src/lib/fidl/c/walker_tests/llcpp_server_test.cc

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <lib/async-loop/cpp/loop.h>
#include <lib/async-loop/default.h>
#include <lib/async/cpp/task.h>
#include <lib/fidl/llcpp/server.h>
#include <lib/sync/completion.h>
#include <zircon/fidl.h>
#include <zircon/syscalls.h>

#include <thread>
#include <vector>

#include <fbl/auto_lock.h>
#include <fbl/mutex.h>
#include <fidl/test/coding/fuchsia/llcpp/fidl.h>
#include <fidl/test/coding/llcpp/fidl.h>
#include <zxtest/zxtest.h>

namespace {

using ::llcpp::fidl::test::coding::fuchsia::Simple;

constexpr uint32_t kNumberOfAsyncs = 10;
constexpr int32_t kExpectedReply = 7;

class Server : public Simple::Interface {
 public:
  explicit Server(sync_completion_t* destroyed) : destroyed_(destroyed) {}
  Server(Server&& other) = delete;
  Server(const Server& other) = delete;
  Server& operator=(Server&& other) = delete;
  Server& operator=(const Server& other) = delete;

  ~Server() override { sync_completion_signal(destroyed_); }

  void Echo(int32_t request, EchoCompleter::Sync& completer) override { completer.Reply(request); }
  void Close(CloseCompleter::Sync& completer) override { completer.Close(ZX_OK); }

 private:
  sync_completion_t* destroyed_;
};

TEST(BindServerTestCase, SyncReply) {
  struct SyncServer : Simple::Interface {
    void Close(CloseCompleter::Sync& completer) override { ADD_FAILURE("Must not call close"); }
    void Echo(int32_t request, EchoCompleter::Sync& completer) override {
      completer.Reply(request);
    }
  };

  // Server launches a thread so we can make sync client calls.
  auto server = std::make_unique<SyncServer>();
  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(loop.StartThread());

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));

  sync_completion_t closed;
  fidl::OnUnboundFn<SyncServer> on_unbound = [&closed](SyncServer*, fidl::UnbindInfo info,
                                                       zx::channel channel) {
    EXPECT_EQ(fidl::UnbindInfo::kPeerClosed, info.reason);
    EXPECT_EQ(ZX_ERR_PEER_CLOSED, info.status);
    EXPECT_TRUE(channel);
    sync_completion_signal(&closed);
  };
  fidl::BindServer(loop.dispatcher(), std::move(remote), server.get(), std::move(on_unbound));

  // Sync client call.
  auto result = Simple::Call::Echo(zx::unowned_channel{local}, kExpectedReply);
  EXPECT_OK(result.status());
  EXPECT_EQ(result->reply, kExpectedReply);

  local.reset();  // To trigger binding destruction before loop's destruction.
  ASSERT_OK(sync_completion_wait(&closed, ZX_TIME_INFINITE));
}

TEST(BindServerTestCase, AsyncReply) {
  struct AsyncServer : Simple::Interface {
    void Close(CloseCompleter::Sync& completer) override { ADD_FAILURE("Must not call close"); }
    void Echo(int32_t request, EchoCompleter::Sync& completer) override {
      worker_ = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
      async::PostTask(worker_->dispatcher(), [request, completer = completer.ToAsync()]() mutable {
        completer.Reply(request);
      });
      ASSERT_OK(worker_->StartThread());
    }
    std::unique_ptr<async::Loop> worker_;
  };

  // Server launches a thread so we can make sync client calls.
  auto server = std::make_unique<AsyncServer>();
  async::Loop main(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(main.StartThread());

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));

  sync_completion_t closed;
  fidl::OnUnboundFn<AsyncServer> on_unbound = [&closed](AsyncServer*, fidl::UnbindInfo info,
                                                        zx::channel channel) {
    EXPECT_EQ(fidl::UnbindInfo::kPeerClosed, info.reason);
    EXPECT_EQ(ZX_ERR_PEER_CLOSED, info.status);
    EXPECT_TRUE(channel);
    sync_completion_signal(&closed);
  };
  fidl::BindServer(main.dispatcher(), std::move(remote), server.get(), std::move(on_unbound));

  // Sync client call.
  auto result = Simple::Call::Echo(zx::unowned_channel{local}, kExpectedReply);
  EXPECT_OK(result.status());
  EXPECT_EQ(result->reply, kExpectedReply);

  local.reset();  // To trigger binding destruction before main's destruction.
  ASSERT_OK(sync_completion_wait(&closed, ZX_TIME_INFINITE));
}

