During #425, @neilalexander gave constructive feedback that the API is
both moving fast, and not good enough yet. This attempts to reduce the
incidental complexity at the cost of a little conflation.
### odd presence of `wasm` and `wasi` packages -> `api` package
We had public API packages in wasm and wasi, which helped us avoid
leaking too many internals as public. That these had names that look
like there should be implementations in them cause unnecessary
confusion. This squashes both into one package "api" which has no
package collission with anything.
We've long struggled with the poorly specified and non-uniformly
implemented WASI specification. Trying to bring visibility to its
constraints knowing they are routinely invalid taints our API for no
good reason. This removes all `WASI` commands for a default to invoke
the function `_start` if it exists. In doing so, there's only one path
to start a module.
Moreover, this puts all wasi code in a top-level package "wasi" as it
isn't re-imported by any internal types.
### Reuse of Module for pre and post instantiation to `Binary` -> `Module`
Module is defined by WebAssembly in many phases, from decoded to
instantiated. However, using the same noun in multiple packages is very
confusing. We at one point tried a name "DecodedModule" or
"InstantiatedModule", but this is a fools errand. By deviating slightly
from the spec we can make it unambiguous what a module is.
This make a result of compilation a `Binary`, retaining `Module` for an
instantiated one. In doing so, there's no longer any name conflicts
whatsoever.
### Confusion about config -> `ModuleConfig`
Also caused by splitting wasm into wasm+wasi is configuration. This
conflates both into the same type `ModuleConfig` as it is simpler than
trying to explain a "will never be finished" api of wasi snapshot-01 in
routine use of WebAssembly. In other words, this further moves WASI out
of the foreground as it has been nothing but burden.
```diff
--- a/README.md
+++ b/README.md
@@ -49,8 +49,8 @@ For example, here's how you can allow WebAssembly modules to read
-wm, err := r.InstantiateModule(wazero.WASISnapshotPreview1())
-defer wm.Close()
+wm, err := wasi.InstantiateSnapshotPreview1(r)
+defer wm.Close()
-sysConfig := wazero.NewSysConfig().WithFS(os.DirFS("/work/home"))
-module, err := wazero.StartWASICommandWithConfig(r, compiled, sysConfig)
+config := wazero.ModuleConfig().WithFS(os.DirFS("/work/home"))
+module, err := r.InstantiateModule(binary, config)
defer module.Close()
...
```
This introduces `SysConfig` to replace `WASIConfig` and formalize documentation around system calls.
The only incompatible change planned after this is to switch from wasi.FS to fs.FS
Implementation Notes:
Defaulting to os.Stdin os.Stdout and os.Stderr doesn't make sense for
the same reasons as why we don't propagate ENV or ARGV: it violates
sand-boxing. Moreover, these are worse as they prevent concurrency and
can also lead to console overload if accidentally not overridden.
This also changes default stdin to read EOF as that is safer than reading
from os.DevNull, which can run the host out of file descriptors.
Finally, this removes "WithPreopens" for "WithFS" and "WithWorkDirFS",
to focus on the intended result. Similar Docker, if the WorkDir isn't set, it
defaults to the same as root.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This reverts `Runtime.NewModule` back to `InstantiateModule` as it calls
more attention to the registration aspect of it, and also makes a chain
of `NewXX` more clear. This is particularly helpful as this change
introduces `ModuleBuilder` which is created by `NewModuleBuilder`.
`ModuleBuilder` is a way to define a WebAssembly 1.0 (20191205) in Go.
The first iteration allows setting the module name and exported
functions. The next PR will add globals.
Ex. Below defines and instantiates a module named "env" with one function:
```go
hello := func() {
fmt.Fprintln(stdout, "hello!")
}
_, err := r.NewModuleBuilder("env").ExportFunction("hello", hello).InstantiateModule()
```
If the same module may be instantiated multiple times, it is more efficient to separate steps. Ex.
```go
env, err := r.NewModuleBuilder("env").ExportFunction("get_random_string", getRandomString).Build()
_, err := r.InstantiateModule(env.WithName("env.1"))
_, err := r.InstantiateModule(env.WithName("env.2"))
```
Note: Builder methods do not return errors, to allow chaining. Any validation errors are deferred until Build.
Note: Insertion order is not retained. Anything defined by this builder is sorted lexicographically on Build.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This converges host-defined modules with Wasm defined modules by
introducing a custom section for host-defined functions. The net result
are far less types and consistent initialization.
