5b0e8a1292
90: Move "last_state = state" assignment r=adamgreig a=adamgreen
I believe that I have found a bug in the samples found in the concurrency chapter where the value of the `last_state` variable should be updated on each loop iteration but it is only updated on the detection of the first leading edge. For example:
```rust
loop {
let state = read_signal_level();
if state && !last_state {
last_state = state;
// DANGER - Not actually safe! Could cause data races.
unsafe { COUNTER += 1 };
}
}
```
I think that loop should actually be written as:
```rust
loop {
let state = read_signal_level();
if state && !last_state {
// DANGER - Not actually safe! Could cause data races.
unsafe { COUNTER += 1 };
}
last_state = state;
}
```
As the code exists today, I think it would detect the first leading edge, set last_state to true and then never be updated again which would also mean that it never detects another leading edge.
Co-authored-by: Adam Green <adamgreen@users.noreply.github.com>
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