Ilia Denisov
51 lines
1.7 KiB
Go
51 lines
1.7 KiB
Go
package session
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import (
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"context"
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"errors"
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"fmt"
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)
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// BackendLookup describes the slice of `backendclient.RESTClient`
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// SessionCache depends on. The narrow interface keeps this package free
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// of any backendclient import.
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type BackendLookup interface {
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LookupSession(ctx context.Context, deviceSessionID string) (Record, error)
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}
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// BackendCache resolves authenticated device sessions by issuing one
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// synchronous REST call to backend per request. The canonical implementation replaces the
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// previous Redis-backed projection with this thin wrapper; gateway no
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// longer keeps a process-local snapshot. See ARCHITECTURE.md §11
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// «backend (sync REST), no Redis projection».
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type BackendCache struct {
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backend BackendLookup
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}
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// NewBackendCache constructs a Cache that delegates every Lookup to
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// backend over REST. backend must not be nil.
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func NewBackendCache(backend BackendLookup) (*BackendCache, error) {
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if backend == nil {
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return nil, errors.New("session.NewBackendCache: backend lookup must not be nil")
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}
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return &BackendCache{backend: backend}, nil
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}
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// Lookup resolves deviceSessionID via backend. ErrNotFound is forwarded
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// unchanged so callers can keep using the existing equality check.
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func (c *BackendCache) Lookup(ctx context.Context, deviceSessionID string) (Record, error) {
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if c == nil {
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return Record{}, errors.New("session backend cache: nil cache")
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}
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if c.backend == nil {
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return Record{}, errors.New("session backend cache: nil backend lookup")
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}
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rec, err := c.backend.LookupSession(ctx, deviceSessionID)
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if err != nil {
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return Record{}, fmt.Errorf("session backend cache: %w", err)
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}
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return rec, nil
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}
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var _ Cache = (*BackendCache)(nil)
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