minix/servers/rs/const.h
Cristiano Giuffrida 1f5841c8ed Basic System Event Framework (SEF) with ping and live update.
SYSLIB CHANGES:
- SEF must be used by every system process and is thereby part of the system
library.
- The framework provides a receive() interface (sef_receive) for system
processes to automatically catch known system even messages and process them.
- SEF provides a default behavior for each type of system event, but allows
system processes to register callbacks to override the default behavior.
- Custom (local to the process) or predefined (provided by SEF) callback
implementations can be registered to SEF.
- SEF currently includes support for 2 types of system events:
  1. SEF Ping. The event occurs every time RS sends a ping to figure out
  whether a system process is still alive. The default callback implementation
  provided by SEF is to notify RS back to let it know the process is alive
  and kicking.
  2. SEF Live update. The event occurs every time RS sends a prepare to update
  message to let a system process know an update is available and to prepare
  for it. The live update support is very basic for now. SEF only deals with
  verifying if the prepare state can be supported by the process, dumping the
  state for debugging purposes, and providing an event-driven programming
  model to the process to react to state changes check-in when ready to update.
- SEF should be extended in the future to integrate support for more types of
system events. Ideally, all the cross-cutting concerns should be integrated into
SEF to avoid duplicating code and ease extensibility. Examples include:
  * PM notify messages primarily used at shutdown.
  * SYSTEM notify messages primarily used for signals.
  * CLOCK notify messages used for system alarms.
  * Debug messages. IS could still be in charge of fkey handling but would
  forward the debug message to the target process (e.g. PM, if the user
  requested debug information about PM). SEF would then catch the message and
  do nothing unless the process has registered an appropriate callback to
  deal with the event. This simplifies the programming model to print debug
  information, avoids duplicating code, and reduces the effort to print
  debug information.

SYSTEM PROCESSES CHANGES:
- Every system process registers SEF callbacks it needs to override the default
system behavior and calls sef_startup() right after being started.
- sef_startup() does almost nothing now, but will be extended in the future to
support callbacks of its own to let RS control and synchronize with every
system process at initialization time.
- Every system process calls sef_receive() now rather than receive() directly,
to let SEF handle predefined system events.

RS CHANGES:
- RS supports a basic single-component live update protocol now, as follows:
  * When an update command is issued (via "service update *"), RS notifies the
  target system process to prepare for a specific update state.
  * If the process doesn't respond back in time, the update is aborted.
  * When the process responds back, RS kills it and marks it for refreshing.
  * The process is then automatically restarted as for a buggy process and can
  start running again.
  * Live update is currently prototyped as a controlled failure.
2009-12-21 14:12:21 +00:00

89 lines
4.3 KiB
C

/* Global constants used in RS.
*/
#ifndef RS_CONST_H
#define RS_CONST_H
/* Space reserved for program and arguments. */
#define MAX_COMMAND_LEN 512 /* maximum argument string length */
#define MAX_LABEL_LEN 16 /* Unique name of (this instance of)
* the service
*/
#define MAX_SCRIPT_LEN 256 /* maximum restart script name length */
#define MAX_NR_ARGS 4 /* maximum number of arguments */
#define MAX_RESCUE_DIR_LEN 64 /* maximum rescue dir length */
#define MAX_IPC_LIST 256 /* Max size of list for IPC target
* process names
*/
#define MAX_VM_LIST 256
/* Flag values. */
#define RS_IN_USE 0x001 /* set when process slot is in use */
#define RS_EXITING 0x004 /* set when exit is expected */
#define RS_REFRESHING 0x008 /* set when refresh must be done */
#define RS_NOPINGREPLY 0x010 /* service failed to reply to a ping request */
#define RS_KILLED 0x020 /* service is killed */
#define RS_CRASHED 0x040 /* service crashed */
#define RS_LATEREPLY 0x080 /* no reply sent to RS_DOWN caller yet */
#define RS_SIGNALED 0x100 /* service crashed */
#define RS_UPDATING 0x200 /* set when update must be done */
/* Sys flag values. */
#define SF_CORE_PROC 0x001 /* set for core system processes
* XXX FIXME: This should trigger a system
* panic when a CORE_PROC service cannot
* be restarted. We need better error-handling
* in RS to change this.
*/
#define SF_NEED_COPY 0x004 /* set when process needs copy to restart */
#define SF_USE_COPY 0x008 /* set when process has a copy in memory */
/* Constants determining RS period and binary exponential backoff. */
#define RS_DELTA_T 60 /* check every T ticks */
#define BACKOFF_BITS (sizeof(long)*8) /* bits in backoff field */
#define MAX_BACKOFF 30 /* max backoff in RS_DELTA_T */
/* Magic process table addresses. */
#define BEG_RPROC_ADDR (&rproc[0])
#define END_RPROC_ADDR (&rproc[NR_SYS_PROCS])
#define NIL_RPROC ((struct mproc *) 0)
/* Constants for live update. */
#define RS_DEFAULT_PREPARE_MAXTIME 2*RS_DELTA_T /* default prepare max time */
#define RS_MAX_PREPARE_MAXTIME 20*RS_DELTA_T /* max prepare max time */
/* Definitions for boot info tables. */
#define NULL_BOOT_NR NR_BOOT_PROCS /* marks a null boot entry */
#define DEFAULT_BOOT_NR NR_BOOT_PROCS /* marks the default boot entry */
#define SYS_ALL_C (NR_SYS_CALLS+0) /* specifies all calls */
#define SYS_NULL_C (NR_SYS_CALLS+1) /* marks a null call entry */
/* Define privilege flags for the various process types. */
#define SRV_F (SYS_PROC | PREEMPTIBLE) /* system services */
#define DSRV_F (SRV_F | DYN_PRIV_ID | CHECK_IO_PORT | CHECK_IRQ)
/* dynamic system services */
#define VM_F (SYS_PROC) /* vm */
#define RUSR_F (BILLABLE | PREEMPTIBLE) /* root user proc */
/* Define system call traps for the various process types. These call masks
* determine what system call traps a process is allowed to make.
*/
#define SRV_T (~0) /* system services */
#define DSRV_T SRV_T /* dynamic system services */
#define RUSR_T (1 << SENDREC) /* root user proc */
/* Send masks determine to whom processes can send messages or notifications. */
#define SRV_M (~0) /* system services */
#define RUSR_M \
( spi_to(PM_PROC_NR) | spi_to(FS_PROC_NR) | spi_to(RS_PROC_NR) \
| spi_to(VM_PROC_NR) ) /* root user proc */
/* Define sys flags for the various process types. */
#define SRV_SF (SF_CORE_PROC | SF_NEED_COPY) /* system services */
#define SRVC_SF (SRV_SF | SF_USE_COPY) /* system services with a copy */
#define DSRV_SF (0) /* dynamic system services */
#endif /* RS_CONST_H */