tree 1f0adcb084a733bc23571f5cbed6b43895be5d0e
parent a451505922cef7fbc7421247d5e2df661c328d1e
author Chuck Jazdzewski <chuckj@google.com> 1651690868 -0700
committer Chuck Jazdzewski <chuckj@google.com> 1651691383 -0700

Fix memory leak when observing derived state objects

When observing derived state objects, if the recompose snapshot changed
id it caused the derived state objects no longer observed by composition
to be retained by the recompose scope, causing them to leak. The
snapshot id would change if the read is the first time a derived state
object is read in the snapshot.

To detect when a derived state object is no longer necessary a token
value is used to record when the derived state was added into the
composition. This token was the current snapshot id. However, since
the id is not static through-out composition, this could cause the
notification to be skipped.

This change fixes the token to be the snapshot id at the beginning of
composition and, after that, ignores the snapshot id. This means the
token is consistent through-out the same composition allowing unused
derived object to be detected.

Fixes 230168389
Test: new test, ./gradlew :compose:r:r:tDUT

Change-Id: I877c826764592a7e424667d3e2b677d385cf0b7f