[OpenSIPS-Devel] [opensips] Slot Based Taildrop algorithm for ratelimit (#728)

[Ionut Ionita]

    In this new algorithm a window is held per every pipe,
which is defined by two parameters: window_size(seconds) and
slot_period(microseconds). The number of slots is
window_size*1000/slot_period. The window is updated with every
call received and it's implemented as a circular vector, which
modifies it's start based on the elements that were dropped.

How is the window updated:
* if no message comes in 2*window_time from when the window start
was set , it means we can't use the values from any of the slots
and we set the value from any of the slots to 0; the window start
time is updated;
* if the message comes in t=[start+window_time; start+2*window_time)
it means that we can keep the values in slots in the interval
[t-window_time;start+window_time) and drop the ones in
[window_time; t-window_time); the window start time is updated;
* it the message come in t=[start; start+window_time) we don't
do any update do the window, only to the value of the slot corresponding
to time t;

The algorithm also shares this value through bin interface, allowing
having the values from all the replicas. Also, before sending the
value through the interface, the replica checks the window in order
to send only the values in valid slots. Two different functions
were made because of efficiency reasons. When replicating
we only do some very short loops or maybe nothing.
You can view, comment on, or merge this pull request online at:

  https://github.com/OpenSIPS/opensips/pull/728

-- Commit Summary --

  * Slot Based Taildrop algorithm for ratelimit

-- File Changes --

    M modules/ratelimit/README (61)
    M modules/ratelimit/doc/ratelimit_admin.xml (91)
    M modules/ratelimit/ratelimit.c (129)
    M modules/ratelimit/ratelimit.h (19)
    M modules/ratelimit/ratelimit_helper.c (81)

-- Patch Links --

https://github.com/OpenSIPS/opensips/pull/728.patch
https://github.com/OpenSIPS/opensips/pull/728.diff

---
Reply to this email directly or view it on GitHub:
https://github.com/OpenSIPS/opensips/pull/728
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