TEST(BindServerTestCase, MultipleAsyncReplies) {
  struct AsyncDelayedServer : Simple::Interface {
    void Close(CloseCompleter::Sync& completer) override { ADD_FAILURE("Must not call close"); }
    void Echo(int32_t request, EchoCompleter::Sync& completer) override {
      auto worker = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
      async::PostTask(worker->dispatcher(),
                      [request, completer = completer.ToAsync(), this]() mutable {
                        static std::atomic<int> count;
                        // Since we block until we get kNumberOfAsyncs concurrent requests
                        // this can only pass if we allow concurrent async replies.
                        if (++count == kNumberOfAsyncs) {
                          sync_completion_signal(&done_);
                        }
                        sync_completion_wait(&done_, ZX_TIME_INFINITE);
                        completer.Reply(request);
                      });
      ASSERT_OK(worker->StartThread());
      loops_.push_back(std::move(worker));
    }
    sync_completion_t done_;
    std::vector<std::unique_ptr<async::Loop>> loops_;
  };

  // Server launches a thread so we can make sync client calls.
  auto server = std::make_unique<AsyncDelayedServer>();
  async::Loop main(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(main.StartThread());

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));

  sync_completion_t closed;
  fidl::OnUnboundFn<AsyncDelayedServer> on_unbound =
      [&closed](AsyncDelayedServer* server, fidl::UnbindInfo info, zx::channel channel) {
        EXPECT_EQ(fidl::UnbindInfo::kPeerClosed, info.reason);
        EXPECT_EQ(ZX_ERR_PEER_CLOSED, info.status);
        EXPECT_TRUE(channel);
        sync_completion_signal(&closed);
      };
  fidl::BindServer(main.dispatcher(), std::move(remote), server.get(), std::move(on_unbound));

  // Sync client calls.
  sync_completion_t done;
  std::vector<std::unique_ptr<async::Loop>> clients;
  for (uint32_t i = 0; i < kNumberOfAsyncs; ++i) {
    auto client = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
    async::PostTask(client->dispatcher(), [&local, &done]() {
      auto result = Simple::Call::Echo(zx::unowned_channel{local}, kExpectedReply);
      ASSERT_EQ(result->reply, kExpectedReply);
      static std::atomic<int> count;
      if (++count == kNumberOfAsyncs) {
        sync_completion_signal(&done);
      }
    });
    ASSERT_OK(client->StartThread());
    clients.push_back(std::move(client));
  }
  sync_completion_wait(&done, ZX_TIME_INFINITE);

  local.reset();  // To trigger binding destruction before main's destruction.
  ASSERT_OK(sync_completion_wait(&closed, ZX_TIME_INFINITE));
}

TEST(BindServerTestCase, MultipleAsyncRepliesOnePeerClose) {
  struct AsyncDelayedServer : Simple::Interface {
    AsyncDelayedServer(std::vector<std::unique_ptr<async::Loop>>* loops) : loops_(loops) {}
    void Close(CloseCompleter::Sync& completer) override { ADD_FAILURE("Must not call close"); }
    void Echo(int32_t request, EchoCompleter::Sync& completer) override {
      auto worker = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
      async::PostTask(worker->dispatcher(),
                      [request, completer = completer.ToAsync(), this]() mutable {
                        bool signal = false;
                        static std::atomic<int> count;
                        if (++count == kNumberOfAsyncs) {
                          signal = true;
                        }
                        if (signal) {
                          sync_completion_signal(&done_);
                          completer.Close(ZX_OK);  // Peer close.
                        } else {
                          sync_completion_wait(&done_, ZX_TIME_INFINITE);
                          completer.Reply(request);
                        }
                      });
      ASSERT_OK(worker->StartThread());
      loops_->push_back(std::move(worker));
    }
    sync_completion_t done_;
    std::vector<std::unique_ptr<async::Loop>>* loops_;
  };

  // Loops must outlive the server, which is destroyed on peer close.
  std::vector<std::unique_ptr<async::Loop>> loops;
  // Server launches a thread so we can make sync client calls.
  auto server = std::make_unique<AsyncDelayedServer>(&loops);
  async::Loop main(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(main.StartThread());

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));

  sync_completion_t closed;
  fidl::OnUnboundFn<AsyncDelayedServer> on_unbound =
      [&closed](AsyncDelayedServer*, fidl::UnbindInfo info, zx::channel channel) {
        EXPECT_EQ(fidl::UnbindInfo::kClose, info.reason);
        EXPECT_OK(info.status);
        EXPECT_TRUE(channel);
        sync_completion_signal(&closed);
      };
  fidl::BindServer(main.dispatcher(), std::move(remote), server.get(), std::move(on_unbound));

  // Sync client calls.
  std::vector<std::unique_ptr<async::Loop>> clients;
  for (uint32_t i = 0; i < kNumberOfAsyncs; ++i) {
    auto client = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
    async::PostTask(client->dispatcher(), [&local, client = client.get()]() {
      auto result = Simple::Call::Echo(zx::unowned_channel{local}, kExpectedReply);
      if (result.status() != ZX_OK && result.status() != ZX_ERR_PEER_CLOSED) {
        FAIL();
      }
      client->Quit();
    });
    ASSERT_OK(client->StartThread());
    clients.push_back(std::move(client));
  }
  for (auto& i : clients) {
    i->JoinThreads();
  }
  ASSERT_OK(sync_completion_wait(&closed, ZX_TIME_INFINITE));

