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package remote
import (
"bytes"
"fmt"
"sync"
"github.com/hashicorp/terraform/state"
"github.com/hashicorp/terraform/terraform"
)
// State implements the State interfaces in the state package to handle
// reading and writing the remote state. This State on its own does no
// local caching so every persist will go to the remote storage and local
// writes will go to memory.
type State struct {
mu sync.Mutex
Client Client
state, readState *terraform.State
}
// StateReader impl.
func (s *State) State() *terraform.State {
s.mu.Lock()
defer s.mu.Unlock()
return s.state.DeepCopy()
}
// StateWriter impl.
func (s *State) WriteState(state *terraform.State) error {
s.mu.Lock()
defer s.mu.Unlock()
if s.readState != nil && !state.SameLineage(s.readState) {
return fmt.Errorf("incompatible state lineage; given %s but want %s", state.Lineage, s.readState.Lineage)
}
// We create a deep copy of the state here, because the caller also has
// a reference to the given object and can potentially go on to mutate
// it after we return, but we want the snapshot at this point in time.
s.state = state.DeepCopy()
// Force our new state to have the same serial as our read state. We'll
// update this if PersistState is called later. (We don't require nor trust
// the caller to properly maintain serial for transient state objects since
// the rest of Terraform treats state as an openly mutable object.)
//
// If we have no read state then we assume we're either writing a new
// state for the first time or we're migrating a state from elsewhere,
// and in both cases we wish to retain the lineage and serial from
// the given state.
if s.readState != nil {
s.state.Serial = s.readState.Serial
}
return nil
}
// StateRefresher impl.
func (s *State) RefreshState() error {
s.mu.Lock()
defer s.mu.Unlock()
payload, err := s.Client.Get()
if err != nil {
return err
}
// no remote state is OK
if payload == nil {
return nil
}
state, err := terraform.ReadState(bytes.NewReader(payload.Data))
if err != nil {
return err
}
s.state = state
s.readState = s.state.DeepCopy() // our states must be separate instances so we can track changes
return nil
}
// StatePersister impl.
func (s *State) PersistState() error {
s.mu.Lock()
defer s.mu.Unlock()
if !s.state.MarshalEqual(s.readState) {
// Our new state does not marshal as byte-for-byte identical to
// the old, so we need to increment the serial.
// Note that in WriteState we force the serial to match that of
// s.readState, if we have a readState.
s.state.Serial++
}
var buf bytes.Buffer
if err := terraform.WriteState(s.state, &buf); err != nil {
return err
}
err := s.Client.Put(buf.Bytes())
if err != nil {
return err
}
// After we've successfully persisted, what we just wrote is our new
// reference state until someone calls RefreshState again.
s.readState = s.state.DeepCopy()
return nil
}
// Lock calls the Client's Lock method if it's implemented.
func (s *State) Lock(info *state.LockInfo) (string, error) {
s.mu.Lock()
defer s.mu.Unlock()
if c, ok := s.Client.(ClientLocker); ok {
return c.Lock(info)
}
return "", nil
}
// Unlock calls the Client's Unlock method if it's implemented.
func (s *State) Unlock(id string) error {
s.mu.Lock()
defer s.mu.Unlock()
if c, ok := s.Client.(ClientLocker); ok {
return c.Unlock(id)
}
return nil
}
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