FLIP 255: Cadence WebAssembly API #256
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Hi @darkdrag00nv2 - This FLIP is not reflected on FLIP project tracker. Can you pls follow the process outlined in https://github.com/onflow/flips? Specifically the following would help show the FLIP on the project tracker-
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Looks good!
As we're finishing work on Cadence 1.0, we can finally come back to proposals like this. Thank you for your patience!
I left some comments and suggestions, and am happy to apply suggested edits and add remaining details. Does that sound good to you @darkdrag00nv2 ?
Once we addressed the outstanding issues, we can schedule to vote on it in the next WG call
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| ### Dependencies | ||
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| None |
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We'll likely won't implement a new WebAssembly runtime and use an existing one
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| While the specifics are dependant on the exact engine used, the high level idea is the following: | ||
| 1. FVM should provide a way to remaining computation units: A new function `RemainingComputation(kind)` will be added in FVM. | ||
| 2. Computation units should be converted to its WASM engine equivalent. For example, in wasmtime, it is called `Fuel`. |
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We'll need to define how fuel translates to computation usage in Flow
| 3. The user code must be executed with the computed amount of wasm engine computation units. | ||
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| ##### Memory | ||
| To limit the memory being consumed, some constraints will be defined on the various ways that memory is used in the wasm-engine. |
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We'll need to define limits. Currently the PoC defines these: https://github.com/onflow/cadence/pull/2760/files#diff-e898ac8338568dfcac62c2017b09e956e5f99c1cda6eedb3f7c48b830595f9d1R76-R90
| ### Drawbacks | ||
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| None | ||
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We'll need to define which WebAssembly features will be supported. Currently the PoC specifies: https://github.com/onflow/cadence/pull/2760/files#diff-e898ac8338568dfcac62c2017b09e956e5f99c1cda6eedb3f7c48b830595f9d1R43-R70
| ### Drawbacks | ||
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| None | ||
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We'll need to point out that deterministic execution is required. WebAssmbly allows non-determinism through NaNs. However, some WebAssembly runtiumes allow determinism by enforcing NaN-normalization.
Fixes #255