Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 823 insertions, 0 deletions

diff --git a/src/test/librbd/io/test_mock_SimpleSchedulerObjectDispatch.cc b/src/test/librbd/io/test_mock_SimpleSchedulerObjectDispatch.cc
new file mode 100644
index 000000000..a3d823d23
--- /dev/null
+++ b/src/test/librbd/io/test_mock_SimpleSchedulerObjectDispatch.cc
@@ -0,0 +1,823 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "test/librbd/test_mock_fixture.h"
+#include "test/librbd/test_support.h"
+#include "test/librbd/mock/MockImageCtx.h"
+#include "test/librbd/mock/MockSafeTimer.h"
+#include "test/librados_test_stub/MockTestMemIoCtxImpl.h"
+#include "test/librados_test_stub/MockTestMemRadosClient.h"
+#include "include/rbd/librbd.hpp"
+#include "librbd/io/ObjectDispatchSpec.h"
+#include "librbd/io/SimpleSchedulerObjectDispatch.h"
+
+namespace librbd {
+namespace {
+
+struct MockTestImageCtx : public MockImageCtx {
+  MockTestImageCtx(ImageCtx &image_ctx) : MockImageCtx(image_ctx) {
+  }
+};
+
+} // anonymous namespace
+
+namespace io {
+
+template <>
+struct TypeTraits<MockTestImageCtx> {
+  typedef ::MockSafeTimer SafeTimer;
+};
+
+template <>
+struct FlushTracker<MockTestImageCtx> {
+  FlushTracker(MockTestImageCtx*) {
+  }
+
+  void shut_down() {
+  }
+
+  void flush(Context*) {
+  }
+
+  void start_io(uint64_t) {
+  }
+
+  void finish_io(uint64_t) {
+  }
+
+};
+
+} // namespace io
+} // namespace librbd
+
+#include "librbd/io/SimpleSchedulerObjectDispatch.cc"
+
+namespace librbd {
+namespace io {
+
+using ::testing::_;
+using ::testing::InSequence;
+using ::testing::Invoke;
+using ::testing::Return;
+
+struct TestMockIoSimpleSchedulerObjectDispatch : public TestMockFixture {
+  typedef SimpleSchedulerObjectDispatch<librbd::MockTestImageCtx> MockSimpleSchedulerObjectDispatch;
+
+  MockSafeTimer m_mock_timer;
+  ceph::mutex m_mock_timer_lock =
+    ceph::make_mutex("TestMockIoSimpleSchedulerObjectDispatch::Mutex");
+
+  TestMockIoSimpleSchedulerObjectDispatch() {
+    MockTestImageCtx::set_timer_instance(&m_mock_timer, &m_mock_timer_lock);
+    EXPECT_EQ(0, _rados.conf_set("rbd_io_scheduler_simple_max_delay", "1"));
+  }
+
+  void expect_get_object_name(MockTestImageCtx &mock_image_ctx,
+                              uint64_t object_no) {
+    EXPECT_CALL(mock_image_ctx, get_object_name(object_no))
+      .WillRepeatedly(Return(
+          mock_image_ctx.image_ctx->get_object_name(object_no)));
+  }
+
+  void expect_dispatch_delayed_requests(MockTestImageCtx &mock_image_ctx,
+                                        int r) {
+    EXPECT_CALL(*mock_image_ctx.io_object_dispatcher, send(_))
+      .WillOnce(Invoke([&mock_image_ctx, r](ObjectDispatchSpec* spec) {
+                  spec->dispatch_result = io::DISPATCH_RESULT_COMPLETE;
+                  mock_image_ctx.image_ctx->op_work_queue->queue(
+                      &spec->dispatcher_ctx, r);
+                }));
+  }
+
+  void expect_cancel_timer_task(Context *timer_task) {
+      EXPECT_CALL(m_mock_timer, cancel_event(timer_task))
+        .WillOnce(Invoke([](Context *timer_task) {
+                    delete timer_task;
+                    return true;
+                  }));
+  }
+
+  void expect_add_timer_task(Context **timer_task) {
+    EXPECT_CALL(m_mock_timer, add_event_at(_, _))
+      .WillOnce(Invoke([timer_task](ceph::real_clock::time_point, Context *task) {
+                  *timer_task = task;
+                  return task;
+                }));
+  }
+
+  void expect_schedule_dispatch_delayed_requests(Context *current_task,
