chore: remove MaxReceiveMessageSize limit from gRPC client (#571)

Removes the max size of messages that can be received by the .NET gRPC
client. This prevents errors when the client receives large values from
the library.

Author: olavloite

spannerlib/wrappers/spannerlib-dotnet/spannerlib-dotnet-grpc-impl/GrpcLibSpanner.cs

@@ -45,7 +45,8 @@ public static GrpcChannel ForUnixSocket(string fileName)
                         throw;
                     }
                 }
-            }
+            },
+            MaxReceiveMessageSize = null,
         });
     }
 
@@ -56,7 +57,8 @@ public static GrpcChannel ForTcpSocket(string address)
             HttpHandler = new SocketsHttpHandler
             {
                 EnableMultipleHttp2Connections = true,
-            }
+            },
+            MaxReceiveMessageSize = null,
         });
     }
 

spannerlib/wrappers/spannerlib-dotnet/spannerlib-dotnet-tests/RowsTests.cs

@@ -77,6 +77,28 @@ public void TestRandomResults([Values] LibType libType)
         var request = Fixture.SpannerMock.Requests.OfType<ExecuteSqlRequest>().First();
         Assert.That(request.Transaction?.SingleUse?.ReadOnly?.HasStrong ?? false);
     }
+    
+    [Test]
+    public void TestLargeStringValue([Values] LibType libType)
+    {
+        const string sql = "select large_value from my_table";
+        var value = TestUtils.GenerateRandomString(10_000_000);
+        Fixture.SpannerMock.AddOrUpdateStatementResult(sql, StatementResult.CreateSingleColumnResultSet(
+            new Spanner.V1.Type{Code = TypeCode.String}, "large_value", value));
+        
+        using var pool = Pool.Create(SpannerLibDictionary[libType], ConnectionString);
+        using var connection = pool.CreateConnection();
+        using var rows = connection.Execute(new ExecuteSqlRequest { Sql = sql });
+        var numRows = 0;
+        while (rows.Next() is { } row)
+        {
+            numRows++;
+            Assert.That(row.Values.Count, Is.EqualTo(1));
+            Assert.That(row.Values[0].HasStringValue);
+            Assert.That(row.Values[0].StringValue, Is.EqualTo(value));
+        }
+        Assert.That(numRows, Is.EqualTo(1));
+    }
 
     [Test]
     public void TestStopHalfway([Values] LibType libType)

spannerlib/wrappers/spannerlib-dotnet/spannerlib-dotnet-tests/TestUtils.cs

@@ -0,0 +1,12 @@
+namespace Google.Cloud.SpannerLib.Tests;
+
+public static class TestUtils
+{
+    private const string Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+
+    public static string GenerateRandomString(int length)
+    {
+        return new string(Enumerable.Repeat(Chars, length)
+            .Select(s => s[Random.Shared.Next(s.Length)]).ToArray());
+    }
+}