[libcamera-devel] [PATCH 2/8] libcamera: request: Add Request::cancel()

[Jacopo Mondi]

Add a cancel() function to the Request class that allows to forcefully
complete the request and its associated buffers in error state.

Only pending requests can be forcefully cancelled. Enforce that
by asserting the request state to be RequestPending.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 include/libcamera/request.h |  1 +
 src/libcamera/request.cpp   | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/include/libcamera/request.h b/include/libcamera/request.h
index 4cf5ff3f7d3b..5596901ddd8e 100644
--- a/include/libcamera/request.h
+++ b/include/libcamera/request.h
@@ -65,6 +65,7 @@ private:
 	friend class PipelineHandler;
 
 	void complete();
+	void cancel();
 
 	bool completeBuffer(FrameBuffer *buffer);
 
diff --git a/src/libcamera/request.cpp b/src/libcamera/request.cpp
index ce2dd7b17f10..fc5e25199112 100644
--- a/src/libcamera/request.cpp
+++ b/src/libcamera/request.cpp
@@ -292,6 +292,36 @@ void Request::complete()
 	LIBCAMERA_TRACEPOINT(request_complete, this);
 }
 
+/**
+ * \brief Cancel a queued request
+ *
+ * Mark the request and its associated buffers as cancelled and complete it.
+ *
+ * Set the status of each buffer in the request to the frame cancelled state and
+ * remove them from the pending buffer queue before completing the request with
+ * error.
+ */
+void Request::cancel()
+{
+	LIBCAMERA_TRACEPOINT(request_cancel, this);
+
+	ASSERT(status_ == RequestPending);
+
+	/*
+	 * We can't simply loop and call completeBuffer() as erase() invalidates
+	 * pointers and iterators, so we have to manually cancel the buffer and
+	 * erase it from the pending buffers list.
+	 */
+	for (auto buffer = pending_.begin(); buffer != pending_.end();) {
+		(*buffer)->cancel();
+		(*buffer)->setRequest(nullptr);
+		buffer = pending_.erase(buffer);
+	}
+
+	cancelled_ = true;
+	complete();
+}
+
 /**
  * \brief Complete a buffer for the request
  * \param[in] buffer The buffer that has completed
-- 
2.31.1