+                                                 Context **new_task) {
+    if (current_task != nullptr) {
+      expect_cancel_timer_task(current_task);
+    }
+    if (new_task != nullptr) {
+      expect_add_timer_task(new_task);
+    }
+  }
+
+  void run_timer_task(Context *timer_task) {
+    std::lock_guard timer_locker{m_mock_timer_lock};
+    timer_task->complete(0);
+  }
+};
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, Read) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  C_SaferCond cond;
+  Context *on_finish = &cond;
+  io::ReadExtents extents = {{0, 4096}, {8192, 4096}};
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.read(
+      0, &extents, mock_image_ctx.get_data_io_context(), 0, 0, {}, nullptr,
+      nullptr, nullptr, &on_finish, nullptr));
+  ASSERT_EQ(on_finish, &cond); // not modified
+  on_finish->complete(0);
+  ASSERT_EQ(0, cond.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, Discard) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  C_SaferCond cond;
+  Context *on_finish = &cond;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.discard(
+      0, 0, 4096, mock_image_ctx.get_data_io_context(), 0, {}, nullptr, nullptr,
+      nullptr, &on_finish, nullptr));
+  ASSERT_NE(on_finish, &cond);
+  on_finish->complete(0);
+  ASSERT_EQ(0, cond.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, Write) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  ceph::bufferlist data;
+  data.append("X");
+  int object_dispatch_flags = 0;
+  C_SaferCond cond;
+  Context *on_finish = &cond;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.write(
+      0, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, nullptr,
+      &on_finish, nullptr));
+  ASSERT_NE(on_finish, &cond);
+  on_finish->complete(0);
+  ASSERT_EQ(0, cond.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, WriteSame) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  io::LightweightBufferExtents buffer_extents;
+  ceph::bufferlist data;
+  C_SaferCond cond;
+  Context *on_finish = &cond;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.write_same(
+      0, 0, 4096, std::move(buffer_extents), std::move(data),
+      mock_image_ctx.get_data_io_context(), 0, {}, nullptr, nullptr, nullptr,
+      &on_finish, nullptr));
+  ASSERT_NE(on_finish, &cond);
+  on_finish->complete(0);
+  ASSERT_EQ(0, cond.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, CompareAndWrite) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  ceph::bufferlist cmp_data;
+  ceph::bufferlist write_data;
+  C_SaferCond cond;
+  Context *on_finish = &cond;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.compare_and_write(
+      0, 0, std::move(cmp_data), std::move(write_data),
+      mock_image_ctx.get_data_io_context(), 0, {}, nullptr, nullptr, nullptr,
+      nullptr, &on_finish, nullptr));
+  ASSERT_NE(on_finish, &cond);
+  on_finish->complete(0);
+  ASSERT_EQ(0, cond.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, Flush) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  io::DispatchResult dispatch_result;
+  C_SaferCond cond;
+  Context *on_finish = &cond;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.flush(
+      FLUSH_SOURCE_USER, {}, nullptr, &dispatch_result, &on_finish, nullptr));
+  ASSERT_EQ(io::DISPATCH_RESULT_CONTINUE, dispatch_result);
+  ASSERT_EQ(on_finish, &cond); // not modified
+  on_finish->complete(0);
+  ASSERT_EQ(0, cond.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, WriteDelayed) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  expect_get_object_name(mock_image_ctx, 0);
