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/**
* @file process_manager.c
* @author Ambroz Bizjak <ambrop7@gmail.com>
*
* @section LICENSE
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the author nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* @section DESCRIPTION
*
* Module which allows starting and controlling template processes using an imperative
* interface.
*
* Synopsis:
* process_manager()
*
* Description:
* Represents a set of managed processes. Each process has a "name", which is a value
* that uniquely identifies it within its process manager.
* When deinitialization is requested, requests termination of all managed processes
* and waits for all of them to terminate before deinitializing.
* Managed processes can access objects as seen from the process_manager() statement
* via the special _caller object.
*
* Synopsis:
* process_manager::start(name, string template_name, list args)
* process_manager::start(string template_name, list args)
*
* Description:
* Creates a new process from the template named 'template_name', with arguments 'args',
* identified by 'name' within the process manager. If the two-argument form of start() is
* used, the process does not have a name, and cannot be imperatively stopped using
* stop().
* If a process with this name already exists and is not being terminated, does nothing.
* If it exists and is being terminated, it will be restarted using the given parameters
* after it terminates. If the process does not exist, it is created immediately, and the
* immediate effects of the process being created happnen before the immediate effects of
* the start() statement going up.
*
* Synopsis:
* process_manager::stop(name)
*
* Description:
* Initiates termination of the process identified by 'name' within the process manager.
* If there is no such process, or the process is already being terminated, does nothing.
* If the process does exist and is not already being terminated, termination of the
* process is requested, and the immediate effects of the termination request happen
* before the immediate effects of the stop() statement going up.
*/
#include <stdlib.h>
#include <string.h>
#include <misc/offset.h>
#include <misc/debug.h>
#include <misc/strdup.h>
#include <misc/balloc.h>
#include <structure/LinkedList1.h>
#include <ncd/module_common.h>
#include <generated/blog_channel_ncd_process_manager.h>
#define RETRY_TIME 10000
#define PROCESS_STATE_RUNNING 1
#define PROCESS_STATE_STOPPING 2
#define PROCESS_STATE_RESTARTING 3
#define PROCESS_STATE_RETRYING 4
struct instance {
NCDModuleInst *i;
LinkedList1 processes_list;
int dying;
};
struct process {
struct instance *manager;
LinkedList1Node processes_list_node;
BSmallTimer retry_timer; // running if state=retrying
int state;
NCD_string_id_t template_name;
NCDValMem current_mem;
NCDValSafeRef current_name;
NCDValSafeRef current_args;
NCDValMem next_mem; // next_* if state=restarting
NCDValSafeRef next_name;
NCDValSafeRef next_args;
NCDModuleProcess module_process; // if state!=retrying
};
static struct process * find_process (struct instance *o, NCDValRef name);
static int process_new (struct instance *o, NCDValMem *mem, NCDValSafeRef name, NCDValSafeRef template_name, NCDValSafeRef args);
static void process_free (struct process *p);
static void process_try (struct process *p);
static void process_retry_timer_handler (BSmallTimer *retry_timer);
static void process_module_process_handler_event (NCDModuleProcess *module_process, int event);
