int execute_all_nodes(node_t* nodes, int num) {
int totalNodes = num;
int numNodesFinished = 0;
int i;
int j;
while(numNodesFinished < totalNodes) {
//check if parents are done, then change state to ready
for(i = 0; i < num ; i++ ) {
if (nodes[i].status == INELIGIBLE) {
if (nodes[i].num_parents_finished == nodes[i].num_parents)
nodes[i].status = READY;
}
}
//For them to fork concurrently first before waiting
for(i = 0; i<num;i++) {
if (nodes[i].status == READY) {
pid_t child_pid;
child_pid = fork();
if (child_pid < 0) {
perror("There was an error forking the process!");
return -1;
}
if (child_pid == 0) {
//is child
if (execute_node(nodes[i]) < 0) {
perror("There was an error running execute_node.");
return -1;
}
} else {
//main thread has child_pid, pid for the child.
nodes[i].status = RUNNING;
nodes[i].pid = child_pid;
}
}
}
for(i = 0; i<num;i++) {
if (nodes[i].status == RUNNING ) {
if (wait(NULL) == -1) {
perror("There was an error waiting for the process to end!");
return -1;
} else {
//successfully waited for forked child to complete
nodes[i].status = FINISHED;
numNodesFinished++;
//update nodes's childs
for(j=0;j < nodes[i].num_children; j++) {
nodes[nodes[i].children[j]].num_parents_finished++;
}
}
}
}
}
return 0;
}
void execute_parallel(command_stream_t commandStream) {
graphnode_list_t adjList = create_list();
command_t cmd;
while ((cmd = read_command_stream (commandStream))) {
string_list_t readList = create_list();
string_list_t writeList = create_list();
build_io_lists(cmd, readList, writeList);
add_to_graph(adjList, cmd, readList, writeList);
}
int adjListSize = size(adjList);
sharedFinished = mmap(NULL, adjListSize * sizeof(bool),
PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
int i;
for (i = 0; i < adjListSize; i++) {
sharedFinished[i] = false;
}
unsigned int numStartedProcesses = 0;
i = 0;
node_t currNode = adjList->head;
while (currNode) {
graphnode_t currGraphNode = currNode->item;
currGraphNode->aid = i;
if (numStartedProcesses >= MAX_PROCS) {
// wait for a spot to open up
wait(NULL);
}
pid_t p = fork();
if (p == 0) {
execute_node(currGraphNode);
}
else if (p > 0) {
numStartedProcesses++;
currNode = currNode->next;
}
i++;
}
while (true) {
int status;
pid_t done = wait(&status);
if (done == -1 && errno == ECHILD) {
break;
}
}
}