* HostModule is removed for Module
* HostFunction is removed for Function
* ModuleContext is removed for Module
Note: One impact of this is that the low-level API no longer accepts a
go context (context.Context), rather a `wasm.Module` which the function
is called in context of. This meant exposing `wasm.Module.WithContext`
to override the default.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This simplifies state management and the amount of terminology end-users
need to learn by using one concept `Runtime` instead of two: `Engine`
and `Store`. This bridges the concepts to the specification by still
having `wazero.Runtime` implement `wasm.Store`.
The net result is that we can know for sure which "engine" is used when
decoding. This allows us a lot of flexibility especially pre-compilation
when JIT is possible.
This also changes the default to JIT based on compiler flags so that
downstream projects like wapc-go don't have to do this individually
(including tracking of which OS+Arch have JIT).
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This moves code for `ValueType` constants public, so that we can
centralize discussion on how values are encoded. We'll need this when
re-introducing a Globals API.
To keep complexity down in consideration that there are only 4 types, I
copied the constants into the internalwasm package. This reduces the
import complexity otherwise would have caused.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
Co-authored-by: Takaya Saeki <takaya@tetrate.io>
This makes instantiating host or wasm-defined modules similar, by using
XXXConfig types. Doing so also allows configuration engines to seed
properties.
Since decoded modules are only usable during instantiation, this pushes
decoding inside those functions. By doing so, the API is easier to use
as it has less choices and less errors to catch. Detection is done
internally by peeking at the magic number.
See https://github.com/tetratelabs/wazero/issues/279
Signed-off-by: Adrian Cole <adrian@tetrate.io>
Before, we emulated the map api by returning `fn, ok` to tell if a
function was there or not. This made a lot of cruft vs returning `nil`
instead, especially as many times configuration of functions is near
where they are called in the source (so they aren't likely to be nil).
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This adds this interface `wasm.Store` which gives access to functions in
a store without leaking an API to change the store. This is primarily to
support configuration use cases where post-initialization, there's no
need or desire to mutate the store. This also backfills codecs needed to
handle float results.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>
This moves to a new end-user API under the root package `wazero`. This
simplifies call sites while hardening function calls to their known
return value. Most importantly, this moves most logic internal, as
noted in the RATIONALE.md.
Ex.
```go
// Read WebAssembly binary containing an exported "fac" function.
source, _ := os.ReadFile("./tests/engine/testdata/fac.wasm")
// Decode the binary as WebAssembly module.
mod, _ := wazero.DecodeModuleBinary(source)
// Initialize the execution environment called "store" with Interpreter-based engine.
store := wazero.NewStore()
// Instantiate the module, which returns its exported functions
functions, _ := store.Instantiate(mod)
// Get the factorial function
fac, _ := functions.GetFunctionI64Return("fac")
// Discover 7! is 5040
fmt.Println(fac(context.Background(), 7))
```
PS I changed the README to factorial because the wat version of
fibonacci is not consistent with the TinyGo one!
Signed-off-by: Adrian Cole <adrian@tetrate.io>
Co-authored-by: Takaya Saeki <takaya@tetrate.io>
Co-authored-by: Takeshi Yoneda <takeshi@tetrate.io>
This adds two interfaces with only one implementation each, used to
decouple end-user code from internals.
* wasm.HostFunctionCallContext - allows access to go Context and Memory
* wasm.Memory - read/write standard types and arbitrary data
This currently ports existing code to use the interfaces. It is true
that over time we can use structs instead of interfaces internally to
save a pointer reference in WASI call sites. However, I'm choosing not
to do this right now, as it is more important to see the interfaces
work. We should defer optimizing towards structs until after we
repackage implementations under the "internal" directory.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
Co-authored-by: Takeshi Yoneda <takeshi@tetrate.io>
Before, we wrote WASI functions with jargon that is not typically used
in go. As this project is in go and implements a text compiler, we can
relay points more directly and specifically. This is the first example
to move to this.
This centralizes documentation through a new interface `wasi.API`
currently instantiated in `wasi.RegisterAPI(store, opts)`. Later, we
can figure out how to export the context needed to use it properly.
Co-authored-by: Takaya Saeki <takaya@tetrate.io>
Co-authored-by: Takeshi Yoneda <takeshi@tetrate.io>
Signed-off-by: Adrian Cole <adrian@tetrate.io>
