*: implements health check #518
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This PR provides simple health check implementations referring to the go version. It provides a `HealthService` to maintain the service statuses and wake up watchers. Signed-off-by: Jay Lee <BusyJayLee@gmail.com>
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Most code are generated by protobuf and prost, you can just skip them as long as it compiles. |
Signed-off-by: Jay Lee <BusyJayLee@gmail.com>
Signed-off-by: Jay Lee <BusyJayLee@gmail.com>
This reverts commit c320d22. Signed-off-by: Jay Lee <BusyJayLee@gmail.com>
health/src/service.rs
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| /// Updates the status to specified one and update version. | ||
| fn broadcast(&self, status: ServingStatus) { | ||
| let mut subscribers = self.subscribers.lock().unwrap(); | ||
| let state = self.state.load(Ordering::Acquire); |
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Guarded by the subscribers mutex, I think it can be Relaxed.
health/src/service.rs
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| let mut subscribers = s.cast.subscribers.lock().unwrap(); | ||
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| let cur_state = s.cast.state.load(Ordering::Acquire); |
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It can be Relaxed because a mutex has memory fence itself.
health/src/service.rs
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| let mut subscribers = self.subscribers.lock().unwrap(); | ||
| let state = self.state.load(Ordering::Acquire); | ||
| let new_state = ((state + VERSION_STEP) & !STATUS_MASK) | (status as usize); | ||
| self.state.store(new_state, Ordering::Release); |
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And because L74 loads with Relaxed, this can be Relaxed as well.
Signed-off-by: Jay Lee <BusyJayLee@gmail.com>
Signed-off-by: Jay Lee <BusyJayLee@gmail.com>
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Code generated by protobuf-build in TiKV will change struct's name, so it's impossible to make them compatible with each other when generate code dynamically. Instead, I use code generated by an old version of protobuf and inline them. |
Signed-off-by: Jay Lee <BusyJayLee@gmail.com>
health/tests/health_check.rs
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| @@ -0,0 +1,161 @@ | |||
| // Copyright 2019 TiKV Project Authors. Licensed under Apache-2.0. | |||
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| // Copyright 2019 TiKV Project Authors. Licensed under Apache-2.0. | |
| // Copyright 2021 TiKV Project Authors. Licensed under Apache-2.0. |
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| let mut subscribers = s.cast.subscribers.lock().unwrap(); | ||
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| let cur_state = s.cast.state.load(Ordering::Relaxed); |
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The first check is a fast path. Only section protected by lock can guarantee state is not updated by others.
| impl StatusCast { | ||
| fn new(status: ServingStatus) -> StatusCast { | ||
| StatusCast { | ||
| state: AtomicUsize::new(VERSION_STEP | (status as usize)), |
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why we can't use status directly?
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Then you can't solve the ABA problem.
Signed-off-by: Jay Lee <BusyJayLee@gmail.com>
…impl-health-server Signed-off-by: Jay Lee <BusyJayLee@gmail.com>
This PR provides simple health check implementations referring to the go
version. It provides a
HealthServiceto maintain the service statusesand wake up watchers.
I use a standalone crate to avoid introduce grpc specific code into the grpcio
crate. And I don't reuse grpcio-proto to avoid the dependency of protobuf-build
which just make things complicated by introducing a lot of dependencies and
resulting in a dependency circle.