When inserting reply, its thread group was re-inserted with the reply as
the root. This is a mistake as threads should never be re-inserted, only
modified.
Instead of using Union/Find to gather mail that belongs in the same
e-mail thread together, add a new entity ThreadGroup that ThreadNodes
point to. ThreadGroup represents an actual Thread: A thread root
ThreadGroup::Group or a reply ThreadGroup::Node.
To make semantics more accurate:
- ThreadNode hash should be renamed to ThreadNodeHash
- ThreadGroupHash should be renamed to ThreadHash
- ThreadGroup::Group should be a struct named Thread instead
- move ThreadGroup::Node logic to ThreadNode akin to Union/Find
- rename ThreaddGroup::Group to Thread
thread_group property of ThreadNode doesn't yet reflect the actual root
ThreadNode (the root of the thread, that is). So find the root manually
instead.
Envelope can now only be accessed from within a RwLock. Two new structs
are introduced: EnvelopeRef and EnvelopeRefMut. These hold a reference
to an Envelope and the mutex guard that keeps them alive.
This change allows sharing of the envelopes hash map amongst threads.
Manos Pitsidianakis