+
+  InSequence seq;
+
+  ceph::bufferlist data;
+  data.append("X");
+  int object_dispatch_flags = 0;
+  C_SaferCond cond1;
+  Context *on_finish1 = &cond1;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.write(
+      0, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, nullptr, &on_finish1,
+      nullptr));
+  ASSERT_NE(on_finish1, &cond1);
+
+  Context *timer_task = nullptr;
+  expect_schedule_dispatch_delayed_requests(nullptr, &timer_task);
+
+  io::DispatchResult dispatch_result;
+  C_SaferCond cond2;
+  Context *on_finish2 = &cond2;
+  C_SaferCond on_dispatched;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish2, &on_dispatched));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish2, &cond2);
+  ASSERT_NE(timer_task, nullptr);
+
+  expect_dispatch_delayed_requests(mock_image_ctx, 0);
+  expect_schedule_dispatch_delayed_requests(timer_task, nullptr);
+
+  on_finish1->complete(0);
+  ASSERT_EQ(0, cond1.wait());
+  ASSERT_EQ(0, on_dispatched.wait());
+  on_finish2->complete(0);
+  ASSERT_EQ(0, cond2.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, WriteDelayedFlush) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  expect_get_object_name(mock_image_ctx, 0);
+
+  InSequence seq;
+
+  ceph::bufferlist data;
+  data.append("X");
+  int object_dispatch_flags = 0;
+  C_SaferCond cond1;
+  Context *on_finish1 = &cond1;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.write(
+      0, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, nullptr, &on_finish1,
+      nullptr));
+  ASSERT_NE(on_finish1, &cond1);
+
+  Context *timer_task = nullptr;
+  expect_schedule_dispatch_delayed_requests(nullptr, &timer_task);
+
+  io::DispatchResult dispatch_result;
+  C_SaferCond cond2;
+  Context *on_finish2 = &cond2;
+  C_SaferCond on_dispatched;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish2, &on_dispatched));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish2, &cond2);
+  ASSERT_NE(timer_task, nullptr);
+
+  expect_dispatch_delayed_requests(mock_image_ctx, 0);
+  expect_schedule_dispatch_delayed_requests(timer_task, nullptr);
+
+  C_SaferCond cond3;
+  Context *on_finish3 = &cond3;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.flush(
+      FLUSH_SOURCE_USER, {}, nullptr, &dispatch_result, &on_finish3, nullptr));
+  ASSERT_EQ(io::DISPATCH_RESULT_CONTINUE, dispatch_result);
+  ASSERT_EQ(on_finish3, &cond3);
+
+  on_finish1->complete(0);
+  ASSERT_EQ(0, cond1.wait());
+  ASSERT_EQ(0, on_dispatched.wait());
+  on_finish2->complete(0);
+  ASSERT_EQ(0, cond2.wait());
+  on_finish3->complete(0);
+  ASSERT_EQ(0, cond3.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, WriteMerged) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  expect_get_object_name(mock_image_ctx, 0);
+
+  InSequence seq;
+
+  ceph::bufferlist data;
+  data.append("X");
+  int object_dispatch_flags = 0;
+  C_SaferCond cond1;
+  Context *on_finish1 = &cond1;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.write(
+      0, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, nullptr, &on_finish1,
+      nullptr));
+  ASSERT_NE(on_finish1, &cond1);
+
+  Context *timer_task = nullptr;
+  expect_schedule_dispatch_delayed_requests(nullptr, &timer_task);
+
+  uint64_t object_off = 20;
+  data.clear();
+  data.append(std::string(10, 'A'));
+  io::DispatchResult dispatch_result;
+  C_SaferCond cond2;
+  Context *on_finish2 = &cond2;
+  C_SaferCond on_dispatched2;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, object_off, std::move(data), mock_image_ctx.get_data_io_context(), 0,