static int process_module_process_func_getspecialobj (NCDModuleProcess *module_process, NCD_string_id_t name, NCDObject *out_object);
static int process_module_process_caller_obj_func_getobj (const NCDObject *obj, NCD_string_id_t name, NCDObject *out_object);
static void process_stop (struct process *p);
static int process_restart (struct process *p, NCDValMem *mem, NCDValSafeRef name, NCDValSafeRef template_name, NCDValSafeRef args);
static void instance_free (struct instance *o);
static struct process * find_process (struct instance *o, NCDValRef name)
{
ASSERT(!NCDVal_IsInvalid(name))
LinkedList1Node *n = LinkedList1_GetFirst(&o->processes_list);
while (n) {
struct process *p = UPPER_OBJECT(n, struct process, processes_list_node);
ASSERT(p->manager == o)
if (!NCDVal_IsInvalid(NCDVal_FromSafe(&p->current_mem, p->current_name)) && NCDVal_Compare(NCDVal_FromSafe(&p->current_mem, p->current_name), name) == 0) {
return p;
}
n = LinkedList1Node_Next(n);
}
return NULL;
}
static int process_new (struct instance *o, NCDValMem *mem, NCDValSafeRef name, NCDValSafeRef template_name, NCDValSafeRef args)
{
ASSERT(!o->dying)
ASSERT(NCDVal_IsInvalid(NCDVal_FromSafe(mem, name)) || !find_process(o, NCDVal_FromSafe(mem, name)))
ASSERT(NCDVal_IsString(NCDVal_FromSafe(mem, template_name)))
ASSERT(NCDVal_IsList(NCDVal_FromSafe(mem, args)))
// allocate structure
struct process *p = BAlloc(sizeof(*p));
if (!p) {
ModuleLog(o->i, BLOG_ERROR, "BAlloc failed");
goto fail0;
}
// set manager
p->manager = o;
// insert to processes list
LinkedList1_Append(&o->processes_list, &p->processes_list_node);
// init retry timer
BSmallTimer_Init(&p->retry_timer, process_retry_timer_handler);
// init template name
p->template_name = ncd_get_string_id(NCDVal_FromSafe(mem, template_name));
if (p->template_name < 0) {
ModuleLog(o->i, BLOG_ERROR, "ncd_get_string_id failed");
goto fail1;
}
// init current mem as a copy of mem
if (!NCDValMem_InitCopy(&p->current_mem, mem)) {
ModuleLog(o->i, BLOG_ERROR, "NCDValMem_InitCopy failed");
goto fail1;
}
// remember name and args
p->current_name = name;
p->current_args = args;
// try starting it
process_try(p);
return 1;
fail1:
LinkedList1_Remove(&o->processes_list, &p->processes_list_node);
BFree(p);
fail0:
return 0;
}
static void process_free (struct process *p)
{
struct instance *o = p->manager;
// free current mem
NCDValMem_Free(&p->current_mem);
// free timer
BReactor_RemoveSmallTimer(o->i->params->iparams->reactor, &p->retry_timer);
// remove from processes list
LinkedList1_Remove(&o->processes_list, &p->processes_list_node);
// free structure
BFree(p);
}
static void process_try (struct process *p)
{
struct instance *o = p->manager;
ASSERT(!o->dying)
ASSERT(!BSmallTimer_IsRunning(&p->retry_timer))
// init module process
if (!NCDModuleProcess_InitId(&p->module_process, o->i, p->template_name, NCDVal_FromSafe(&p->current_mem, p->current_args), process_module_process_handler_event)) {
ModuleLog(o->i, BLOG_ERROR, "NCDModuleProcess_Init failed");
goto fail;
}
// set special objects function
NCDModuleProcess_SetSpecialFuncs(&p->module_process, process_module_process_func_getspecialobj);
// set state
p->state = PROCESS_STATE_RUNNING;
return;
fail:
// set timer
BReactor_SetSmallTimer(o->i->params->iparams->reactor, &p->retry_timer, BTIMER_SET_RELATIVE, RETRY_TIME);
// set state
p->state = PROCESS_STATE_RETRYING;
}
static void process_retry_timer_handler (BSmallTimer *retry_timer)
{
struct process *p = UPPER_OBJECT(retry_timer, struct process, retry_timer);
struct instance *o = p->manager;
B_USE(o)
