/* cmd_fg() function.
* with no arguments, it just put the latest bg job back;
* with one argument, it put the process with the input
* job number back.
*/
int
cmd_fg(int argc, char** argv)
{
if (argc > 2) {
printf("Shell: fg: too many arguments!\n");
return SYNTAX_ERROR;
}
else if (argc == 2) {
if (atoi(argv[1]) > bg_top + 1) {
printf("Shell: fg: no such job!\n");
return OTHER_ERROR;
}
else {
int i = atoi(argv[1]) - 1;
pid_t to_call = bg_list[i].pid;
if (pid_exist(to_call)) {
/* start to wait for the process */
bg_remove(i);
setpgid(to_call, getpgrp());
if (waitpid(to_call, 0, 0) < 0) {
printf("Shell: error: waitpid error!\n");
return OTHER_ERROR;
}
return NORMAL;
}
/* the process already somehow quit */
else {
printf("[ %d ] pid = %d Done.\n", i+1, to_call);
return NORMAL;
}
}
}
else if (argc == 1) {
if (bg_top == -1) {
printf("Shell: no background jobs!\n");
return OTHER_ERROR;
}
else {
pid_t to_call = bg_list[bg_top].pid;
if (pid_exist(to_call)) {
/* start to wait for the process */
bg_remove(bg_top);
if (waitpid(to_call, 0, 0) < 0) {
printf("Shell: error: waitpid error!\n");
return OTHER_ERROR;
}
return NORMAL;
}
/* the process already somehow quit */
else {
printf("[ %d ] pid = %d Done.\n", bg_top+1, to_call);
return NORMAL;
}
}
}
}
/* check each pid's status in the bg list */
void
bg_checkall(void)
{
//debug information
//printf("debug: in bg_checkall() function\n");
int i;
if (bg_top == -1)
return;
for (i = 0; i <= bg_top; i++) {
if ( waitpid(bg_list[i].pid, 0, WNOHANG) < 0) {
printf("[ %d ] pid = %d Done.\n", i, bg_list[i].pid);
bg_remove(i);
}
}
}
/**
* bg_trav_nodes - traverse node level of skip list and maintain
* @ptst: per-thread state
*
* Note: this will try to remove each of the nodes in the list,
* in order to extract nodes that have already been logically deleted
* but that are still accessible.
*/
static void bg_trav_nodes(ptst_t *ptst)
{
node_t *prev, *node;
assert(NULL != set && NULL != set->head);
prev = set->head;
node = prev->next;
while (NULL != node) {
bg_remove(prev, node, ptst);
if (NULL != node->val && node != node->val)
++bg_non_deleted;
else if (node->level >= 1)
++bg_tall_deleted;
prev = node;
node = node->next;
}
}
/**
* bg_trav_nodes - traverse node level of skip list
* @ptst: per-thread state
*
* Returns 1 if a raise was done and 0 otherwise.
*
* Note: this tries to raise non-deleted nodes, and finished deletions that
* have been started but not completed.
*/
static int bg_trav_nodes(ptst_t *ptst)
{
node_t *prev, *node, *next;
node_t *above_head = set->head, *above_prev, *above_next;
unsigned long zero = sl_zero;
int raised = 0;
assert(NULL != set && NULL != set->head);
ptst = ptst_critical_enter();
above_prev = above_next = above_head;
prev = set->head;
node = prev->next;
if (NULL == node)
return 0;
next = node->next;
while (NULL != next) {
if (NULL == node->val) {
bg_remove(prev, node, ptst);
if (node->level >= 1)
++bg_tall_deleted;
++bg_deleted;
}
else if (node->val != node) {
if ((((0 == prev->level
&& 0 == node->level)
&& 0 == next->level))
&& CAS(&node->raise_or_remove, 0, 1)) {
node->level = 1;
raised = 1;
get_index_above(above_head, &above_prev,
&above_next, 0, node->key,
zero);
// swap the pointers
node->succs[IDX(0,zero)] = above_next;
BARRIER(); // make sure above happens first
above_prev->succs[IDX(0,zero)] = node;
above_next = above_prev = above_head = node;
}
}
if (NULL != node->val && node != node->val) {
++bg_non_deleted;
}
prev = node;
node = next;
next = next->next;
}
ptst_critical_exit(ptst);
return raised;
}
