Wrap PostgreSQL errors

Author: trasch

Sources/PostgresConnectionPool/PoolError.swift

@@ -3,6 +3,7 @@
 //
 
 import Foundation
+import PostgresNIO
 
 /// Possible errors from the connection pool.
 public enum PoolError: Error {
@@ -13,6 +14,10 @@ public enum PoolError: Error {
     case connectionFailed
     /// The pool was already shut down.
     case poolDestroyed
+    /// Some PostgreSQL error
+    case postgresError(PSQLError)
+    /// The query was cancelled by the server.
+    case queryCancelled
     /// Something unexpected happened.
     case unknown
 

Sources/PostgresConnectionPool/PostgresConnectionWrapper.swift

@@ -21,10 +21,28 @@ public final class PostgresConnectionWrapper {
         else { throw PoolError.unknown }
 
         connectionWrapper.poolConnection.query = nil
-        let result = try await callback(connectionWrapper)
-        connectionWrapper.poolConnection.query = nil
+        defer {
+            connectionWrapper.poolConnection.query = nil
+        }
+
+        do {
+            return try await callback(connectionWrapper)
+        }
+        catch let error as PSQLError {
+            guard let serverInfo = error.serverInfo,
+                  let code = serverInfo[.sqlState]
+            else { throw error }
 
-        return result
+            switch PostgresError.Code(raw: code) {
+            case .queryCanceled:
+                throw PoolError.queryCancelled
+            default:
+                throw PoolError.postgresError(error)
+            }
+        }
+        catch {
+            throw error
+        }
     }
 
     init?(_ poolConnection: PoolConnection) {