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path: root/pkg/tcpip/timer.go
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2020-07-12Do not copy sleep.WakerGhanan Gowripalan
sleep.Waker's fields are modified as values. PiperOrigin-RevId: 320873451
2020-04-24Do not copy tcpip.CancellableTimerGhanan Gowripalan
A CancellableTimer's AfterFunc timer instance creates a closure over the CancellableTimer's address. This closure makes a CancellableTimer unsafe to copy. No behaviour change, existing tests pass. PiperOrigin-RevId: 308306664
2020-04-20Prevent race when reassigning CancellableTimerGhanan Gowripalan
Capture a timer's locker for each instance of a CancellableTimer so that reassigning a tcpip.CancellableTimer does not cause a data race. Reassigning a tcpip.CancellableTimer updates its underlying locker. When a timer fires, it does a read of the timer's locker variable to lock it. This read of the locker was not synchronized so a race existed where one goroutine may reassign the timer (updating the locker) and another handles the timer firing (attempts to lock the timer's locker). Test: tcpip_test.TestCancellableTimerReassignment PiperOrigin-RevId: 307499822
2020-01-08CancellableTimer to encapsulate the work of safely stopping timersGhanan Gowripalan
Add a new CancellableTimer type to encapsulate the work of safely stopping timers when it fires at the same time some "related work" is being handled. The term "related work" is some work that needs to be done while having obtained some common lock (L). Example: Say we have an invalidation timer that may be extended or cancelled by some event. Creating a normal timer and simply cancelling may not be sufficient as the timer may have already fired when the event handler attemps to cancel it. Even if the timer and event handler obtains L before doing work, once the event handler releases L, the timer will eventually obtain L and do some unwanted work. To prevent the timer from doing unwanted work, it checks if it should early return instead of doing the normal work after obtaining L. When stopping the timer callers must have L locked so the timer can be safely informed that it should early return. Test: Tests that CancellableTimer fires and resets properly. Test to make sure the timer fn is not called after being stopped within the lock L. PiperOrigin-RevId: 288806984