+      0, std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish2, &on_dispatched2));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish2, &cond2);
+  ASSERT_NE(timer_task, nullptr);
+
+  object_off = 0;
+  data.clear();
+  data.append(std::string(10, 'B'));
+  C_SaferCond cond3;
+  Context *on_finish3 = &cond3;
+  C_SaferCond on_dispatched3;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, object_off, std::move(data), mock_image_ctx.get_data_io_context(), 0,
+      0, std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish3, &on_dispatched3));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish3, &cond3);
+
+  object_off = 10;
+  data.clear();
+  data.append(std::string(10, 'C'));
+  C_SaferCond cond4;
+  Context *on_finish4 = &cond4;
+  C_SaferCond on_dispatched4;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, object_off, std::move(data), mock_image_ctx.get_data_io_context(), 0,
+      0, std::nullopt, {},&object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish4, &on_dispatched4));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish4, &cond4);
+
+  object_off = 30;
+  data.clear();
+  data.append(std::string(10, 'D'));
+  C_SaferCond cond5;
+  Context *on_finish5 = &cond5;
+  C_SaferCond on_dispatched5;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, object_off, std::move(data), mock_image_ctx.get_data_io_context(), 0,
+      0, std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish5, &on_dispatched5));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish5, &cond5);
+
+  object_off = 50;
+  data.clear();
+  data.append(std::string(10, 'E'));
+  C_SaferCond cond6;
+  Context *on_finish6 = &cond6;
+  C_SaferCond on_dispatched6;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, object_off, std::move(data), mock_image_ctx.get_data_io_context(), 0,
+      0, std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish6, &on_dispatched6));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish6, &cond6);
+
+  // expect two requests dispatched:
+  // 0~40 (merged 0~10, 10~10, 20~10, 30~10) and 50~10
+  expect_dispatch_delayed_requests(mock_image_ctx, 0);
+  expect_dispatch_delayed_requests(mock_image_ctx, 0);
+  expect_schedule_dispatch_delayed_requests(timer_task, nullptr);
+
+  on_finish1->complete(0);
+  ASSERT_EQ(0, cond1.wait());
+  ASSERT_EQ(0, on_dispatched2.wait());
+  ASSERT_EQ(0, on_dispatched3.wait());
+  ASSERT_EQ(0, on_dispatched4.wait());
+  ASSERT_EQ(0, on_dispatched5.wait());
+  ASSERT_EQ(0, on_dispatched6.wait());
+  on_finish2->complete(0);
+  on_finish3->complete(0);
+  on_finish4->complete(0);
+  on_finish5->complete(0);
+  on_finish6->complete(0);
+  ASSERT_EQ(0, cond2.wait());
+  ASSERT_EQ(0, cond3.wait());
+  ASSERT_EQ(0, cond4.wait());
+  ASSERT_EQ(0, cond5.wait());
+  ASSERT_EQ(0, cond6.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, WriteNonSequential) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  expect_get_object_name(mock_image_ctx, 0);
+
+  InSequence seq;
+
+  ceph::bufferlist data;
+  int object_dispatch_flags = 0;
+  C_SaferCond cond1;
+  Context *on_finish1 = &cond1;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.write(
+      0, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, nullptr, &on_finish1,
+      nullptr));
+  ASSERT_NE(on_finish1, &cond1);
+
+  Context *timer_task = nullptr;
+  expect_schedule_dispatch_delayed_requests(nullptr, &timer_task);
+
+  uint64_t object_off = 0;
+  data.clear();
+  data.append(std::string(10, 'X'));
+  io::DispatchResult dispatch_result;
+  C_SaferCond cond2;
