<?php
/**
* SeekQuarry/Yioop --
* Open Source Pure PHP Search Engine, Crawler, and Indexer
*
* Copyright (C) 2009 - 2024 Chris Pollett chris@pollett.org
*
* LICENSE:
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
* END LICENSE
*
* @author Chris Pollett chris@pollett.org
* @license https://www.gnu.org/licenses/ GPL3
* @link https://www.seekquarry.com/
* @copyright 2009 - 2024
* @filesource
*/
namespace seekquarry\yioop\library;
use seekquarry\yioop\configs as C;
/** For remoteAddress and crawlHash function and Yioop constants */
require_once __DIR__ . "/../library/Utility.php";
/**
* Encapsulates the temporary storage of messages sent between QueueServers
* and Fetchers during the course of a Crawl
*
* @author Chris Pollett
*/
class MessagesBundle implements CrawlConstants
{
/**
* Reference to a database object. Used since has directory manipulation
* functions
* @var object
*/
public $db;
/**
* The folder name of this MessagesBundle
* @var string
*/
public $dir_name;
/**
* Largest sequence number currently in use for sliding window protocol
* messages used for fetch batches of urls and downloaded web page
* for those urls responses
* @var int
*/
public $max_sequence_number;
/**
* Contains sequence_number => filename associations about which fetch
* batches have been successfully downloaded, received and should be
* moved for further processing. These will be moved once all earlier
* sequence numbers have been similarly received.
* @var array
*/
public $receive;
/**
* Contains sequence_number => [filename, schedule_time, tries] associations
* for fetch batches of urls to crawl which have been produced. Here
* filename is the name of the file that has the data for the batch,
* schedule_time is the last time the batch was scheduled to a Fetcher,
* and tries is the number of times it has been scheduled.
* @var array
*/
public $send;
/**
* Used in a crawl to set the maximum number of schedules generated at a
* time (if these many schedules are created already, queue server pauses
* on schedule creation until one or more of them have been successfully
* downloaded)
* In the QueueServer the window size is set to be the total number of
* currently active fetchers
* @var int
*/
public $window_size;
/**
* String prefix to be used before filenames of message files in the
* ETAG_EXPIRES_FOLDER, INDEX_DATA_FOLDER, ROBOTS_FOLDER, and
* SCHEDULES_FOLDER folders.
*/
const MESSAGE_PREFIX = "At";
/**
* Folder name for the folder within the MessageBundle folder used to
* contain files with etag and expires header information waiting to be
* processed by the scheduler
*/
const ETAG_EXPIRES_FOLDER = "etag_expires";
/**
* Folder name for the folder within the MessageBundle folder used to
* contain files with web page summaries and downloaded page information
* waiting to be by the indexer (i.e., to make an inverted index)
* processed
*/
const INDEX_DATA_FOLDER = "index_data";
/**
* Folder name for the folder within the MessageBundle folder used to
* contain files with robots.txt information waiting to be
* processed by the scheduler
*/
const ROBOTS_FOLDER = "robots";
/**
* Folder name for the folder within the MessageBundle folder used to
* contain files with to crawl url information waiting to be
* processed by the scheduler
*/
const SCHEDULES_FOLDER = "schedules";
/**
* Makes a MessagesBundle with the provided parameters. This method
* does not initialize send and receive properties related to
* the fetch batch window.
*
* @param string $dir_name folder name used by this MessagesBundle
* @param int $window_size number of number of outstanding url fetch batch
* files to allow before stop accepting new ones
*
*/
public function __construct($dir_name, $window_size = 1)
{
$this->dir_name = $dir_name;
if (!file_exists($dir_name)) {
mkdir($dir_name);
set_error_handler(null);
@chmod($dir_name, 0777);
set_error_handler(C\NS_CONFIGS . "yioop_error_handler");
}
$this->window_size = $window_size;
$db_class = C\NS_DATASOURCES . ucfirst(C\DBMS) . "Manager";
$this->db = new $db_class();
}
/**
* Use to intialize the send and receiver property arrays for the
* send and receive fetch batch window.
