tapgarden: remove duplicate batch freeze

In this commit, we update the caretaker start logic to remove an
unnecessary batch write. Before we start the caretaker, we write the
batch with the Frozen state, but we don't update the in-memory pending
batch to move from the Pending to Frozen state. This causes the
caretaker to write the batch again on start. We can address this by
updating the in-memory batch after a successful batch freeze.

Author: jharveyb

tapgarden/planter.go

@@ -636,8 +636,6 @@ func (c *ChainPlanter) gardener() {
 					}
 
 					delete(c.caretakers, batchKeySerial)
-					c.pendingBatch = nil
-					continue
 
 				case <-c.Quit:
 					return
@@ -677,10 +675,6 @@ func (c *ChainPlanter) gardener() {
 func (c *ChainPlanter) finalizeBatch(
 	feeRate *chainfee.SatPerKWeight) (*BatchCaretaker, error) {
 
-	// Prep the new care taker that'll be launched assuming the call below
-	// to freeze the batch succeeds.
-	caretaker := c.newCaretakerForBatch(c.pendingBatch, feeRate)
-
 	// At this point, we have a non-empty batch, so we'll first finalize it
 	// on disk. This means no further seedlings can be added to this batch.
 	ctx, cancel := c.WithCtxQuit()
@@ -691,9 +685,11 @@ func (c *ChainPlanter) finalizeBatch(
 			err)
 	}
 
-	// Now that the batch has been frozen, we'll launch a new caretaker
-	// state machine for the batch that'll drive all the seedlings do
-	// adulthood.
+	// Now that the batch has been frozen on disk, we can update the batch
+	// state to frozen before launching a new caretaker state machine for
+	// the batch that'll drive all the seedlings do adulthood.
+	c.pendingBatch.UpdateState(BatchStateFrozen)
+	caretaker := c.newCaretakerForBatch(c.pendingBatch, feeRate)
 	if err := caretaker.Start(); err != nil {
 		return nil, fmt.Errorf("unable to start new caretaker: %w", err)
 	}