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<?php
/*
* Copyright 2017 MongoDB, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
namespace MongoDB\Operation;
use MongoDB\ChangeStream;
use MongoDB\BSON\TimestampInterface;
use MongoDB\Driver\Command;
use MongoDB\Driver\Cursor;
use MongoDB\Driver\Manager;
use MongoDB\Driver\ReadConcern;
use MongoDB\Driver\ReadPreference;
use MongoDB\Driver\Server;
use MongoDB\Driver\Session;
use MongoDB\Driver\Exception\RuntimeException;
use MongoDB\Driver\Monitoring\CommandFailedEvent;
use MongoDB\Driver\Monitoring\CommandSubscriber;
use MongoDB\Driver\Monitoring\CommandStartedEvent;
use MongoDB\Driver\Monitoring\CommandSucceededEvent;
use MongoDB\Exception\InvalidArgumentException;
use MongoDB\Exception\UnexpectedValueException;
use MongoDB\Exception\UnsupportedException;
/**
* Operation for creating a change stream with the aggregate command.
*
* Note: the implementation of CommandSubscriber is an internal implementation
* detail and should not be considered part of the public API.
*
* @api
* @see \MongoDB\Collection::watch()
* @see https://docs.mongodb.com/manual/changeStreams/
*/
class Watch implements Executable, /* @internal */ CommandSubscriber
{
private static $wireVersionForOperationTime = 7;
const FULL_DOCUMENT_DEFAULT = 'default';
const FULL_DOCUMENT_UPDATE_LOOKUP = 'updateLookup';
private $aggregate;
private $aggregateOptions;
private $changeStreamOptions;
private $collectionName;
private $databaseName;
private $operationTime;
private $pipeline;
private $resumeCallable;
/**
* Constructs an aggregate command for creating a change stream.
*
* Supported options:
*
* * batchSize (integer): The number of documents to return per batch.
*
* * collation (document): Specifies a collation.
*
* * fullDocument (string): Determines whether the "fullDocument" field
* will be populated for update operations. By default, change streams
* only return the delta of fields during the update operation (via the
* "updateDescription" field). To additionally return the most current
* majority-committed version of the updated document, specify
* "updateLookup" for this option. Defaults to "default".
*
* Insert and replace operations always include the "fullDocument" field
* and delete operations omit the field as the document no longer exists.
*
* * maxAwaitTimeMS (integer): The maximum amount of time for the server to
* wait on new documents to satisfy a change stream query.
*
* * readConcern (MongoDB\Driver\ReadConcern): Read concern.
*
* * readPreference (MongoDB\Driver\ReadPreference): Read preference. This
* will be used to select a new server when resuming. Defaults to a
* "primary" read preference.
*
* * resumeAfter (document): Specifies the logical starting point for the
* new change stream.
*
* Using this option in conjunction with "startAtOperationTime" will
* result in a server error. The options are mutually exclusive.
*
* * session (MongoDB\Driver\Session): Client session.
*
* Sessions are not supported for server versions < 3.6.
*
* * startAtOperationTime (MongoDB\BSON\TimestampInterface): If specified,
* the change stream will only provide changes that occurred at or after
* the specified timestamp. Any command run against the server will
* return an operation time that can be used here. Alternatively, an
* operation time may be obtained from MongoDB\Driver\Server::getInfo().
*
* Using this option in conjunction with "resumeAfter" will result in a
* server error. The options are mutually exclusive.
*
* This option is not supported for server versions < 4.0.
*
* * typeMap (array): Type map for BSON deserialization. This will be
* applied to the returned Cursor (it is not sent to the server).
*
* Note: A database-level change stream may be created by specifying null
* for the collection name. A cluster-level change stream may be created by
* specifying null for both the database and collection name.
