Remove Pop from queues

Author: Rafał Hibner

cpp/src/arrow/acero/concurrent_queue_internal.h

@@ -31,12 +31,6 @@ namespace arrow::acero {
 template <class T>
 class ConcurrentQueue {
  public:
-  // Pops the last item from the queue. Must be called on a non-empty queue
-  T Pop() {
-    std::unique_lock<std::mutex> lock(mutex_);
-    return PopUnlocked();
-  }
-
   // Pops the last item from the queue but waits if the queue is empty until new items are
   // pushed.
   T WaitAndPop() {
@@ -140,13 +134,6 @@ class BackpressureConcurrentQueue : public ConcurrentQueue<T> {
   explicit BackpressureConcurrentQueue(BackpressureHandler handler)
       : handler_(std::move(handler)) {}
 
-  // Pops the last item from the queue. Must be called on a non-empty queue
-  T Pop() {
-    std::unique_lock<std::mutex> lock(ConcurrentQueue<T>::GetMutex());
-    DoHandle do_handle(*this);
-    return ConcurrentQueue<T>::PopUnlocked();
-  }
-
   // Pops the last item from the queue but waits if the queue is empty until new items are
   // pushed.
   T WaitAndPop() {

cpp/src/arrow/acero/util_test.cc

@@ -193,7 +193,7 @@ void ConcurrentQueueBasicTest(Queue& queue) {
   ASSERT_TRUE(queue.Empty());
   queue.Push(1);
   ASSERT_FALSE(queue.Empty());
-  ASSERT_EQ(queue.Pop(), 1);
+  ASSERT_EQ(queue.TryPop(), std::make_optional(1));
   ASSERT_TRUE(queue.Empty());
 
   auto fut_pop = std::async(std::launch::async, [&]() { return queue.WaitAndPop(); });
@@ -225,7 +225,7 @@ TEST(ConcurrentQueue, BasicTest) {
 class BackpressureTestExecNode : public ExecNode {
  public:
   BackpressureTestExecNode() : ExecNode(nullptr, {}, {}, nullptr) {}
-  const char* kind_name() const { return "BackpressureTestNode"; }
+  const char* kind_name() const override { return "BackpressureTestNode"; }
   Status InputReceived(ExecNode* input, ExecBatch batch) override {
     return Status::NotImplemented("Test only node");
   }
@@ -283,10 +283,10 @@ TEST(BackpressureConcurrentQueue, BackpressureTest) {
   queue.Push(9);
   ASSERT_TRUE(dummy_node.paused);
   ASSERT_FALSE(dummy_node.stopped);
-  ASSERT_EQ(queue.Pop(), 6);
+  ASSERT_EQ(queue.TryPop(), std::make_optional(6));
   ASSERT_TRUE(dummy_node.paused);
   ASSERT_FALSE(dummy_node.stopped);
-  ASSERT_EQ(queue.Pop(), 7);
+  ASSERT_EQ(queue.TryPop(), std::make_optional(7));
   ASSERT_FALSE(dummy_node.paused);
   ASSERT_FALSE(dummy_node.stopped);
   queue.Push(10);