opentofu/internal/getproviders/memoize_source.go
Martin Atkins b9a93a0fe7 Move addrs/ to internal/addrs/
This is part of a general effort to move all of Terraform's non-library
package surface under internal in order to reinforce that these are for
internal use within Terraform only.

If you were previously importing packages under this prefix into an
external codebase, you could pin to an earlier release tag as an interim
solution until you've make a plan to achieve the same functionality some
other way.
2021-05-17 14:09:07 -07:00

104 lines
3.1 KiB
Go

package getproviders
import (
"context"
"sync"
"github.com/hashicorp/terraform/internal/addrs"
)
// MemoizeSource is a Source that wraps another Source and remembers its
// results so that they can be returned more quickly on future calls to the
// same object.
//
// Each MemoizeSource maintains a cache of response it has seen as part of its
// body. All responses are retained for the remaining lifetime of the object.
// Errors from the underlying source are also cached, and so subsequent calls
// with the same arguments will always produce the same errors.
//
// A MemoizeSource can be called concurrently, with incoming requests processed
// sequentially.
type MemoizeSource struct {
underlying Source
availableVersions map[addrs.Provider]memoizeAvailableVersionsRet
packageMetas map[memoizePackageMetaCall]memoizePackageMetaRet
mu sync.Mutex
}
type memoizeAvailableVersionsRet struct {
VersionList VersionList
Warnings Warnings
Err error
}
type memoizePackageMetaCall struct {
Provider addrs.Provider
Version Version
Target Platform
}
type memoizePackageMetaRet struct {
PackageMeta PackageMeta
Err error
}
var _ Source = (*MemoizeSource)(nil)
// NewMemoizeSource constructs and returns a new MemoizeSource that wraps
// the given underlying source and memoizes its results.
func NewMemoizeSource(underlying Source) *MemoizeSource {
return &MemoizeSource{
underlying: underlying,
availableVersions: make(map[addrs.Provider]memoizeAvailableVersionsRet),
packageMetas: make(map[memoizePackageMetaCall]memoizePackageMetaRet),
}
}
// AvailableVersions requests the available versions from the underlying source
// and caches them before returning them, or on subsequent calls returns the
// result directly from the cache.
func (s *MemoizeSource) AvailableVersions(ctx context.Context, provider addrs.Provider) (VersionList, Warnings, error) {
s.mu.Lock()
defer s.mu.Unlock()
if existing, exists := s.availableVersions[provider]; exists {
return existing.VersionList, nil, existing.Err
}
ret, warnings, err := s.underlying.AvailableVersions(ctx, provider)
s.availableVersions[provider] = memoizeAvailableVersionsRet{
VersionList: ret,
Err: err,
Warnings: warnings,
}
return ret, warnings, err
}
// PackageMeta requests package metadata from the underlying source and caches
// the result before returning it, or on subsequent calls returns the result
// directly from the cache.
func (s *MemoizeSource) PackageMeta(ctx context.Context, provider addrs.Provider, version Version, target Platform) (PackageMeta, error) {
s.mu.Lock()
defer s.mu.Unlock()
key := memoizePackageMetaCall{
Provider: provider,
Version: version,
Target: target,
}
if existing, exists := s.packageMetas[key]; exists {
return existing.PackageMeta, existing.Err
}
ret, err := s.underlying.PackageMeta(ctx, provider, version, target)
s.packageMetas[key] = memoizePackageMetaRet{
PackageMeta: ret,
Err: err,
}
return ret, err
}
func (s *MemoizeSource) ForDisplay(provider addrs.Provider) string {
return s.underlying.ForDisplay(provider)
}