[v0.4.5] Database-side debounce (experimental)

Features

• Database-side debounce (experimental)
  • It is possible to debounce consecutive 'put' and 'update' to the same id document.
  • Database-side debouncing is intended to make it easy to debounce persistence procedures of data stores with exclusive locks on the application side in data flows with DB synchronization processing.
  • Debouncing on the database side may seem strange, but this is an experimental implementation and may be changed in the future.

Breaking changes

• Added TaskQueue#start(). start() must be called right after new TaskQueue().
• TaskQueue#clear() was renamed TaskQueue#stop()