Congestion control

[vetss]

We need to introduce a congestion control into jss7 library.

We can use the following congestion levels:
0 - no congestion
1 - minor level (just warning, no traffic limitaton)
2 - major level (new incoming from a peer TCAP dialogs are rejected, user application must reduce outgoing traffic issuing only for high priority messages)
3 - critical level (all incoming from a peer TCAP messages are rejected, user application must avoid of message sending)

1. we have to update "congestion" module to support several levels congestion. This module will provide MemoryCongestionMonitor for memory usage monitoring and ExecutorCongestionMonitor for monitoring of congestion in threads executing.

2. congestion for outgoing messages:

• sctp level must control the load of outgoing message buffer. After it becomes larger then a threadhold then SCTP Association must provide info for this
• m3ua level must check at the each writing procedure the congestion state of SCTP association and then following procedure by MTP spec for issuing of MTP-STATUS indication to the upper level
• m3ua level (and mtp stack) must provide a new listner method onMtp3EndCongestionMessage() which will be invoked when the congestion at SCTP part is gone
• sccp level must care of MTP-STATUS indications and process them as for SCCP spec and issue
  PCSTATE indication to upper levels. Congestion level is calculated per DCP and per networkID.
• sccp level must also calculate congestion and availability status for the whole networlId are and provide it for upper levels.
• TCAP must keep the congestion level for outgoing messages and provide it to upper levels (MAP / CAP stacks and MAP / CAP users).
• Stacks users must reduce traffic to a congested networkID / DPC

TCAPProvider provides methods for checking of congestion and availability status of networkId area:
FastMap<Integer, NetworkIdState> getNetworkIdStateList();
NetworkIdState getNetworkIdState(int networkId);

NetworkIdState:
public interface NetworkIdState {
boolean isAvailavle();
int getCongLevel();
}

3. congestion for incoming messages:

• MTP3 level has a management for threads that process incoming messages from a peer (ExecutorCongestionMonitor). We can monitor the congestion at this side and provide congestion level into TCAP level.
• TCAP must have MemoryCongestionMonitor on board + get data from all MTP3 levels ExecutorCongestionMonitors + upper stacks may provide info to TCAP stack for their congestion level + may be SLEE congestion level. All this will generate the level of the "TCAP + upper stacks" congestion level
• then this value is used at TCAP level for processing of incoming TCAP primitives.
  a) In case of level 2 TCAP will reject new dialogs with TC-PROVIDER-ABORT resource limitation error
  b) In case of level 3 TCAP will drop all incoming primitives

4. we can think also to reuse same threads for processing of putgoing TCAP messages for uniform.

[vetss]

this task "1) we have to update "congestion" module" was implemened by:
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[vetss]

this task "2) congestion for outgoing messages:" was implemented by:
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[vetss]

this task "3) congestion for incoming messages:" was implemented by:

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[vetss]

Multithreading test:
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