From bf3dbaece91e7f9be00923a225a62a918bf71f5b Mon Sep 17 00:00:00 2001 From: Tomi Valkeinen Date: Fri, 19 Aug 2022 14:16:15 +0300 Subject: py: Switch to non-blocking eventfd Blocking wait can be easily implemented on top in Python, so rather than supporting only blocking reads, or supporting both non-blocking and blocking reads, let's support only non-blocking reads. Signed-off-by: Tomi Valkeinen Reviewed-by: Laurent Pinchart Signed-off-by: Laurent Pinchart --- src/py/examples/simple-cam.py | 5 +++-- src/py/examples/simple-capture.py | 12 ++++++++++-- src/py/examples/simple-continuous-capture.py | 5 +++-- src/py/libcamera/py_camera_manager.cpp | 22 +++++++++++++++++----- src/py/libcamera/py_camera_manager.h | 2 +- 5 files changed, 34 insertions(+), 12 deletions(-) (limited to 'src') diff --git a/src/py/examples/simple-cam.py b/src/py/examples/simple-cam.py index 2b81bb65..b3e97ca7 100755 --- a/src/py/examples/simple-cam.py +++ b/src/py/examples/simple-cam.py @@ -19,8 +19,9 @@ TIMEOUT_SEC = 3 def handle_camera_event(cm): - # cm.get_ready_requests() will not block here, as we know there is an event - # to read. + # cm.get_ready_requests() returns the ready requests, which in our case + # should almost always return a single Request, but in some cases there + # could be multiple or none. reqs = cm.get_ready_requests() diff --git a/src/py/examples/simple-capture.py b/src/py/examples/simple-capture.py index a6a9b33e..5f93574f 100755 --- a/src/py/examples/simple-capture.py +++ b/src/py/examples/simple-capture.py @@ -14,6 +14,7 @@ import argparse import libcamera as libcam +import selectors import sys # Number of frames to capture @@ -107,11 +108,18 @@ def main(): # The main loop. Wait for the queued Requests to complete, process them, # and re-queue them again. + sel = selectors.DefaultSelector() + sel.register(cm.event_fd, selectors.EVENT_READ) + while frames_done < TOTAL_FRAMES: - # cm.get_ready_requests() blocks until there is an event and returns - # all the ready requests. Here we should almost always get a single + # cm.get_ready_requests() does not block, so we use a Selector to wait + # for a camera event. Here we should almost always get a single # Request, but in some cases there could be multiple or none. + events = sel.select() + if not events: + continue + reqs = cm.get_ready_requests() for req in reqs: diff --git a/src/py/examples/simple-continuous-capture.py b/src/py/examples/simple-continuous-capture.py index fe78a2dd..26a8060b 100755 --- a/src/py/examples/simple-continuous-capture.py +++ b/src/py/examples/simple-continuous-capture.py @@ -88,8 +88,9 @@ class CaptureContext: camera_contexts: list[CameraCaptureContext] = [] def handle_camera_event(self): - # cm.get_ready_requests() will not block here, as we know there is an event - # to read. + # cm.get_ready_requests() returns the ready requests, which in our case + # should almost always return a single Request, but in some cases there + # could be multiple or none. reqs = self.cm.get_ready_requests() diff --git a/src/py/libcamera/py_camera_manager.cpp b/src/py/libcamera/py_camera_manager.cpp index ea4ae825..9ccb7aad 100644 --- a/src/py/libcamera/py_camera_manager.cpp +++ b/src/py/libcamera/py_camera_manager.cpp @@ -24,7 +24,7 @@ PyCameraManager::PyCameraManager() cameraManager_ = std::make_unique(); - int fd = eventfd(0, EFD_CLOEXEC); + int fd = eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK); if (fd == -1) throw std::system_error(errno, std::generic_category(), "Failed to create eventfd"); @@ -62,7 +62,13 @@ py::list PyCameraManager::cameras() std::vector PyCameraManager::getReadyRequests() { - readFd(); + int ret = readFd(); + + if (ret == -EAGAIN) + return std::vector(); + + if (ret != 0) + throw std::system_error(-ret, std::generic_category()); std::vector py_reqs; @@ -96,12 +102,18 @@ void PyCameraManager::writeFd() LOG(Python, Fatal) << "Unable to write to eventfd"; } -void PyCameraManager::readFd() +int PyCameraManager::readFd() { uint8_t buf[8]; - if (read(eventFd_.get(), buf, 8) != 8) - throw std::system_error(errno, std::generic_category()); + ssize_t ret = read(eventFd_.get(), buf, 8); + + if (ret == 8) + return 0; + else if (ret < 0) + return -errno; + else + return -EIO; } void PyCameraManager::pushRequest(Request *req) diff --git a/src/py/libcamera/py_camera_manager.h b/src/py/libcamera/py_camera_manager.h index 56bea13d..3525057d 100644 --- a/src/py/libcamera/py_camera_manager.h +++ b/src/py/libcamera/py_camera_manager.h @@ -39,7 +39,7 @@ private: LIBCAMERA_TSA_GUARDED_BY(completedRequestsMutex_); void writeFd(); - void readFd(); + int readFd(); void pushRequest(Request *req); std::vector getCompletedRequests(); }; -- cgit v1.2.1