Camera: Avoid Metadata re-allocation during shrinkCaptureResult

If capture result metadata is to be shrinked, reserve enough space so
that CameraMetadata isn't re-allocated when std::vector expands.

If vector expansion happens, CameraMetadata is re-allocated, causing
camera_metadata_t being re-allocated as well.

Test: Camera CTS
Bug: 109672123
Change-Id: Idaf5bf409bdbbccf617614edc96c0478260b4c30

1 files changed, 2 insertions, 0 deletions

diff --git a/camera/device/3.2/default/CameraDeviceSession.cpp b/camera/device/3.2/default/CameraDeviceSession.cpp
index 8d002646..69f85356 100644
--- a/camera/device/3.2/default/CameraDeviceSession.cpp
+++ b/camera/device/3.2/default/CameraDeviceSession.cpp
@@ -1391,6 +1391,8 @@ void CameraDeviceSession::sShrinkCaptureResult(
         std::vector<const camera_metadata_t*>* physCamMdArray,
         bool handlePhysCam) {
     *dst = *src;
+    // Reserve maximum number of entries to avoid metadata re-allocation.
+    mds->reserve(1 + (handlePhysCam ? src->num_physcam_metadata : 0));
     if (sShouldShrink(src->result)) {
         mds->emplace_back(sCreateCompactCopy(src->result));
         dst->result = mds->back().getAndLock();