  // Verify the epitaph from Close().
  fidl_epitaph_t epitaph;
  ASSERT_OK(local.read(0, &epitaph, nullptr, sizeof(fidl_epitaph_t), 0, nullptr, nullptr));
  EXPECT_EQ(ZX_OK, epitaph.error);
}

TEST(BindServerTestCase, CallbackDestroyOnClientClose) {
  sync_completion_t destroyed;
  auto server = std::make_unique<Server>(&destroyed);
  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));

  fidl::OnUnboundFn<Server> on_unbound = [](Server* server, fidl::UnbindInfo info,
                                            zx::channel channel) {
    EXPECT_EQ(fidl::UnbindInfo::kPeerClosed, info.reason);
    EXPECT_EQ(ZX_ERR_PEER_CLOSED, info.status);
    EXPECT_TRUE(channel);
    delete server;
  };

  fidl::BindServer(loop.dispatcher(), std::move(remote), server.release(), std::move(on_unbound));
  loop.RunUntilIdle();
  ASSERT_FALSE(sync_completion_signaled(&destroyed));

  local.reset();
  loop.RunUntilIdle();
  ASSERT_OK(sync_completion_wait(&destroyed, ZX_TIME_INFINITE));
}

TEST(BindServerTestCase, CallbackErrorClientTriggered) {
  struct ErrorServer : Simple::Interface {
    explicit ErrorServer(sync_completion_t* worker_start, sync_completion_t* worker_done)
        : worker_start_(worker_start), worker_done_(worker_done) {}
    void Echo(int32_t request, EchoCompleter::Sync& completer) override {
      // Launches a thread so we can hold the transaction in progress.
      worker_ = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
      async::PostTask(worker_->dispatcher(),
                      [request, completer = completer.ToAsync(), this]() mutable {
                        sync_completion_signal(worker_start_);
                        sync_completion_wait(worker_done_, ZX_TIME_INFINITE);
                        completer.Reply(request);
                      });
      ASSERT_OK(worker_->StartThread());
    }
    void Close(CloseCompleter::Sync& completer) override { ADD_FAILURE("Must not call close"); }
    sync_completion_t* worker_start_;
    sync_completion_t* worker_done_;
    std::unique_ptr<async::Loop> worker_;
  };
  sync_completion_t worker_start, worker_done, error, closed;

  // Launches a thread so we can wait on the server error.
  auto server = std::make_unique<ErrorServer>(&worker_start, &worker_done);
  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(loop.StartThread());

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));

  fidl::OnUnboundFn<ErrorServer> on_unbound = [&error](ErrorServer*, fidl::UnbindInfo info,
                                                       zx::channel channel) {
    EXPECT_EQ(fidl::UnbindInfo::kPeerClosed, info.reason);
    EXPECT_EQ(ZX_ERR_PEER_CLOSED, info.status);
    EXPECT_TRUE(channel);
    sync_completion_signal(&error);
  };

  fidl::BindServer<ErrorServer>(loop.dispatcher(), std::move(remote), server.get(),
                                std::move(on_unbound));

  ASSERT_FALSE(sync_completion_signaled(&worker_start));
  ASSERT_FALSE(sync_completion_signaled(&worker_done));
  ASSERT_FALSE(sync_completion_signaled(&error));

  // Client launches a thread so we can hold the transaction in progress.
  auto client = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
  async::PostTask(client->dispatcher(), [&local, client = client.get()]() {
    auto result = Simple::Call::Echo(zx::unowned_channel{local}, kExpectedReply);
    if (result.status() != ZX_ERR_CANCELED) {  // Client closes the channel before server replies.
      FAIL();
    }
  });
  ASSERT_OK(client->StartThread());

  // Wait until worker_start so we have an in-flight transaction.
  ASSERT_OK(sync_completion_wait(&worker_start, ZX_TIME_INFINITE));

  // Client closes the channel, triggers an error and on_unbound is called.
  local.reset();

  // Wait for the error callback to be called.
  ASSERT_OK(sync_completion_wait(&error, ZX_TIME_INFINITE));

  // Trigger finishing the only outstanding transaction.
  sync_completion_signal(&worker_done);
  loop.Quit();
}

