Read the BCM status before creating a Task #638
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Currently bus.send_periodic blindly wraps the BCM socket API, and sends a BCM operation with the TX_SETUP opcode. However, the semantics that the kernel driver provides are an "upsert". As such, when one attempts to create two Tasks with the same CAN Arbitration ID, it ends up silently modifying the periodic messages, which is contrary to what our API implies. This fixes the problem by first sending a TX_READ opcode with the CAN Arbitration ID that we wish to create. The kernel driver will return -EINVAL if a periodic transmission with the given Arbitration ID does not exist. If this is the case, then we can continue creating the Task, otherwise we error and notify the user. Fixes hardbyte#605
hardbyte approved these changes Jul 12, 2019
felixdivo reviewed Jul 13, 2019
Codecov Report
@@ Coverage Diff @@ ## develop #638 +/- ## =========================================== + Coverage 63.87% 63.89% +0.02% =========================================== Files 66 66 Lines 5946 5955 +9 =========================================== + Hits 3798 3805 +7 - Misses 2148 2150 +2 |
Codecov Report
@@ Coverage Diff @@ ## develop #638 +/- ## =========================================== - Coverage 63.87% 61.09% -2.78% =========================================== Files 66 66 Lines 5946 5953 +7 =========================================== - Hits 3798 3637 -161 - Misses 2148 2316 +168 |
felixdivo approved these changes Jul 14, 2019
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Currently
bus.send_periodicblindly wraps the BCM socket API, and sendsa BCM operation with the
TX_SETUPopcode. However, the semantics thatthe kernel driver provides are an "upsert". As such, when one attempts
to create two Tasks with the same CAN Arbitration ID, it ends up
silently modifying the periodic messages, which is contrary to what our
API implies.
This fixes the problem by first sending a
TX_READopcode with the CANArbitration ID that we wish to create. The kernel driver will return
-EINVALif a periodic transmission with the given Arbitration ID doesnot exist. If this is the case, then we can continue creating the Task,
otherwise we error and notify the user.
Fixes #605