Microsoft.Xna.Framework.Graphics.Shader.GetShaderHandle C# (CSharp) Method

        internal int GetShaderHandle()
        {
            // If the shader has already been created then return it.
            if (_shaderHandle != -1)
                return _shaderHandle;
            
            //
            _shaderHandle = GL.CreateShader(Stage == ShaderStage.Vertex ? ShaderType.VertexShader : ShaderType.FragmentShader);
            GraphicsExtensions.CheckGLError();
            GL.ShaderSource(_shaderHandle, _glslCode);
            GraphicsExtensions.CheckGLError();
            GL.CompileShader(_shaderHandle);
            GraphicsExtensions.CheckGLError();
            var compiled = 0;
            GL.GetShader(_shaderHandle, ShaderParameter.CompileStatus, out compiled);
            GraphicsExtensions.CheckGLError();
            if (compiled == (int)All.False)
            {
                var log = GL.GetShaderInfoLog(_shaderHandle);
                Console.WriteLine(log);

                if (GL.IsShader(_shaderHandle))
                {
                    GL.DeleteShader(_shaderHandle);
                    GraphicsExtensions.CheckGLError();
                }
                _shaderHandle = -1;

                throw new InvalidOperationException("Shader Compilation Failed");
            }

            return _shaderHandle;
        }

        private void Link(Shader vertexShader, Shader pixelShader)
        {
            // NOTE: No need to worry about background threads here
            // as this is only called at draw time when we're in the
            // main drawing thread.
            var program = GL.CreateProgram();

            GraphicsExtensions.CheckGLError();

            GL.AttachShader(program, vertexShader.GetShaderHandle());
            GraphicsExtensions.CheckGLError();

            GL.AttachShader(program, pixelShader.GetShaderHandle());
            GraphicsExtensions.CheckGLError();

            //vertexShader.BindVertexAttributes(program);

            GL.LinkProgram(program);
            GraphicsExtensions.CheckGLError();

            GL.UseProgram(program);
            GraphicsExtensions.CheckGLError();

            vertexShader.GetVertexAttributeLocations(program);

            pixelShader.ApplySamplerTextureUnits(program);

            var linked = 0;

#if GLES
            GL.GetProgram(program, ProgramParameter.LinkStatus, ref linked);
#else
            GL.GetProgram(program, ProgramParameter.LinkStatus, out linked);
#endif
            GraphicsExtensions.LogGLError("VertexShaderCache.Link(), GL.GetProgram");
            if (linked == 0)
            {
#if !GLES
                var log = GL.GetProgramInfoLog(program);
                Console.WriteLine(log);
#endif
                GL.DetachShader(program, vertexShader.GetShaderHandle());
                GL.DetachShader(program, pixelShader.GetShaderHandle());
#if MONOMAC
                GL.DeleteProgram(1, ref program);
#else
                GL.DeleteProgram(program);
#endif
                throw new InvalidOperationException("Unable to link effect program");
            }

            ShaderProgramInfo info;
            info.program     = program;
            info.posFixupLoc = GL.GetUniformLocation(program, "posFixup");

            _programCache.Add(vertexShader.HashKey | pixelShader.HashKey, info);
        }