uDIG

Deleting Layers does not cancel WMS Requests

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Description

Add a WMS layer (preferably a moderately slow one).
Zoom into the layer (job meter starts running).
Right click and delete layer (job meter keeps running).

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Jesse Eichar added a comment -
This occurs because the geotools wms codes does not provide a way to cancel the getMap request so the UDIG renderer blocks on the request and is unable to respond to a cancel. If the getMap request performed its request in a seperate thread the UDIG code could be something like the following.

wms.startRequest();
while ( !cancelled && !wms.hasResult )
   this.wait(500);

if( !cancelled )
   draw(wms.getResult());
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Jesse Eichar added a comment - This occurs because the geotools wms codes does not provide a way to cancel the getMap request so the UDIG renderer blocks on the request and is unable to respond to a cancel. If the getMap request performed its request in a seperate thread the UDIG code could be something like the following. wms.startRequest(); while ( !cancelled && !wms.hasResult )    this.wait(500); if( !cancelled )    draw(wms.getResult());
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Jody Garnett added a comment -
So jesse can we not just abandon the renderer? Just becase it will finish (and will try to draw a map at that time), does not mean we still have to listen to it (or do anything when it tells us it is ready).

What is stopping us from:
1) telling the old renderers to stop
2) starting up a new set of renderers
3) carrying on like normal?

I suspect the answer is trying to reuse the renderers? I would not worry:
a) they externalize all state to Layer (StyleBlack blackboard, and properties)
b) They don't even manage their "context", they don't own a raster for example
c) they don't own/hold resources (you have your resource decorator that captures FeatureSources)

The only thing they could do (back in the day) is listen to a resource they were interested in and redraw without further intervention. I am not sure if that is still there responsibility (or does someone else listen now?)

Jody
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Jody Garnett added a comment - So jesse can we not just abandon the renderer? Just becase it will finish (and will try to draw a map at that time), does not mean we still have to listen to it (or do anything when it tells us it is ready). What is stopping us from: 1) telling the old renderers to stop 2) starting up a new set of renderers 3) carrying on like normal? I suspect the answer is trying to reuse the renderers? I would not worry: a) they externalize all state to Layer (StyleBlack blackboard, and properties) b) They don't even manage their "context", they don't own a raster for example c) they don't own/hold resources (you have your resource decorator that captures FeatureSources) The only thing they could do (back in the day) is listen to a resource they were interested in and redraw without further intervention. I am not sure if that is still there responsibility (or does someone else listen now?) Jody
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Jody Garnett added a comment -
Is this fixed now? We did make the move to abandon renderer that are waiting for external services such as WMS. But I am not sure if this applys when deleting?
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Jody Garnett added a comment - Is this fixed now? We did make the move to abandon renderer that are waiting for external services such as WMS. But I am not sure if this applys when deleting?

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  • Assignee:
    Unassigned
    Reporter:
    Paul Ramsey
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    Updated: