Extending agent-based Mobile Petri Nets with access control

Research and Improvement of SQLite's Concurrency Control Mechanism

“…At the same time, all the blocking requests in each transaction precede all unlock requests, the two phases refer to the lock growth phase and the lock shrink phase, 1) the lock growth phase: before any data is read and written, the transaction first obtains the data of the blockade; 2) lock shrink phase: after the release of a blockade, the transaction no longer get any lock. The SQLite system manages a lock table that enables the transaction to be locked at the last minute to ensure maximum concurrency and efficiency [3,4].SQLite contains 5 different lock states: unlocked state, shared state, hold status, pending state, and exclusive status, each transaction can only be in one of the states at the same time. In addition to the unlocked state, each state has a lock corresponding to it: 1) shared locks; 2) reserved locks; 3) pending locks; 4) exclusive locks,.…”