*
* @param bool $reset_schedule_times whether to reset the schedule
* times of each batch current in the send folder, but not acknowledged
* to 0, forcing them to eb rescheduled.
*/
public function initWindows($reset_schedule_times = false)
{
$receive_dir = $this->dir_name . "/receive";
$send_dir = $this->dir_name . "/send";
$max_sequence_number = 0;
foreach (['receive' => $receive_dir, 'send' => $send_dir] as
$window_name => $dir) {
if (!file_exists($dir)) {
mkdir($dir);
set_error_handler(null);
@chmod($dir, 0777);
set_error_handler(C\NS_CONFIGS . "yioop_error_handler");
}
$files = glob("$dir/*.txt");
$window_data = [];
$sequence_number = 0;
$len_prefix = strlen("$dir/");
$len_suffix = strlen(".txt");
foreach ($files as $file) {
$base_name = substr($file, $len_prefix, -$len_suffix);
$base_parts = explode("-", $base_name);
$expected_num_parts = ($window_name == 'receive') ? 1 : 3;
if (count($base_parts) != $expected_num_parts) {
continue;
}
$sequence_number = intval($base_parts[0]);
if ($sequence_number > $max_sequence_number) {
$max_sequence_number = $sequence_number;
}
if ($window_name == 'send') {
list(, $schedule_time, $tries) = $base_parts;
$item = ['file' => $file,
'schedule_time' => intval($schedule_time),
'tries' => intval($tries)];
if ($reset_schedule_times) {
$schedule_time = 0;
$item['file'] = $this->makeSendWindowFilename(
$sequence_number, $schedule_time, $tries);
rename($file, $item['file']);
}
} else {
$item = $file;
}
$window_data[$sequence_number] = $item;
}
$this->$window_name = $window_data;
}
$this->max_sequence_number = $max_sequence_number;
}
/**
* Returns where the send folder (containing fetch batches which have been
* received but not yet downloaded) can hold another fetch batch given
* the window size.
* @return bool true if it can hold another fetch batch, fall otherwise
*/
public function isSendFull()
{
return (count($this->receive) + count($this->send) >=
$this->window_size);
}
/**
* Returns the data from the least sequence numbered file in the send
* window that either has not previously been returned (tries 0) or
* that has been previously returned but more than timeout seconds earlier
* In both cases the try count of the file is bumped. If a file is
* found in the search process with a try count above
* MAX_RESCHEDULE_ATTEMPTS, it is moved instead to the receive window
* but with no data received.
*
* @return string file contents of found file
*/
public function extractSendWindow()
{
ksort($this->send);
$data = false;
$time = time();
foreach($this->send as $sequence_number => $item) {
$tries = $item['tries'];
$timeout = ($item['schedule_time'] + C\SCHEDULE_TIMEOUT) < $time;
if($item['tries'] == 0 || ($timeout &&
$tries < C\MAX_RESCHEDULE_ATTEMPTS)) {
$data = file_get_contents($item['file']);
$tries++;
$this->send[$sequence_number]['tries'] = $tries;
$schedule_time = ($timeout) ? $time : $item['schedule_time'];
$filename = $this->makeSendWindowFilename(
$sequence_number, $schedule_time, $tries);
clearstatcache();
if (file_exists($item['file'])) {
rename($item['file'], $filename);
}
$this->send[$sequence_number]['file'] = $filename;
break;
} else if ($timeout) {
$this->updateReceiveWindow($sequence_number, "");
}
}
return $data;
}
/**
* Add a fetch batch to the send folder of the messages bundle if there
* space in the folder given the current window size
* @param string $tmp_send_filename filename of the file with the
* fetch batch. If this operation succeeds, the file at this location
* will be moved to the send folder
* @return bool whether operation was successful
*/
public function insertSendWindow($tmp_send_filename)
{
if ($this->isSendFull()) {
return false;
}
$schedule_time = time();
$tries = 0;
$this->max_sequence_number++;
$sequence_number = $this->max_sequence_number;
$filename = $this->makeSendWindowFilename($sequence_number,
$schedule_time, $tries);
rename($tmp_send_filename, $filename);
set_error_handler(null);
@chmod($filename, 0777);
set_error_handler(C\NS_CONFIGS . "yioop_error_handler");
$this->send[$sequence_number] = ['file' => $filename,
'schedule_time' => $schedule_time, 'tries' => $tries];
return true;
}
/**
* Used to output the filename of a file storing a fetch batch of urls in
* the send folder
* @param int $sequence_number sequence number used for sliding window
* algorithm
* @param int $schedule_time time at which the given file was last scheduled
* for download
* @param int $tries number of times a fetcher has been scheduled to try
* to download the given list of urls
* @return string the filename to use for the fetch batch with the given
* parameters
*/
public function makeSendWindowFilename($sequence_number, $schedule_time,
$tries)
{
return $this->dir_name .