TEST(BindServerTestCase, DestroyBindingWithPendingCancel) {
  struct WorkingServer : Simple::Interface {
    explicit WorkingServer(sync_completion_t* worker_start, sync_completion_t* worker_done)
        : worker_start_(worker_start), worker_done_(worker_done) {}
    void Echo(int32_t request, EchoCompleter::Sync& completer) override {
      sync_completion_signal(worker_start_);
      sync_completion_wait(worker_done_, ZX_TIME_INFINITE);
      EXPECT_EQ(ZX_ERR_PEER_CLOSED, completer.Reply(request).status());
    }
    void Close(CloseCompleter::Sync& completer) override { ADD_FAILURE("Must not call close"); }
    sync_completion_t* worker_start_;
    sync_completion_t* worker_done_;
  };
  sync_completion_t worker_start, worker_done;

  // Launches a new thread for the server so we can wait on the worker.
  auto server = std::make_unique<WorkingServer>(&worker_start, &worker_done);
  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(loop.StartThread());

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));

  sync_completion_t closed;
  fidl::OnUnboundFn<WorkingServer> on_unbound = [&closed](WorkingServer*, fidl::UnbindInfo info,
                                                          zx::channel channel) {
    EXPECT_EQ(fidl::UnbindInfo::kPeerClosed, info.reason);
    EXPECT_EQ(ZX_ERR_PEER_CLOSED, info.status);
    EXPECT_TRUE(channel);
    sync_completion_signal(&closed);
  };
  fidl::BindServer(loop.dispatcher(), std::move(remote), server.get(), std::move(on_unbound));

  ASSERT_FALSE(sync_completion_signaled(&worker_start));
  ASSERT_FALSE(sync_completion_signaled(&worker_done));
  ASSERT_FALSE(sync_completion_signaled(&closed));

  // Client launches a thread so we can hold the transaction in progress.
  auto client = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
  async::PostTask(client->dispatcher(), [&local, client = client.get()]() {
    auto result = Simple::Call::Echo(zx::unowned_channel{local}, kExpectedReply);
    if (result.status() != ZX_ERR_CANCELED) {  // Client closes the channel before server replies.
      FAIL();
    }
  });
  ASSERT_OK(client->StartThread());

  // Wait until worker_start so we have an in-flight transaction.
  ASSERT_OK(sync_completion_wait(&worker_start, ZX_TIME_INFINITE));

  // Client closes its end of the channel, we trigger an error but can't close until the in-flight
  // transaction is destroyed.
  local.reset();

  // Trigger finishing the transaction, Reply() will fail (closed channel) and the transaction will
  // Close(). We make sure the channel error by the client happens first and the in-flight
  // transaction tries to Reply() second.
  sync_completion_signal(&worker_done);

  // Wait for the closed callback to be called.
  ASSERT_OK(sync_completion_wait(&closed, ZX_TIME_INFINITE));
}

TEST(BindServerTestCase, CallbackErrorServerTriggered) {
  struct ErrorServer : Simple::Interface {
    explicit ErrorServer(sync_completion_t* worker_start, sync_completion_t* worker_done)
        : worker_start_(worker_start), worker_done_(worker_done) {}
    void Echo(int32_t request, EchoCompleter::Sync& completer) override {
      // Launches a thread so we can hold the transaction in progress.
      worker_ = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
      async::PostTask(worker_->dispatcher(),
                      [request, completer = completer.ToAsync(), this]() mutable {
                        sync_completion_signal(worker_start_);
                        sync_completion_wait(worker_done_, ZX_TIME_INFINITE);
                        completer.Reply(request);
                      });
      ASSERT_OK(worker_->StartThread());
    }
    void Close(CloseCompleter::Sync& completer) override { completer.Close(ZX_ERR_INTERNAL); }
    sync_completion_t* worker_start_;
    sync_completion_t* worker_done_;
    std::unique_ptr<async::Loop> worker_;
  };
  sync_completion_t worker_start, worker_done, closed;

  // Launches a thread so we can wait on the server error.
  auto server = std::make_unique<ErrorServer>(&worker_start, &worker_done);
  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(loop.StartThread());

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));

  fidl::OnUnboundFn<ErrorServer> on_unbound = [&closed](ErrorServer*, fidl::UnbindInfo info,
                                                        zx::channel channel) {
    EXPECT_EQ(fidl::UnbindInfo::kClose, info.reason);
    EXPECT_OK(info.status);
    EXPECT_TRUE(channel);
    sync_completion_signal(&closed);
  };

  fidl::BindServer<ErrorServer>(loop.dispatcher(), std::move(remote), server.get(),
                                std::move(on_unbound));

  ASSERT_FALSE(sync_completion_signaled(&worker_start));
  ASSERT_FALSE(sync_completion_signaled(&worker_done));
  ASSERT_FALSE(sync_completion_signaled(&closed));

  // Client1 launches a thread so we can hold its transaction in progress.
  auto client1 = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
  async::PostTask(client1->dispatcher(),
                  [&local]() { Simple::Call::Echo(zx::unowned_channel{local}, kExpectedReply); });
  ASSERT_OK(client1->StartThread());

