Crate holochain_wasmer_host 

Host-side runtime for executing wasm guests via wasmer. Used by Holochain ribosomes to instantiate, cache and call zome wasms, and by anything else that needs to embed wasm with a similar shape: a long-lived host process making short-lived calls into many guest modules built from cached compiled artifacts.

The two entry points most callers reach for are module::ModuleCache for managing compiled-module reuse and guest::call for invoking a guest function with a serializable payload. Errors from both sides flow through prelude::WasmError.

Cargo features

At least one wasmer backend must be enabled. The two backends are independent and can be enabled simultaneously; the choice is then made at the call site by passing the appropriate engine factory to module::ModuleBuilder::new.

• wasmer-sys (default) — enables the wasmer native backend that compiles wasm via a real compiler. Requires at least one of the compiler sub-features below.
  • wasmer-sys-cranelift (default) — Cranelift compiler. Fast to compile, good runtime performance, the default development compiler.
  • wasmer-sys-llvm — LLVM compiler. Slower to compile, faster at runtime, the recommended choice for production deployments where compile time is amortised over many calls. Can be enabled alongside wasmer-sys-cranelift.
• wasmer-wasmi — enables the wasmi pure-Rust interpreter backend. No native code generation; suitable for environments where a compiler is not available or not desired (e.g. iOS, sandboxed builds).
• error-as-host (default) — when constructing a prelude::WasmError from a bare String, classify it as prelude::WasmErrorInner::Host rather than prelude::WasmErrorInner::Guest. Hosts that build error strings should enable this; guests should leave it off.
• debug-memory — enable verbose tracing::debug! logging for every host↔guest memory copy. Off by default; useful only when chasing memory bugs.

Modules

env

error

guest

module

Build, cache and instantiate wasmer Modules.

prelude

Macros

wasm_host_error