"/send/{$sequence_number}-$schedule_time-$tries.txt";
}
/**
* Used to output the filename of a file returned from a fetcher containing
* downloaded pages for a set of urls
*
* @param int $sequence_number sequence number used for sliding window
* algorithm
* @return string the filename to use for the fetch batch with the given
* parameters
*/
public function makeReceiveWindowFilename($sequence_number)
{
return $this->dir_name . "/receive/{$sequence_number}.txt";
}
/**
* Adds a new messages file to the received subfolder of the
* MessagesBundle with the given sequence number and containing the
* passed data
*
* @param int $sequence_number sequence number to use in making the
* filename of the new file to add to the receive folder
* @param string $data message contents of the file to add
*/
public function updateReceiveWindow($sequence_number, $data)
{
if (empty($this->send[$sequence_number])) {
return;
}
$target_name = $this->makeReceiveWindowFilename($sequence_number);
file_put_contents($target_name, $data);
set_error_handler(null);
@chmod($target_name, 0777);
set_error_handler(C\NS_CONFIGS . "yioop_error_handler");
$this->receive[$sequence_number] = $target_name;
unlink($this->send[$sequence_number]['file']);
unset($this->send[$sequence_number]);
}
/**
* Searches for a file is in the receive subfolder of this MessagesBundle
* of least sequence number. If there is no file in the send subfolder
* of the MessagesBundle with smaller sequence number, then the file
* is read, deleted and its contents returned. Otherwise, this function
* returns false.
*
* @return string|bool Data of found file or file
*/
public function extractReceiveWindow()
{
ksort($this->send);
$first_send_number = array_key_first($this->send);
ksort($this->receive);
$first_receive_number = array_key_first($this->receive);
if ($first_send_number !== null &&
$first_send_number < $first_receive_number) {
return false;
}
$filename = $this->receive[$first_receive_number] ?? "";
clearstatcache();
if (!empty($filename) && file_exists($filename)) {
$data = file_get_contents($filename);
set_error_handler(null);
@unlink($filename);
set_error_handler(C\NS_CONFIGS . "yioop_error_handler");
} else {
$data = false;
}
unset($this->receive[$first_receive_number]);
return $data;
}
/**
* Adds a file with contents $data and with name containing $address and
* $time to a subfolder $day in the folder $messages_type subfolder of
* the MessagesBundle
*
* @param string $messages_type the kind of messages being saved
* @param string &$data_string encoded, compressed, serialized data the
* schedule is to contain
* @param int $time
*/
public function addMessages($messages_type, &$data_string, $time = 0)
{
$dir = $this->dir_name . "/$messages_type";
$address = strtr(remoteAddress(), ["." => "-", ":" => "_"]);
$time = ($time == 0) ? time() : $time;
$day = floor($time/C\ONE_DAY);
if (!file_exists($dir)) {
mkdir($dir);
chmod($dir, 0777);
}
$dir .= "/$day";
if (!file_exists($dir)) {
mkdir($dir);
chmod($dir, 0777);
}
$data_hash = crawlHash($data_string);
file_put_contents($dir . "/" . self::MESSAGE_PREFIX . $time .
