blob: 833f3eb843310d0c96fc2c60562babb29e5038c0 [file] [log] [blame]
// Copyright 2015 The Chromium 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 <stddef.h>
#include <memory>
#include <queue>
#include <vector>
#include "base/callback.h"
#include "base/callback_helpers.h"
#include "base/containers/circular_deque.h"
#include "base/macros.h"
#include "base/run_loop.h"
#include "base/single_thread_task_runner.h"
#include "base/synchronization/condition_variable.h"
#include "base/synchronization/lock.h"
#include "base/test/test_pending_task.h"
#include "base/threading/thread_checker_impl.h"
#include "base/time/clock.h"
#include "base/time/tick_clock.h"
#include "base/time/time.h"
namespace base {
class ThreadTaskRunnerHandle;
// ATTENTION: Prefer using base::test::SingleThreadTaskEnvironment with a
// base::test::SingleThreadTaskEnvironment::TimeSource::MOCK_TIME trait instead.
// The only case where TestMockTimeTaskRunner is necessary is when instantiating
// multiple TestMockTimeTaskRunners in the same test to deterministically
// exercise the result of a race between two simulated threads.
// Runs pending tasks in the order of the tasks' post time + delay, and keeps
// track of a mock (virtual) tick clock time that can be fast-forwarded.
// TestMockTimeTaskRunner has the following properties:
// - Methods RunsTasksInCurrentSequence() and Post[Delayed]Task() can be
// called from any thread, but the rest of the methods must be called on
// the same thread the TestMockTimeTaskRunner was created on.
// - It allows for reentrancy, in that it handles the running of tasks that in
// turn call back into it (e.g., to post more tasks).
// - Tasks are stored in a priority queue, and executed in the increasing
// order of post time + delay, but ignoring nestability.
// - It does not check for overflow when doing time arithmetic. A sufficient
// condition for preventing overflows is to make sure that the sum of all
// posted task delays and fast-forward increments is still representable by
// a TimeDelta, and that adding this delta to the starting values of Time
// and TickTime is still within their respective range.
// A TestMockTimeTaskRunner of Type::kBoundToThread has the following additional
// properties:
// - Thread/SequencedTaskRunnerHandle refers to it on its thread.
// - It can be driven by a RunLoop on the thread it was created on.
// RunLoop::Run() will result in running non-delayed tasks until idle and
// then, if RunLoop::QuitWhenIdle() wasn't invoked, fast-forwarding time to
// the next delayed task and looping again. And so on, until either
// RunLoop::Quit() is invoked (quits immediately after the current task) or
// RunLoop::QuitWhenIdle() is invoked (quits before having to fast forward
// time once again). Should RunLoop::Run() process all tasks (including
// delayed ones), it will block until more are posted. As usual,
// RunLoop::RunUntilIdle() is equivalent to RunLoop::Run() followed by an
// immediate RunLoop::QuitWhenIdle().
// This is a slightly more sophisticated version of TestSimpleTaskRunner, in
// that it supports running delayed tasks in the correct temporal order.
class TestMockTimeTaskRunner : public SingleThreadTaskRunner,
public RunLoop::Delegate {
// Everything that is executed in the scope of a ScopedContext will behave as
// though it ran under |scope| (i.e. ThreadTaskRunnerHandle,
// RunsTasksInCurrentSequence, etc.). This allows the test body to be all in
// one block when multiple TestMockTimeTaskRunners share the main thread.
// Note: RunLoop isn't supported: will DCHECK if used inside a ScopedContext.
// For example:
// class ExampleFixture {
// protected:
// DoBarOnFoo() {
// DCHECK(foo_task_runner_->RunsOnCurrentThread());
// EXPECT_EQ(foo_task_runner_, ThreadTaskRunnerHandle::Get());
// DoBar();
// }
// // Mock main task runner.
// base::MessageLoop message_loop_;
// base::ScopedMockTimeMessageLoopTaskRunner main_task_runner_;
// // Mock foo task runner.
// scoped_refptr<TestMockTimeTaskRunner> foo_task_runner_ =
// new TestMockTimeTaskRunner();
// };
// TEST_F(ExampleFixture, DoBarOnFoo) {
// DoThingsOnMain();
// {
// TestMockTimeTaskRunner::ScopedContext scoped_context(
// foo_task_runner_.get());
// DoBarOnFoo();
// }
// DoMoreThingsOnMain();
// }
class ScopedContext {
// Note: |scope| is ran until idle as part of this constructor to ensure
// that anything which runs in the underlying scope runs after any already
// pending tasks (the contrary would break the SequencedTaskRunner
// contract).
explicit ScopedContext(scoped_refptr<TestMockTimeTaskRunner> scope);
ScopedClosureRunner on_destroy_;
enum class Type {
// A TestMockTimeTaskRunner which can only be driven directly through its
// API. Thread/SequencedTaskRunnerHandle will refer to it only in the scope
// of its tasks.
// A TestMockTimeTaskRunner which will associate to the thread it is created
// on, enabling RunLoop to drive it and making
// Thread/SequencedTaskRunnerHandle refer to it on that thread.
// Constructs an instance whose virtual time will start at the Unix epoch, and
// whose time ticks will start at zero.
TestMockTimeTaskRunner(Type type = Type::kStandalone);
// Constructs an instance starting at the given virtual time and time ticks.