ASSERT(p->state == PROCESS_STATE_RETRYING)
ASSERT(!o->dying)
// retry
process_try(p);
}
void process_module_process_handler_event (NCDModuleProcess *module_process, int event)
{
struct process *p = UPPER_OBJECT(module_process, struct process, module_process);
struct instance *o = p->manager;
ASSERT(p->state != PROCESS_STATE_RETRYING)
ASSERT(p->state != PROCESS_STATE_RESTARTING || !o->dying)
ASSERT(!BSmallTimer_IsRunning(&p->retry_timer))
switch (event) {
case NCDMODULEPROCESS_EVENT_UP: {
ASSERT(p->state == PROCESS_STATE_RUNNING)
} break;
case NCDMODULEPROCESS_EVENT_DOWN: {
ASSERT(p->state == PROCESS_STATE_RUNNING)
// allow process to continue
NCDModuleProcess_Continue(&p->module_process);
} break;
case NCDMODULEPROCESS_EVENT_TERMINATED: {
ASSERT(p->state == PROCESS_STATE_RESTARTING || p->state == PROCESS_STATE_STOPPING)
// free module process
NCDModuleProcess_Free(&p->module_process);
if (p->state == PROCESS_STATE_RESTARTING) {
// free current mem
NCDValMem_Free(&p->current_mem);
// move next mem/values over current mem/values
p->current_mem = p->next_mem;
p->current_name = p->next_name;
p->current_args = p->next_args;
// try starting it again
process_try(p);
return;
}
// free process
process_free(p);
// if manager is dying and there are no more processes, let it die
if (o->dying && LinkedList1_IsEmpty(&o->processes_list)) {
instance_free(o);
}
} break;
}
}
static int process_module_process_func_getspecialobj (NCDModuleProcess *module_process, NCD_string_id_t name, NCDObject *out_object)
{
struct process *p = UPPER_OBJECT(module_process, struct process, module_process);
ASSERT(p->state != PROCESS_STATE_RETRYING)
if (name == NCD_STRING_CALLER) {
*out_object = NCDObject_Build(-1, p, NCDObject_no_getvar, process_module_process_caller_obj_func_getobj);
return 1;
}
return 0;
}
static int process_module_process_caller_obj_func_getobj (const NCDObject *obj, NCD_string_id_t name, NCDObject *out_object)
{
struct process *p = NCDObject_DataPtr(obj);
struct instance *o = p->manager;
ASSERT(p->state != PROCESS_STATE_RETRYING)
return NCDModuleInst_Backend_GetObj(o->i, name, out_object);
}
static void process_stop (struct process *p)
{
switch (p->state) {
case PROCESS_STATE_RETRYING: {
// free process
process_free(p);
} break;
case PROCESS_STATE_RUNNING: {
// request process to terminate
NCDModuleProcess_Terminate(&p->module_process);
// set state
p->state = PROCESS_STATE_STOPPING;
} break;
case PROCESS_STATE_RESTARTING: {
// free next mem
NCDValMem_Free(&p->next_mem);
// set state
p->state = PROCESS_STATE_STOPPING;
} break;
case PROCESS_STATE_STOPPING: {
// nothing to do
} break;
default: ASSERT(0);
}
}
static int process_restart (struct process *p, NCDValMem *mem, NCDValSafeRef name, NCDValSafeRef template_name, NCDValSafeRef args)
{
struct instance *o = p->manager;
ASSERT(!o->dying)
ASSERT(p->state == PROCESS_STATE_STOPPING)
ASSERT(!NCDVal_IsInvalid(NCDVal_FromSafe(&p->current_mem, p->current_name)) || NCDVal_IsInvalid(NCDVal_FromSafe(mem, name)))
ASSERT(NCDVal_IsInvalid(NCDVal_FromSafe(&p->current_mem, p->current_name)) || NCDVal_Compare(NCDVal_FromSafe(mem, name), NCDVal_FromSafe(&p->current_mem, p->current_name)) == 0)
ASSERT(NCDVal_IsString(NCDVal_FromSafe(mem, template_name)))
ASSERT(NCDVal_IsList(NCDVal_FromSafe(mem, args)))
// copy mem to next mem
if (!NCDValMem_InitCopy(&p->next_mem, mem)) {
ModuleLog(o->i, BLOG_ERROR, "NCDValMem_InitCopy failed");
goto fail0;
}
// remember name and args to next
p->next_name = name;
p->next_args = args;
// set state
p->state = PROCESS_STATE_RESTARTING;
return 1;
fail0:
