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Merge pull request #46135 from DanRoscigno/add-mermaid

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Use mermaid chart in dev architecture doc
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Alexey Milovidov 2023-02-08 01:30:50 +03:00 committed by GitHub
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docs/en/development/architecture.md
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@ -198,7 +198,19 @@ Each slot can be seen as an independent state machine with the following states:
Note that `allocated` slot can be in two different states: `granted` and `acquired`. The former is a transitional state, that actually should be short (from the instant when a slot is allocated to a query till the moment when the up-scaling procedure is run by any thread of that query).
![state diagram](@site/docs/en/development/images/concurrency.png)
```mermaid
stateDiagram-v2
direction LR
[*] --> free
free --> allocated: allocate
state allocated {
direction LR
[*] --> granted
granted --> acquired: acquire
acquired --> [*]
}
allocated --> free: release
```
API of `ConcurrencyControl` consists of the following functions:
1. Create a resource allocation for a query: `auto slots = ConcurrencyControl::instance().allocate(1, max_threads);`. It will allocate at least 1 and at most `max_threads` slots. Note that the first slot is granted immediately, but the remaining slots may be granted later. Thus limit is soft, because every query will obtain at least one thread.