[libcamera-devel] [PATCH v4 6/6] libcamera: request: Make it extensible

[Kieran Bingham]

Provide an extensible private object for the Request class.
This allows us to make modifications to the private API and storage of
requests without affecting the public API or ABI.

The D pointer is obtained in all Request functions implemented in the
request.cpp file along with an assertion that the D pointer was valid to
provide extra validation checking that the Request has not been
deleted, while in use as it is 'owned' by the application.

Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

---
The assertions added in findBuffer, complete() and completeBuffer()
allow us to ensure that the Request is still valid while asynchronous
actions occur on the Request internally in libcamera, and provide
(almost) equivalent functionality as the Request Canary previously
proposed.

The additions in reuse() and addBuffer() are called from applications,
so the assertions may be less helpful there, but I've added them for
consistency.

 include/libcamera/request.h |  4 +++-
 src/libcamera/request.cpp   | 34 ++++++++++++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/include/libcamera/request.h b/include/libcamera/request.h
index 4cf5ff3f7d3b..909a1aebc2d2 100644
--- a/include/libcamera/request.h
+++ b/include/libcamera/request.h
@@ -24,8 +24,10 @@ class CameraControlValidator;
 class FrameBuffer;
 class Stream;
 
-class Request
+class Request : public Extensible
 {
+	LIBCAMERA_DECLARE_PRIVATE(Request)
+
 public:
 	enum Status {
 		RequestPending,
diff --git a/src/libcamera/request.cpp b/src/libcamera/request.cpp
index ce2dd7b17f10..977bfac4fce6 100644
--- a/src/libcamera/request.cpp
+++ b/src/libcamera/request.cpp
@@ -28,6 +28,19 @@ namespace libcamera {
 
 LOG_DEFINE_CATEGORY(Request)
 
+class Request::Private : public Extensible::Private
+{
+	LIBCAMERA_DECLARE_PUBLIC(Request)
+
+public:
+	Private(Request *request);
+};
+
+Request::Private::Private(Request *request)
+	: Extensible::Private(request)
+{
+}
+
 /**
  * \enum Request::Status
  * Request completion status
@@ -73,8 +86,8 @@ LOG_DEFINE_CATEGORY(Request)
  *
  */
 Request::Request(Camera *camera, uint64_t cookie)
-	: camera_(camera), sequence_(0), cookie_(cookie),
-	  status_(RequestPending), cancelled_(false)
+	: Extensible(new Private(this)), camera_(camera), sequence_(0),
+	  cookie_(cookie), status_(RequestPending), cancelled_(false)
 {
 	/**
 	 * \todo Should the Camera expose a validator instance, to avoid
@@ -114,6 +127,9 @@ Request::~Request()
  */
 void Request::reuse(ReuseFlag flags)
 {
+	Private *const d = LIBCAMERA_D_PTR();
+	ASSERT(d);
+
 	LIBCAMERA_TRACEPOINT(request_reuse, this);
 
 	pending_.clear();
@@ -179,6 +195,9 @@ void Request::reuse(ReuseFlag flags)
  */
 int Request::addBuffer(const Stream *stream, FrameBuffer *buffer)
 {
+	Private *const d = LIBCAMERA_D_PTR();
+	ASSERT(d);
+
 	if (!stream) {
 		LOG(Request, Error) << "Invalid stream reference";
 		return -EINVAL;
@@ -214,6 +233,9 @@ int Request::addBuffer(const Stream *stream, FrameBuffer *buffer)
  */
 FrameBuffer *Request::findBuffer(const Stream *stream) const
 {
+	const Private *const d = LIBCAMERA_D_PTR();
+	ASSERT(d);
+
 	const auto it = bufferMap_.find(stream);
 	if (it == bufferMap_.end())
 		return nullptr;
@@ -282,6 +304,8 @@ FrameBuffer *Request::findBuffer(const Stream *stream) const
  */
 void Request::complete()
 {
+	Private *const d = LIBCAMERA_D_PTR();
+	ASSERT(d);
 	ASSERT(status_ == RequestPending);
 	ASSERT(!hasPendingBuffers());
 
@@ -307,6 +331,9 @@ void Request::complete()
  */
 bool Request::completeBuffer(FrameBuffer *buffer)
 {
+	Private *const d = LIBCAMERA_D_PTR();
+	ASSERT(d);
+
 	LIBCAMERA_TRACEPOINT(request_complete_buffer, this, buffer);
 
 	int ret = pending_.erase(buffer);
@@ -330,6 +357,9 @@ bool Request::completeBuffer(FrameBuffer *buffer)
  */
 std::string Request::toString() const
 {
+	const Private *const d = LIBCAMERA_D_PTR();
+	ASSERT(d);
+
 	std::stringstream ss;
 
 	/* Pending, Completed, Cancelled(X). */
-- 
2.25.1