Define the thread-safety attributes of the classes and methods that are
either thread-safe or thread-bound. The CameraManager, Camera and
PipelineHandler will be addressed separately.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
The Object class stores the number of pending messages that have been
posted for it, while the actual messages are stored in a per-thread list
in the ThreadData class. When dispatching messages, the message is
removed from the list, passed to the receiver, and the number of pending
messages is updated.
In order to avoid too much contention on the list lock, the lock is
dropped to pass the message to the receiver and then taken again. This
creates a race condition window with Thread::removeMessages(), as the
number of pending messages for a receiver is briefly out of sync with
the pending messages list. The assertion at the end of removeMessages()
thus sometimes fails.
Fix this by decrementing the pending messages counter before releasing
the lock in Thread::dispatchMessages(). This fixes the slow message
receiver test in MessageTest.
Fixes: 01b930964a ("libcamera: thread: Add a messaging passing API")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
When moving an Object to a Thread, messages posted for the object are
move to the target thread's message queue. This requires locking the
message queues of the current and target threads, as the target thread
may (and is usually) running. The implementation is faulty as it locks
the thread data instead of the message queue. This creates a race
condition with a tiny but exploitable time window.
The issue was noticed by the event-thread test rarely but reproducibly
failing with the following assertion error:
[1:39:33.850878042]FATAL default thread.cpp:440 assertion "data_ == receiver->thread()->data_" failed
The issue only occurred when libcamera was compiled in release mode,
further hinting of a race condition.
Fixes: 01b930964a ("libcamera: thread: Add a messaging passing API")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Comply with the coding style by removing lots of unneeded semicolons.
Fix a few other coding style violations on the lines touched by those
fixes.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Add a parent Object to Object instances, and track the parent-children
relationships. Children are bound to the same thread as their parent,
and moving an Object to a thread automatically moves all its children.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Threads contain message queues and dispatch queued messages in their
event loop, in Thread::exec(). This mechanism prevents the main thread
from dispatching messages as it doesn't run Thread::exec().
Fix this by moving message dispatching from Thread::exec() to
EventDispatcher::processEvents().
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
When moving an object to a different thread, messages posted for the
object are moved to the message queue of the new thread. Wake up the new
thread to ensure it processes the moved messages.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Create a new Message class to model a message that can be passed to an
object living in another thread. Only an invalid message type is
currently defined, more messages will be added in the future.
The Thread class is extended with a messages queue, and the Object class
with thread affinity.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
The new Thread class wraps std::thread in order to integrate it with the
Object, Signal and EventDispatcher classes. By default new threads run
an internal event loop, and their run() method can be overloaded to
provide a custom thread loop.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
