Redesign of DownloadManager update loop.
Previously, the service lifecycle was managed through a large for()
loop which was extremely tricky to reason about. This resulted in
several race conditions that could leave the service running
indefinitely, or terminate it early before tasks had finished.
This change redesigns the update loop to be event driven based on
database updates, and to collapse mutiple pending update passes. It
is much easier to reason about service termination conditions, and
it correctly uses startId to handle races during command delivery.
Also moves scanner into isolated class, and switches to using public
API instead of binding to private interface.
Bug: 7638470, 7455406, 7162341
Change-Id: I380e77f5432223b2acb4e819e37f29f98ee4782b
7 files changed
