learning_tla/lamport_video/docs/lecture05.md

Transaction commit

Transition diagram for each wedding participant, bride and groom:

flowchart
    unsure --> prepared
    unsure --> aborted
    prepared --> committed
    prepared --> aborted

• In databases, a transaction is performed by a collection of resource managers.
• Transactions can commit or abort.
• They can only commit if all RMs are prepared to commit.
• They must abort if any RM wants to abort

flowchart
    working --> prepared
    working --> aborted
    prepared --> committed
    prepared --> aborted

Programming	Math
Array	Function
Index set	Domain
f[e] array application	f(e) function application
Programs	Formulas

BUT TLA+ uses [] for function application, not (), to avoid confusion with other uses of parentheses.

Always be suspicious of success.

• When running a spec, a "Count" of 0 usually means an error in the spec.
• Check the invariance of conditions that should be invariant.