+  Context *on_finish2 = &cond2;
+  C_SaferCond on_dispatched2;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, object_off, std::move(data), mock_image_ctx.get_data_io_context(), 0,
+      0, std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish2, &on_dispatched2));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish2, &cond2);
+  ASSERT_NE(timer_task, nullptr);
+
+  expect_dispatch_delayed_requests(mock_image_ctx, 0);
+  expect_schedule_dispatch_delayed_requests(timer_task, nullptr);
+
+  object_off = 5;
+  data.clear();
+  data.append(std::string(10, 'Y'));
+  C_SaferCond cond3;
+  Context *on_finish3 = &cond3;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.write(
+      0, object_off, std::move(data), mock_image_ctx.get_data_io_context(), 0,
+      0, std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish3, nullptr));
+  ASSERT_NE(on_finish3, &cond3);
+
+  on_finish1->complete(0);
+  ASSERT_EQ(0, cond1.wait());
+  ASSERT_EQ(0, on_dispatched2.wait());
+  on_finish2->complete(0);
+  ASSERT_EQ(0, cond2.wait());
+  on_finish3->complete(0);
+  ASSERT_EQ(0, cond3.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, Mixed) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  expect_get_object_name(mock_image_ctx, 0);
+
+  InSequence seq;
+
+  // write (1) 0~0 (in-flight)
+  // will wrap on_finish with dispatch_seq=1 to dispatch future delayed writes
+  ceph::bufferlist data;
+  int object_dispatch_flags = 0;
+  C_SaferCond cond1;
+  Context *on_finish1 = &cond1;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.write(
+      0, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, nullptr, &on_finish1,
+      nullptr));
+  ASSERT_NE(on_finish1, &cond1);
+
+  // write (2) 0~10 (delayed)
+  // will wait for write (1) to finish or a non-seq io comes
+  Context *timer_task = nullptr;
+  expect_schedule_dispatch_delayed_requests(nullptr, &timer_task);
+  uint64_t object_off = 0;
+  data.clear();
+  data.append(std::string(10, 'A'));
+  io::DispatchResult dispatch_result;
+  C_SaferCond cond2;
+  Context *on_finish2 = &cond2;
+  C_SaferCond on_dispatched2;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, object_off, std::move(data), mock_image_ctx.get_data_io_context(), 0,
+      0, std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish2, &on_dispatched2));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish2, &cond2);
+  ASSERT_NE(timer_task, nullptr);
+
+  // write (3) 10~10 (delayed)
+  // will be merged with write (2)
+  object_off = 10;
+  data.clear();
+  data.append(std::string(10, 'B'));
+  C_SaferCond cond3;
+  Context *on_finish3 = &cond3;
+  C_SaferCond on_dispatched3;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, object_off, std::move(data), mock_image_ctx.get_data_io_context(), 0,
+      0, std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish3, &on_dispatched3));
+  ASSERT_NE(on_finish3, &cond3);
+
+  // discard (1) (non-seq io)
+  // will dispatch the delayed writes (2) and (3) and wrap on_finish
+  // with dispatch_seq=2 to dispatch future delayed writes
+  expect_dispatch_delayed_requests(mock_image_ctx, 0);
+  expect_schedule_dispatch_delayed_requests(timer_task, nullptr);
+  C_SaferCond cond4;
+  Context *on_finish4 = &cond4;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.discard(
+      0, 4096, 4096, mock_image_ctx.get_data_io_context(), 0, {}, nullptr,
+      nullptr, nullptr, &on_finish4, nullptr));
+  ASSERT_NE(on_finish4, &cond4);
+  ASSERT_EQ(0, on_dispatched2.wait());
+  ASSERT_EQ(0, on_dispatched3.wait());
+
