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by Jiří {x2} Činčura

Getting closer to the “v1” with external procedures in Firebird in .NET

25 May 2017 .NET, C#, Databases in general, Firebird, SQL

It’s been a while since the last time I blogged about FbNetExternalEngine. That doesn’t mean there was nothing happening. I was slowly working on it (really slowly, because of … time), plus some companies took interest in it, confirming it’s worth working on it and providing some feedback or nice-to-have features wishes (feel free to share your ideas in comments). So what’s really new?

As the C# 7 came out, I played with it and decided it’s a nice fit for this project to provide results from procedures. Even if you’re not yet ready to use C# 7, you can use the ValueTuple direcly and create external procedures because C# 7 just adds syntax sugar on top of it. The idea still the same. Input parameters are regular parameters as you’d expect. The returned type needs to be IEnumerator<(...)>. Here’s an example.

public static IEnumerator<(int?, int?)> IncrementInteger(int? i)
{
	yield return (i, i + 1);
}

Another big change – in fact it took a lot of try-error-repeat cycles, although the code is fairly straightforward at the end – is loading the assembly only when the execution is happening and releasing it right after. As you can probably guess, it is using application domains. What that means is that you can replace the assembly with your procedures on the fly without stopping the server. I’m really excited about this. Sadly it adds a little bit overhead with execution (because of the marshalling), but I haven’t jumped into performance optimizations yet (or possibly providing two execution models).

If you’d like to give it a try, download 32-bit or 64-bit build and enjoy. The package contains plugins.conf to help you register the plugin and also Example.dll (with source) and corresponding SQL script showing all supported datatypes on both sides.

namespace Example
{
	public static class Procedures
	{
		public static IEnumerator<(int?, int?)> IncrementInteger(int? i)
		{
			yield return (i, i + 1);
		}

		public static IEnumerator<(long?, long?)> IncrementBigint(long? i)
		{
			yield return (i, i + 1);
		}

		public static IEnumerator<(short?, short?)> IncrementSmallint(short? i)
		{
			yield return (i, (short?)(i + 1));
		}

		public static IEnumerator<(float?, float?)> IncrementFloat(float? i)
		{
			yield return (i, i + 1);
		}

		public static IEnumerator<(double?, double?)> IncrementDouble(double? i)
		{
			yield return (i, i + 1);
		}

		public static IEnumerator<(decimal?, decimal?)> IncrementDecimal(decimal? i)
		{
			yield return (i, i + 1);
		}

		public static IEnumerator<(decimal?, decimal?)> IncrementNumeric(decimal? i)
		{
			yield return (i, i + 1);
		}

		public static IEnumerator<(string, string)> ReverseVarchar(string s)
		{
			yield return (s, s?.Reverse());
		}

		public static IEnumerator<(string, string)> ReverseChar(string s)
		{
			yield return (s, s?.Reverse());
		}

		public static IEnumerator<(DateTime?, DateTime?)> AddDayTimestamp(DateTime? timestamp)
		{
			yield return (timestamp, timestamp?.AddDays(1));
		}

		public static IEnumerator<(DateTime?, DateTime?)> AddDayDate(DateTime? date)
		{
			yield return (date, date?.AddDays(1));
		}

		public static IEnumerator<(TimeSpan?, TimeSpan?)> AddHourTime(TimeSpan? time)
		{
			yield return (time, time?.Add(TimeSpan.FromHours(1)));
		}

		public static IEnumerator<(bool?, bool?)> NegateBoolean(bool? b)
		{
			yield return (b, !b);
		}

		public static IEnumerator<ValueTuple<DateTime?>> CurrentUtcTimestamp()
		{
			var value = DateTime.UtcNow;
			yield return new ValueTuple<DateTime?>(value);
		}
	}

	public static class Ext
	{
		public static string Reverse(this string s)
		{
			var chars = s.ToCharArray();
			Array.Reverse(chars);
			return new string(chars);
		}
	}
}
recreate procedure increment_integer(input int)
returns (original int, new int)
external name 'Example!Example.Procedures.IncrementInteger'
engine FbNetExternalEngine;

recreate procedure increment_bigint(input bigint)
returns (original bigint, new bigint)
external name 'Example!Example.Procedures.IncrementBigint'
engine FbNetExternalEngine;

recreate procedure increment_smallint(input smallint)
returns (original smallint, new smallint)
external name 'Example!Example.Procedures.IncrementSmallint'
engine FbNetExternalEngine;

recreate procedure increment_float(input float)
returns (original float, new float)
external name 'Example!Example.Procedures.IncrementFloat'
engine FbNetExternalEngine;

recreate procedure increment_double(input double precision)
returns (original double precision, new double precision)
external name 'Example!Example.Procedures.IncrementDouble'
engine FbNetExternalEngine;

recreate procedure increment_decimal(input decimal(18,4))
returns (original decimal(18,4), new decimal(18,4))
external name 'Example!Example.Procedures.IncrementDecimal'
engine FbNetExternalEngine;

recreate procedure increment_numeric(input numeric(18,4))
returns (original numeric(18,4), new numeric(18,4))
external name 'Example!Example.Procedures.IncrementNumeric'
engine FbNetExternalEngine;

recreate procedure reverse_varchar(input varchar(20))
returns (original varchar(20), new varchar(20))
external name 'Example!Example.Procedures.ReverseVarchar'
engine FbNetExternalEngine;

recreate procedure reverse_char(input char(20))
returns (original char(20), new char(20))
external name 'Example!Example.Procedures.ReverseChar'
engine FbNetExternalEngine;

recreate procedure add_day_timestamp(input timestamp)
returns (original timestamp, new timestamp)
external name 'Example!Example.Procedures.AddDayTimestamp'
engine FbNetExternalEngine;

recreate procedure add_day_date(input date)
returns (original date, new date)
external name 'Example!Example.Procedures.AddDayDate'
engine FbNetExternalEngine;

recreate procedure add_hour_time(input time)
returns (original time, new time)
external name 'Example!Example.Procedures.AddHourTime'
engine FbNetExternalEngine;

recreate procedure negate_boolean(input boolean)
returns (original boolean, new boolean)
external name 'Example!Example.Procedures.NegateBoolean'
engine FbNetExternalEngine;

recreate procedure current_utc_timestamp
returns (result timestamp)
external name 'Example!Example.Procedures.CurrentUtcTimestamp'
engine FbNetExternalEngine;

Right now I want to gather some feedback from you, work on some easy performance gains and start on functions. All this, at least now, will be v1 in my mind.