1 files changed, 86 insertions, 7 deletions

diff --git a/src/process_group.c b/src/process_group.c
index 318babb..71f180b 100644
--- a/src/process_group.c
+++ b/src/process_group.c
@@ -1,8 +1,8 @@
-#include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <limits.h>
 #include <sys/time.h>
+#include <signal.h>
 
 #include <assert.h>
 
@@ -10,6 +10,81 @@
 #include "process_group.h"
 #include "list.h"
 
+// look for a process by pid
+// search_pid   : pid of the wanted process
+// return:  pid of the found process, if successful
+//          negative pid, if the process does not exist or if the signal fails
+int find_process_by_pid(pid_t pid)
+{
+	return (kill(pid,0)==0) ? pid : -pid;
+}
+
+// look for a process with a given name
+// process: the name of the wanted process. it can be an absolute path name to the executable file
+//         or just the file name
+// return:  pid of the found process, if it is found
+//         0, if it's not found
+//         negative pid, if it is found but it's not possible to control it
+int find_process_by_name(const char *process_name)
+{
+	//whether the variable process_name is the absolute path or not
+	int is_absolute_path = process_name[0] == '/';
+	//flag indicating if the a process with given name was found
+	int found = 0;
+	pid_t pid = -1;
+
+	//process iterator
+	struct process_iterator it;
+	struct process proc;
+	struct process_filter filter;
+	filter.pid = 0;
+	filter.include_children = 0;
+	init_process_iterator(&it, &filter);
+	while (get_next_process(&it, &proc) != -1)
+	{
+		pid = proc.pid;
+		int size = strlen(proc.command);
+
+		found = 0;
+		if (is_absolute_path && strncmp(proc.command, process_name, size)==0 && size==strlen(process_name)) {
+			//process found
+			found = 1;
+		}
+		else {
+			//process found
+			if (strncmp(proc.command + size - strlen(process_name), process_name, strlen(process_name))==0) {
+				found = 1;
+			}
+		}
+		if (found==1) {
+			if (kill(pid,SIGCONT)==0) {
+				//process is ok!
+				break;
+			}
+			else {
+				//we don't have permission to send signal to that process
+				//so, don't exit from the loop and look for another one with the same name
+				found = -1;
+			}
+		}
+	}
+	if (close_process_iterator(&it) != 1) exit(1);
+	if (found == 1) {
+		//ok, the process was found
+		return pid;
+	}
+	else if (found == 0) {
+		//no process found
+		return 0;
+	}
+	else if (found == -1) {
+		//the process was found, but we haven't permission to control it
+		return -pid;
+	}
+	//this MUST NOT happen
+	exit(2);
+}
+
 int init_process_group(struct process_group *pgroup, int target_pid, int include_children)
 {
 	//hashtable initialization
@@ -19,6 +94,7 @@ int init_process_group(struct process_group *pgroup, int target_pid, int include
 	pgroup->proclist = (struct list*)malloc(sizeof(struct list));
 	init_list(pgroup->proclist, 4);
 	memset(&pgroup->last_update, 0, sizeof(pgroup->last_update));
+	update_process_group(pgroup);
 	return 0;
 }
 
@@ -53,21 +129,23 @@ static inline unsigned long timediff(const struct timeval *t1,const struct timev
 
 //parameter in range 0-1
 #define ALFA 0.08
+#define MIN_DT 20
 
 void update_process_group(struct process_group *pgroup)
 {
 	struct process_iterator it;
 	struct process tmp_process;
 	struct process_filter filter;
+	struct timeval now;
+	gettimeofday(&now, NULL);
+	//time elapsed from previous sample (in ms)
+	long dt = timediff(&now, &pgroup->last_update) / 1000;
 	filter.pid = pgroup->target_pid;
 	filter.include_children = pgroup->include_children;
 	init_process_iterator(&it, &filter);
 	clear_list(pgroup->proclist);
 	init_list(pgroup->proclist, 4);
-	struct timeval now;
-	gettimeofday(&now, NULL);
-	//time elapsed from previous sample (in ms)
-	long dt = timediff(&now, &pgroup->last_update) / 1000;
+
 	while (get_next_process(&it, &tmp_process) != -1)
 	{
 //		struct timeval t;
@@ -103,6 +181,8 @@ void update_process_group(struct process_group *pgroup)
 				assert(tmp_process.pid == p->pid);
 				assert(tmp_process.ppid == p->ppid);
 				assert(tmp_process.starttime == p->starttime);
+				add_elem(pgroup->proclist, p);
+				if (dt < MIN_DT) continue;
 				//process exists. update CPU usage
 				double sample = 1.0 * (tmp_process.cputime - p->cputime) / dt;
 				if (p->cpu_usage == -1) {
@@ -113,12 +193,11 @@ void update_process_group(struct process_group *pgroup)
 					//usage adjustment
 					p->cpu_usage = (1.0-ALFA) * p->cpu_usage + ALFA * sample;
 				}
-				p->cpu_usage = (1.0-ALFA) * p->cpu_usage + ALFA * sample;
 				p->cputime = tmp_process.cputime;
-				add_elem(pgroup->proclist, p);
 			}
 		}
 	}
 	close_process_iterator(&it);
+	if (dt < MIN_DT) return;
 	pgroup->last_update = now;
 }