  // Wait until worker_start so we have an in-flight transaction.
  ASSERT_OK(sync_completion_wait(&worker_start, ZX_TIME_INFINITE));

  // Client2 launches a thread to continue the test while its transaction is still in progress.
  auto client2 = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
  async::PostTask(client2->dispatcher(), [&local]() {
    // Server will close the channel, on_unbound is not called.
    auto result = Simple::Call::Close(zx::unowned_channel{local});
    if (result.status() != ZX_ERR_PEER_CLOSED) {
      FAIL();
    }
  });
  ASSERT_OK(client2->StartThread());

  // Trigger finishing the client1 outstanding transaction.
  sync_completion_signal(&worker_done);

  // Wait for the closed callback to be called.
  ASSERT_OK(sync_completion_wait(&closed, ZX_TIME_INFINITE));

  // Verify the epitaph from Close().
  fidl_epitaph_t epitaph;
  ASSERT_OK(local.read(0, &epitaph, nullptr, sizeof(fidl_epitaph_t), 0, nullptr, nullptr));
  EXPECT_EQ(ZX_ERR_INTERNAL, epitaph.error);
}

TEST(BindServerTestCase, CallbackDestroyOnServerClose) {
  sync_completion_t destroyed;
  // Server launches a thread so we can make sync client calls.
  auto server = std::make_unique<Server>(&destroyed);
  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(loop.StartThread());

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));

  fidl::OnUnboundFn<Server> on_unbound = [](Server* server, fidl::UnbindInfo info,
                                            zx::channel channel) {
    EXPECT_EQ(fidl::UnbindInfo::kClose, info.reason);
    EXPECT_OK(info.status);
    EXPECT_TRUE(channel);
    delete server;
  };

  fidl::BindServer(loop.dispatcher(), std::move(remote), server.release(), std::move(on_unbound));
  ASSERT_FALSE(sync_completion_signaled(&destroyed));

  auto result = Simple::Call::Close(zx::unowned_channel{local});
  EXPECT_EQ(result.status(), ZX_ERR_PEER_CLOSED);

  ASSERT_OK(sync_completion_wait(&destroyed, ZX_TIME_INFINITE));
  // Make sure the other end closed
  ASSERT_OK(local.wait_one(ZX_CHANNEL_PEER_CLOSED, zx::time::infinite(), nullptr));

  // Verify the epitaph from Close().
  fidl_epitaph_t epitaph;
  ASSERT_OK(local.read(0, &epitaph, nullptr, sizeof(fidl_epitaph_t), 0, nullptr, nullptr));
  EXPECT_EQ(ZX_OK, epitaph.error);
}

TEST(BindServerTestCase, ExplicitUnbind) {
  // Server launches a thread so we can make sync client calls.
  sync_completion_t destroyed;
  auto server = new Server(&destroyed);
  async::Loop main(&kAsyncLoopConfigNoAttachToCurrentThread);
  main.StartThread();

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));
  auto remote_handle = remote.get();

  fidl::OnUnboundFn<Server> on_unbound = [remote_handle](Server* server, fidl::UnbindInfo info,
                                                         zx::channel channel) {
    EXPECT_EQ(fidl::UnbindInfo::kUnbind, info.reason);
    EXPECT_OK(info.status);
    EXPECT_EQ(channel.get(), remote_handle);
    delete server;
  };
  auto binding_ref =
      fidl::BindServer(main.dispatcher(), std::move(remote), server, std::move(on_unbound));
  ASSERT_TRUE(binding_ref.is_ok());

  // Unbind() and wait for the hook.
  binding_ref.value().Unbind();
  ASSERT_OK(sync_completion_wait(&destroyed, ZX_TIME_INFINITE));
}

TEST(BindServerTestCase, ExplicitUnbindWithPendingTransaction) {
  struct WorkingServer : Simple::Interface {
    explicit WorkingServer(sync_completion_t* worker_start, sync_completion_t* worker_done)
        : worker_start_(worker_start), worker_done_(worker_done) {}
    void Echo(int32_t request, EchoCompleter::Sync& completer) override {
      sync_completion_signal(worker_start_);
      sync_completion_wait(worker_done_, ZX_TIME_INFINITE);
      completer.Reply(request);
    }
    void Close(CloseCompleter::Sync& completer) override { ADD_FAILURE("Must not call close"); }
    sync_completion_t* worker_start_;
    sync_completion_t* worker_done_;
  };
  sync_completion_t worker_start, worker_done;

  // Launches a new thread for the server so we can wait on the worker.
  auto server = std::make_unique<WorkingServer>(&worker_start, &worker_done);
  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(loop.StartThread());

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));
  zx_handle_t remote_handle = remote.get();

