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Made process library thread-safe.

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This commit is contained in:
Thulinma 2016-05-18 23:33:27 +02:00
parent 0ea2a5e4b1
commit 5da3c24eae
2 changed files with 98 additions and 46 deletions
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136
lib/procs.cpp
View file

@ -24,12 +24,29 @@
std::set<pid_t> Util::Procs::plist;
std::set<int> Util::Procs::socketList;
bool Util::Procs::handler_set = false;
bool Util::Procs::thread_handler = false;
tthread::mutex Util::Procs::plistMutex;
tthread::thread * Util::Procs::reaper_thread = 0;
static bool childRunning(pid_t p) {
pid_t ret = waitpid(p, 0, WNOHANG);
/// Local-only function. Attempts to reap child and returns current running status.
bool Util::Procs::childRunning(pid_t p) {
int status;
pid_t ret = waitpid(p, &status, WNOHANG);
if (ret == p) {
tthread::lock_guard<tthread::mutex> guard(plistMutex);
int exitcode = -1;
if (WIFEXITED(status)) {
exitcode = WEXITSTATUS(status);
} else if (WIFSIGNALED(status)) {
exitcode = -WTERMSIG(status);
}
if (plist.count(ret)) {
HIGH_MSG("Process %d fully terminated with code %d", ret, exitcode);
plist.erase(ret);
} else {
HIGH_MSG("Child process %d exited with code %d", ret, exitcode);
}
return false;
}
if (ret < 0 && errno == EINTR) {
@ -49,7 +66,17 @@ bool Util::Procs::isRunning(pid_t pid){
/// all remaining children. Waits one more second for cleanup to finish, then exits.
void Util::Procs::exit_handler() {
int waiting = 0;
std::set<pid_t> listcopy = plist;
std::set<pid_t> listcopy;
{
tthread::lock_guard<tthread::mutex> guard(plistMutex);
listcopy = plist;
thread_handler = false;
}
if (reaper_thread){
reaper_thread->join();
delete reaper_thread;
reaper_thread = 0;
}
std::set<pid_t>::iterator it;
if (listcopy.empty()) {
return;
@ -72,7 +99,7 @@ void Util::Procs::exit_handler() {
return;
}
DEBUG_MSG(DLVL_DEVEL, "Sending SIGINT to remaining %d children", (int)listcopy.size());
WARN_MSG("Sending SIGINT to remaining %d children", (int)listcopy.size());
//send sigint to all remaining
if (!listcopy.empty()) {
for (it = listcopy.begin(); it != listcopy.end(); it++) {
@ -81,7 +108,7 @@ void Util::Procs::exit_handler() {
}
}
DEBUG_MSG(DLVL_DEVEL, "Waiting up to 5 seconds for %d children to terminate.", (int)listcopy.size());
INFO_MSG("Waiting up to 5 seconds for %d children to terminate.", (int)listcopy.size());
waiting = 0;
//wait up to 5 seconds for applications to shut down
while (!listcopy.empty() && waiting <= 250) {
@ -100,7 +127,7 @@ void Util::Procs::exit_handler() {
return;
}
DEBUG_MSG(DLVL_DEVEL, "Sending SIGKILL to remaining %d children", (int)listcopy.size());
ERROR_MSG("Sending SIGKILL to remaining %d children", (int)listcopy.size());
//send sigkill to all remaining
if (!listcopy.empty()) {
for (it = listcopy.begin(); it != listcopy.end(); it++) {
@ -109,7 +136,7 @@ void Util::Procs::exit_handler() {
}
}
DEBUG_MSG(DLVL_DEVEL, "Waiting up to a second for %d children to terminate.", (int)listcopy.size());
INFO_MSG("Waiting up to a second for %d children to terminate.", (int)listcopy.size());
waiting = 0;
//wait up to 1 second for applications to shut down
while (!listcopy.empty() && waiting <= 50) {
@ -127,14 +154,17 @@ void Util::Procs::exit_handler() {
if (listcopy.empty()) {
return;
}
DEBUG_MSG(DLVL_DEVEL, "Giving up with %d children left.", (int)listcopy.size());
FAIL_MSG("Giving up with %d children left.", (int)listcopy.size());
}
/// Sets up exit and childsig handlers.
/// Spawns grim_reaper. exit handler despawns grim_reaper
/// Called by every Start* function.
void Util::Procs::setHandler() {
tthread::lock_guard<tthread::mutex> guard(plistMutex);
if (!handler_set) {
thread_handler = true;
reaper_thread = new tthread::thread(grim_reaper, 0);
struct sigaction new_action;
new_action.sa_handler = childsig_handler;
sigemptyset(&new_action.sa_mask);
@ -145,41 +175,48 @@ void Util::Procs::setHandler() {
}
}
/// Used internally to capture child signals and update plist.
void Util::Procs::childsig_handler(int signum) {
if (signum != SIGCHLD) {
return;
}
int status;
