Playing with background processing: parent and child process fetching data

from the "same" result handle and checking with each other if the fetched
rows are the same or not. Inspired by a bug report. There seem to be really
people doing this...

1 files changed, 262 insertions, 0 deletions

diff --git a/ext/mysqli/tests/mysqli_fork.phpt b/ext/mysqli/tests/mysqli_fork.phpt
new file mode 100644
index 0000000000..f4fca5b7b2
--- /dev/null
+++ b/ext/mysqli/tests/mysqli_fork.phpt
@@ -0,0 +1,262 @@
+--TEST--
+Forking a child and using the same connection.
+--SKIPIF--
+<?php
+require_once('skipif.inc');
+require_once('skipifemb.inc');
+if (!function_exists('pcntl_fork'))
+	die("skip Process Control Functions not available");
+
+if (!function_exists('posix_getpid'))
+	die("skip POSIX functions not available");
+
+require_once('connect.inc');
+if (!$link = mysqli_connect($host, $user, $passwd, $db, $port, $socket)) {
+	die(sprintf("skip Cannot connect to the server using host=%s, user=%s, passwd=***, dbname=%s, port=%s, socket=%s\n",
+		$host, $user, $db, $port, $socket));
+}
+
+if (!$res = mysqli_query($link, "SHOW VARIABLES LIKE 'have_innodb'")) {
+	die(sprintf("skip Cannot fetch have_innodb variable\n"));
+}
+
+$row = mysqli_fetch_row($res);
+mysqli_free_result($res);
+mysqli_close($link);
+
+if ($row[1] == "DISABLED" || $row[1] == "NO") {
+	die(sprintf ("skip Innodb support is not installed or enabled."));
+}
+?>
+--FILE--
+<?php
+	require_once("connect.inc");
+	require_once("table.inc");
+
+	$res = mysqli_query($link, "SELECT 'dumped by the parent' AS message");
+	$pid = pcntl_fork();
+	switch ($pid) {
+		case -1:
+			printf("[001] Cannot fork child");
+			break;
+
+		case 0:
+			/* child */
+			exit(0);
+			break;
+
+		default:
+			/* parent */
+			$status = null;
+			$wait_id = pcntl_waitpid($pid, $status);
+			if (pcntl_wifexited($status) && (0 != ($tmp = pcntl_wexitstatus($status)))) {
+				printf("Exit code: %s\n", (pcntl_wifexited($status)) ? pcntl_wexitstatus($status) : 'n/a');
+				printf("Signal: %s\n", (pcntl_wifsignaled($status)) ? pcntl_wtermsig($status) : 'n/a');
+				printf("Stopped: %d\n", (pcntl_wifstopped($status)) ? pcntl_wstopsig($status) : 'n/a');
+			}
+			var_dump(mysqli_fetch_assoc($res));
+			mysqli_free_result($res);
+			break;
+	}
+
+	if (@mysqli_query($link, "SELECT id FROM test WHERE id = 1"))
+		printf("[003] Expecting error and closed connection, child exit should have closed connection\n");
+	else if ((($errno = mysqli_errno($link)) == 0) || ('' == ($error = mysqli_error($link))))
+		printf("[004] Expecting error string and error code from MySQL, got errno = %s/%s, error = %s/%s\n",
+			gettype($errno), $errno, gettype($error), $error);
+
+	mysqli_close($link);
+	if (!$link = mysqli_connect($host, $user, $passwd, $db, $port, $socket))
+		printf("[005] Cannot connect to the server using host=%s, user=%s, passwd=***, dbname=%s, port=%s, socket=%s\n",
+			$host, $user, $db, $port, $socket);
+
+	/* non trivial tests require a message list for parent-child communication */
+	if (!mysqli_query($link, "DROP TABLE IF EXISTS messages"))
+		printf("[006] [%d] %s\n", mysqli_error($link), mysqli_errno($link));
+
+	if (!mysqli_query($link, "CREATE TABLE messages(
+		msg_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
+		msg_time TIMESTAMP,
+		pid INT NOT NULL,
+		sender ENUM('child', 'parent') NOT NULL,
+		msg TEXT) ENGINE = InnoDB"))
+		printf("[007] [%d] %s\n", mysqli_error($link), mysqli_errno($link));
+
+	mysqli_autocommit($link, false);
+	if (!$res = mysqli_query($link, "SELECT id, label FROM test ORDER BY id ASC LIMIT 3", MYSQLI_USE_RESULT))
+		printf("[008] [%d] %s\n", mysqli_error($link), mysqli_errno($link));
+
+	$pid = pcntl_fork();
+
+	switch ($pid) {
+		case -1:
+			printf("[009] Cannot fork child");
+			break;
+
+		case 0:
+			/* child */
+			if (!($plink = mysqli_connect($host, $user, $passwd, $db, $port, $socket)) || !mysqli_autocommit($plink, true))
+				exit(mysqli_errno($plink));
+
+			$sql = sprintf("INSERT INTO messages(pid, sender, msg) VALUES (%d, 'child', '%%s')", posix_getpid());
+			if (!mysqli_query($plink, sprintf($sql, 'start')))
+				exit(mysqli_errno($plink));
+
+			$parent_sql = sprintf("SELECT msg_id, msg_time, msg FROM messages WHERE pid = %d  AND sender = 'parent' ORDER BY msg_id DESC LIMIT 1", posix_getppid());
+			$msg_id = 0;
+			while ($row = mysqli_fetch_assoc($res)) {
+				/* send row to parent */
+				ob_start();
+				var_dump($row);
+				$tmp = ob_get_contents();
+				ob_end_clean();
+				if (!mysqli_query($plink, sprintf($sql, $tmp)))
+					exit(mysqli_errno($plink));
+
+				/* let the parent reply... */
+				$start = time();
+				do {
+					usleep(100);
