msdkenc: fix leaks on windows

commit ce2a94f5:

msdk: Use gst_clear_object()
`gst_object_replace()` is not supposed to be used for unreffing and
NULLing objects.

commit 2c4c9828:

msdk: Fix warning about unused variable on Windows

commit 4384dbd8:

msdk: Reorganize context preparation code
Split it out into a separate function with early exits to make the
flow clearer, and document what the function is doing clearly.
No functional changes.

commit b64693fe:

msdk: Fix increasing memory usage in dynamic pipelines
Our context is non-persistent, and we propagate it throughout the
pipeline. This means that if we try to reuse any gstmsdk element by
removing it from the pipeline and then re-adding it, we'll clone the
mfxSession and create a new gstmsdk context as a child of the old one
inside `gst_msdk_context_new_with_parent()`.

Normally this only allocates a few KB inside the driver, but on
Windows it seems to allocate tens of MBs which leads to linearly
increasing memory usage for each PLAYING->NULL->PLAYING state cycle
for the process. The contexts will only be freed when the pipeline
itself goes to `NULL`, which would defeat the purpose of dynamic
pipelines.

Essentially, we need to optimize the case in which the element is
removed from the pipeline and re-added and the same context is re-set
on it. To detect that case, we set the context on `old_context`, and
compare it to the new one when preparing the context. If they're the
same, we don't need to do anything.

Fixes #946 (closed)

added 1.16 Needs backport labels

added 2 commits

• eb66a2eb - msdk: Reorganize context preparation code
• fea4785d - msdk: Fix increasing memory usage in dynamic pipelines

Compare with previous version

added Windows label

mentioned in issue #946 (closed)

Just a glance, but they lgtm

added 1 commit

• 1dd3fb27 - msdk: Fix increasing memory usage in dynamic pipelines

Compare with previous version

mentioned in merge request !987 (merged)

removed Needs backport label

changed title from Fix msdkenc leak windows to msdkenc: fix leaks on windows

changed the description

added Memory label

added Backported into 1.16 label

added 2 commits

• 337e502c - msdk: Reorganize context preparation code
• 6ec15d5f - msdk: Fix increasing memory usage in dynamic pipelines

Compare with previous version

added 22 commits

• 6ec15d5f...0c39068c - 18 commits from branch gstreamer:master
• 6a847f73 - msdk: Use gst_clear_object()
• fc200e08 - msdk: Fix warning about unused variable on Windows
• bf36fbfc - msdk: Reorganize context preparation code
• 04aa692c - msdk: Fix increasing memory usage in dynamic pipelines

Compare with previous version

resolved all threads

changed the description

LGTM! Could you submit a PR to https://github.com/intel-media-ci/gst-plugins-bad as well? It will do some pre-check and make sure no regression will be introduced (currently it is for Linux only).

resolved all threads

added 7 commits

• 04aa692c...bda68734 - 3 commits from branch gstreamer:master
• c0d778c2 - msdk: Use gst_clear_object()
• e83d5fd8 - msdk: Fix warning about unused variable on Windows
• 6834a121 - msdk: Reorganize context preparation code
• 1bcf44bb - msdk: Fix increasing memory usage in dynamic pipelines

Compare with previous version

assigned to @gstreamer-merge-bot

merged

changed milestone to %1.17.1