pid_t ret = -1;
while (ret != 0) {
ret = waitpid(-1, &status, WNOHANG);
if (ret <= 0) { //ignore, would block otherwise
if (ret == 0 || errno != EINTR) {
return;
///Thread that loops until thread_handler is false.
///Reaps available children and then sleeps for a second.
///Not done in signal handler so we can use a mutex to prevent race conditions.
void Util::Procs::grim_reaper(void * n){
VERYHIGH_MSG("Grim reaper start");
while (thread_handler){
{
tthread::lock_guard<tthread::mutex> guard(plistMutex);
int status;
pid_t ret = -1;
while (ret != 0) {
ret = waitpid(-1, &status, WNOHANG);
if (ret <= 0) { //ignore, would block otherwise
if (ret == 0 || errno != EINTR) {
break;
}
continue;
}
int exitcode;
if (WIFEXITED(status)) {
exitcode = WEXITSTATUS(status);
} else if (WIFSIGNALED(status)) {
exitcode = -WTERMSIG(status);
} else { // not possible
break;
}
if (plist.count(ret)) {
HIGH_MSG("Process %d fully terminated with code %d", ret, exitcode);
plist.erase(ret);
} else {
HIGH_MSG("Child process %d exited with code %d", ret, exitcode);
}
}
continue;
}
int exitcode;
if (WIFEXITED(status)) {
exitcode = WEXITSTATUS(status);
} else if (WIFSIGNALED(status)) {
exitcode = -WTERMSIG(status);
} else { // not possible
return;
}
plist.erase(ret);
#if DEBUG >= DLVL_HIGH
if (!isActive(pname)) {
DEBUG_MSG(DLVL_HIGH, "Process %d fully terminated", ret);
} else {
DEBUG_MSG(DLVL_HIGH, "Child process %d exited", ret);
}
#endif
Util::sleep(500);
}
VERYHIGH_MSG("Grim reaper stop");
}
/// Ignores everything. Separate thread handles waiting for children.
void Util::Procs::childsig_handler(int signum) {
return;
}
@ -188,7 +225,7 @@ std::string Util::Procs::getOutputOf(char * const * argv) {
std::string ret;
int fin = 0, fout = -1, ferr = 0;
pid_t myProc = StartPiped(argv, &fin, &fout, &ferr);
while (isActive(myProc)) {
while (childRunning(myProc)) {
Util::sleep(100);
}
FILE * outFile = fdopen(fout, "r");
@ -349,7 +386,10 @@ pid_t Util::Procs::StartPiped(char * const * argv, int * fdin, int * fdout, int
}
return 0;
} else { //parent
plist.insert(pid);
{
tthread::lock_guard<tthread::mutex> guard(plistMutex);
plist.insert(pid);
}
DEBUG_MSG(DLVL_HIGH, "Piped process %s started, PID %d", argv[0], pid);
if (devnull != -1) {
close(devnull);
@ -384,7 +424,11 @@ void Util::Procs::Murder(pid_t name) {
/// (Attempts to) stop all running child processes.
void Util::Procs::StopAll() {
std::set<pid_t> listcopy = plist;
std::set<pid_t> listcopy;
{
tthread::lock_guard<tthread::mutex> guard(plistMutex);
listcopy = plist;
}
std::set<pid_t>::iterator it;
for (it = listcopy.begin(); it != listcopy.end(); it++) {
Stop(*it);
@ -393,11 +437,13 @@ void Util::Procs::StopAll() {
/// Returns the number of active child processes.
int Util::Procs::Count() {
tthread::lock_guard<tthread::mutex> guard(plistMutex);
return plist.size();
}
/// Returns true if a process with this PID is currently active.
bool Util::Procs::isActive(pid_t name) {
tthread::lock_guard<tthread::mutex> guard(plistMutex);
return (plist.count(name) == 1) && (kill(name, 0) == 0);
}

8
lib/procs.h
View file

@ -7,6 +7,7 @@
#include <set>
#include <vector>
#include <deque>
#include "tinythread.h"
/// Contains utility code, not directly related to streaming media
namespace Util {
@ -14,13 +15,18 @@ namespace Util {
/// Deals with spawning, monitoring and stopping child processes
class Procs {
private:
static std::set<pid_t> plist; ///< Holds active processes
static bool childRunning(pid_t p);
static tthread::mutex plistMutex;
static tthread::thread * reaper_thread;
static std::set<pid_t> plist; ///< Holds active process list.
static bool handler_set; ///< If true, the sigchld handler has been setup.
static bool thread_handler;///< True while thread handler should be running.
static void childsig_handler(int signum);
static void exit_handler();
static void runCmd(std::string & cmd);
static void setHandler();
static char* const* dequeToArgv(std::deque<std::string> & argDeq);
static void grim_reaper(void * n);
public:
static std::string getOutputOf(char * const * argv);
static std::string getOutputOf(std::deque<std::string> & argDeq);