GtkSharp/generator/VirtualMethod.cs
Bertrand Lorentz e48ac63d54 generator: Dispose ownable method parameters in VM callback (bxc#237)
Some virtual methods are passed a native object that is wrapped in an
IDisposable managed object, which is then passed on to the managed
overrides. We need to dispose those objects as soon as possible,
otherwise their native counterpart will not be freed until the next
garbage collection. Requiring the overrides to dispose them would be
cumbersome and error-prone.

Those parameters will now be disposed in a finally {...} block, after
the virtual method has returned. This means that overrides should not
keep a reference to such a parameter outside of the scope of the method,
as it will be diposed when the method returns.

This change only affects Cairo.Context parameter for now, but it was
particularly needed for them, as they could happily hold on to tens of
MBs of memory until the next garbage collection.
2013-11-09 16:26:17 +01:00

158 lines
4.7 KiB
C#

// GtkSharp.Generation.VirtualMethod.cs - The VirtualMethod Generatable.
//
// Author: Mike Kestner <mkestner@novell.com>
//
// Copyright (c) 2003-2004 Novell, Inc.
// Copyright (c) 2009 Christian Hoff
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of version 2 of the GNU General Public
// License as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public
// License along with this program; if not, write to the
// Free Software Foundation, Inc., 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.
namespace GtkSharp.Generation {
using System;
using System.Collections;
using System.IO;
using System.Xml;
public abstract class VirtualMethod : MethodBase {
protected ReturnValue retval;
protected ManagedCallString call;
protected string modifiers = "";
public VirtualMethod (XmlElement elem, ObjectBase container_type) : base (elem, container_type)
{
if (container_type.ParserVersion == 1) {
// The old pre 2.14 parser didn't drop the 1st parameter in all <signal> and <virtual_method> elements
parms = new Parameters (elem ["parameters"], true);
}
retval = new ReturnValue (elem ["return-type"]);
}
protected abstract string CallString {
get;
}
VMSignature signature;
protected new VMSignature Signature {
get {
if (signature == null)
signature = new VMSignature (parms);
return signature;
}
}
/* Creates a callback method which invokes the corresponding virtual method
* @implementor is the class that implements the virtual method(e.g. the class that derives from an interface) or NULL if containing and declaring type are equal
*/
public void GenerateCallback (StreamWriter sw, ClassBase implementor)
{
LogWriter log = new LogWriter ();
log.Type = container_type.QualifiedName;
if (!Validate (log))
return;
string native_signature = "";
if (!IsStatic) {
native_signature += "IntPtr inst";
if (parms.Count > 0)
native_signature += ", ";
}
if (parms.Count > 0)
native_signature += parms.ImportSignature;
sw.WriteLine ("\t\t[UnmanagedFunctionPointer (CallingConvention.Cdecl)]");
sw.WriteLine ("\t\tdelegate {0} {1}NativeDelegate ({2});", retval.ToNativeType, this.Name, native_signature);
sw.WriteLine ();
sw.WriteLine ("\t\tstatic {0} {1}_cb ({2})", retval.ToNativeType, this.Name, native_signature);
sw.WriteLine ("\t\t{");
string unconditional = call.Unconditional ("\t\t\t");
if (unconditional.Length > 0)
sw.WriteLine (unconditional);
sw.WriteLine ("\t\t\ttry {");
if (!this.IsStatic) {
string type;
if (implementor != null)
type = implementor.QualifiedName;
else if (this.container_type is InterfaceGen)
// We are in an interface/adaptor, invoke the method in the implementor class
type = (this.container_type as InterfaceGen).ImplementorName;
else
type = this.container_type.Name;
sw.WriteLine ("\t\t\t\t{0} __obj = GLib.Object.GetObject (inst, false) as {0};", type);
}
string indent = "\t\t\t\t";
if (!retval.IsVoid)
sw.WriteLine (indent + retval.CSType + " __result;");
sw.Write (call.Setup (indent));
sw.Write (indent);
if (!retval.IsVoid)
sw.Write ("__result = ");
if (!this.IsStatic)
sw.Write ("__obj.");
sw.WriteLine (this.CallString + ";");
sw.Write (call.Finish (indent));
if (!retval.IsVoid)
sw.WriteLine ("\t\t\t\treturn " + retval.ToNative ("__result") + ";");
bool fatal = parms.HasOutParam || !retval.IsVoid;
sw.WriteLine ("\t\t\t} catch (Exception e) {");
sw.WriteLine ("\t\t\t\tGLib.ExceptionManager.RaiseUnhandledException (e, " + (fatal ? "true" : "false") + ");");
if (fatal) {
sw.WriteLine ("\t\t\t\t// NOTREACHED: above call does not return.");
sw.WriteLine ("\t\t\t\tthrow e;");
}
if (call.HasDisposeParam) {
sw.WriteLine ("\t\t\t} finally {");
sw.Write (call.DisposeParams (indent));
}
sw.WriteLine ("\t\t\t}");
sw.WriteLine ("\t\t}");
sw.WriteLine ();
}
enum ValidState {
Unvalidated,
Invalid,
Valid
}
ValidState vstate = ValidState.Unvalidated;
public override bool Validate (LogWriter log)
{
if (vstate != ValidState.Unvalidated)
return vstate == ValidState.Valid;
vstate = ValidState.Valid;
log.Member = Name;
if (!parms.Validate (log) || !retval.Validate (log)) {
vstate = ValidState.Invalid;
return false;
}
call = new ManagedCallString (parms);
return true;
}
}
}