From 78528bd60972f7c5fe333afe4857acfa8e4166bc Mon Sep 17 00:00:00 2001
From: Tyler Neely <t@jujit.su>
Date: Wed, 2 Nov 2022 17:12:21 +0000
Subject: [PATCH] Avoid the ShutDown explicit acknowledgement due to jthread
 already blocking on this

---
 src/storage/v3/shard_manager.hpp | 12 +-----------
 src/storage/v3/shard_worker.hpp  | 11 +++--------
 2 files changed, 4 insertions(+), 19 deletions(-)

diff --git a/src/storage/v3/shard_manager.hpp b/src/storage/v3/shard_manager.hpp
index 4d7507e87..559f51afe 100644
--- a/src/storage/v3/shard_manager.hpp
+++ b/src/storage/v3/shard_manager.hpp
@@ -84,8 +84,6 @@ class ShardManager {
       : io_(io), coordinator_leader_(coordinator_leader) {
     MG_ASSERT(shard_worker_threads >= 1);
 
-    shard_worker::Queue queue;
-
     for (int i = 0; i < shard_worker_threads; i++) {
       shard_worker::Queue queue;
       shard_worker::ShardWorker worker{io, queue};
@@ -103,16 +101,8 @@ class ShardManager {
   ShardManager &operator=(const ShardManager &) = delete;
 
   ~ShardManager() {
-    auto shutdown_acks = std::vector<io::Future<bool>>{};
     for (auto worker : workers_) {
-      auto [future, promise] = io::FuturePromisePair<bool>();
-      worker.Push(shard_worker::ShutDown{.acknowledge_shutdown = std::move(promise)});
-      shutdown_acks.emplace_back(std::move(future));
-    }
-
-    for (auto &&ack : shutdown_acks) {
-      bool acked = std::move(ack).Wait();
-      MG_ASSERT(acked);
+      worker.Push(shard_worker::ShutDown{});
     }
 
     // The jthread handes for our shard worker threads will be
diff --git a/src/storage/v3/shard_worker.hpp b/src/storage/v3/shard_worker.hpp
index ae590c541..4cca118e7 100644
--- a/src/storage/v3/shard_worker.hpp
+++ b/src/storage/v3/shard_worker.hpp
@@ -55,9 +55,7 @@ using storage::v3::ShardRsm;
 template <typename IoImpl>
 using ShardRaft = Raft<IoImpl, ShardRsm, WriteRequests, WriteResponses, ReadRequests, ReadResponses>;
 
-struct ShutDown {
-  io::Promise<bool> acknowledge_shutdown;
-};
+struct ShutDown {};
 
 struct Cron {};
 
@@ -96,7 +94,7 @@ class Queue {
     {
       std::unique_lock<std::mutex> lock(inner_->mu);
 
-      inner_->queue.push_back(std::forward<Message>(message));
+      inner_->queue.emplace_back(std::forward<Message>(message));
     }  // lock dropped before notifying condition variable
 
     inner_->cv.notify_all();
@@ -125,10 +123,7 @@ class ShardWorker {
   Time next_cron_ = Time::min();
   std::map<uuid, ShardRaft<IoImpl>> rsm_map_;
 
-  bool Process(ShutDown &&shut_down) {
-    shut_down.acknowledge_shutdown.Fill(true);
-    return false;
-  }
+  bool Process(ShutDown && /* shut_down */) { return false; }
 
   bool Process(Cron &&cron) {
     Cron();