Process Control

Data Structures
struct	_amxp_proc_ctrl
	Structure containing the child process control. More...

Typedefs
typedef int(*	amxp_proc_ctrl_cmd_t) (amxc_array_t *cmd, amxc_var_t *settings)
	Command builder callback function signature. More...
typedef struct _amxp_proc_ctrl	amxp_proc_ctrl_t
	Structure containing the child process control. More...

Functions
int	amxp_proc_ctrl_new (amxp_proc_ctrl_t **proc, amxp_proc_ctrl_cmd_t cmd_build_fn)
	Allocates and initializes an amxp_proc_ctrl_t. More...
void	amxp_proc_ctrl_delete (amxp_proc_ctrl_t **proc)
	Clean-up and frees previously allocated memory. More...
int	amxp_proc_ctrl_start (amxp_proc_ctrl_t *proc, uint32_t minutes, amxc_var_t *settings)
	Launches the child process. More...
int	amxp_proc_ctrl_stop (amxp_proc_ctrl_t *proc)
	Stops the child process. More...
void	amxp_proc_ctrl_set_active_duration (amxp_proc_ctrl_t *proc, uint32_t minutes)
	Sets the active time durations. More...
void	amxp_proc_ctrl_stop_childs (amxp_proc_ctrl_t *proc)
	Stop all child processes of the child process. More...
int	amxp_proc_ctrl_get_child_pids (amxp_proc_ctrl_t *proc)
	Fetches the process ids of the children of the launched child process. More...

Detailed Description

Child Process Control and monitor

Typedef Documentation

amxp_proc_ctrl_cmd_t

typedef int(* amxp_proc_ctrl_cmd_t) (amxc_array_t *cmd, amxc_var_t *settings)

Command builder callback function signature.

A callback function is used to build the command that must be launched.

In the callback function a configuration file can be built.

An array must be filled with the command and the command arguments.

Definition at line 87 of file amxp_proc_ctrl.h.

amxp_proc_ctrl_t

typedef struct _amxp_proc_ctrl amxp_proc_ctrl_t

Structure containing the child process control.

Function Documentation

amxp_proc_ctrl_delete()

void amxp_proc_ctrl_delete

(

amxp_proc_ctrl_t **

proc

)

Clean-up and frees previously allocated memory.

Each allocated amxp_proc_trl_t structure with amxp_proc_ctrl_new must be freed when not needed anymore using this function.

Parameters

proc	pointer to previously allocated amxp_proc_ctrl_t struct, will be set to NULL.

Definition at line 201 of file amxp_proc_ctrl.c.

                                                    {
    when_null(proc, leave);
    when_null(*proc, leave);
 
    amxp_slot_disconnect((*proc)->proc->sigmngr, "stop", amxp_proc_ctrl_stopped);
 
    amxp_proc_ctrl_stop(*proc);
    amxp_subproc_delete(&(*proc)->proc);
    amxp_timer_delete(&(*proc)->timer);
    amxc_array_clean(&(*proc)->cmd, amxp_proc_ctrl_free_char);
    amxc_var_clean(&(*proc)->child_proc_pids);
 
    free(*proc);
    *proc = NULL;
 
leave:
    return;
}

amxp_proc_ctrl_get_child_pids()

int amxp_proc_ctrl_get_child_pids

(

amxp_proc_ctrl_t *

proc

)

Fetches the process ids of the children of the launched child process.

The list of found process ids is stored in the amxp_proc_ctrl_t structure.

The function returns the number of children found.

Two methods are used to find the list of children:

• reading file /proc/[pid]/task/[tid]/children
• scanning all processes in /proc/ and read /proc/[pid]/stat and check the field parent pid.

Parameters

proc	pointer to amxp_proc_trl_t structure, previously allocated with amxp_proc_ctrl_new

Returns

the number of children found

Definition at line 294 of file amxp_proc_ctrl.c.

                                                          {
    int retval = -1;
    when_null(proc, leave);
 
    when_false(amxp_subproc_is_running(proc->proc), leave);
    retval = amxp_proc_ctrl_get_child_pids_proc_children(proc);
    if(retval == 0) {
        goto leave;
    }
 
    retval = amxp_proc_ctrl_get_child_pids_scan_proc(proc);
 
leave:
    if(retval == 0) {
        const amxc_llist_t* list = amxc_var_constcast(amxc_llist_t, &proc->child_proc_pids);
        retval = amxc_llist_size(list);
    }
    return retval;
}

amxp_proc_ctrl_new()

int amxp_proc_ctrl_new	(	amxp_proc_ctrl_t **	proc,
		amxp_proc_ctrl_cmd_t	cmd_build_fn
	)

Allocates and initializes an amxp_proc_ctrl_t.

Allocates memory on the heap for an amxp_proc_ctrl_t structure and initializes it.

The pointer to the allocated memory will be stored in the proc argument. The *proc must be initialized to NULL before calling this function.

To free all allocated memory use amxp_proc_ctrl_delete.

Parameters

proc	will be filled with the pointer to the new allocated amxp_proc_ctrl_t structure
cmd_build_fn	callback function that fills the command array

Returns

0 when successful, otherwise an error code

Definition at line 170 of file amxp_proc_ctrl.c.

