libcamera: control_serializer: Save serialized ControlInfoMap in a cache

The ControlSerializer saves all ControlInfoMaps that it has already
(de)serialized, in order to (de)serialize ControlLists that contain the
ControlInfoMaps. Leverage this to cache ControlInfoMaps, such that the
ControlSerializer will not re-(de)serialize a ControlInfoMap that it has
previously (de)serialized.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/src/libcamera/control_serializer.cpp b/src/libcamera/control_serializer.cpp
index 258db6df..09744413 100644
--- a/src/libcamera/control_serializer.cpp
+++ b/src/libcamera/control_serializer.cpp
@@ -173,6 +173,12 @@ void ControlSerializer::store(const ControlInfo &info, ByteStreamBuffer &buffer)
 int ControlSerializer::serialize(const ControlInfoMap &infoMap,
 				 ByteStreamBuffer &buffer)
 {
+	if (isCached(infoMap)) {
+		LOG(Serializer, Debug)
+			<< "Skipping already serialized ControlInfoMap";
+		return 0;
+	}
+
 	/* Compute entries and data required sizes. */
 	size_t entriesSize = infoMap.size()
 			   * sizeof(struct ipa_control_info_entry);
@@ -347,6 +353,12 @@ ControlInfoMap ControlSerializer::deserialize<ControlInfoMap>(ByteStreamBuffer &
 		return {};
 	}
 
+	auto iter = infoMaps_.find(hdr->handle);
+	if (iter != infoMaps_.end()) {
+		LOG(Serializer, Debug) << "Use cached ControlInfoMap";
+		return iter->second;
+	}
+
 	if (hdr->version != IPA_CONTROLS_FORMAT_VERSION) {
 		LOG(Serializer, Error)
 			<< "Unsupported controls format version "
@@ -485,4 +497,18 @@ ControlList ControlSerializer::deserialize<ControlList>(ByteStreamBuffer &buffer
 	return ctrls;
 }
 
+/**
+ * \brief Check if a ControlInfoMap is cached
+ * \param[in] infoMap The ControlInfoMap to check
+ *
+ * The ControlSerializer caches all ControlInfoMaps that it has (de)serialized.
+ * This function checks if \a infoMap is in the cache.
+ *
+ * \return True if \a infoMap is in the cache or false otherwise
+ */
+bool ControlSerializer::isCached(const ControlInfoMap &infoMap)
+{
+	return infoMapHandles_.count(&infoMap);
+}
+
 } /* namespace libcamera */