proto: Fix accessors mislabeled as mutators

Besides other things, the accessor/mutator label for RPCs influences
routing decisions, queueing of replication jobs and registration of
transactions. While accessors may get routed to any up-to-date node,
mutators will need to get routed either to the primary or to all nodes
at once when strong consistency is enabled. As a result, accessors are
typically served a lot more efficiently.

We currently have two functions which seem to be mislabeled as mutators
while they will only access repository info:

    - /gitaly.RepositoryService/RepositorySize: this reports the
      repository size by spawning `du -sk` on the repository.

    - /gitaly.SSHService/SSHUploadArchive: this spawns `git
      upload-archive`, which will create a Git archive on the server
      side and feed it into a client-side `git archive` call.

Both are readonly and thus shouldn't have a mutator label, so let's fix
this and reclassify them as accessors.

1 files changed, 1 insertions, 1 deletions

diff --git a/proto/repository-service.proto b/proto/repository-service.proto
index 3b886d858..a4759fe49 100644
--- a/proto/repository-service.proto
+++ b/proto/repository-service.proto
@@ -35,7 +35,7 @@ service RepositoryService {
   }
   rpc RepositorySize(RepositorySizeRequest) returns (RepositorySizeResponse) {
     option (op_type) = {
-      op: MUTATOR
+      op: ACCESSOR
     };
   }
   rpc ApplyGitattributes(ApplyGitattributesRequest) returns (ApplyGitattributesResponse) {