+  // write (4) 20~10 (delayed)
+  // will wait for discard (1) to finish or a non-seq io comes
+  timer_task = nullptr;
+  expect_schedule_dispatch_delayed_requests(nullptr, &timer_task);
+  object_off = 20;
+  data.clear();
+  data.append(std::string(10, 'C'));
+  C_SaferCond cond5;
+  Context *on_finish5 = &cond5;
+  C_SaferCond on_dispatched5;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, object_off, std::move(data), mock_image_ctx.get_data_io_context(), 0,
+      0, std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish5, &on_dispatched5));
+  ASSERT_NE(on_finish5, &cond5);
+  ASSERT_NE(timer_task, nullptr);
+
+  // discard (2) (non-seq io)
+  // will dispatch the delayed write (4) and wrap on_finish with dispatch_seq=3
+  // to dispatch future delayed writes
+  expect_dispatch_delayed_requests(mock_image_ctx, 0);
+  expect_schedule_dispatch_delayed_requests(timer_task, nullptr);
+  C_SaferCond cond6;
+  Context *on_finish6 = &cond6;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.discard(
+      0, 4096, 4096, mock_image_ctx.get_data_io_context(), 0, {}, nullptr,
+      nullptr, nullptr, &on_finish6, nullptr));
+  ASSERT_NE(on_finish6, &cond6);
+  ASSERT_EQ(0, on_dispatched5.wait());
+
+  // write (5) 30~10 (delayed)
+  // will wait for discard (2) to finish or a non-seq io comes
+  timer_task = nullptr;
+  expect_schedule_dispatch_delayed_requests(nullptr, &timer_task);
+  object_off = 30;
+  data.clear();
+  data.append(std::string(10, 'D'));
+  C_SaferCond cond7;
+  Context *on_finish7 = &cond7;
+  C_SaferCond on_dispatched7;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, object_off, std::move(data), mock_image_ctx.get_data_io_context(), 0,
+      0, std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish7, &on_dispatched7));
+  ASSERT_NE(on_finish7, &cond7);
+  ASSERT_NE(timer_task, nullptr);
+
+  // write (1) finishes
+  // on_finish wrapper will skip dispatch delayed write (5)
+  // due to dispatch_seq(1) < m_dispatch_seq(3)
+  on_finish1->complete(0);
+  ASSERT_EQ(0, cond1.wait());
+
+  // writes (2) and (3) finish ("dispatch delayed" is not called)
+  on_finish2->complete(0);
+  on_finish3->complete(0);
+  ASSERT_EQ(0, cond2.wait());
+  ASSERT_EQ(0, cond3.wait());
+
+  // discard (1) finishes
+  // on_finish wrapper will skip dispatch delayed write (5)
+  // due to dispatch_seq(2) < m_dispatch_seq(3)
+  on_finish4->complete(0);
+  ASSERT_EQ(0, cond4.wait());
+
+  // writes (4) finishes ("dispatch delayed" is not called)
+  on_finish5->complete(0);
+  ASSERT_EQ(0, cond5.wait());
+
+  // discard (2) finishes
+  // on_finish wrapper will dispatch the delayed write (5)
+  // due to dispatch_seq(3) == m_dispatch_seq(3)
+  expect_dispatch_delayed_requests(mock_image_ctx, 0);
+  expect_schedule_dispatch_delayed_requests(timer_task, nullptr);
+  on_finish6->complete(0);
+  ASSERT_EQ(0, cond6.wait());
+  ASSERT_EQ(0, on_dispatched7.wait());
+
+  // write (5) finishes ("dispatch delayed" is not called)
+  on_finish7->complete(0);
+  ASSERT_EQ(0, cond7.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, DispatchQueue) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  expect_get_object_name(mock_image_ctx, 0);
+  expect_get_object_name(mock_image_ctx, 1);
+
+  InSequence seq;
+
+  // send 2 writes to object 0
+
+  uint64_t object_no = 0;
+  ceph::bufferlist data;
+  int object_dispatch_flags = 0;
+  C_SaferCond cond1;
+  Context *on_finish1 = &cond1;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.write(
+      object_no, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, nullptr, &on_finish1,