                                                                                   {
    int retval = -1;
    when_null(proc, leave);
    when_null(cmd_build_fn, leave);
 
    *proc = (amxp_proc_ctrl_t*) calloc(1, sizeof(amxp_proc_ctrl_t));
    when_null(*proc, leave);
 
    when_failed(amxp_subproc_new(&(*proc)->proc), leave);
    when_failed(amxp_timer_new(&(*proc)->timer, amxp_proc_ctrl_timer_callback, *proc), leave);
    when_failed(amxc_array_init(&(*proc)->cmd, 10), leave);
    when_failed(amxc_var_init(&(*proc)->child_proc_pids), leave);
 
    (*proc)->build = cmd_build_fn;
    amxp_slot_connect((*proc)->proc->sigmngr, "stop", NULL, amxp_proc_ctrl_stopped, *proc);
 
    retval = 0;
 
leave:
    if((retval != 0) &&
       ((proc != NULL) && (*proc != NULL))) {
        amxp_subproc_delete(&(*proc)->proc);
        amxp_timer_delete(&(*proc)->timer);
        amxc_array_clean(&(*proc)->cmd, NULL);
        amxc_var_clean(&(*proc)->child_proc_pids);
        free(*proc);
        *proc = NULL;
    }
    return retval;
}

amxp_proc_ctrl_set_active_duration()

void amxp_proc_ctrl_set_active_duration	(	amxp_proc_ctrl_t *	proc,
		uint32_t	minutes
	)

Sets the active time durations.

Sets or changes the active duration.

If the process was already started with an active time (see amxp_proc_ctrl_start), the running timer is stopped and restarted with the new provided time.

If the process was running without an active time set, the timer is started with the given time and the child process will be stopped when the timer expires.

When the new time is set to 0 the timer is stopped and the child process will keep running until stopped manually.

Parameters

proc	pointer to amxp_proc_ctrl_t structure, previously allocated with amxp_proc_ctrl_new
minutes	new active time

Definition at line 264 of file amxp_proc_ctrl.c.

                                                                                  {
    when_null(proc, leave);
 
    if(minutes == 0) {
        amxp_timer_stop(proc->timer);
    } else {
        if(amxp_subproc_is_running(proc->proc)) {
            // reset timer to new duration time
            amxp_timer_start(proc->timer, minutes * 60 * 1000);
        }
    }
 
leave:
    return;
}

amxp_proc_ctrl_start()

int amxp_proc_ctrl_start	(	amxp_proc_ctrl_t *	proc,
		uint32_t	minutes,
		amxc_var_t *	settings
	)

Launches the child process.

Will call the amxp_proc_ctrl_cmd_t callback function. That callback function must fill the command array. The provided variant containing child process settings will be passed to the callback function as is.

When an active time is provided in the argument minutes, a timer is started. When the timer expires, the launched process is stopped.

When the time in minutes is set to 0, no timer is started and the child process will keep runnning until stopped.

Parameters

proc	pointer to amxp_proc_ctrl_t structure, previously allocated with amxp_proc_ctrl_new
minutes	time in minutes the launched process can keep running
settings	a variant containing settings, passed to the callback function as is.

Returns

0 when successful, otherwise an error code

Definition at line 220 of file amxp_proc_ctrl.c.

                                                                                         {
    int retval = -1;
    when_null(proc, leave);
 
    amxc_array_clean(&proc->cmd, amxp_proc_ctrl_free_char);
    retval = proc->build(&proc->cmd, settings);
    when_failed(retval, leave);
    when_true(amxc_array_is_empty(&proc->cmd), leave);
 
    retval = amxp_subproc_astart(proc->proc, &proc->cmd);
    when_failed(retval, leave);
 
    if(minutes != 0) {
        amxp_timer_start(proc->timer, minutes * 60 * 1000);
    }
 
    retval = 0;
 
leave:
    return retval;
}

amxp_proc_ctrl_stop()

int amxp_proc_ctrl_stop

(

amxp_proc_ctrl_t *

proc

)

Stops the child process.

Stops the child process and the children of the child process.

Parameters

proc	pointer to amxp_proc_trl_t structure, previously allocated with amxp_proc_ctrl_new

Returns

0 when successful, otherwise an error code

Definition at line 242 of file amxp_proc_ctrl.c.

                                                {
    int retval = -1;
    when_null(proc, leave);
 
    amxp_timer_stop(proc->timer);
 
    amxp_proc_ctrl_get_child_pids(proc);
    amxp_proc_ctrl_stop_childs(proc);
 
    amxp_subproc_kill(proc->proc, SIGTERM);
    retval = amxp_subproc_wait(proc->proc, 2000);
    if(retval == 1) {
        // not stopped after waiting for 2 seconds
        // forcekill
        amxp_subproc_kill(proc->proc, SIGKILL);
        retval = amxp_subproc_wait(proc->proc, 2000);
    }
 
leave:
    return retval;
}

amxp_proc_ctrl_stop_childs()

void amxp_proc_ctrl_stop_childs

(

amxp_proc_ctrl_t *

proc

)

Stop all child processes of the child process.

A child process monitored with the amxp_proc_ctrl can launch its own children. These child processes can be stopped using this function.

Parameters

proc	pointer to amxp_proc_trl_t structure, previously allocated with amxp_proc_ctrl_new

Definition at line 280 of file amxp_proc_ctrl.c.

                                                        {
    when_null(proc, leave);
 
    if(amxc_var_type_of(&proc->child_proc_pids) == AMXC_VAR_ID_LIST) {
        amxc_var_for_each(child_pid, (&proc->child_proc_pids)) {
            pid_t pid = amxc_var_dyncast(uint32_t, child_pid);
            kill(pid, SIGTERM);
        }
    }
 
leave:
    return;
}