eive-obsw/watchdog/Watchdog.cpp
2021-07-29 11:59:32 +02:00

160 lines
4.8 KiB
C++

#include "Watchdog.h"
#include "watchdogConf.h"
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <poll.h>
#include <unistd.h>
#include <fcntl.h>
#include <iostream>
#include <thread>
#include <cstring>
#include <filesystem>
WatchdogTask::WatchdogTask (): fd(0) {
int result = 0;
// Only create the FIFO if it does not exist yet
if(not std::filesystem::exists(watchdog::FIFO_NAME)) {
// Permission 666 or rw-rw-rw-
mode_t mode = DEFFILEMODE;
result = mkfifo(watchdog::FIFO_NAME.c_str(), mode);
if(result != 0) {
std::cerr << "eive-watchdog: Could not created named pipe at " <<
watchdog::FIFO_NAME << ", error " << errno << ": " << strerror(errno) <<
std::endl;
throw std::runtime_error("eive-watchdog: FIFO creation failed");
}
#if WATCHDOG_VERBOSE_LEVEL >= 1
std::cout << "eive-watchdog: Pipe at " << watchdog::FIFO_NAME <<
" created successfully" << std::endl;
#endif
}
}
WatchdogTask::~WatchdogTask() {
}
int WatchdogTask::performOperation() {
// Open FIFO read only and non-blocking
fd = open(watchdog::FIFO_NAME.c_str(), O_RDONLY | O_NONBLOCK);
if(fd < 0) {
std::cerr << "eive-watchdog: Opening pipe " << watchdog::FIFO_NAME <<
"read-only failed with " << errno << ": " << strerror(errno) << std::endl;
}
state = States::RUNNING;
while(true) {
WatchdogTask::LoopResult loopResult = watchdogLoop();
switch(loopResult) {
case(LoopResult::OK): {
break;
}
case(LoopResult::CANCEL_RQ): {
if(state == States::RUNNING) {
state = States::SUSPENDED;
}
break;
}
case(LoopResult::TIMEOUT): {
std::cout << "eive-watchdog: The FIFO timed out!" << std::endl;
break;
}
case(LoopResult::RESTART_RQ): {
if(state == States::SUSPENDED) {
state = States::RUNNING;
}
break;
}
}
}
if (close(fd) < 0) {
std::cerr << "eive-watchdog: Closing named pipe at " << watchdog::FIFO_NAME <<
"failed, error " << errno << ": " << strerror(errno) << std::endl;
}
std::cout << "eive-watchdog: Finished" << std::endl;
return 0;
}
WatchdogTask::LoopResult WatchdogTask::watchdogLoop() {
using namespace std::chrono_literals;
char readChar;
struct pollfd waiter = {};
waiter.fd = fd;
waiter.events = POLLIN;
switch(state) {
case(States::SUSPENDED): {
// Sleep, then check whether a restart request was received
std::this_thread::sleep_for(1000ms);
break;
}
case(States::RUNNING): {
// Continue as usual
break;
}
case(States::NOT_STARTED): {
// This should not happen
std::cerr << "eive-watchdog: State is NOT_STARTED, configuration error" << std::endl;
break;
}
case(States::FAULTY): {
// TODO: Not sure what to do yet. Continue for now
break;
}
}
// 10 seconds timeout, only poll one file descriptor
switch(poll(&waiter, 1, watchdog::TIMEOUT_MS)) {
case(0): {
return LoopResult::TIMEOUT;
}
case(1): {
if (waiter.revents & POLLIN) {
ssize_t readLen = read(fd, buf.data(), buf.size());
if (readLen < 0) {
std::cerr << "eive-watchdog: Read error on pipe " << watchdog::FIFO_NAME <<
", error " << errno << ": " << strerror(errno) << std::endl;
break;
}
for(ssize_t idx = 0; idx < readLen; idx++) {
readChar = buf[idx];
// Cancel request
if(readChar == 'c') {
return LoopResult::CANCEL_RQ;
}
// Begin request. Does not work if the operation was not suspended before
else if(readChar == 'b') {
return LoopResult::RESTART_RQ;
}
// Everything else: All working as expected
else {
}
}
#if WATCHDOG_VERBOSE_LEVEL == 2
std::cout << "Read " << readLen << " byte(s) on the pipe " << FIFO_NAME
<< std::endl;
#endif
}
else if(waiter.revents & POLLERR) {
std::cerr << "eive-watchdog: Poll error error on pipe " << watchdog::FIFO_NAME <<
std::endl;
}
else if (waiter.revents & POLLHUP) {
// Writer closed its end
}
break;
}
default: {
std::cerr << "eive-watchdog: Unknown poll error at " << watchdog::FIFO_NAME << ", error " <<
errno << ": " << strerror(errno) << std::endl;
break;
}
}
return LoopResult::OK;
}