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RPC delay metrics #2293

Merged
merged 5 commits into from
Jul 3, 2024
Merged

RPC delay metrics #2293

merged 5 commits into from
Jul 3, 2024

Commits on Jun 25, 2024

  1. rpc: Fix hard-coded constants when sending unknown verb reply 

    Ths code should stick to response_frame_headroom constant, not introduce
magic numbers on its own.

Signed-off-by: Pavel Emelyanov <[email protected]>
    @xemul
    xemul committed Jun 25, 2024
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  2. rpc: Track handler execution time 

    Note the time it took handler (server-side) callback to run and
propagate it via optional argument down to .respond() method. Error
handlers call respond() too, pass this argument disengaged in this case.

Signed-off-by: Pavel Emelyanov <[email protected]>
    @xemul
    xemul committed Jun 25, 2024
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  3. rpc: Exchange handler duration with server responses 

    Introduce new negotiation parameter that tells if the client wants
server to send it back the handler execution duration. This is for
compatibility with older clients that expect server reply to be of some
fixed (shorter) size.

New response frame, if negotiated, includes the 32 bit handler duration
value in microseconds right next to the existing bits. If no duration
was provided (sending error response, for example), the value is 0xF..F.
After parsing, the duration is returned as optional value and 0xF..F
maps to disengaged one.

For now client makes no use of it, next patch will.

Signed-off-by: Pavel Emelyanov <[email protected]>
    @xemul
    xemul committed Jun 25, 2024
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  4. rpc: Calculate delay and export it via metrics 

    Now the client has two durations using which it can estimate the
rount-trip time of a packet -- the duration between sending request and
receiving response and the time it too handler to execute on the server
side. Difference is the delay value.

Those values from different calls are accumulated in a client counter as
well as the total number of delay samples received (errors and old
servers don't send it). Metrics export both as counters, so one can rate
it over time and monitor average delay.

Signed-off-by: Pavel Emelyanov <[email protected]>
    @xemul
    xemul committed Jun 25, 2024
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  5. test,rpc: Extend simple ping-pong case 

    By default RPC client uses new frames, that include handler execution
time. Tune up one simple test to validate that legacy frames still work
too.

Signed-off-by: Pavel Emelyanov <[email protected]>
    @xemul
    xemul committed Jun 25, 2024
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