Remove ReadOnlyMode error struct

src/controllers/user/session.rs

@@ -15,8 +15,8 @@
 use crate::models::{NewUser, User};
 use crate::schema::users;
 use crate::tasks::spawn_blocking;
-use crate::util::diesel::Conn;
-use crate::util::errors::{bad_request, server_error, AppResult, BoxedAppError, ReadOnlyMode};
+use crate::util::diesel::{is_read_only_error, Conn};
+use crate::util::errors::{bad_request, server_error, AppResult};
 use crate::views::EncodableMe;
 use crates_io_github::GithubUser;
 
@@ -145,11 +145,10 @@
         access_token,
     )
     .create_or_update(user.email.as_deref(), emails, conn)
-    .map_err(Into::into)
-    .or_else(|e: BoxedAppError| {
+    .or_else(|e| {
         // If we're in read only mode, we can't update their details
         // just look for an existing user
-        if e.is::<ReadOnlyMode>() {
+        if is_read_only_error(&e) {
             users::table
                 .filter(users::gh_id.eq(user.id))
                 .first(conn)
@@ -159,6 +158,7 @@
             Err(e)
         }
     })
+    .map_err(Into::into)
 }
 
 /// Handles the `DELETE /api/private/session` route.

src/util/diesel.rs

@@ -1,10 +1,15 @@
 use diesel::connection::LoadConnection;
 use diesel::pg::Pg;
+use diesel::result::Error;
 
 pub trait Conn: LoadConnection<Backend = Pg> {}
 
 impl<T> Conn for T where T: LoadConnection<Backend = Pg> {}
 
+pub fn is_read_only_error(error: &Error) -> bool {
+    matches!(error, Error::DatabaseError(_, info) if info.message().ends_with("read-only transaction"))
+}
+
 pub mod prelude {
     //! Inline diesel prelude
     pub use diesel::associations::{Associations, GroupedBy, Identifiable};

src/util/errors.rs

@@ -30,9 +30,10 @@ use crate::middleware::log_request::ErrorField;
 mod json;
 
 use crate::email::EmailError;
+use crate::util::diesel::is_read_only_error;
 use crates_io_github::GitHubError;
 pub use json::TOKEN_FORMAT_ERROR;
-pub(crate) use json::{custom, InsecurelyGeneratedTokenRevoked, ReadOnlyMode, TooManyRequests};
+pub(crate) use json::{custom, InsecurelyGeneratedTokenRevoked, TooManyRequests};
 
 pub type BoxedAppError = Box<dyn AppError>;
 
@@ -145,10 +146,9 @@ impl From<DieselError> for BoxedAppError {
     fn from(err: DieselError) -> BoxedAppError {
         match err {
             DieselError::NotFound => not_found(),
-            DieselError::DatabaseError(_, info)
-                if info.message().ends_with("read-only transaction") =>
-            {
-                Box::new(ReadOnlyMode)
+            e if is_read_only_error(&e) => {
+                let detail = "crates.io is currently in read-only mode for maintenance. Please try again later.";
+                custom(StatusCode::SERVICE_UNAVAILABLE, detail)
             }
             DieselError::DatabaseError(DatabaseErrorKind::ClosedConnection, _) => {
                 service_unavailable()

src/util/errors/json.rs

@@ -17,25 +17,6 @@ fn json_error(detail: &str, status: StatusCode) -> Response {
     (status, json).into_response()
 }
 
-// The following structs are empty and do not provide a custom message to the user
-
-#[derive(Debug)]
-pub(crate) struct ReadOnlyMode;
-
-impl AppError for ReadOnlyMode {
-    fn response(&self) -> Response {
-        let detail = "crates.io is currently in read-only mode for maintenance. \
-                      Please try again later.";
-        json_error(detail, StatusCode::SERVICE_UNAVAILABLE)
-    }
-}
-
-impl fmt::Display for ReadOnlyMode {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        "Tried to write in read only mode".fmt(f)
-    }
-}
-
 // The following structs wrap owned data and provide a custom message to the user
 
 pub fn custom(status: StatusCode, detail: impl Into<Cow<'static, str>>) -> BoxedAppError {