Mark empty slots with invalid msgid, and don't try to unsubscribe all on them

[skliper]

Is your feature request related to a problem? Please describe.
Unsubscribe all currently loops through the entire table unsubscribing, including the MSGID 0x0's (which is a valid MSGID). This causes numerous errors:

EVS Port1 66/1/CFE_SB 12: Unsubscribe Err:No subs for Msg 0x0 on TO_LAB_TLM_PIPE,app TO_LAB_APP

Describe the solution you'd like
Mark as invalid, skip invalid

Describe alternatives you've considered
Keep a count

Additional context
Observed in fixing #71

Requester Info
Jacob Hageman - NASA/GSFC

[thnkslprpt]

@skliper could we just change the if condition before the attempt to unsubscribe:

to_lab/fsw/src/to_lab_cmds.c

Line 205 in 9b1d6d0

if (CFE_SB_IsValidMsgId(SubEntry->Stream))

to something like this?

if ((CFE_SB_IsValidMsgId(SubEntry->Stream)) && (CFE_SB_MsgIdToValue(SubEntry->Stream) != 0))

[skliper]

This issue is likely obsolete, since CFE_SB_INVALID_MSG_ID is now 0:
https://github.com/nasa/cFE/blob/7f5ebcd15032fe31e7ef0e5ff4ef624d51d66e16/modules/core_api/fsw/inc/cfe_sb_api_typedefs.h#L113

I suggest sending the to_lab remove all packets command and see if it now behaves as expected (shouldn't report errors on unsubscribing from 0x0).

[keegan-moore]

This looks related to #206

[thnkslprpt]

@skliper is right, this particular issue is cleared by the updates to the software bus.

test:

1980-012-14:03:20.61697 CFE_ES_Main: CFE_ES_Main entering APPS_INIT state
1980-012-14:03:20.61705 CFE_ES_Main: CFE_ES_Main entering OPERATIONAL state
EVS Port1 1980-012-14:03:21.00004 66/1/CFE_TIME 21: Stop FLYWHEEL
EVS Port1 1980-012-14:03:47.67451 66/1/SAMPLE_APP 3: SAMPLE: NOOP command v7.0.0+dev0
EVS Port1 1980-012-14:03:56.75337 66/1/TO_LAB 18: TO: NOOP command. TO Lab v7.0.0+dev0 (Draco) v7.0.0 Official Release, EDS disabled
EVS Port1 1980-012-14:04:02.19682 66/1/TO_LAB 17: L228 TO Unsubscribed to all Commands and Telemetry

This issue can be closed as no longer relevant.