TestMockTimeTaskRunner(Time start_time,
TimeTicks start_ticks,
Type type = Type::kStandalone);
// Fast-forwards virtual time by |delta|, causing all tasks with a remaining
// delay less than or equal to |delta| to be executed. |delta| must be
// non-negative.
void FastForwardBy(TimeDelta delta);
// Fast-forwards virtual time by |delta| but not causing any task execution.
void AdvanceMockTickClock(TimeDelta delta);
// Fast-forward virtual time, but not tick time. May be useful for testing
// timers when simulating suspend/resume or time adjustments. As it doesn't
// advance tick time, no tasks are automatically processed
// (ProcessAllTasksNoLaterThan is not called).
void AdvanceWallClock(TimeDelta delta);
// Fast-forwards virtual time just until all tasks are executed.
void FastForwardUntilNoTasksRemain();
// Executes all tasks that have no remaining delay. Tasks with a remaining
// delay greater than zero will remain enqueued, and no virtual time will
// elapse.
void RunUntilIdle();
// Clears the queue of pending tasks without running them.
void ClearPendingTasks();
// Returns the current virtual time (initially starting at the Unix epoch).
Time Now() const;
// Returns the current virtual tick time (initially starting at 0).
TimeTicks NowTicks() const;
// Returns a Clock that uses the virtual time of |this| as its time source.
// The returned Clock will hold a reference to |this|.
Clock* GetMockClock() const;
// Returns a TickClock that uses the virtual time ticks of |this| as its tick
// source. The returned TickClock will hold a reference to |this|.
const TickClock* GetMockTickClock() const;
// Cancelled pending tasks get pruned automatically.
base::circular_deque<TestPendingTask> TakePendingTasks();
bool HasPendingTask();
size_t GetPendingTaskCount();
TimeDelta NextPendingTaskDelay();
// SingleThreadTaskRunner:
bool RunsTasksInCurrentSequence() const override;
bool PostDelayedTask(const Location& from_here,
OnceClosure task,
TimeDelta delay) override;
bool PostNonNestableDelayedTask(const Location& from_here,
OnceClosure task,
TimeDelta delay) override;
~TestMockTimeTaskRunner() override;
// Called before the next task to run is selected, so that subclasses have a
// last chance to make sure all tasks are posted.
virtual void OnBeforeSelectingTask();
// Called after the current mock time has been incremented so that subclasses
// can react to the passing of time.
virtual void OnAfterTimePassed();
// Called after each task is run so that subclasses may perform additional
// activities, e.g., pump additional task runners.
virtual void OnAfterTaskRun();
class NonOwningProxyTaskRunner;
// MockClock implements TickClock and Clock. Always returns the then-current
// mock time of |task_runner| as the current time or time ticks.
class MockClock : public TickClock, public Clock {
explicit MockClock(TestMockTimeTaskRunner* task_runner)
: task_runner_(task_runner) {}
// TickClock:
TimeTicks NowTicks() const override;
// Clock:
Time Now() const override;
TestMockTimeTaskRunner* task_runner_;
struct TestOrderedPendingTask;
// Predicate that defines a strict weak temporal ordering of tasks.
class TemporalOrder {
bool operator()(const TestOrderedPendingTask& first_task,
const TestOrderedPendingTask& second_task) const;
typedef std::priority_queue<TestOrderedPendingTask,
TemporalOrder> TaskPriorityQueue;
// Core of the implementation for all flavors of fast-forward methods. Given a
// non-negative |max_delta|, runs all tasks with a remaining delay less than
// or equal to |max_delta|, and moves virtual time forward as needed for each
// processed task. Pass in TimeDelta::Max() as |max_delta| to run all tasks.
void ProcessAllTasksNoLaterThan(TimeDelta max_delta);
// Forwards |now_ticks_| until it equals |later_ticks|, and forwards |now_| by
// the same amount. Calls OnAfterTimePassed() if |later_ticks| > |now_ticks_|.
// Does nothing if |later_ticks| <= |now_ticks_|.
void ForwardClocksUntilTickTime(TimeTicks later_ticks);
// Returns the |next_task| to run if there is any with a running time that is
// at most |reference| + |max_delta|. This additional complexity is required
// so that |max_delta| == TimeDelta::Max() can be supported.
bool DequeueNextTask(const TimeTicks& reference,
const TimeDelta& max_delta,
TestPendingTask* next_task);
// RunLoop::Delegate:
void Run(bool application_tasks_allowed, TimeDelta timeout) override;
void Quit() override;
void EnsureWorkScheduled() override;
// Also used for non-dcheck logic (RunsTasksInCurrentSequence()) and as such
// needs to be a ThreadCheckerImpl.
ThreadCheckerImpl thread_checker_;
Time now_;
TimeTicks now_ticks_;
// Temporally ordered heap of pending tasks. Must only be accessed while the
// |tasks_lock_| is held.
TaskPriorityQueue tasks_;
// The ordinal to use for the next task. Must only be accessed while the
// |tasks_lock_| is held.
size_t next_task_ordinal_ = 0;
mutable Lock tasks_lock_;
ConditionVariable tasks_lock_cv_;
const scoped_refptr<NonOwningProxyTaskRunner> proxy_task_runner_;
std::unique_ptr<ThreadTaskRunnerHandle> thread_task_runner_handle_;
// Set to true in RunLoop::Delegate::Quit() to signal the topmost
// RunLoop::Delegate::Run() instance to stop, reset to false when it does.
bool quit_run_loop_ = false;
mutable MockClock mock_clock_;
} // namespace base