[core] Improved periodic NAK report timing #961
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maxsharabayko
added
Type: Maintenance
ethouris
reviewed
Nov 14, 2019
srtcore/core.cpp
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| { | ||
| // If there are no losses so far, update the next NACK time, | ||
| // so that a loss report is not sent too erly right after a new loss happens. | ||
| m_ullNextNAKTime_tk = currtime_tk + m_ullNAKInt_tk; |
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This instruction can be now common for both conditions
|
ethouris
approved these changes
Nov 14, 2019
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Periodic NAK Reports
Periodic NAK report is a mechanism for the receiver to periodically resend reports on the current loss list. Roughly, NAK interval equals to
max(300ms; RTT / 2). More precise description is here.Problem Statement
Periodic NAK report timing has several minor issues. They are mainly described in #701.
Those issues can be split into two groups:
Suggested Fix
CUDT::checkNAKTimer()is called with every incoming packet. Previously it was only checking if it is time to send NAK report. But if the receiver's loss list is empty, nothing happens.This means a newly detected loss, observed after more than 300 ms from previous LOSS, will trigger sending immediate loss report, and almost immediate periodic NAK report with the same sequence range.
In this PR the
m_ullNextNAKTime_tkis updated in case the receiver's loss list is empty. This fixes group 1 problems.