mysqlmanager.cc File Reference

#include <my_global.h>
#include <my_sys.h>
#include <string.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "manager.h"
#include "options.h"
#include "log.h"

Include dependency graph for mysqlmanager.cc:

Enumerations
enum	{ CHILD_OK = 0, CHILD_NEED_RESPAWN, CHILD_EXIT_ANGEL }
Functions
void	init_environment (char *progname)
void	daemonize (const char *log_file_name)
void	angel (const Options &options)
int	main (int argc, char *argv[])
void	reap_child (int __attribute__((unused)) signo)
void	terminate (int signo)
Variables
volatile sig_atomic_t	child_status = CHILD_OK
volatile sig_atomic_t	is_terminated = 0

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Enumeration Type Documentation

anonymous enum

Enumeration values: CHILD_OK  CHILD_NEED_RESPAWN  CHILD_EXIT_ANGEL  { CHILD_OK= 0, CHILD_NEED_RESPAWN, CHILD_EXIT_ANGEL };

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Function Documentation

void angel (  const Options &  options  )  [static]

{ /* install signal handlers */ sigset_t zeromask; // to sigsuspend in parent struct sigaction sa_chld, sa_term; struct sigaction sa_chld_out, sa_term_out, sa_int_out, sa_hup_out; sigemptyset(&zeromask); sigemptyset(&sa_chld.sa_mask); sigemptyset(&sa_term.sa_mask); sa_chld.sa_handler= reap_child; sa_chld.sa_flags= SA_NOCLDSTOP; sa_term.sa_handler= terminate; sa_term.sa_flags= 0; /* sigaction can fail only on wrong arguments */ sigaction(SIGCHLD, &sa_chld, &sa_chld_out); sigaction(SIGTERM, &sa_term, &sa_term_out); sigaction(SIGINT, &sa_term, &sa_int_out); sigaction(SIGHUP, &sa_term, &sa_hup_out); /* spawn a child */ spawn: pid_t pid= fork(); switch (pid) { case -1: die("angel(): fork failed, %s", strerror(errno)); case 0: // child, success /* restore default actions for signals to let the manager work with signals as he wishes */ sigaction(SIGCHLD, &sa_chld_out, 0); sigaction(SIGTERM, &sa_term_out, 0); sigaction(SIGINT, &sa_int_out, 0); sigaction(SIGHUP, &sa_hup_out, 0); manager(options.socket_file_name); default: // parent, success while (child_status == CHILD_OK && is_terminated == 0) sigsuspend(&zeromask); if (is_terminated) log_info("angel got signal %d, exiting", is_terminated); else if (child_status == CHILD_NEED_RESPAWN) { child_status= CHILD_OK; log_error("angel(): mysqlmanager exited abnormally: respawning..."); sleep(1); /* don't respawn too fast */ goto spawn; } /* mysqlmanager successfully exited, let's silently evaporate */ } }

void daemonize (  const char *  log_file_name  )  [static]

{ pid_t pid= fork(); switch (pid) { case -1: // parent, fork error die("daemonize(): fork failed, %s", strerror(errno)); case 0: // child, fork ok int fd; /* Become a session leader: setsid must succeed because child is guaranteed not to be a process group leader (it belongs to the process group of the parent.) The goal is not to have a controlling terminal. */ setsid(); /* As we now don't have a controlling terminal we will not receive tty-related signals - no need to ignore them. */ close(STDIN_FILENO); fd= open(log_file_name, O_WRONLY | O_CREAT | O_APPEND | O_NOCTTY, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP); if (fd < 0) die("daemonize(): failed to open log file %s, %s", log_file_name, strerror(errno)); dup2(fd, STDOUT_FILENO); dup2(fd, STDERR_FILENO); if (fd != STDOUT_FILENO && fd != STDERR_FILENO) close(fd); /* TODO: chroot() and/or chdir() here */ break; default: /* successfully exit from parent */ exit(0); } }

void init_environment (  char *  progname  )  [static]

{ MY_INIT(progname); log_init(); umask(0117); }

int main (  int  argc, char *  argv[] )

{ init_environment(argv[0]); Options options; options.load(argc, argv); if (options.run_as_service) { daemonize(options.log_file_name); angel(options); } else manager(options.log_file_name); return 0; }

void reap_child (  int __attribute__((unused))  signo  )

{ int child_exit_status; /* As we have only one child, no need to cycle waitpid */ if (waitpid(0, &child_exit_status, WNOHANG) > 0) { if (WIFSIGNALED(child_exit_status)) child_status= CHILD_NEED_RESPAWN; else /* As we reap_child is not called for SIGSTOP, we should be here only if the child exited normally. */ child_status= CHILD_EXIT_ANGEL; } }

void terminate (  int  signo  )

{ is_terminated= signo; }

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Variable Documentation

volatile sig_atomic_t child_status = CHILD_OK [static]

volatile sig_atomic_t is_terminated = 0

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