Crate sc_executor

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A crate that provides means of executing/dispatching calls into the runtime.

There are a few responsibilities of this crate at the moment:

  • It provides an implementation of a common entrypoint for calling into the runtime, both wasm and compiled.
  • It defines the environment for the wasm execution, namely the host functions that are to be provided into the wasm runtime module.
  • It also provides the required infrastructure for executing the current wasm runtime (specified by the current value of :code in the provided externalities), i.e. interfacing with wasm engine used, instance cache.


pub use wasmi;


Rust executor possible errors.


A generic CodeExecutor implementation that uses a delegate to determine wasm code equivalence and dispatch to native code when possible, falling back on WasmExecutor when not.
The version of the native runtime.
Runtime version. This should not be thought of as classic Semver (major/minor/tiny). This triplet have different semantics and mis-interpretation could cause problems. In particular: bug fixes should result in an increment of spec_version and possibly authoring_version, absolutely not impl_version since they change the semantics of the runtime.
An abstraction over Wasm code executor. Supports selecting execution backend and manages runtime cache.


Specification of different methods of executing the runtime Wasm code.
The instantiation strategy to use for the WASM executor.


Trait that allows zero-copy read/write of value-references to/from slices in LE format.
Delegate for dispatching a CodeExecutor call.
Extracts the runtime version of a given runtime code.


Take the runtime blob and scan it for the custom wasm sections containing the version information and construct the RuntimeVersion from them.
Set up the externalities and safe calling environment to execute runtime calls.