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bundle.go
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bundle.go
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/*
*
* k6 - a next-generation load testing tool
* Copyright (C) 2016 Load Impact
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package js
import (
"context"
"encoding/json"
"path/filepath"
"reflect"
"github.com/dop251/goja"
"github.com/loadimpact/k6/js/common"
"github.com/loadimpact/k6/js/compiler"
"github.com/loadimpact/k6/lib"
"github.com/pkg/errors"
"github.com/spf13/afero"
)
// A Bundle is a self-contained bundle of scripts and resources.
// You can use this to produce identical BundleInstance objects.
type Bundle struct {
Filename string
Program *goja.Program
Options lib.Options
BaseInitContext *InitContext
}
// A BundleInstance is a self-contained instance of a Bundle.
type BundleInstance struct {
Runtime *goja.Runtime
Context *context.Context
Default goja.Callable
}
// Creates a new bundle from a source file and a filesystem.
func NewBundle(src *lib.SourceData, fs afero.Fs) (*Bundle, error) {
// Compile the main program.
code, _, err := compiler.Transform(string(src.Data), src.Filename)
if err != nil {
return nil, errors.Wrap(err, "Transform")
}
pgm, err := goja.Compile(src.Filename, code, true)
if err != nil {
return nil, errors.Wrap(err, "Compile")
}
// We want to eliminate disk access at runtime, so we set up a memory mapped cache that's
// written every time something is read from the real filesystem. This cache is then used for
// successive spawns to read from (they have no access to the real disk).
// CURRENTLY BROKEN: https://github.com/spf13/afero/issues/115
// mirrorFS := afero.NewMemMapFs()
// cachedFS := afero.NewCacheOnReadFs(fs, mirrorFS, 0)
// Make a bundle, instantiate it into a throwaway VM to populate caches.
rt := goja.New()
bundle := Bundle{
Filename: src.Filename,
Program: pgm,
BaseInitContext: NewInitContext(rt, new(context.Context), fs, filepath.Dir(src.Filename)),
}
if err := bundle.instantiate(rt, bundle.BaseInitContext); err != nil {
return nil, err
}
// Validate exports.
exportsV := rt.Get("exports")
if goja.IsNull(exportsV) || goja.IsUndefined(exportsV) {
return nil, errors.New("exports must be an object")
}
exports := exportsV.ToObject(rt)
// Validate the default function.
def := exports.Get("default")
if def == nil || goja.IsNull(def) || goja.IsUndefined(def) {
return nil, errors.New("script must export a default function")
}
if def.ExportType().Kind() != reflect.Func {
return nil, errors.New("default export must be a function")
}
// Extract exported options.
optV := exports.Get("options")
if optV != nil && !goja.IsNull(optV) && !goja.IsUndefined(optV) {
optdata, err := json.Marshal(optV.Export())
if err != nil {
return nil, err
}
if err := json.Unmarshal(optdata, &bundle.Options); err != nil {
return nil, err
}
}
// Swap out the init context's filesystem for the in-memory cache.
// bundle.InitContext.fs = mirrorFS
return &bundle, nil
}
// Instantiates a new runtime from this bundle.
func (b *Bundle) Instantiate() (*BundleInstance, error) {
// Placeholder for a real context.
ctxPtr := new(context.Context)
// Instantiate the bundle into a new VM using a bound init context. This uses a context with a
// runtime, but no state, to allow module-provided types to function within the init context.
rt := goja.New()
init := newBoundInitContext(b.BaseInitContext, ctxPtr, rt)
if err := b.instantiate(rt, init); err != nil {
return nil, err
}
// Grab the default function; type is already checked in NewBundle().
exports := rt.Get("exports").ToObject(rt)
def, _ := goja.AssertFunction(exports.Get("default"))
return &BundleInstance{
Runtime: rt,
Context: ctxPtr,
Default: def,
}, nil
}
// Instantiates the bundle into an existing runtime. Not public because it also messes with a bunch
// of other things, will potentially thrash data and makes a mess in it if the operation fails.
func (b *Bundle) instantiate(rt *goja.Runtime, init *InitContext) error {
rt.SetFieldNameMapper(common.FieldNameMapper{})
rt.SetRandSource(common.DefaultRandSource)
exports := rt.NewObject()
rt.Set("exports", exports)
module := rt.NewObject()
_ = module.Set("exports", exports)
rt.Set("module", module)
*init.ctxPtr = common.WithRuntime(context.Background(), rt)
unbindInit := common.BindToGlobal(rt, common.Bind(rt, init, init.ctxPtr))
if _, err := rt.RunProgram(b.Program); err != nil {
return err
}
unbindInit()
*init.ctxPtr = nil
rt.SetRandSource(common.NewRandSource())
return nil
}