Push and wait on WorkQueueThread items using PushBlocking. Previously we
created a Common::Event sync_event on the caller's stack, called Wait on
it, then had the WorkQueueThread call Set on the sync_event once the
thread was done.
In addition to being simpler the new way avoids a use-after-free that
could happen in convoluted and unlikely yet possible thread scheduling
sequences.
One such case can be triggered as follows:
* Set your audio backend to Cubeb
* In CubebStream::SetVolume set a breakpoint at the call to Wait and at
the call to cubeb_stream_set_volume.
* Start a game.
* Continue until the Cubeb Worker thread hits the
cubeb_stream_set_volume breakpoint and Emuthread hits the Wait
breakpoint, freezing each thread when it hits its breakpoint.
* Unfreeze Cubeb Worker.
* In Event::Set set a breakpoint at the end of the scope containing the
lock_guard such that the guard has been constructed but not destructed
when the breakpoint is hit.
* Continue until that breakpoint is hit by Cubeb Worker. If other
threads hit it first keep going.
* Freeze Cubeb Worker.
* For convenience remove the breakpoint in Event::Set so other threads
don't trigger it.
* In CubebStream::SetRunning set a breakpoint at the call to Wait.
* Unfreeze Emuthread and continue until the breakpoint is hit.
* In Cubeb Worker go to Event::Set and examine the values of m_mutex's
member variables. In Visual Studio Debug these are locking_thread_id
== 0xcccccc01 and ownership_levels == 0xcccccccc. This is the result
of Visual Studio overwriting the memory used on the stack by
sync_event in CubebStream::SetVolume with cc bytes to represent
uninitialized memory on the stack (since that function already
returned), and then allocating enough memory on the stack when calling
AudioCommon::SetSoundStreamRunning and then CubebStream::SetRunning
that it overwrote one byte of the memory formerly occupied by
locking_thread_id.
* If you unfreeze Cubeb Worker at this point it will trigger the lock
guard's destructor which will then try to unlock m_mutex. Since
m_mutex is no longer in scope this is a use-after-free, and in VS
debug triggers a debug assert due to locking_thread_id not matching
the current thread id.
Displays a different message at game launch if RetroAchievements fails specifically due to an invalid or expired API token, instructing the player to log back in with the game closed.
This is a hassle-free BBA option intended for local play with multiple
Dolphin instances running *in the same system*. After selecting
**Broadband Adapter (IPC)** in the **SP1** slot in the GameCube section
in the settings, games that support LAN play will be able to discover
each other, without requiring third-party software or relatively complex
TAP setups.
The implementation is based on cpp-ipc, a high-performance inter-process
communication library that uses shared memory as transport layer.
Supported platforms are:
- [x] Linux
- [x] Windows
- [ ] macOS (cpp-ipc does not support this platform)
- [ ] FreeBSD (cpp-ipc does not support this platform)
- [ ] Android (cpp-ipc needs some adjustments; while it could work,
launching two Dolphin instances within the same Android system may be
both challenging and impractical)
