Use a TickClock instead of TimeTicks::Now() in Timer.
Code that uses a Timer cannot be unit tested without using sleep
or a mock timer because Timer uses TimeTicks::Now() to calculate the
run time for scheduled tasks. Using sleep makes tests slow and
unreliable, and using mock timers frequently requires unit tests to
have knowledge of internal implementation details of the code being
tested. By using a TickClock, tests can provide a mock implementation
of the TickClock that can be advanced without the use of sleep,
allowing tests to reliably verify the behavior of code as time
advances.
BUG=internal b/32644077
Review-Url: https://codereview.chromium.org/2484023002
Cr-Commit-Position: refs/heads/master@{#432113}
diff --git a/base/timer/timer.cc b/base/timer/timer.cc
index e554905..aba8fc8d 100644
--- a/base/timer/timer.cc
+++ b/base/timer/timer.cc
@@ -6,11 +6,15 @@
#include <stddef.h>
+#include <utility>
+
#include "base/logging.h"
+#include "base/memory/ptr_util.h"
#include "base/memory/ref_counted.h"
#include "base/single_thread_task_runner.h"
#include "base/threading/platform_thread.h"
#include "base/threading/thread_task_runner_handle.h"
+#include "base/time/tick_clock.h"
namespace base {
@@ -60,26 +64,36 @@
};
Timer::Timer(bool retain_user_task, bool is_repeating)
- : scheduled_task_(NULL),
+ : Timer(retain_user_task, is_repeating, nullptr) {}
+
+Timer::Timer(bool retain_user_task, bool is_repeating, TickClock* tick_clock)
+ : scheduled_task_(nullptr),
thread_id_(0),
is_repeating_(is_repeating),
retain_user_task_(retain_user_task),
- is_running_(false) {
-}
+ tick_clock_(tick_clock),
+ is_running_(false) {}
Timer::Timer(const tracked_objects::Location& posted_from,
TimeDelta delay,
const base::Closure& user_task,
bool is_repeating)
- : scheduled_task_(NULL),
+ : Timer(posted_from, delay, user_task, is_repeating, nullptr) {}
+
+Timer::Timer(const tracked_objects::Location& posted_from,
+ TimeDelta delay,
+ const base::Closure& user_task,
+ bool is_repeating,
+ TickClock* tick_clock)
+ : scheduled_task_(nullptr),
posted_from_(posted_from),
delay_(delay),
user_task_(user_task),
thread_id_(0),
is_repeating_(is_repeating),
retain_user_task_(true),
- is_running_(false) {
-}
+ tick_clock_(tick_clock),
+ is_running_(false) {}
Timer::~Timer() {
StopAndAbandon();
@@ -123,7 +137,7 @@
// Set the new desired_run_time_.
if (delay_ > TimeDelta::FromMicroseconds(0))
- desired_run_time_ = TimeTicks::Now() + delay_;
+ desired_run_time_ = Now() + delay_;
else
desired_run_time_ = TimeTicks();
@@ -139,6 +153,10 @@
PostNewScheduledTask(delay_);
}
+TimeTicks Timer::Now() const {
+ return tick_clock_ ? tick_clock_->NowTicks() : TimeTicks::Now();
+}
+
void Timer::SetTaskInfo(const tracked_objects::Location& posted_from,
TimeDelta delay,
const base::Closure& user_task) {
@@ -155,7 +173,7 @@
GetTaskRunner()->PostDelayedTask(posted_from_,
base::Bind(&BaseTimerTaskInternal::Run, base::Owned(scheduled_task_)),
delay);
- scheduled_run_time_ = desired_run_time_ = TimeTicks::Now() + delay;
+ scheduled_run_time_ = desired_run_time_ = Now() + delay;
} else {
GetTaskRunner()->PostTask(posted_from_,
base::Bind(&BaseTimerTaskInternal::Run, base::Owned(scheduled_task_)));
@@ -189,9 +207,9 @@
// First check if we need to delay the task because of a new target time.
if (desired_run_time_ > scheduled_run_time_) {
- // TimeTicks::Now() can be expensive, so only call it if we know the user
- // has changed the desired_run_time_.
- TimeTicks now = TimeTicks::Now();
+ // Now() can be expensive, so only call it if we know the user has changed
+ // the desired_run_time_.
+ TimeTicks now = Now();
// Task runner may have called us late anyway, so only post a continuation
// task if the desired_run_time_ is in the future.
if (desired_run_time_ > now) {