+					if (!$pres = mysqli_query($plink, $parent_sql))
+						continue;
+					$tmp = mysqli_fetch_assoc($pres);
+					mysqli_free_result($pres);
+					if ($tmp['msg_id'] == $msg_id)
+						/* no new message */
+						continue;
+					if ($tmp['msg'] == 'stop')
+						break 2;
+					$msg_id = $tmp['msg_id'];
+					break;
+				} while ((time() - $start) < 5);
+
+			}
+
+			if (!mysqli_query($plink, sprintf($sql, 'stop')) || !mysqli_commit($link))
+				exit(mysqli_errno($plink));
+			exit(0);
+			break;
+
+		default:
+			/* parent */
+			if (!$plink = mysqli_connect($host, $user, $passwd, $db, $port, $socket))
+					printf("[010] Cannot connect to the server using host=%s, user=%s, passwd=***, dbname=%s, port=%s, socket=%s\n",
+					$host, $user, $db, $port, $socket);
+
+			$status = null;
+			$start = time();
+			$sql = sprintf("SELECT msg_id, msg_time, msg FROM messages WHERE pid = %d AND sender = 'child' ORDER BY msg_id DESC LIMIT 1", $pid);
+			$parent_sql = sprintf("INSERT INTO messages (pid, sender, msg) VALUES (%d, 'parent', '%%s')", posix_getpid());
+			$last_msg_id = 0;
+			$num_rows = 0;
+			do {
+				$wait_id = pcntl_waitpid($pid, $status, WNOHANG);
+				if ($pres = mysqli_query($plink, $sql)) {
+					$row = mysqli_fetch_assoc($pres);
+					if ($row['msg_id'] != $last_msg_id) {
+						$last_msg_id = $row['msg_id'];
+						switch ($row['msg']) {
+							case 'start':
+								break;
+							case 'stop':
+								break 2;
+							default:
+								/* client has started fetching rows */
+								$client_row = $row['msg'];
+
+								$num_rows++;
+								if ($num_rows > 3) {
+									printf("[011] Child has fetched more than three rows!\n");
+									var_dump($client_row);
+									if (!mysqli_query($plink, sprintf($parent_sql, 'stop'))) {
+										printf("[012] Parent cannot inform child\n", mysqli_errno($plink), mysqli_error($plink));
+									}
+									break 2;
+								}
+
+								if (!$parent_row = mysqli_fetch_assoc($res)) {
+									printf("[013] Parent cannot fetch row %d\n", $num_rows, mysqli_errno($link), mysqli_error($link));
+									if (!mysqli_query($plink, sprintf($parent_sql, 'stop'))) {
+										printf("[014] Parent cannot inform child\n", mysqli_errno($plink), mysqli_error($plink));
+									}
+									break 2;
+								}
+
+								ob_start();
+								var_dump($parent_row);
+								$parent_row = ob_get_contents();
+								ob_end_clean();
+
+								if ($parent_row != $client_row) {
+									printf("[015] Child indicates different results than parent.\n");
+									var_dump($child_row);
+									var_dump($parent_row);
+									if (!mysqli_query($plink, sprintf($parent_sql, 'stop'))) {
+										printf("[016] Parent cannot inform child\n", mysqli_errno($plink), mysqli_error($plink));
+									}
+									break 2;
+								}
+
+								if (!mysqli_query($plink, sprintf($parent_sql, 'continue'))) {
+									printf("[017] Parent cannot inform child to continue.\n", mysqli_errno($plink), mysqli_error($plink));
+								}
+								break;
+						}
+					}
+					mysqli_free_result($pres);
+				}
+				usleep(100);
+			} while (((time() - $start) < 5) && ($num_rows < 3));
+			mysqli_close($plink);
+			$wait_id = pcntl_waitpid($pid, $status);
+			if (pcntl_wifexited($status) && (0 != ($tmp = pcntl_wexitstatus($status)))) {
+				printf("Exit code: %s\n", (pcntl_wifexited($status)) ? pcntl_wexitstatus($status) : 'n/a');
+				printf("Signal: %s\n", (pcntl_wifsignaled($status)) ? pcntl_wtermsig($status) : 'n/a');
+				printf("Stopped: %d\n", (pcntl_wifstopped($status)) ? pcntl_wstopsig($status) : 'n/a');
+			}
+			break;
+	}
+	mysqli_free_result($res);
+	mysqli_close($link);
+
+	if (!$link = mysqli_connect($host, $user, $passwd, $db, $port, $socket))
+		printf("[018] Cannot connect to the server using host=%s, user=%s, passwd=***, dbname=%s, port=%s, socket=%s\n",
+			$host, $user, $db, $port, $socket);
+
+	if (!$res = mysqli_query($link, "SELECT sender, msg FROM messages ORDER BY msg_id ASC"))
+		printf("[019] [%d] %s\n", mysqli_errno($link), mysqli_error($link));
+
+	while ($row = mysqli_fetch_assoc($res))
+		printf("%10s %s\n", $row['sender'], substr($row['msg'], 0, 5));
+	mysqli_free_result($res);
+
+	print "done!";
+?>
+--EXPECTF--
+array(1) {
+  ["message"]=>
+  string(20) "dumped by the parent"
+}
+     child start
+     child array
+    parent conti
+     child array
+    parent conti
+     child array
+    parent conti
+     child stop
+done!
+--UEXPECTF--
+array(1) {
+  [u"message"]=>
+  unicode(20) "dumped by the parent"
+}
+     child start
+     child array
+    parent conti
+     child array
+    parent conti
+     child array
+    parent conti
+     child stop
+done!
\ No newline at end of file