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jetpack / vendor / wp-php-toolkit / data-liberation / EntityReader / class-databaserowsentityreader.php

class-databaserowsentityreader.php

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1	<?php
2
3	namespace WordPress\DataLiberation\EntityReader;
4
5	use PDO;
6	use PDOStatement;
7	use WordPress\DataLiberation\DataLiberationException;
8	use WordPress\DataLiberation\ImportEntity;
9
10	/**
11	* Reads the database rows, one table at a time, from the first row to the last row.
12	* Enables efficiently exporting large databases into an SQL file, but it's not useful
13	* for content dumps – the latter need to emit resources in a "topological content order,"
14	* e.g. post 1, post 1 meta, post 1 categories, post 1 comments, then post 2 (child of 1) etc.
15	*
16	* Note this is just a reader. It doesn't import any data into WordPress. It
17	* only reads rows from the database.
18	*
19	* @since WP_VERSION
20	*/
21	class DatabaseRowsEntityReader implements EntityReader {
22
23	/**
24	* State constants for the finite state machine
25	*/
26	const STATE_INIT = 'init';
27	const STATE_NEXT_ROW = 'next_row';
28	const STATE_NEXT_TABLE = 'next_table';
29	const STATE_CREATE_TABLE = 'create_table';
30	const STATE_FINISHED = 'finished';
31
32	/**
33	* The database connection used to fetch records.
34	*
35	* @since WP_VERSION
36	* @var PDO
37	*/
38	private $db;
39
40	/**
41	* The current entity being processed.
42	*
43	* @since WP_VERSION
44	* @var ImportEntity\|null
45	*/
46	private $current_entity = null;
47
48	/**
49	* The ID of the last processed record.
50	*
51	* @since WP_VERSION
52	* @var int\|null
53	*/
54	private $last_record_id = 0;
55
56	/**
57	* The number of entities read so far.
58	*
59	* @since WP_VERSION
60	* @var int
61	*/
62	private $entities_read_so_far = 0;
63
64	/**
65	* The current table being processed.
66	*
67	* @since WP_VERSION
68	* @var string\|null
69	*/
70	private $current_table = null;
71
72	/**
73	* The current query result set.
74	*
75	* @since WP_VERSION
76	* @var PDOStatement\|null
77	*/
78	private $current_result_set = null;
79
80	/**
81	* The list of tables to process.
82	*
83	* @since WP_VERSION
84	* @var array
85	*/
86	private $tables_to_process;
87
88	/**
89	* Whether to export the CREATE TABLE query for each table.
90	*
91	* @since WP_VERSION
92	* @var bool
93	*/
94	private $create_table_query;
95
96	/**
97	* The current state of the reader.
98	*
99	* @since WP_VERSION
100	* @var string
101	*/
102	private $state = self::STATE_INIT;
103
104	/**
105	* The type of the database.
106	*
107	* One of: "sqlite", "mysql"
108	*
109	* @since WP_VERSION
110	* @var string
111	*/
112	private $db_type;
113
114	public static function create( PDO $db, $options = array() ) {
115	return new DatabaseRowsEntityReader( $db, $options );
116	}
117
118	/**
119	* Constructor.
120	*
121	* @param PDO $db The database connection to use.
122	* @param array $options The options to configure the reader.
123	*
124	* @since WP_VERSION
125	*/
126	public function __construct( PDO $db, $options = array() ) {
127	$this->db = $db;
128	$this->tables_to_process = $options['tables_to_process'] ?? null;
129	$this->create_table_query = $options['create_table_query'] ?? false;
130	$this->db_type = $db->getAttribute( PDO::ATTR_DRIVER_NAME );
131	if ( ! in_array( $this->db_type, array( 'sqlite', 'mysql' ), true ) ) {
132	throw new DataLiberationException( esc_html( 'Unsupported database type: ' . $this->db_type ) );
133	}
134	if ( isset( $options['cursor'] ) ) {
135	$this->initialize_from_cursor( $options['cursor'] );
136	}
137	}
138
139	/**
140	* Gets the data for the current entity.
141	*
142	* @return ImportEntity The entity.
143	* @since WP_VERSION
144	*/
145	public function get_entity(): ImportEntity {
146	return $this->current_entity;
147	}
148
149	/**
150	* Gets the ID of the last processed record.
151	*
152	* @return int\|null The record ID, or null if no records have been processed.
153	* @since WP_VERSION
154	*/
155	public function get_last_record_id() {
156	return $this->last_record_id;
157	}
158
159	public function is_finished(): bool {
160	return self::STATE_FINISHED === $this->state;
161	}
162
163	/**
164	* Advances to the next entity in the database.
165	*
166	* @return bool Whether another entity was found.
