diff options
| author | Michael Stahl <mstahl@redhat.com> | 2013-11-26 12:58:31 +0100 |
|---|---|---|
| committer | Michael Stahl <mstahl@redhat.com> | 2014-01-09 13:44:24 +0100 |
| commit | bcfd016c88f2da271fc77da608b42d2f5bd83448 (patch) | |
| tree | cf5a413ccfb8befd4bf5f1c2485230c23ad63d86 /winaccessibility | |
| parent | 4eae9d19cce5356d536ae509861a5c95f65aea4a (diff) | |
some notes about COM threading in LO generally and winaccessibility
- document general COM threading architecture in vcl README
- document winaccessiblitiy locking in README
- define _ATL_APARTMENT_THREADED for UAccCOM
Change-Id: I7c3fd952f2cdee7d245a818bf33c477e7ea20fc2
Diffstat (limited to 'winaccessibility')
| -rw-r--r-- | winaccessibility/README | 16 | ||||
| -rw-r--r-- | winaccessibility/source/UAccCOM/stdafx.h | 4 |
2 files changed, 19 insertions, 1 deletions
diff --git a/winaccessibility/README b/winaccessibility/README index eb425e419b75..bac3681e720a 100644 --- a/winaccessibility/README +++ b/winaccessibility/README @@ -26,6 +26,22 @@ Here is one way of visualising the code / control flow VCL <-> UNO toolkit <-> UNO a11y <-> win a11y <-> COM / IAccessible2 vcl/ <-> toolkit/ <-> accessibility/ <-> winaccessibility/ <-> UAccCom/ +Threading + +It's possible that the UNO components are called from threads other +than the main thread, so they have to be synchronized. It would be nice +to put the component into an UNO apartment (and the COM components into STA) +but UNO would spawn a new thread for it so it's not possible. +The COM components also call into the same global AccObjectWinManager +as the UNO components do so both have to be synchronized in the same way. +So we use the SolarMutex for all synchronization since anything else +would be rather difficult to make work. Unfortunately there is a +pre-exising problem in vcl with Win32 Window creation and destruction +on non-main threads where a synchronous SendMessage is used while +the SolarMutex is locked that can cause deadlocks if the main thread is +waiting on the SolarMutex itself at that time and thus not handing the +Win32 message; this is easy to trigger with JunitTests but hopefully +not by actual end users. Debugging / playing with winaccessibility diff --git a/winaccessibility/source/UAccCOM/stdafx.h b/winaccessibility/source/UAccCOM/stdafx.h index 66019e2f043a..e71ac0b0a506 100644 --- a/winaccessibility/source/UAccCOM/stdafx.h +++ b/winaccessibility/source/UAccCOM/stdafx.h @@ -28,7 +28,9 @@ #pragma once #endif // _MSC_VER > 1000 -//#define _ATL_APARTMENT_THREADED +// this turns off ATL's locking in the COM component implementations +// (we don't need it since we use SolarMutex instead) +#define _ATL_APARTMENT_THREADED #include <prewin.h> #include <windows.h> |