {
     // Nothing to merge with, just return the head we already have
-    firstJob = processedJobHead;
+    // firstJob = processedJobHead;
+    firstJob = newFirst;
   }
+  JobQueueTraits::setLast(firstJob, newLast);
 
   return firstJob;
 }
@@ -1365,7 +1402,16 @@ Job * DefaultActorImpl::drainOne() {
 
     auto newState = oldState;
     // Dequeue the first job and set up a new head
-    newState = newState.withFirstJob(getNextJobInQueue(firstJob));
+    JobRef nextRef = getNextJobInQueue(firstJob);
+    if (nextRef) {
+      assert(!nextRef.needsPreprocessing());
+      Job* next = nextRef.getAsPreprocessedJob();
+      Job* last = JobQueueTraits::getLast(firstJob);
+      assert(last != firstJob);
+      JobQueueTraits::setLast(next, last);
+    }
+
+    newState = newState.withFirstJob(nextRef);
     if (_status().compare_exchange_weak(oldState, newState,
                             /* success */ std::memory_order_relaxed,
                             /* failure */ std::memory_order_relaxed)) {