  // Client launches a thread so we can hold the transaction in progress.
  auto client = std::make_unique<async::Loop>(&kAsyncLoopConfigNoAttachToCurrentThread);
  async::PostTask(client->dispatcher(), [&local, client = client.get()]() {
    Simple::Call::Echo(zx::unowned_channel{local}, kExpectedReply);
  });
  ASSERT_OK(client->StartThread());

  sync_completion_t unbound;
  fidl::OnUnboundFn<WorkingServer> on_unbound =
      [remote_handle, &unbound](WorkingServer*, fidl::UnbindInfo info, zx::channel channel) {
        EXPECT_EQ(fidl::UnbindInfo::kUnbind, info.reason);
        EXPECT_OK(info.status);
        EXPECT_EQ(channel.get(), remote_handle);
        sync_completion_signal(&unbound);
      };
  auto binding_ref =
      fidl::BindServer(loop.dispatcher(), std::move(remote), server.get(), std::move(on_unbound));
  ASSERT_TRUE(binding_ref.is_ok());

  // Wait until worker_start so we have an in-flight transaction.
  ASSERT_OK(sync_completion_wait(&worker_start, ZX_TIME_INFINITE));

  // Unbind the server end of the channel.
  binding_ref.value().Unbind();

  // The unboudn hook will not run until the thread inside Echo() returns.
  sync_completion_signal(&worker_done);

  // Wait for the unbound hook.
  ASSERT_OK(sync_completion_wait(&unbound, ZX_TIME_INFINITE));
}

TEST(BindServerTestCase, ConcurrentSyncReply) {
  struct ConcurrentSyncServer : Simple::Interface {
    ConcurrentSyncServer(int max_reqs) : max_reqs_(max_reqs) {}
    void Close(CloseCompleter::Sync& completer) override { ADD_FAILURE("Must not call close"); }
    void Echo(int32_t request, EchoCompleter::Sync& completer) override {
      // Increment the request count. Yield to allow other threads to execute.
      auto i = ++req_cnt_;
      zx_nanosleep(0);
      // Ensure that no other threads have entered Echo() after this thread.
      ASSERT_EQ(i, req_cnt_);
      // Let other threads in.
      completer.EnableNextDispatch();
      // The following should be a NOP. An additional wait should not be added. If it is, the above
      // assertion may fail if two requests arrive concurrently.
      completer.EnableNextDispatch();
      // Calls to Echo() block until max_reqs requests have arrived.
      if (i < max_reqs_) {
        sync_completion_wait(&on_max_reqs_, ZX_TIME_INFINITE);
      } else {
        sync_completion_signal(&on_max_reqs_);
      }
      completer.Reply(request);
    }
    sync_completion_t on_max_reqs_;
    const int max_reqs_;
    std::atomic<int> req_cnt_ = 0;
  };

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));

  // Launch server with 10 threads.
  constexpr int kMaxReqs = 10;
  auto server = std::make_unique<ConcurrentSyncServer>(kMaxReqs);
  async::Loop server_loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  for (int i = 0; i < kMaxReqs; ++i)
    ASSERT_OK(server_loop.StartThread());

  // Bind the server.
  auto res = fidl::BindServer(server_loop.dispatcher(), std::move(remote), server.get());
  ASSERT_TRUE(res.is_ok());
  fidl::ServerBindingRef<Simple> binding(std::move(res.value()));

  // Launch 10 client threads to make two-way Echo() calls.
  std::vector<std::thread> threads;
  for (int i = 0; i < kMaxReqs; ++i) {
    threads.emplace_back([&] {
      auto result = Simple::Call::Echo(zx::unowned_channel{local}, kExpectedReply);
      EXPECT_EQ(result.status(), ZX_OK);
    });
  }

  // Join the client threads.
  for (auto& thread : threads)
    thread.join();

  // Unbind the server.
  binding.Unbind();
}

TEST(BindServerTestCase, ConcurrentIdempotentClose) {
  struct ConcurrentSyncServer : Simple::Interface {
    void Close(CloseCompleter::Sync& completer) override {
      // Add the wait back to the dispatcher. Sleep to allow another thread in.
      completer.EnableNextDispatch();
      zx_nanosleep(0);
      // Close with ZX_OK.
      completer.Close(ZX_OK);
    }
    void Echo(int32_t, EchoCompleter::Sync&) override { ADD_FAILURE("Must not call echo"); }
  };

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));

  // Launch server with 10 threads.
  constexpr int kMaxReqs = 10;
  auto server = std::make_unique<ConcurrentSyncServer>();
  async::Loop server_loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  for (int i = 0; i < kMaxReqs; ++i)
    ASSERT_OK(server_loop.StartThread());

