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selectabletimer: add mutex to start() and stop() #614

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merged 3 commits into from
May 11, 2022

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ds952811
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Add mutex protection to avoid having the timer expiration reset due to
subsequent calls of start()

Avoid having the timer expiration reset due to subsequent calls of start()

Add mutex protection to start() and stop()

Signed-off-by: Dante Su [email protected]

Add mutex protection to avoid having the timer expiration reset due to
subsequent calls of start()

Avoid having the timer expiration reset due to subsequent calls of start()

Add mutex protection to start() and stop()

Signed-off-by: Dante Su <[email protected]>
@adyeung
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adyeung commented May 5, 2022

@zhangyanzhao @yxieca @qiluo-msft pls help signoff and merge

@@ -21,6 +21,7 @@ SelectableTimer::SelectableTimer(const timespec& interval, int pri)
SWSS_LOG_THROW("failed to create timerfd, errno: %s", strerror(errno));
}
setInterval(interval);
m_alive = false;
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@qiluo-msft qiluo-msft May 6, 2022

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m_alive

better name m_running. #Closed

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Done

@@ -36,22 +37,40 @@ SelectableTimer::~SelectableTimer()

void SelectableTimer::start()
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@qiluo-msft qiluo-msft May 6, 2022

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start

Could you add new test case which will fail with original code? #Closed

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Done

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@ds952811 ds952811 May 9, 2022

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Please refer to timer_ut.cpp: line 43-51

@@ -653,42 +653,6 @@ TEST(DBConnector, selectableevent)
EXPECT_EQ(value, 2);
}

TEST(DBConnector, selectabletimer)
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Moved to timer_ut.cpp

ASSERT_EQ(result, Select::OBJECT);
ASSERT_EQ(sel, &timer);

// Check if the timer gets reset by subsequent timer.start()
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Check if the timer gets reset by subsequent timer.start()

Could you help me understand what is the behavior of original code in this testcase? How does it fail?

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In the case of original code, since the timer is created with flag=0, a relative timer is started, and everytime that timer.start() gets invoked, timerfd_settime() will reset the timeout based on the current timestamp, hence it will cause unexpected delay here.

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Do you mean original code will fail on this line?

ASSERT_EQ(result, Select::OBJECT);

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Yes, it'll fail at that line without the changes in the PR

@qiluo-msft qiluo-msft merged commit a90b2b7 into sonic-net:master May 11, 2022
itamar-talmon pushed a commit to itamar-talmon/sonic-swss-common that referenced this pull request Jul 19, 2022
Add mutex protection to avoid having the timer expiration reset due to
subsequent calls of start()

Avoid having the timer expiration reset due to subsequent calls of start()

Add mutex protection to start() and stop()
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3 participants