Add system daemon class

src/System/Daemon.php

@@ -0,0 +1,153 @@
+<?php
+
+namespace Friendica\System;
+
+use Friendica\Database\Database;
+use Psr\Log\LoggerInterface;
+
+final class Daemon
+{
+	private LoggerInterface $logger;
+	private Database $dba;
+	private ?string $pidfile = null;
+	private ?int $pid = null;
+
+	public function getPid(): ?int
+	{
+		return $this->pid;
+	}
+
+	public function getPidfile(): ?string
+	{
+		return $this->pidfile;
+	}
+
+	public function __construct(LoggerInterface $logger, Database $dba)
+	{
+		$this->logger = $logger;
+		$this->dba    = $dba;
+	}
+
+	public function init($pidfile = null): void
+	{
+		if (!empty($pidfile)) {
+			$this->pid     = null;
+			$this->pidfile = $pidfile;
+		}
+
+		if (!empty($this->pid)) {
+			return;
+		}
+
+		if (is_readable($this->pidfile)) {
+			$this->pid = intval(file_get_contents($this->pidfile));
+		}
+	}
+
+	public function start(callable $daemonLogic, bool $foreground = false): bool
+	{
+		$this->init();
+
+		if (!empty($this->pid)) {
+			$this->logger->notice('process is already running', ['pid' => $this->pid, 'pidfile' => $this->pidfile]);
+			return false;
+		}
+
+		$this->logger->notice('starting daemon', ['pid' => $this->pid, 'pidfile' => $this->pidfile]);
+
+		if (!$foreground) {
+			$this->dba->disconnect();
+
+			// fork a daemon process
+			$this->pid = pcntl_fork();
+			if ($this->pid < 0) {
+				$this->logger->warning('Could not fork daemon');
+				return false;
+			} elseif ($this->pid) {
+				// The parent process continues here
+				if (!file_put_contents($this->pidfile, $this->pid)) {
+					$this->logger->warning('Could not store pid file', ['pid' => $this->pid, 'pidfile' => $this->pidfile]);
+					posix_kill($this->pid, SIGTERM);
+					return false;
+				}
+				$this->logger->notice('Child process started', ['pid' => $this->pid, 'pidfile' => $this->pidfile]);
+				return true;
+			}
+
+			// We now are in the child process
+			register_shutdown_function(function (): void {
+				posix_kill(posix_getpid(), SIGTERM);
+				posix_kill(posix_getpid(), SIGHUP);
+			});
+
+			// Make the child the main process, detach it from the terminal
+			if (posix_setsid() < 0) {
+				return true;
+			}
+
+			// Closing all existing connections with the outside
+			fclose(STDIN);
+
+			// And now connect the database again
+			$this->dba->connect();
+		}
+
+		// Just to be sure that this script really runs endlessly
+		set_time_limit(0);
+
+		$daemonLogic();
+
+		return true;
+	}
+
+	public function isRunning(): bool
+	{
+		$this->init();
+
+		if (empty($this->pid)) {
+			$this->logger->notice("Pid wasn't found");
+
+			if (is_readable($this->pidfile)) {
+				unlink($this->pidfile);
+				$this->logger->notice("Pidfile removed", ['pidfile' => $this->pidfile]);
+			}
+			return false;
+		}
+
+		if (posix_kill($this->pid, 0)) {
+			$this->logger->notice("daemon process is running");
+			return true;
+		} else {
+			unlink($this->pidfile);
+			$this->logger->notice("daemon process isn't running");
+			return false;
+		}
+	}
+
+	public function stop(): bool
+	{
+		$this->init();
+
+		if (empty($this->pid)) {
+			$this->logger->notice("Pidfile wasn't found", ['pidfile' => $this->pidfile]);
+			return true;
+		}
+
+		posix_kill($this->pid, SIGTERM);
+		unlink($this->pidfile);
+
+		$this->logger->notice('daemon process was killed', ['pid' => $this->pid, 'pidfile' => $this->pidfile]);
+
+		return true;
+	}
+
+	public function sleep(int $duration)
+	{
+		usleep($duration);
+
+		$this->pid = pcntl_waitpid(-1, $status, WNOHANG);
+		if ($this->pid > 0) {
+			$this->logger->info('Children quit via pcntl_waitpid', ['pid' => $this->pid, 'status' => $status]);
+		}
+	}
+}