296: Slot no more: overhauled internal algorithm r=nikomatsakis a=nikomatsakis
This is the overhauled implementation that avoids slots, is more parallel friendly, and paves the way to fixed point and more expressive cycle handling.
We just spent 90 minutes going over it. [Some rough notes are available here,](https://hackmd.io/6x9f6mavTRS2imfG96tP5A) and a video will be posted soon.
You may find the [flowgraph useful](https://raw.githubusercontent.com/nikomatsakis/salsa/slot-no-more/book/src/derived-query-read.drawio.svg).
Co-authored-by: Niko Matsakis <niko@alum.mit.edu>
This change resolves a fixme that referenced #120.
This change breaks no tests, and, if I understand
correctly, does not affect user-facing API.
Here is the difference for the `HelloWorldGroupStorage__` struct
generated from macros in the `hello_world` example:
**Before:**
```rs
struct HelloWorldGroupStorage__ {
pub input_string:std::sync::Arc<<InputStringQuery as salsa::Query> ::Storage> ,pub length:std::sync::Arc<<LengthQuery as salsa::Query> ::Storage> ,
}
```
**After:**
```rs
struct HelloWorldGroupStorage__ {
input_string:std::sync::Arc<<InputStringQuery as salsa::Query> ::Storage> ,length:std::sync::Arc<<LengthQuery as salsa::Query> ::Storage> ,
}
```
Instead of grabbing the arc, just pass back an `&mut Runtime`.
The eventual goal is to get rid of the lock on the `set` pathway
altogether, but one step at a time.
290: Update doc in macro about query.in_db for dyn db r=nikomatsakis a=mheiber
Update the macro for `query_group` so the comment
on `fn in_db` no longer says that it is more common
to use the trait method on `db`.
Afaict, the trait methods referred to were removed
when dyn database were introduced in RFC0006:
./book/src/rfcs/RFC0006-Dynamic-Databases.md, as
described in the section
"Instead of `db.query(Q)`, you write `Q.in_db(&db)`"
Co-authored-by: Maxwell Elliot Heiber <mheiber@fb.com>
Update the macro for `query_group` so the comment
on `fn in_db` no longer says that it is more common
to use the trait method on `db`.
Afaict, the trait methods referred to were removed
when dyn database were introduced in RFC0006:
./book/src/rfcs/RFC0006-Dynamic-Databases.md, as
described in the section
"Instead of `db.query(Q)`, you write `Q.in_db(&db)`"
Rather than checking return value of from `Q::cycle_fallback`, we
now consult the computed recovery strategy to decide whether to
panic or to recover. We can thus assume that we will successfully
recover and don't need to check for `None` results anymore.