167	* @since WP_VERSION
168	*/
169	public function next_entity() {
170	if ( $this->is_finished() ) {
171	return false;
172	}
173
174	if ( self::STATE_INIT === $this->state ) {
175	if ( null === $this->tables_to_process ) {
176	$this->initialize_tables_to_process();
177	}
178	$this->state = self::STATE_NEXT_TABLE;
179	}
180
181	while ( true ) {
182	switch ( $this->state ) {
183	case self::STATE_NEXT_TABLE:
184	if ( $this->move_to_next_table() ) {
185	$this->state = $this->create_table_query ? self::STATE_CREATE_TABLE : self::STATE_NEXT_ROW;
186	} else {
187	$this->state = self::STATE_FINISHED;
188
189	return false;
190	}
191	break;
192
193	case self::STATE_CREATE_TABLE:
194	$this->export_create_table_query();
195	$this->state = self::STATE_NEXT_ROW;
196
197	return true;
198
199	case self::STATE_NEXT_ROW:
200	if ( $this->read_next_entity() ) {
201	return true;
202	}
203	$this->state = self::STATE_NEXT_TABLE;
204
205	return $this->next_entity();
206
207	case self::STATE_FINISHED:
208	return false;
209	}
210	}
211
212	return false;
213	}
214
215	/**
216	* Advances to the next entity in the current table.
217	*
218	* @return bool Whether another entity was found.
219	* @since WP_VERSION
220	*/
221	private function read_next_entity() {
222	if ( ! $this->current_result_set ) {
223	$this->current_result_set = $this->db->query( "SELECT * FROM {$this->current_table} WHERE ID > {$this->last_record_id}" );
224	}
225
226	$record = $this->current_result_set->fetch( PDO::FETCH_ASSOC );
227	if ( ! $record ) {
228	$this->current_result_set = null;
229
230	return false;
231	}
232
233	$this->current_entity = new ImportEntity(
234	'database_row',
235	array(
236	'table' => $this->current_table,
237	'record' => $record,
238	)
239	);
240	$this->last_record_id = $record['ID'] ?? null;
241	++$this->entities_read_so_far;
242
243	return true;
244	}
245
246	/**
247	* Moves to the next table in the list of tables to process.
248	*
249	* @return bool Whether there is another table to process.
250	* @since WP_VERSION
251	*/
252	private function move_to_next_table() {
253	if ( ! $this->current_table ) {
254	$this->current_table = reset( $this->tables_to_process );
255	} else {
256	$this->current_table = next( $this->tables_to_process );
257	}
258	$this->last_record_id = 0;
259
260	return (bool) $this->current_table;
261	}
262
263	/**
264	* Exports the CREATE TABLE query for the current table.
265	*
266	* @since WP_VERSION
267	*/
268	private function export_create_table_query() {
269	switch ( $this->db_type ) {
270	case 'sqlite':
271	$result = $this->db->query( "SELECT sql FROM sqlite_master WHERE type='table' AND name='{$this->current_table}'" );
272	$row = $result->fetch( PDO::FETCH_ASSOC );
273	$sql = $row ? $row['sql'] . ';' : null;
274	break;
275	case 'mysql':
276	$result = $this->db->query( "SHOW CREATE TABLE {$this->current_table}" );
277	$row = $result->fetch( PDO::FETCH_ASSOC );
278	$sql = $row ? $row['Create Table'] : null;
279	break;
280	}
281
282	$this->current_entity = new ImportEntity( 'sql_query', $sql );
283	++$this->entities_read_so_far;
284	}
285
286	/**
287	* Initializes the list of tables to process by fetching all tables from the database
288	* and sorting them alphabetically.
289	*
290	* @since WP_VERSION
291	*/
292	private function initialize_tables_to_process() {
293	$this->tables_to_process = array();
294	$result = $this->db->query( 'SHOW TABLES' );
295	while ( $row = $result->fetch( PDO::FETCH_NUM ) ) { // phpcs:ignore Generic.CodeAnalysis.AssignmentInCondition.FoundInWhileCondition
296	$this->tables_to_process[] = $row[0];
297	}
298	sort( $this->tables_to_process );
299	}
300
301	public function get_reentrancy_cursor() {
302	return json_encode(
303	array(
304	'last_record_id' => $this->last_record_id,
305	'current_table' => $this->current_table,
306	'state' => $this->state,
307	)
308	);
309	}
310
311	/**
312	* Initializes the reader from a cursor.
313	*
314	* @param string $cursor The cursor to initialize from.
315	*
316	* @since WP_VERSION
317	*/
318	private function initialize_from_cursor( $cursor ) {
319	$cursor_data = json_decode( $cursor, true );
320	if ( $cursor_data ) {
321	$this->last_record_id = $cursor_data['last_record_id'] ?? null;
322	$this->current_table = $cursor_data['current_table'] ?? null;
323	$this->state = $cursor_data['state'] ?? self::STATE_INIT;
324	}
325	}
326	}
327