cranelift

rust jit wasm webassembly runtime wasi cranelift sandbox wasmtime

Tyler Rockwood 85c0a2df54 Switch to simpler fuel APIs (#7298 ) In an effort to simplify the many fuel related APIs, simplify the interface here to a single counter with get and set methods. Additionally the async yield is reduced to an interval of the total fuel instead of injecting fuel, so it's easy to still reason about how much fuel is left even with yielding turned on. Internally this works by keeping two counters - one the VM uses to increment towards 0 for fuel, the other to track how much is in "reserve". Then when we're out of gas, we pull from the reserve to refuel and continue. We use the reserve in two cases: one for overflow of the fuel (which is an i64 and the API expresses fuel as u64) and the other for async yieling, which then the yield interval acts as a cap to how much we can refuel with. This also means that `get_fuel` can return the full range of `u64` before this change it could only return up to `i64::MAX`. This is important because this PR is removing the functionality to track fuel consumption, and this makes the API less error prone for embedders to track consumption themselves. Careful to note that the VM counter that is stored as `i64` can be positive if an instruction "costs" multiple units of fuel when the fuel ran out. prtest:full Signed-off-by: Tyler Rockwood <rockwood@redpanda.com>	1 year ago
..
wasm	Upgrade all crates to the Rust 2021 edition (#3991)	3 years ago
main.rs	Switch to simpler fuel APIs (#7298)	1 year ago

In an effort to simplify the many fuel related APIs, simplify the
interface here to a single counter with get and set methods.
Additionally the async yield is reduced to an interval of the total fuel
instead of injecting fuel, so it's easy to still reason about how much
fuel is left even with yielding turned on.

Internally this works by keeping two counters - one the VM uses to
increment towards 0 for fuel, the other to track how much is in
"reserve". Then when we're out of gas, we pull from the reserve to
refuel and continue. We use the reserve in two cases: one for overflow
of the fuel (which is an i64 and the API expresses fuel as u64) and the
other for async yieling, which then the yield interval acts as a cap to
how much we can refuel with.

This also means that `get_fuel` can return the full range of `u64`
before this change it could only return up to `i64::MAX`. This is
important because this PR is removing the functionality to track fuel
consumption, and this makes the API less error prone for embedders to
track consumption themselves.

Careful to note that the VM counter that is stored as `i64` can be
positive if an instruction "costs" multiple units of fuel when the fuel
ran out.

prtest:full

Signed-off-by: Tyler Rockwood <rockwood@redpanda.com>

1 year ago

wasm

Upgrade all crates to the Rust 2021 edition (#3991)

3 years ago

main.rs

Switch to simpler fuel APIs (#7298)

1 year ago