+      nullptr));
+  ASSERT_NE(on_finish1, &cond1);
+
+  Context *timer_task = nullptr;
+  expect_schedule_dispatch_delayed_requests(nullptr, &timer_task);
+
+  data.clear();
+  io::DispatchResult dispatch_result;
+  C_SaferCond cond2;
+  Context *on_finish2 = &cond2;
+  C_SaferCond on_dispatched2;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      object_no, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish2, &on_dispatched2));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish2, &cond2);
+  ASSERT_NE(timer_task, nullptr);
+
+  // send 2 writes to object 1
+
+  object_no = 1;
+  data.clear();
+  C_SaferCond cond3;
+  Context *on_finish3 = &cond3;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.write(
+      object_no, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, nullptr, &on_finish3,
+      nullptr));
+  ASSERT_NE(on_finish3, &cond3);
+
+  data.clear();
+  C_SaferCond cond4;
+  Context *on_finish4 = &cond4;
+  C_SaferCond on_dispatched4;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      object_no, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish4, &on_dispatched4));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish4, &cond4);
+
+  // finish write (1) to object 0
+  expect_dispatch_delayed_requests(mock_image_ctx, 0);
+  expect_schedule_dispatch_delayed_requests(timer_task, &timer_task);
+  on_finish1->complete(0);
+  ASSERT_EQ(0, cond1.wait());
+  ASSERT_EQ(0, on_dispatched2.wait());
+
+  // finish write (2) to object 0
+  on_finish2->complete(0);
+  ASSERT_EQ(0, cond2.wait());
+
+  // finish write (1) to object 1
+  expect_dispatch_delayed_requests(mock_image_ctx, 0);
+  expect_schedule_dispatch_delayed_requests(timer_task, nullptr);
+  on_finish3->complete(0);
+  ASSERT_EQ(0, cond3.wait());
+  ASSERT_EQ(0, on_dispatched4.wait());
+
+  // finish write (2) to object 1
+  on_finish4->complete(0);
+  ASSERT_EQ(0, cond4.wait());
+}
+
+TEST_F(TestMockIoSimpleSchedulerObjectDispatch, Timer) {
+  librbd::ImageCtx *ictx;
+  ASSERT_EQ(0, open_image(m_image_name, &ictx));
+
+  MockTestImageCtx mock_image_ctx(*ictx);
+  MockSimpleSchedulerObjectDispatch
+      mock_simple_scheduler_object_dispatch(&mock_image_ctx);
+
+  expect_get_object_name(mock_image_ctx, 0);
+  expect_op_work_queue(mock_image_ctx);
+
+  InSequence seq;
+
+  ceph::bufferlist data;
+  int object_dispatch_flags = 0;
+  C_SaferCond cond1;
+  Context *on_finish1 = &cond1;
+  ASSERT_FALSE(mock_simple_scheduler_object_dispatch.write(
+      0, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, nullptr, &on_finish1,
+      nullptr));
+  ASSERT_NE(on_finish1, &cond1);
+
+  Context *timer_task = nullptr;
+  expect_schedule_dispatch_delayed_requests(nullptr, &timer_task);
+
+  data.clear();
+  io::DispatchResult dispatch_result;
+  C_SaferCond cond2;
+  Context *on_finish2 = &cond2;
+  C_SaferCond on_dispatched;
+  ASSERT_TRUE(mock_simple_scheduler_object_dispatch.write(
+      0, 0, std::move(data), mock_image_ctx.get_data_io_context(), 0, 0,
+      std::nullopt, {}, &object_dispatch_flags, nullptr, &dispatch_result,
+      &on_finish2, &on_dispatched));
+  ASSERT_EQ(dispatch_result, io::DISPATCH_RESULT_COMPLETE);
+  ASSERT_NE(on_finish2, &cond2);
+  ASSERT_NE(timer_task, nullptr);
+
+  expect_dispatch_delayed_requests(mock_image_ctx, 0);
+
+  run_timer_task(timer_task);
+  ASSERT_EQ(0, on_dispatched.wait());
+
+  on_finish1->complete(0);
+  ASSERT_EQ(0, cond1.wait());
+  on_finish2->complete(0);
+  ASSERT_EQ(0, cond2.wait());
+}
+
+} // namespace io
+} // namespace librbd