Add QueryMerger test.

test/CMakeLists.txt

@@ -11,6 +11,7 @@ set(TD_TEST_SOURCE
   ${CMAKE_CURRENT_SOURCE_DIR}/message_entities.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/mtproto.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/poll.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/query_merger.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/secret.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/secure_storage.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/set_with_position.cpp

test/query_merger.cpp

@@ -0,0 +1,96 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2023
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/telegram/QueryMerger.h"
+
+#include "td/actor/actor.h"
+#include "td/actor/ConcurrentScheduler.h"
+#include "td/actor/SleepActor.h"
+
+#include "td/utils/common.h"
+#include "td/utils/FlatHashSet.h"
+#include "td/utils/Random.h"
+#include "td/utils/tests.h"
+
+#include <queue>
+
+class TestQueryMerger : public td::Actor {
+  void start_up() override {
+    query_merger_.set_merge_function([this](td::vector<td::int64> query_ids, td::Promise<td::Unit> &&promise) {
+      ASSERT_TRUE(!query_ids.empty());
+      ASSERT_EQ(query_ids.size(), td::min(next_query_ids_.size(), MAX_MERGED_QUERY_COUNT));
+      for (auto query_id : query_ids) {
+        auto next_query_id = next_query_ids_.front();
+        next_query_ids_.pop();
+        ASSERT_EQ(query_id, next_query_id);
+      }
+      current_query_count_++;
+      ASSERT_TRUE(current_query_count_ <= MAX_CONCURRENT_QUERY_COUNT);
+      if (!next_query_ids_.empty()) {
+        ASSERT_EQ(current_query_count_, MAX_CONCURRENT_QUERY_COUNT);
+      }
+      td::create_actor<td::SleepActor>("CompleteMergeQuery", 0.02,
+                                       td::PromiseCreator::lambda([this, query_ids, promise = std::move(promise)](
+                                                                      td::Result<td::Unit> result) mutable {
+                                         for (auto query_id : query_ids) {
+                                           LOG(INFO) << "Complete " << query_id;
+                                           bool is_erased = pending_query_ids_.erase(query_id);
+                                           ASSERT_TRUE(is_erased);
+                                         }
+                                         current_query_count_--;
+                                         promise.set_result(std::move(result));
+                                       }))
+          .release();
+      yield();
+    });
+    loop();
+  }
+
+  void loop() {
+    std::size_t query_count = 0;
+    std::size_t added_queries = td::Random::fast(1, 3);
+    while (query_count++ < added_queries && total_query_count_++ < MAX_QUERY_COUNT) {
+      td::int64 query_id = td::Random::fast(1, 20);
+      if (pending_query_ids_.insert(query_id).second) {
+        next_query_ids_.push(query_id);
+      }
+      query_merger_.add_query(query_id,
+                              td::PromiseCreator::lambda([this, query_id](td::Result<td::Unit> result) mutable {
+                                completed_query_count_++;
+                                if (completed_query_count_ == MAX_QUERY_COUNT) {
+                                  ASSERT_EQ(current_query_count_, 0u);
+                                  ASSERT_TRUE(next_query_ids_.empty());
+                                  ASSERT_TRUE(pending_query_ids_.empty());
+                                  td::Scheduler::instance()->finish();
+                                } else {
+                                  yield();
+                                }
+                              }));
+    }
+  }
+
+  static constexpr std::size_t MAX_CONCURRENT_QUERY_COUNT = 5;
+  static constexpr std::size_t MAX_MERGED_QUERY_COUNT = 3;
+  static constexpr std::size_t MAX_QUERY_COUNT = 1000;
+
+  td::QueryMerger query_merger_{"QueryMerger", MAX_CONCURRENT_QUERY_COUNT, MAX_MERGED_QUERY_COUNT};
+  std::size_t current_query_count_ = 0;
+  std::size_t total_query_count_ = 0;
+  std::size_t completed_query_count_ = 0;
+
+  std::queue<td::int64> next_query_ids_;
+  td::FlatHashSet<td::int64> pending_query_ids_;
+};
+
+TEST(QueryMerger, stress) {
+  td::ConcurrentScheduler sched(0, 0);
+  sched.create_actor_unsafe<TestQueryMerger>(0, "TestQueryMerger").release();
+  sched.start();
+  while (sched.run_main(10)) {
+    // empty
+  }
+  sched.finish();
+}