Struct Wizer 

pub struct Wizer { /* private fields */ }

Wizer: the WebAssembly pre-initializer!

Don’t wait for your Wasm module to initialize itself, pre-initialize it! Wizer instantiates your WebAssembly module, executes its initialization function, and then serializes the instance’s initialized state out into a new WebAssembly module. Now you can use this new, pre-initialized WebAssembly module to hit the ground running, without making your users wait for that first-time set up code to complete.

Caveats

• The initialization function may not call any imported functions. Doing so will trigger a trap and wizer will exit.

• The Wasm module may not import globals, tables, or memories.

• Reference types are not supported yet. This is tricky because it would allow the Wasm module to mutate tables, and we would need to be able to snapshot the new table state, but funcrefs and externrefs don’t have identity and aren’t comparable in the Wasm spec, which makes snapshotting difficult.

Implementations

impl Wizer

pub async fn run<T: Send>( &self, store: &mut Store<T>, wasm: &[u8], instantiate: impl AsyncFnOnce(&mut Store<T>, &Module) -> Result<Instance>, ) -> Result<Vec<u8>>

Available on crate feature wasmtime only.

Initialize the given Wasm, snapshot it, and return the serialized snapshot as a new, pre-initialized Wasm module.

impl Wizer

pub async fn run_component<T: Send>( &self, store: &mut Store<T>, wasm: &[u8], instantiate: impl AsyncFnOnce(&mut Store<T>, &Component) -> Result<Instance>, ) -> Result<Vec<u8>>

Available on crate features component-model and wasmtime only.

Same as Wizer::run, except for components.

impl Wizer

pub fn instrument_component<'a>( &self, wasm: &'a [u8], ) -> Result<(ComponentContext<'a>, Vec<u8>)>

Available on crate feature component-model only.

Same as Wizer::instrument, except for components.

pub async fn snapshot_component( &self, cx: ComponentContext<'_>, instance: &mut impl ComponentInstanceState, ) -> Result<Vec<u8>>

Available on crate feature component-model only.

Same as Wizer::snapshot, except for components.

impl Wizer

pub fn new() -> Self

Construct a new Wizer builder.

pub fn init_func(&mut self, init_func: impl Into<String>) -> &mut Self

The export name of the initializer function.

Defaults to "wizer-initialize".

pub fn get_init_func(&self) -> &str

Returns the initialization function that will be run for wizer.

pub fn func_rename(&mut self, new_name: &str, old_name: &str) -> &mut Self

Add a function rename to perform.

pub fn keep_init_func(&mut self, keep: bool) -> &mut Self

After initialization, should the Wasm module still export the initialization function?

This is false by default, meaning that the initialization function is no longer exported from the Wasm module.

pub fn instrument<'a>( &self, wasm: &'a [u8], ) -> Result<(ModuleContext<'a>, Vec<u8>)>

First half of Self::run which instruments the provided wasm and produces a new wasm module which should be run by a runtime.

After the returned wasm is executed the context returned here and the state of the instance should be passed to Self::snapshot.

pub async fn snapshot( &self, cx: ModuleContext<'_>, instance: &mut impl InstanceState, ) -> Result<Vec<u8>>

Second half of Self::run which takes the ModuleContext returned by Self::instrument and the state of the instance after it has possibly executed its initialization function.

This returns a new WebAssembly binary which has all state pre-initialized.

Trait Implementations

impl Args for Wizer

fn group_id() -> Option<Id>

Report the ArgGroup::id for this set of arguments

fn augment_args<'b>(__clap_app: Command) -> Command

Append to Command so it can instantiate Self via FromArgMatches::from_arg_matches_mut

fn augment_args_for_update<'b>(__clap_app: Command) -> Command

Append to Command so it can instantiate self via FromArgMatches::update_from_arg_matches_mut

impl Clone for Wizer

fn clone(&self) -> Wizer

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl CommandFactory for Wizer

fn command<'b>() -> Command

Build a Command that can instantiate Self.

fn command_for_update<'b>() -> Command

Build a Command that can update self.

impl Debug for Wizer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl FromArgMatches for Wizer

fn from_arg_matches(__clap_arg_matches: &ArgMatches) -> Result<Self, Error>

Instantiate Self from ArgMatches, parsing the arguments as needed.

fn from_arg_matches_mut( __clap_arg_matches: &mut ArgMatches, ) -> Result<Self, Error>

Instantiate Self from ArgMatches, parsing the arguments as needed.

fn update_from_arg_matches( &mut self, __clap_arg_matches: &ArgMatches, ) -> Result<(), Error>

Assign values from ArgMatches to self.

fn update_from_arg_matches_mut( &mut self, __clap_arg_matches: &mut ArgMatches, ) -> Result<(), Error>

Assign values from ArgMatches to self.

impl Parser for Wizer

fn parse() -> Self

Parse from std::env::args_os(), exit on error.

fn try_parse() -> Result<Self, Error>

Parse from std::env::args_os(), return Err on error.

fn parse_from<I, T>(itr: I) -> Self

where I: IntoIterator<Item = T>, T: Into<OsString> + Clone,

Parse from iterator, exit on error.

fn try_parse_from<I, T>(itr: I) -> Result<Self, Error>

where I: IntoIterator<Item = T>, T: Into<OsString> + Clone,

Parse from iterator, return Err on error.

fn update_from<I, T>(&mut self, itr: I)

where I: IntoIterator<Item = T>, T: Into<OsString> + Clone,

Update from iterator, exit on error.

fn try_update_from<I, T>(&mut self, itr: I) -> Result<(), Error>

where I: IntoIterator<Item = T>, T: Into<OsString> + Clone,

Update from iterator, return Err on error.