*
* @param Manager $manager Manager instance from the driver
* @param string|null $databaseName Database name
* @param string|null $collectionName Collection name
* @param array $pipeline List of pipeline operations
* @param array $options Command options
* @throws InvalidArgumentException for parameter/option parsing errors
*/
public function __construct(Manager $manager, $databaseName, $collectionName, array $pipeline, array $options = [])
{
if (isset($collectionName) && ! isset($databaseName)) {
throw new InvalidArgumentException('$collectionName should also be null if $databaseName is null');
}
$options += [
'fullDocument' => self::FULL_DOCUMENT_DEFAULT,
'readPreference' => new ReadPreference(ReadPreference::RP_PRIMARY),
];
if (isset($options['fullDocument']) && ! is_string($options['fullDocument'])) {
throw InvalidArgumentException::invalidType('"fullDocument" option', $options['fullDocument'], 'string');
}
if (isset($options['resumeAfter']) && ! is_array($options['resumeAfter']) && ! is_object($options['resumeAfter'])) {
throw InvalidArgumentException::invalidType('"resumeAfter" option', $options['resumeAfter'], 'array or object');
}
if (isset($options['startAtOperationTime']) && ! $options['startAtOperationTime'] instanceof TimestampInterface) {
throw InvalidArgumentException::invalidType('"startAtOperationTime" option', $options['startAtOperationTime'], TimestampInterface::class);
}
/* In the absence of an explicit session, create one to ensure that the
* initial aggregation and any resume attempts can use the same session
* ("implicit from the user's perspective" per PHPLIB-342). Since this
* is filling in for an implicit session, we default "causalConsistency"
* to false. */
if ( ! isset($options['session'])) {
try {
$options['session'] = $manager->startSession(['causalConsistency' => false]);
} catch (RuntimeException $e) {
/* We can ignore the exception, as libmongoc likely cannot
* create its own session and there is no risk of a mismatch. */
}
}
$this->aggregateOptions = array_intersect_key($options, ['batchSize' => 1, 'collation' => 1, 'maxAwaitTimeMS' => 1, 'readConcern' => 1, 'readPreference' => 1, 'session' => 1, 'typeMap' => 1]);
$this->changeStreamOptions = array_intersect_key($options, ['fullDocument' => 1, 'resumeAfter' => 1, 'startAtOperationTime' => 1]);
// Null database name implies a cluster-wide change stream
if ($databaseName === null) {
$databaseName = 'admin';
$this->changeStreamOptions['allChangesForCluster'] = true;
}
$this->databaseName = (string) $databaseName;
$this->collectionName = isset($collectionName) ? (string) $collectionName : null;
$this->pipeline = $pipeline;
$this->aggregate = $this->createAggregate();
$this->resumeCallable = $this->createResumeCallable($manager);
}
/** @internal */
final public function commandFailed(CommandFailedEvent $event)
{
}
/** @internal */
final public function commandStarted(CommandStartedEvent $event)
{
}
/** @internal */
final public function commandSucceeded(CommandSucceededEvent $event)
{
if ($event->getCommandName() !== 'aggregate') {
return;
}
$reply = $event->getReply();
if (isset($reply->operationTime) && $reply->operationTime instanceof TimestampInterface) {
$this->operationTime = $reply->operationTime;
}
}
/**
* Execute the operation.
*
* @see Executable::execute()
* @param Server $server
* @return ChangeStream
* @throws UnsupportedException if collation or read concern is used and unsupported
* @throws RuntimeException for other driver errors (e.g. connection errors)
*/
public function execute(Server $server)
{
return new ChangeStream($this->executeAggregate($server), $this->resumeCallable);
}
/**
* Create the aggregate command for creating a change stream.
*
* This method is also used to recreate the aggregate command when resuming.
*
* @return Aggregate
*/
private function createAggregate()
{
$pipeline = $this->pipeline;
array_unshift($pipeline, ['$changeStream' => (object) $this->changeStreamOptions]);
return new Aggregate($this->databaseName, $this->collectionName, $pipeline, $this->aggregateOptions);
}
private function createResumeCallable(Manager $manager)
{
return function($resumeToken = null) use ($manager) {
/* If a resume token was provided, update the "resumeAfter" option
* and ensure that "startAtOperationTime" is no longer set. */
if ($resumeToken !== null) {
$this->changeStreamOptions['resumeAfter'] = $resumeToken;
unset($this->changeStreamOptions['startAtOperationTime']);
}
/* If we captured an operation time from the first aggregate command
* and there is no "resumeAfter" option, set "startAtOperationTime"
* so that we can resume from the original aggregate's time. */
if ($this->operationTime !== null && ! isset($this->changeStreamOptions['resumeAfter'])) {
$this->changeStreamOptions['startAtOperationTime'] = $this->operationTime;
}
$this->aggregate = $this->createAggregate();
/* Select a new server using the read preference, execute this
* operation on it, and return the new ChangeStream. */
$server = $manager->selectServer($this->aggregateOptions['readPreference']);
return $this->execute($server);
};
}
/**
* Execute the aggregate command and optionally capture its operation time.
*
* @param Server $server
* @return Cursor
*/
private function executeAggregate(Server $server)
{
/* If we've already captured an operation time or the server does not
* support returning an operation time (e.g. MongoDB 3.6), execute the
* aggregation directly and return its cursor. */
if ($this->operationTime !== null || ! \MongoDB\server_supports_feature($server, self::$wireVersionForOperationTime)) {
return $this->aggregate->execute($server);
}
/* Otherwise, execute the aggregation using command monitoring so that
* we can capture its operation time with commandSucceeded(). */
\MongoDB\Driver\Monitoring\addSubscriber($this);
try {
return $this->aggregate->execute($server);
} finally {
\MongoDB\Driver\Monitoring\removeSubscriber($this);
}
}
}