return 0;
}
static void func_new (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
{
struct instance *o = vo;
o->i = i;
// check arguments
if (!NCDVal_ListRead(params->args, 0)) {
ModuleLog(o->i, BLOG_ERROR, "wrong arity");
goto fail0;
}
// init processes list
LinkedList1_Init(&o->processes_list);
// set not dying
o->dying = 0;
// signal up
NCDModuleInst_Backend_Up(o->i);
return;
fail0:
NCDModuleInst_Backend_DeadError(i);
}
void instance_free (struct instance *o)
{
ASSERT(LinkedList1_IsEmpty(&o->processes_list))
NCDModuleInst_Backend_Dead(o->i);
}
static void func_die (void *vo)
{
struct instance *o = vo;
ASSERT(!o->dying)
// request all processes to die
LinkedList1Node *n = LinkedList1_GetFirst(&o->processes_list);
while (n) {
LinkedList1Node *next = LinkedList1Node_Next(n);
struct process *p = UPPER_OBJECT(n, struct process, processes_list_node);
process_stop(p);
n = next;
}
// if there are no processes, die immediately
if (LinkedList1_IsEmpty(&o->processes_list)) {
instance_free(o);
return;
}
// set dying
o->dying = 1;
}
static void start_func_new (void *unused, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
{
// check arguments
NCDValRef name_arg = NCDVal_NewInvalid();
NCDValRef template_name_arg;
NCDValRef args_arg;
if (!NCDVal_ListRead(params->args, 2, &template_name_arg, &args_arg) &&
!NCDVal_ListRead(params->args, 3, &name_arg, &template_name_arg, &args_arg)
) {
ModuleLog(i, BLOG_ERROR, "wrong arity");
goto fail0;
}
if (!NCDVal_IsString(template_name_arg) || !NCDVal_IsList(args_arg)) {
ModuleLog(i, BLOG_ERROR, "wrong type");
goto fail0;
}
// signal up.
// Do it before creating the process so that the process starts initializing before our own process continues.
NCDModuleInst_Backend_Up(i);
// get method object
struct instance *mo = NCDModuleInst_Backend_GetUser((NCDModuleInst *)params->method_user);
if (!mo->dying) {
struct process *p = (NCDVal_IsInvalid(name_arg) ? NULL : find_process(mo, name_arg));
if (!p || p->state == PROCESS_STATE_STOPPING) {
if (p) {
if (!process_restart(p, args_arg.mem, NCDVal_ToSafe(name_arg), NCDVal_ToSafe(template_name_arg), NCDVal_ToSafe(args_arg))) {
ModuleLog(i, BLOG_ERROR, "failed to restart process");
goto fail0;
}
} else {
if (!process_new(mo, args_arg.mem, NCDVal_ToSafe(name_arg), NCDVal_ToSafe(template_name_arg), NCDVal_ToSafe(args_arg))) {
ModuleLog(i, BLOG_ERROR, "failed to create process");
goto fail0;
}
}
}
}
return;
fail0:
NCDModuleInst_Backend_DeadError(i);
}
static void stop_func_new (void *unused, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
{
// check arguments
NCDValRef name_arg;
if (!NCDVal_ListRead(params->args, 1, &name_arg)) {
ModuleLog(i, BLOG_ERROR, "wrong arity");
goto fail0;
}
// signal up.
// Do it before stopping the process so that the process starts terminating before our own process continues.
NCDModuleInst_Backend_Up(i);
// get method object
struct instance *mo = NCDModuleInst_Backend_GetUser((NCDModuleInst *)params->method_user);
if (!mo->dying) {
struct process *p = find_process(mo, name_arg);
if (p && p->state != PROCESS_STATE_STOPPING) {
process_stop(p);
}
}
return;
fail0:
NCDModuleInst_Backend_DeadError(i);
}
static struct NCDModule modules[] = {
{
.type = "process_manager",
.func_new2 = func_new,
.func_die = func_die,
.alloc_size = sizeof(struct instance)
}, {
.type = "process_manager::start",
.func_new2 = start_func_new
}, {
.type = "process_manager::stop",
.func_new2 = stop_func_new
}, {
.type = NULL
}
};
const struct NCDModuleGroup ncdmodule_process_manager = {
.modules = modules
};