opentofu/terraform/shadow_context.go
Mitchell Hashimoto 0b00bbde4e
terraform: switch to a component factory
This is necessary so that the shadow version can actually keep track of
what provider is used for what. Before, providers for different alises
were just initialized but the factory had no idea. Arguably this is fine
but when trying to build a shadow graph this presents challenges.

With these changes, we now pass an opaque "uid" through that is used to
keep track of the providers and what real maps to what shadow.
2016-10-11 22:17:29 +08:00

76 lines
2.2 KiB
Go

package terraform
import (
"io"
"github.com/mitchellh/copystructure"
)
// newShadowContext creates a new context that will shadow the given context
// when walking the graph. The resulting context should be used _only once_
// for a graph walk.
//
// The returned io.Closer should be closed after the graph walk with the
// real context is complete. The result of the Close function will be any
// errors caught during the shadowing operation.
//
// Most importantly, any operations done on the shadow context (the returned
// context) will NEVER affect the real context. All structures are deep
// copied, no real providers or resources are used, etc.
func newShadowContext(c *Context) (*Context, *Context, io.Closer) {
// Copy the targets
targetRaw, err := copystructure.Copy(c.targets)
if err != nil {
panic(err)
}
// Copy the variables
varRaw, err := copystructure.Copy(c.variables)
if err != nil {
panic(err)
}
// The factories
componentsReal, componentsShadow := newShadowComponentFactory(c.components)
// Create the shadow
shadow := &Context{
components: componentsShadow,
destroy: c.destroy,
diff: c.diff.DeepCopy(),
hooks: nil, // TODO: do we need to copy? stop hook?
module: c.module,
state: c.state.DeepCopy(),
targets: targetRaw.([]string),
uiInput: nil, // TODO
variables: varRaw.(map[string]interface{}),
// Hardcoded to 4 since parallelism in the shadow doesn't matter
// a ton since we're doing far less compared to the real side
// and our operations are MUCH faster.
parallelSem: NewSemaphore(4),
providerInputConfig: make(map[string]map[string]interface{}),
}
// Create the real context. This is effectively just a copy of
// the context given except we need to modify some of the values
// to point to the real side of a shadow so the shadow can compare values.
real := *c
real.components = componentsReal
return &real, shadow, &shadowContextCloser{
Components: componentsShadow,
}
}
// shadowContextCloser is the io.Closer returned by newShadowContext that
// closes all the shadows and returns the results.
type shadowContextCloser struct {
Components interface{}
}
// Close closes the shadow context.
func (c *shadowContextCloser) Close() error {
return nil
}