libcamera: request: Add cookie to make request tracking easier

Applications often have to map requests queued to a camera to external
resources. To make this easy, add a 64-bit integer cookie to the Request
class that is set when the request is created and can be retrieved at
any time, especially in the request completion handler. The cookie is
completely transparent for libcamera and is never modified.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

2 files changed, 6 insertions, 2 deletions

diff --git a/include/libcamera/camera.h b/include/libcamera/camera.h
index 6d693d9a..21fac550 100644
--- a/include/libcamera/camera.h
+++ b/include/libcamera/camera.h
@@ -10,6 +10,7 @@
 #include <map>
 #include <memory>
 #include <set>
+#include <stdint.h>
 #include <string>
 
 #include <libcamera/controls.h>
@@ -93,7 +94,7 @@ public:
 	int allocateBuffers();
 	int freeBuffers();
 
-	Request *createRequest();
+	Request *createRequest(uint64_t cookie = 0);
 	int queueRequest(Request *request);
 
 	int start();
diff --git a/include/libcamera/request.h b/include/libcamera/request.h
index a93468d7..4fdb3b51 100644
--- a/include/libcamera/request.h
+++ b/include/libcamera/request.h
@@ -8,6 +8,7 @@
 #define __LIBCAMERA_REQUEST_H__
 
 #include <map>
+#include <stdint.h>
 #include <unordered_set>
 
 #include <libcamera/controls.h>
@@ -29,7 +30,7 @@ public:
 		RequestCancelled,
 	};
 
-	explicit Request(Camera *camera);
+	Request(Camera *camera, uint64_t cookie = 0);
 	Request(const Request &) = delete;
 	Request &operator=(const Request &) = delete;
 
@@ -38,6 +39,7 @@ public:
 	int setBuffers(const std::map<Stream *, Buffer *> &streamMap);
 	Buffer *findBuffer(Stream *stream) const;
 
+	uint64_t cookie() const { return cookie_; }
 	Status status() const { return status_; }
 
 	bool hasPendingBuffers() const { return !pending_.empty(); }
@@ -56,6 +58,7 @@ private:
 	std::map<Stream *, Buffer *> bufferMap_;
 	std::unordered_set<Buffer *> pending_;
 
+	const uint64_t cookie_;
 	Status status_;
 };