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#1952 P25 Traffic Channel Manager Aggregating Multiple Call Events Into One #1953

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Merged
merged 1 commit into from
Aug 23, 2024
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#1952 P25 Traffic Channel Manager Aggregating Multiple Call Events Into One #1953

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101 changes: 95 additions & 6 deletions src/main/java/io/github/dsheirer/module/decode/p25/P25TrafficChannelManager.java
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,7 @@ public class P25TrafficChannelManager extends TrafficChannelManager implements I
private static final LoggingSuppressor LOGGING_SUPPRESSOR = new LoggingSuppressor(mLog);
public static final String CHANNEL_START_REJECTED = "CHANNEL START REJECTED";
public static final String MAX_TRAFFIC_CHANNELS_EXCEEDED = "MAX TRAFFIC CHANNELS EXCEEDED";
private static final long STALE_EVENT_THRESHOLD_MS = 2000;

private Queue<Channel> mAvailablePhase1TrafficChannelQueue = new LinkedTransferQueue<>();
private List<Channel> mManagedPhase1TrafficChannels;
Expand Down Expand Up @@ -366,8 +367,28 @@ public void processP2CurrentUser(long frequency, int timeslot, Identifier identi

try
{
DecodeEvent event = timeslot == P25P1Message.TIMESLOT_1 ?
mTS1ChannelGrantEventMap.get(frequency) : mTS2ChannelGrantEventMap.get(frequency);
DecodeEvent event = null;

if(timeslot == P25P1Message.TIMESLOT_1)
{
event = mTS1ChannelGrantEventMap.get(frequency);

if(isStaleEvent(event, timestamp))
{
event = null;
mTS1ChannelGrantEventMap.remove(frequency);
}
}
else if(timeslot == P25P1Message.TIMESLOT_2)
{
event = mTS2ChannelGrantEventMap.get(frequency);

if(isStaleEvent(event, timestamp))
{
event = null;
mTS1ChannelGrantEventMap.remove(frequency);
}
}

if(event != null)
{
Expand Down Expand Up @@ -408,8 +429,28 @@ public IChannelDescriptor processP2CurrentUser(long frequency, int timeslot, ICh

try
{
DecodeEvent event = timeslot == P25P1Message.TIMESLOT_1 ?
mTS1ChannelGrantEventMap.get(frequency) : mTS2ChannelGrantEventMap.get(frequency);
DecodeEvent event = null;

if(timeslot == P25P1Message.TIMESLOT_1)
{
event = mTS1ChannelGrantEventMap.get(frequency);

if(isStaleEvent(event, timestamp))
{
event = null;
mTS1ChannelGrantEventMap.remove(frequency);
}
}
else if(timeslot == P25P1Message.TIMESLOT_2)
{
event = mTS2ChannelGrantEventMap.get(frequency);

if(isStaleEvent(event, timestamp))
{
event = null;
mTS2ChannelGrantEventMap.remove(frequency);
}
}

if(event != null)
{
Expand Down Expand Up @@ -751,10 +792,22 @@ public void processP1ChannelUpdate(APCO25Channel channel, ServiceOptions service
if(channel.isTDMAChannel() && channel.getTimeslot() == P25P1Message.TIMESLOT_2)
{
event = mTS2ChannelGrantEventMap.get(channel.getDownlinkFrequency());
// If the event is stale, remove it and allow a new event to be created.
if(isStaleEvent(event, timestamp))
{
event = null;
mTS2ChannelGrantEventMap.remove(channel.getDownlinkFrequency());
}
}
else
{
event = mTS1ChannelGrantEventMap.get(channel.getDownlinkFrequency());
// If the event is stale, remove it and allow a new event to be created.
if(isStaleEvent(event, timestamp))
{
event = null;
mTS1ChannelGrantEventMap.remove(channel.getDownlinkFrequency());
}
}

//If we have an event, update it. Otherwise, make sure we have the traffic channel allocated
Expand All @@ -763,8 +816,7 @@ public void processP1ChannelUpdate(APCO25Channel channel, ServiceOptions service
event.update(timestamp);
broadcast(event);
}
else if(channel.getDownlinkFrequency() > 0 &&
!mAllocatedTrafficChannelMap.containsKey(channel.getDownlinkFrequency()))
else
{
processP1ChannelGrant(channel, serviceOptions, ic, opcode, timestamp);
}
Expand Down Expand Up @@ -799,6 +851,24 @@ public void closeP1CallEvent(long frequency, long timestamp)
}
}

/**
* Indicates if the event is stale and should be replaced with a new decode event. Compares the event down time
* to the reference timestamp argument and indicates if that staleness exceeds a staleness threshold (2 seconds).
*
* Note: some decode events can remain in the channel grant event map if a traffic channel is not allocated for the
* event (ie tuner unavailable). The control channel only tells us that the traffic channel is active, but doesn't
* tell us when the traffic channel is torn down. So, we use this staleness evaluation to remove stale events that
* are left over from a previous traffic channel allocation.
*
* @param decodeEvent to evaluate
* @param timestamp for reference of event staleness.
* @return true if the event is stale.
*/
private static boolean isStaleEvent(DecodeEvent decodeEvent, long timestamp)
{
return decodeEvent != null && (timestamp - decodeEvent.getTimeEnd() > STALE_EVENT_THRESHOLD_MS);
}

/**
* Processes Phase 1 channel grants to allocate traffic channels and track overall channel usage. Generates
* decode events for each new channel that is allocated.
Expand All @@ -820,6 +890,13 @@ private void processPhase1ChannelGrant(APCO25Channel apco25Channel, ServiceOptio

P25ChannelGrantEvent event = mTS1ChannelGrantEventMap.get(frequency);

// If the event is stale, remove it and allow a new event to be created.
if(isStaleEvent(event, timestamp))
{
event = null;
mTS1ChannelGrantEventMap.remove(frequency);
}

if(event != null && isSameCallUpdate(identifierCollection, event.getIdentifierCollection()))
{
Identifier from = identifierCollection.getFromIdentifier();
Expand Down Expand Up @@ -973,10 +1050,22 @@ private DecodeEvent processPhase2ChannelGrant(APCO25Channel apco25Channel, Servi
if(timeslot == P25P1Message.TIMESLOT_0 || timeslot == P25P1Message.TIMESLOT_1)
{
event = mTS1ChannelGrantEventMap.get(frequency);
// If the event is stale, remove it and allow a new event to be created.
if(isStaleEvent(event, timestamp))
{
event = null;
mTS1ChannelGrantEventMap.remove(frequency);
}
}
else if(timeslot == P25P1Message.TIMESLOT_2)
{
event = mTS2ChannelGrantEventMap.get(frequency);
// If the event is stale, remove it and allow a new event to be created.
if(isStaleEvent(event, timestamp))
{
event = null;
mTS2ChannelGrantEventMap.remove(frequency);
}
}
else
{
Expand Down
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