master_proto.h

[詳解]

/*++
/* NAME
/*  master_proto 3h
/* SUMMARY
/*  master process protocol
/* SYNOPSIS
/*  #include <master_proto.h>
/* DESCRIPTION
/* .nf

 /*
  * Transport names. The master passes the transport name on the command
  * line, and thus the name is part of the master to child protocol.
  */
#define MASTER_XPORT_NAME_UNIX  "unix"  /* local IPC */
#define MASTER_XPORT_NAME_FIFO  "fifo"  /* local IPC */
#define MASTER_XPORT_NAME_INET  "inet"  /* non-local IPC */
#define MASTER_XPORT_NAME_PASS  "pass"  /* local IPC */

 /*
  * Format of a status message sent by a child process to the process
  * manager. Since this is between processes on the same machine we need not
  * worry about byte order and word length.
  */
typedef struct MASTER_STATUS {
    int     pid;            /* process ID */
    unsigned gen;           /* child generation number */
    int     avail;          /* availability */
} MASTER_STATUS;

#define MASTER_GEN_NAME "GENERATION"    /* passed via environment */

#define MASTER_STAT_TAKEN   0   /* this one is occupied */
#define MASTER_STAT_AVAIL   1   /* this process is idle */

extern int master_notify(int, unsigned, int);   /* encapsulate status msg */

 /*
  * File descriptors inherited from the master process. The flow control pipe
  * is read by receive processes and is written to by send processes. If
  * receive processes get too far ahead they will pause for a brief moment.
  */
#define MASTER_FLOW_READ    3
#define MASTER_FLOW_WRITE   4

 /*
  * File descriptors inherited from the master process. All processes that
  * provide a given service share the same status file descriptor, and listen
  * on the same service socket(s). The kernel decides what process gets the
  * next connection. Usually the number of listening processes is small, so
  * one connection will not cause a "thundering herd" effect. When no process
  * listens on a given socket, the master process will. MASTER_LISTEN_FD is
  * actually the lowest-numbered descriptor of a sequence of descriptors to
  * listen on.
  */
#define MASTER_STATUS_FD    5   /* shared channel to parent */
#define MASTER_LISTEN_FD    6   /* accept connections here */

/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/