Compositor debug improvements

Cleanup and improvements of the compositor debug output.

Debug code for graphviz output moved to a dedicated file COM_Debug.h/cpp.

The DebugInfo class has only static functions, which are called from a number of places to keep track of what is happening in the compositor. If debugging is disabled these are just inline stubs, so we don't need #ifdefs everywhere and don't get any overhead.

The graphviz output is much more useful now. DebugInfo keeps track of node names in a static string map for meaningful names. It uses a number of colors for various special operation classes. ExecutionGroups are indicated in graphviz with clusters.

Currently the graphviz .dot files are stored in the BLI_temporary_dir() folder. A separate dot file is generated for each stage of the ExecutionGroup scheduling, this is intended to give some idea of the compositor progress, but could still be improved.

[sergey.vfx, 2013-09-13 13:18:41]

Apart from some really minor notes, LGTM.

https://codereview.appspot.com/13699043/diff/1/source/blender/compositor/inte...
File source/blender/compositor/intern/COM_Debug.cpp (right):

https://codereview.appspot.com/13699043/diff/1/source/blender/compositor/inte...
source/blender/compositor/intern/COM_Debug.cpp:2: * Copyright 2011, Blender
Foundation.
Sure about 2011, not 2013?

https://codereview.appspot.com/13699043/diff/1/source/blender/compositor/inte...
source/blender/compositor/intern/COM_Debug.cpp:402: std::string
DebugInfo::node_name(NodeBase *node) { return ""; }
Afraid strict compiler flags would be unhappy with unused argument. Would do
this:

std::string DebugInfo::node_name(NodeBase * /*node*/) { return ""; }

Same applies to some few functions below as well.

https://codereview.appspot.com/13699043/diff/1/source/blender/compositor/inte...
File source/blender/compositor/intern/COM_ExecutionSystemHelper.cpp (right):

https://codereview.appspot.com/13699043/diff/1/source/blender/compositor/inte...
source/blender/compositor/intern/COM_ExecutionSystemHelper.cpp:40: #include
"MEM_guardedalloc.h"
Not sure why guardedalloc is needed? Is it to support guarded allocating of
DebugInfo?

[lukas.toenne1, 2013-09-13 13:29:31]

https://codereview.appspot.com/13699043/diff/1/source/blender/compositor/inte...
File source/blender/compositor/intern/COM_Debug.cpp (right):

https://codereview.appspot.com/13699043/diff/1/source/blender/compositor/inte...
source/blender/compositor/intern/COM_Debug.cpp:2: * Copyright 2011, Blender
Foundation.
On 2013/09/13 13:18:41, sergey.vfx wrote:
> Sure about 2011, not 2013?

Lazy copying, fixed.

https://codereview.appspot.com/13699043/diff/1/source/blender/compositor/inte...
source/blender/compositor/intern/COM_Debug.cpp:402: std::string
DebugInfo::node_name(NodeBase *node) { return ""; }
On 2013/09/13 13:18:41, sergey.vfx wrote:
> Afraid strict compiler flags would be unhappy with unused argument. Would do
> this:
> 
> std::string DebugInfo::node_name(NodeBase * /*node*/) { return ""; }
> 
> Same applies to some few functions below as well.

Done.

https://codereview.appspot.com/13699043/diff/1/source/blender/compositor/inte...
File source/blender/compositor/intern/COM_ExecutionSystemHelper.cpp (right):

https://codereview.appspot.com/13699043/diff/1/source/blender/compositor/inte...
source/blender/compositor/intern/COM_ExecutionSystemHelper.cpp:40: #include
"MEM_guardedalloc.h"
On 2013/09/13 13:18:41, sergey.vfx wrote:
> Not sure why guardedalloc is needed? Is it to support guarded allocating of
> DebugInfo?

Leftover include, removed.