  // Bind the server.
  sync_completion_t unbound;
  fidl::OnUnboundFn<ConcurrentSyncServer> on_unbound =
      [&unbound](ConcurrentSyncServer*, fidl::UnbindInfo info, zx::channel channel) {
        static std::atomic_flag invoked = ATOMIC_FLAG_INIT;
        ASSERT_FALSE(invoked.test_and_set());  // Must only be called once.
        EXPECT_EQ(fidl::UnbindInfo::kClose, info.reason);
        EXPECT_OK(info.status);
        EXPECT_TRUE(channel);
        sync_completion_signal(&unbound);
      };
  fidl::BindServer(server_loop.dispatcher(), std::move(remote), server.get(),
                   std::move(on_unbound));

  // Launch 10 client threads to make two-way Echo() calls.
  std::vector<std::thread> threads;
  for (int i = 0; i < kMaxReqs; ++i) {
    threads.emplace_back([&] {
      auto result = Simple::Call::Close(zx::unowned_channel{local});
      EXPECT_EQ(result.status(), ZX_ERR_PEER_CLOSED);
    });
  }

  // Join the client threads.
  for (auto& thread : threads)
    thread.join();

  // Wait for the unbound handler before letting the loop be destroyed.
  ASSERT_OK(sync_completion_wait(&unbound, ZX_TIME_INFINITE));
}

TEST(BindServerTestCase, ServerUnbind) {
  // Create the server.
  sync_completion_t destroyed;
  auto* server = new Server(&destroyed);
  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(loop.StartThread());

  // Create and bind the channel.
  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));
  auto remote_handle = remote.get();
  fidl::OnUnboundFn<Server> on_unbound =
      [remote_handle, &remote](Server* server, fidl::UnbindInfo info, zx::channel channel) {
        EXPECT_EQ(fidl::UnbindInfo::kUnbind, info.reason);
        EXPECT_OK(info.status);
        EXPECT_EQ(channel.get(), remote_handle);
        remote = std::move(channel);
        delete server;
      };
  auto binding_ref =
      fidl::BindServer(loop.dispatcher(), std::move(remote), server, std::move(on_unbound));
  ASSERT_TRUE(binding_ref.is_ok());

  // The binding should be destroyed without waiting for the Server to be destroyed.
  binding_ref.value().Unbind();
  ASSERT_OK(sync_completion_wait(&destroyed, ZX_TIME_INFINITE));

  // Unbind()/Close() may still be called from the Server.
  binding_ref.value().Unbind();
  binding_ref.value().Close(ZX_OK);

  // The channel should still be valid.
  EXPECT_EQ(remote.get(), remote_handle);

  // No epitaph should have been sent.
  EXPECT_EQ(ZX_ERR_TIMED_OUT,
            local.wait_one(ZX_CHANNEL_READABLE, zx::time::infinite_past(), nullptr));
}

TEST(BindServerTestCase, ServerClose) {
  // Create the server.
  sync_completion_t destroyed;
  auto* server = new Server(&destroyed);
  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(loop.StartThread());

  // Create and bind the channel.
  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));
  fidl::OnUnboundFn<Server> on_unbound = [](Server* server, fidl::UnbindInfo info,
                                            zx::channel channel) {
    EXPECT_EQ(fidl::UnbindInfo::kClose, info.reason);
    EXPECT_OK(info.status);
    EXPECT_TRUE(channel);
    delete server;
  };
  auto binding_ref =
      fidl::BindServer(loop.dispatcher(), std::move(remote), server, std::move(on_unbound));
  ASSERT_TRUE(binding_ref.is_ok());

  // The binding should be destroyed without waiting for the Server to be destroyed.
  binding_ref.value().Close(ZX_OK);
  ASSERT_OK(local.wait_one(ZX_CHANNEL_PEER_CLOSED, zx::time::infinite(), nullptr));
  ASSERT_OK(sync_completion_wait(&destroyed, ZX_TIME_INFINITE));

  // Unbind()/Close() may still be called from the Server.
  binding_ref.value().Unbind();
  binding_ref.value().Close(ZX_OK);

  // Verify the epitaph from Close().
  fidl_epitaph_t epitaph;
  ASSERT_OK(local.read(0, &epitaph, nullptr, sizeof(fidl_epitaph_t), 0, nullptr, nullptr));
  EXPECT_EQ(ZX_OK, epitaph.error);
}

TEST(BindServerTestCase, UnbindInfoChannelError) {
  struct WorkingServer : Simple::Interface {
    WorkingServer() = default;
    void Echo(int32_t request, EchoCompleter::Sync& completer) override {
      EXPECT_EQ(ZX_ERR_ACCESS_DENIED, completer.Reply(request).status());
    }
    void Close(CloseCompleter::Sync& completer) override { ADD_FAILURE("Must not call close"); }
  };

  // Launches a new thread for the server so we can wait on the worker.
  auto server = std::make_unique<WorkingServer>();
  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(loop.StartThread());

