[libcamera-devel] [RFC PATCH 3/5] android: post_processor: Notify post processing completion status

[Umang Jain]

When a post-processor is running asynchronously, we should be able to
know whether the post-processing operation on the stream has been
completed or not. Secondly, we should be able to know if it completed
successfully or encountered some errors. This commit introduces a
Signal<> which when connected, will notify that the post-processing
has been completed. The status of PostProcessor::process() will be
passed as a PostProcessor::Status argument. The populated
CameraMetadata shall also be available in the signal-handler.

/*
 * DNI: I do not like the multiple places of signal emission.
 * We need to use goto but first we need to make a single point
 * of return somehow, and restructure the error paths a bit.
 */

Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
---
 src/android/jpeg/post_processor_jpeg.cpp | 9 ++++++++-
 src/android/post_processor.h             | 7 +++++++
 src/android/yuv/post_processor_yuv.cpp   | 4 ++++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/android/jpeg/post_processor_jpeg.cpp b/src/android/jpeg/post_processor_jpeg.cpp
index 723e8d18..9366934d 100644
--- a/src/android/jpeg/post_processor_jpeg.cpp
+++ b/src/android/jpeg/post_processor_jpeg.cpp
@@ -87,8 +87,11 @@ int PostProcessorJpeg::process(const FrameBuffer *source,
 			       const CameraMetadata &requestMetadata,
 			       CameraMetadata *resultMetadata)
 {
-	if (!encoder_)
+	if (!encoder_) {
+		processComplete.emit(PostProcessor::Status::Failed,
+				     resultMetadata);
 		return 0;
+	}
 
 	ASSERT(destination->numPlanes() == 1);
 
@@ -181,6 +184,8 @@ int PostProcessorJpeg::process(const FrameBuffer *source,
 					 exif.data(), quality);
 	if (jpeg_size < 0) {
 		LOG(JPEG, Error) << "Failed to encode stream image";
+		processComplete.emit(PostProcessor::Status::Failed,
+				     resultMetadata);
 		return jpeg_size;
 	}
 
@@ -195,5 +200,7 @@ int PostProcessorJpeg::process(const FrameBuffer *source,
 	/* Update the JPEG result Metadata. */
 	resultMetadata->addEntry(ANDROID_JPEG_SIZE, jpeg_size);
 
+	processComplete.emit(PostProcessor::Status::Success, resultMetadata);
+
 	return 0;
 }
diff --git a/src/android/post_processor.h b/src/android/post_processor.h
index 5b8f1ab8..73fa79e9 100644
--- a/src/android/post_processor.h
+++ b/src/android/post_processor.h
@@ -8,6 +8,7 @@
 #define __ANDROID_POST_PROCESSOR_H__
 
 #include <libcamera/base/object.h>
+#include <libcamera/base/signal.h>
 
 #include <libcamera/framebuffer.h>
 #include <libcamera/stream.h>
@@ -27,6 +28,12 @@ public:
 			    CameraBuffer *destination,
 			    const CameraMetadata &requestMetadata,
 			    CameraMetadata *resultMetadata) = 0;
+
+	enum Status {
+		Success,
+		Failed,
+	};
+	libcamera::Signal<Status, CameraMetadata *> processComplete;
 };
 
 #endif /* __ANDROID_POST_PROCESSOR_H__ */
diff --git a/src/android/yuv/post_processor_yuv.cpp b/src/android/yuv/post_processor_yuv.cpp
index 4b507d33..1877e54b 100644
--- a/src/android/yuv/post_processor_yuv.cpp
+++ b/src/android/yuv/post_processor_yuv.cpp
@@ -60,6 +60,7 @@ int PostProcessorYuv::process(const FrameBuffer *source,
 	const MappedFrameBuffer sourceMapped(source, MappedFrameBuffer::MapFlag::Read);
 	if (!sourceMapped.isValid()) {
 		LOG(YUV, Error) << "Failed to mmap camera frame buffer";
+		processComplete.emit(PostProcessor::Status::Failed, metadata);
 		return -EINVAL;
 	}
 
@@ -77,9 +78,12 @@ int PostProcessorYuv::process(const FrameBuffer *source,
 				    libyuv::FilterMode::kFilterBilinear);
 	if (ret) {
 		LOG(YUV, Error) << "Failed NV12 scaling: " << ret;
+		processComplete.emit(PostProcessor::Status::Failed, metadata);
 		return -EINVAL;
 	}
 
+	processComplete.emit(PostProcessor::Status::Success, metadata);
+
 	return 0;
 }
 
-- 
2.31.1