1.3 Architecture Components

As described in the previous sections, the hot restart feature uses the following two restart-specific actors to implement hot restart services:

• A supervisor actor called the Persistent Memory Manager (PMM), which offers services for allocating and freeing persistent memory blocks.

• A supervisor actor called the Hot Restart Controller, (HR_CTRL). It offers the system calls that create and kill restartable actors, monitors restartable actors for abnormal termination, and takes the appropriate restart action when a failure occurs.

The Persistent Memory Manager and Hot Restart Controller principally use the services of the following:

• The C_INIT actor, for the interpretation of hot restart-specific commands entered on the target or host console.

• The system actor AM, solicited by the Hot Restart Controller for loading and running restartable actors.

• The ChorusOS microkernel, for the low-level allocation of persistent memory, and for support for site restart.

The resulting architecture is summarized in the following diagram. Hot restart-specific components appear in gray, together with the API calls they provide. Other components appear in white. Arrows from A to B say that A calls functions which are implemented in B.

Figure 1-4 Hot Restart Architecture

Further information about the hot restart API is provided in the rest of this guide, and in the corresponding man pages.