  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));
  ASSERT_OK(remote.replace(ZX_DEFAULT_CHANNEL_RIGHTS & ~ZX_RIGHT_WRITE, &remote));

  sync_completion_t closed;
  fidl::OnUnboundFn<WorkingServer> on_unbound = [&closed](WorkingServer*, fidl::UnbindInfo info,
                                                          zx::channel) {
    EXPECT_EQ(fidl::UnbindInfo::kChannelError, info.reason);
    EXPECT_EQ(ZX_ERR_ACCESS_DENIED, info.status);
    sync_completion_signal(&closed);
  };
  fidl::BindServer(loop.dispatcher(), std::move(remote), server.get(), std::move(on_unbound));

  auto result = Simple::Call::Echo(zx::unowned_channel{local}, kExpectedReply);
  EXPECT_EQ(ZX_ERR_PEER_CLOSED, result.status());

  // Wait for the closed callback to be called.
  ASSERT_OK(sync_completion_wait(&closed, ZX_TIME_INFINITE));
}

TEST(BindServerTestCase, UnbindInfoDispatcherError) {
  // Create the server.
  sync_completion_t destroyed;
  auto* server = new Server(&destroyed);
  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(loop.StartThread());

  // Create and bind the channel.
  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));
  auto remote_handle = remote.get();
  fidl::OnUnboundFn<Server> on_unbound =
      [remote_handle, &remote](Server* server, fidl::UnbindInfo info, zx::channel channel) {
        EXPECT_EQ(fidl::UnbindInfo::kDispatcherError, info.reason);
        EXPECT_EQ(ZX_ERR_CANCELED, info.status);
        EXPECT_EQ(channel.get(), remote_handle);
        remote = std::move(channel);
        delete server;
      };
  auto binding_ref =
      fidl::BindServer(loop.dispatcher(), std::move(remote), server, std::move(on_unbound));
  ASSERT_TRUE(binding_ref.is_ok());

  // This should destroy the binding, running the error handler before returning.
  loop.Shutdown();
  ASSERT_OK(sync_completion_wait(&destroyed, ZX_TIME_INFINITE_PAST));

  // The channel should still be valid.
  EXPECT_EQ(remote.get(), remote_handle);

  // No epitaph should have been sent.
  EXPECT_EQ(ZX_ERR_TIMED_OUT,
            local.wait_one(ZX_CHANNEL_READABLE, zx::time::infinite_past(), nullptr));
}

TEST(BindServerTestCase, ReplyNotRequiredAfterUnbound) {
  struct WorkingServer : Simple::Interface {
    explicit WorkingServer(std::optional<EchoCompleter::Async>* async_completer,
                           sync_completion_t* ready)
        : async_completer_(async_completer), ready_(ready) {}
    void Echo(int32_t request, EchoCompleter::Sync& completer) override {
      sync_completion_signal(ready_);
      *async_completer_ = completer.ToAsync();  // Releases ownership of the binding.
    }
    void Close(CloseCompleter::Sync& completer) override { ADD_FAILURE("Must not call close"); }
    std::optional<EchoCompleter::Async>* async_completer_;
    sync_completion_t* ready_;
  };

  async::Loop loop(&kAsyncLoopConfigNoAttachToCurrentThread);
  ASSERT_OK(loop.StartThread());

  // Create the channel and bind it with the server and dispatcher.
  zx::channel local, remote;
  ASSERT_OK(zx::channel::create(0, &local, &remote));
  sync_completion_t ready, unbound;
  std::optional<Server::EchoCompleter::Async> async_completer;
  auto server = std::make_unique<WorkingServer>(&async_completer, &ready);
  fidl::OnUnboundFn<WorkingServer> on_unbound = [&unbound](WorkingServer*, fidl::UnbindInfo info,
                                                           zx::channel) {
    EXPECT_EQ(fidl::UnbindInfo::kUnbind, info.reason);
    EXPECT_EQ(ZX_OK, info.status);
    sync_completion_signal(&unbound);
  };
  auto binding_ref =
      fidl::BindServer(loop.dispatcher(), std::move(remote), server.get(), std::move(on_unbound));
  ASSERT_TRUE(binding_ref.is_ok());

  // Start another thread to make the outgoing call.
  std::thread([local = std::move(local)]() mutable {
    auto result = Simple::Call::Echo(zx::unowned_channel{local}, kExpectedReply);
    EXPECT_EQ(ZX_ERR_PEER_CLOSED, result.status());
  }).detach();

  // Wait for the server to enter Echo().
  ASSERT_OK(sync_completion_wait(&ready, ZX_TIME_INFINITE));

  // Unbind the server.
  binding_ref.value().Unbind();

  // Wait for the OnUnboundFn.
  ASSERT_OK(sync_completion_wait(&unbound, ZX_TIME_INFINITE));

  // The AsyncCompleter will be destroyed without having Reply()d or Close()d
  // but should not crash.
}

}  // namespace