Very basic prebuild reassignment

Signed-off-by: Danny Kopping <danny@coder.com>

coderd/prebuilds/claim.go

@@ -0,0 +1,35 @@
+package prebuilds
+
+import (
+	"context"
+	"github.com/coder/coder/v2/coderd/database"
+	"github.com/google/uuid"
+	"golang.org/x/xerrors"
+)
+
+func Claim(ctx context.Context, store database.Store, userID uuid.UUID) (*uuid.UUID, error) {
+	var prebuildID *uuid.UUID
+	err := store.InTx(func(db database.Store) error {
+		// TODO: do we need this?
+		//// Ensure no other replica can claim a prebuild for this user simultaneously.
+		//err := store.AcquireLock(ctx, database.GenLockID(fmt.Sprintf("prebuild-user-claim-%s", userID.String())))
+		//if err != nil {
+		//	return xerrors.Errorf("acquire claim lock for user %q: %w", userID.String(), err)
+		//}
+
+		id, err := db.ClaimPrebuild(ctx, userID)
+		if err != nil {
+			return xerrors.Errorf("claim prebuild for user %q: %w", userID.String(), err)
+		}
+
+		if id != uuid.Nil {
+			prebuildID = &id
+		}
+
+		return nil
+	}, &database.TxOptions{
+		TxIdentifier: "prebuild-claim",
+	})
+
+	return prebuildID, err
+}