use the new clistate.Locker in the local backend

Use the new StateLocker field to provide a wrapper for locking the state
during terraform.Context creation. We can then remove all the state
locking code from individual operations, and unlock them in one place
inside the main Operation method.

backend/local/backend.go

@@ -13,6 +13,7 @@ import (
 	"sync"
 
 	"github.com/hashicorp/terraform/backend"
+	"github.com/hashicorp/terraform/command/clistate"
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/state"
 	"github.com/hashicorp/terraform/terraform"
@@ -260,12 +261,21 @@ func (b *Local) Operation(ctx context.Context, op *backend.Operation) (*backend.
 	cancelCtx, cancel := context.WithCancel(context.Background())
 	runningOp.Cancel = cancel
 
+	if op.LockState {
+		op.StateLocker = clistate.NewLocker(stopCtx, op.StateLockTimeout, b.CLI, b.Colorize())
+	} else {
+		op.StateLocker = clistate.NewNoopLocker()
+	}
+
 	// Do it
 	go func() {
 		defer done()
 		defer stop()
 		defer cancel()
 
+		// the state was locked during context creation, unlock the state when
+		// the operation completes
+		defer op.StateLocker.Unlock(runningOp.Err)
 		defer b.opLock.Unlock()
 		f(stopCtx, cancelCtx, op, runningOp)
 	}()

backend/local/backend_apply.go

@@ -11,7 +11,6 @@ import (
 	"github.com/hashicorp/errwrap"
 	"github.com/hashicorp/go-multierror"
 	"github.com/hashicorp/terraform/backend"
-	"github.com/hashicorp/terraform/command/clistate"
 	"github.com/hashicorp/terraform/command/format"
 	"github.com/hashicorp/terraform/config/module"
 	"github.com/hashicorp/terraform/state"
@@ -55,20 +54,6 @@ func (b *Local) opApply(
 		return
 	}
 
-	if op.LockState {
-		lockCtx, cancel := context.WithTimeout(stopCtx, op.StateLockTimeout)
-		defer cancel()
-
-		unlock, err := clistate.Lock(lockCtx, opState, op.Type.String(), "", b.CLI, b.Colorize())
-		if err != nil {
-			runningOp.Err = errwrap.Wrapf("Error locking state: {{err}}", err)
-			return
-		}
-		defer func() {
-			runningOp.Err = unlock(runningOp.Err)
-		}()
-	}
-
 	// Setup the state
 	runningOp.State = tfCtx.State()
 

backend/local/backend_local.go

@@ -1,9 +1,11 @@
 package local
 
 import (
+	"context"
 	"errors"
 	"log"
 
+	"github.com/hashicorp/terraform/command/clistate"
 	"github.com/hashicorp/terraform/command/format"
 
 	"github.com/hashicorp/terraform/tfdiags"
@@ -20,6 +22,12 @@ func (b *Local) Context(op *backend.Operation) (*terraform.Context, state.State,
 	// to ask for input/validate.
 	op.Type = backend.OperationTypeInvalid
 
+	if op.LockState {
+		op.StateLocker = clistate.NewLocker(context.Background(), op.StateLockTimeout, b.CLI, b.Colorize())
+	} else {
+		op.StateLocker = clistate.NewNoopLocker()
+	}
+
 	return b.context(op)
 }
 
@@ -30,6 +38,10 @@ func (b *Local) context(op *backend.Operation) (*terraform.Context, state.State,
 		return nil, nil, errwrap.Wrapf("Error loading state: {{err}}", err)
 	}
 
+	if err := op.StateLocker.Lock(s, op.Type.String()); err != nil {
+		return nil, nil, errwrap.Wrapf("Error locking state: {{err}}", err)
+	}
+
 	if err := s.RefreshState(); err != nil {
 		return nil, nil, errwrap.Wrapf("Error loading state: {{err}}", err)
 	}

backend/local/backend_plan.go

@@ -10,7 +10,6 @@ import (
 
 	"github.com/hashicorp/errwrap"
 	"github.com/hashicorp/terraform/backend"
-	"github.com/hashicorp/terraform/command/clistate"
 	"github.com/hashicorp/terraform/command/format"
 	"github.com/hashicorp/terraform/config/module"
 	"github.com/hashicorp/terraform/terraform"
@@ -60,20 +59,6 @@ func (b *Local) opPlan(
 		return
 	}
 
-	if op.LockState {
-		lockCtx, cancel := context.WithTimeout(stopCtx, op.StateLockTimeout)
-		defer cancel()
-
-		unlock, err := clistate.Lock(lockCtx, opState, op.Type.String(), "", b.CLI, b.Colorize())
-		if err != nil {
-			runningOp.Err = errwrap.Wrapf("Error locking state: {{err}}", err)
-			return
-		}
-		defer func() {
-			runningOp.Err = unlock(runningOp.Err)
-		}()
-	}
-
 	// Setup the state
 	runningOp.State = tfCtx.State()
 

backend/local/backend_refresh.go

@@ -9,7 +9,6 @@ import (
 
 	"github.com/hashicorp/errwrap"
 	"github.com/hashicorp/terraform/backend"
-	"github.com/hashicorp/terraform/command/clistate"
 	"github.com/hashicorp/terraform/config/module"
 	"github.com/hashicorp/terraform/terraform"
 )
@@ -51,20 +50,6 @@ func (b *Local) opRefresh(
 		return
 	}
 
-	if op.LockState {
-		lockCtx, cancel := context.WithTimeout(stopCtx, op.StateLockTimeout)
-		defer cancel()
-
-		unlock, err := clistate.Lock(lockCtx, opState, op.Type.String(), "", b.CLI, b.Colorize())
-		if err != nil {
-			runningOp.Err = errwrap.Wrapf("Error locking state: {{err}}", err)
-			return
-		}
-		defer func() {
-			runningOp.Err = unlock(runningOp.Err)
-		}()
-	}
-
 	// Set our state
 	runningOp.State = opState.State()
 	if runningOp.State.Empty() || !runningOp.State.HasResources() {