Fixes #130

src/SIL.Machine.AspNetCore/Configuration/IMachineBuilderExtensions.cs

@@ -316,7 +316,11 @@ public static IMachineBuilder AddServalTranslationEngineService(
         IEnumerable<TranslationEngineType>? engineTypes = null
     )
     {
-        builder.Services.AddGrpc(options => options.Interceptors.Add<UnimplementedInterceptor>());
+        builder.Services.AddGrpc(options =>
+        {
+            options.Interceptors.Add<CancellationInterceptor>();
+            options.Interceptors.Add<UnimplementedInterceptor>();
+        });
         builder.AddServalPlatformService(connectionString ?? builder.Configuration.GetConnectionString("Serval"));
         engineTypes ??=
             builder.Configuration?.GetSection("TranslationEngines").Get<TranslationEngineType[]?>()

src/SIL.Machine.AspNetCore/Services/CancellationInterceptor.cs

@@ -0,0 +1,35 @@
+namespace SIL.Machine.AspNetCore.Services;
+
+public class CancellationInterceptor : Interceptor
+{
+    private readonly ILogger<CancellationInterceptor> _logger;
+
+    public CancellationInterceptor(ILogger<CancellationInterceptor> logger)
+    {
+        _logger = logger;
+    }
+
+    public override async Task<TResponse> UnaryServerHandler<TRequest, TResponse>(
+        TRequest request,
+        ServerCallContext context,
+        UnaryServerMethod<TRequest, TResponse> continuation
+    )
+    {
+        try
+        {
+            return await continuation(request, context);
+        }
+        catch (Exception ex)
+        {
+            if (ex is OperationCanceledException)
+            {
+                _logger.LogInformation(exception: ex, message: null);
+                return null;
+            }
+            else
+            {
+                throw;
+            }
+        }
+    }
+}