/mordor/daemon.h

 1#ifndef __MORDOR_SERVICE_H__
 2#define __MORDOR_SERVICE_H__
 3// Copyright (c) 2010 - Mozy, Inc.
 4
 5#include <string>
 6#ifdef POSIX
 7#include <sys/types.h>
 8#endif
 9#include <vector>
10
11#include <boost/function.hpp>
12#include <boost/signals2/signal.hpp>
13
14#include "version.h"
15
16namespace Mordor {
17namespace Daemon {
18
19/// @brief Run a process as a daemon
20///
21/// Runs daemonMain as a daemon process, that can be externally controlled.
22/// It is cross platform, and will adapt for how this process is run.
23/// The words in parenthesis describe behavior for how the signal handler
24/// interacts with the platform's normal actions:
25///     * default: if no slots are connected to the signal, it gets passed
26///       to the default handler for that platform
27///     * always: the default handler for that platform is always invoked
28///       (after all slots are signalled)
29///     * ignored: the default handler for that platform is ignored
30///     * ExitProcess: there is no default handler for a Windows System Service
31///       so a stop request that is unhandled will terminate the process
32///
33/// Windows Console:
34///     * argc/argv are passed through
35///     * Ctrl-C triggers onInterrupt (default)
36///     * Ctrl-Break and End Task trigger onTerminate (default)
37///
38/// Windows System Service:
39///     * argc/argv are ignored; daemonMain receives the arguments from
40///       ServiceStart
41///     * SERVICE_CONTROL_STOP triggers onTerminate (ExitProcess)
42///     * SERVICE_CONTROL_PAUSE triggers onPause (ignored)
43///     * SERVICE_CONTROL_CONTINUE triggers onContinue (ignored)
44///     * SERVICE_CONTROL_PARAMCHANGE triggers onReload (ignored)
45///
46/// POSIX:
47///     * argc/argv are passed through
48///     * SIGTERM triggers onTerminate (default)
49///     * SIGINT triggers onInterrupt (default)
50///     * SIGTSTP triggers onPause (always)
51///     * SIGCONT triggers onContinue (always)
52///     * SIGHUP triggers onReload (default)
53///
54/// @note On Windows run automagically determines if it is being run as a
55///       system service or from the console.
56///       On OS X, you should be using launchd, and never daemonize.
57///       On Linux, run attempts to automagically determine if it needs to
58///       daemonize by seeing if it is being run directly from an script in
59///       /etc/init.d, or by start-stop-daemon (Debian)
60/// @note If enableWatchdog is true, the daemonMain will be run in a forked
61///       process, the parent process will restart it whenever it dies.
62///       onChildProcessExit is also provided to empower user to stop restarting
63///       and quit when necessary. (works for POSIX only)
64/// @note In all cases, the signals are invoked on a thread separate from
65///       the thread daemonMain is called on, or any that it created
66/// @note run should be called *exactly* once, since the signals are global
67///       for the process
68int run(int argc, char **argv, boost::function<int (int, char **)> daemonMain,
69        bool enableWatchdog = false);
70
71extern boost::signals2::signal<void ()> onTerminate;
72extern boost::signals2::signal<void ()> onInterrupt;
73extern boost::signals2::signal<void ()> onReload;
74extern boost::signals2::signal<void ()> onPause;
75extern boost::signals2::signal<void ()> onContinue;
76#ifdef POSIX
77/// Works together with watchdog, callback whenever child process exits.
78/// Watchdog will check the return value to restart child (if false) or
79/// just shutdown the program (if true).
80/// @note If this function is not hooked, watchdog will by default repeatly
81///       restart child process whenever it exits. If one-shot running is
82///       expected, please set enableWatchdog = false in run.
83extern boost::function<bool (pid_t, int)> onChildProcessExit;
84#endif
85
86}}
87
88#endif