Mercurial > hg > orthanc-book
comparison Sphinx/source/plugins/python.rst @ 591:2397b0e12bc8
solution to avoid deadlock in Python OnChange()
| author | Sebastien Jodogne <s.jodogne@gmail.com> |
|---|---|
| date | Thu, 07 Jan 2021 14:53:36 +0100 |
| parents | 404aca6160f0 |
| children | 4038ae299b18 |
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| 590:404aca6160f0 | 591:2397b0e12bc8 |
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| 287 the REST API of Orthanc in the callback. If you have to call other | 287 the REST API of Orthanc in the callback. If you have to call other |
| 288 primitives of Orthanc, you should make these calls in a separate | 288 primitives of Orthanc, you should make these calls in a separate |
| 289 thread, passing the pending events to be processed through a | 289 thread, passing the pending events to be processed through a |
| 290 message queue. | 290 message queue. |
| 291 | 291 |
| 292 Here is the template of a possible solution to avoid such deadlocks by | |
| 293 relying on the multithreading primitives of Python:: | |
| 294 | |
| 295 import orthanc | |
| 296 import threading | |
| 297 | |
| 298 def OnChange(changeType, level, resource): | |
| 299 # One can safely invoke the "orthanc" module in this function | |
| 300 orthanc.LogWarning("Hello world") | |
| 301 | |
| 302 def _OnChange(changeType, level, resource): | |
| 303 # Invoke the actual "OnChange()" function in a separate thread | |
| 304 t = threading.Timer(0, function = OnChange, args = (changeType, level, resource)) | |
| 305 t.start() | |
| 306 | |
| 307 orthanc.RegisterOnChangeCallback(_OnChange) | |
| 308 | |
| 309 | |
| 292 | 310 |
| 293 Accessing the content of a new instance | 311 Accessing the content of a new instance |
| 294 ....................................... | 312 ....................................... |
| 295 | 313 |
| 296 .. highlight:: python | 314 .. highlight:: python |