"From" . $address . "WithHash$data_hash.txt", $data_string);
}
/**
* Get the next messages file by timestamp stored in the MessagesBundle
* subfolder of of the given type (etag_expires, robots, schedules,
* index_data) and either return it as a string or as a deserialized array
* or object. This subfolder is typically organized into days subsubfolders
* with the appropriately timestamped files in a given days folder.
* After reading its data, but before returning it from
* this method the file itself is deleted.
*
* @param string $type kind of data to look for messages about. This
* kind should correspond to a folder in the messages bundle. Typically,
* these folders will be (etag_expires, robots, schedules, index_data)
* @param bool $unpack whether to unpack (decode/gzunzip/wddx_deserialize)
* the first found file and return its data, or just return its string
* contents after webdecode them.
* @param string $message_prefix prefix string of filenames in
* given folder (etag_expires, robots, schedules, index_data) that have
* messages data
* @return (string|array|object)?
*/
public function nextMessages($type, $unpack = true, $message_prefix =
self::MESSAGE_PREFIX)
{
$dirs = glob("{$this->dir_name}/$type/*", GLOB_ONLYDIR);
$len_prefix = strlen($message_prefix);
foreach ($dirs as $dir) {
$files = glob($dir . '/*.txt');
if (isset($old_dir)) {
crawlLog("Deleting $old_dir\n");
$this->db->unlinkRecursive($old_dir);
/* The idea is that only go through outer loop more than once
if earlier data directory empty.
Note: older directories should only have data dirs or
deleting like this might cause problems!
*/
}
/* the code below returns the data
from the lex-first file beginning with self::MESSAGE_PREFIX
*/
foreach ($files as $file) {
$path_parts = pathinfo($file);
$base_name = $path_parts['basename'];
$file_root_name = substr($base_name, 0, $len_prefix);
if (strcmp($file_root_name, $message_prefix) == 0) {
if ($unpack) {
$message_data = $this->unpackMessages($file);
} else {
$message_data = webdecode(file_get_contents($file));
}
unlink($file);
return $message_data;
}
}
$old_dir = $dir;
}
return null;
}
/**
* Returns whether they are any as yet to be produced to crawl schedules
* for the crawl queue in the given MessagesBundle's scheduler folder.
* @param string $messages_bundle_dir folder to check from schedules
* @return bool whether any found (true, if yes)
*/
public static function isResumable($messages_bundle_dir)
{
$schedules_dir_name = "$messages_bundle_dir/" . self::SCHEDULES_FOLDER;
if (!is_dir($schedules_dir_name)) {
return false;
}
$schedules_dir = opendir($schedules_dir_name);
$schedule_prefix = self::MESSAGE_PREFIX;
$len_prefix = strlen(self::MESSAGE_PREFIX);
while (($name = readdir($schedules_dir)) !== false) {
$sub_path = "$schedules_dir_name/$name";
if (!is_dir($sub_path) || $name == '.' ||
$name == '..') {
continue;
}
$sub_dir = opendir($sub_path);
while (($sub_name = readdir($sub_dir)) !== false) {
if (substr($sub_name, 0, $len_prefix) == $schedule_prefix) {
return true;
}
}
closedir($sub_dir);
}
closedir($schedules_dir);
return false;
}
/**
* Decodes the web-string safety encoding and then gunzips and deserializes
* the result for a messages file used for communication between a Fetcher
* and the QueueServer
* @param string $file name of the
* @return array|object unserialized data array or object contained in the
* messages file to be processed
*/
public function unpackMessages($file)
{
crawlLog("Processing File: $file");
$decode = file_get_contents($file);
$decode = webdecode($decode);
set_error_handler(null);
$decode = @gzuncompress($decode);
$sites = @unserialize($decode);
set_error_handler(C\NS_CONFIGS . "yioop_error_handler");
return $sites;
}
}