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DOCSP-42104 CSOT #136

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1 change: 1 addition & 0 deletions source/connect.txt
Original file line number Diff line number Diff line change
@@ -27,3 +27,4 @@ Connect to MongoDB
Choose a Connection Target </connect/connection-targets>
Connection Option </connect/connection-options>
Configure TLS </connect/tls>
Limit Server Execution Time </connect/csot>
241 changes: 241 additions & 0 deletions source/connect/csot.txt
Original file line number Diff line number Diff line change
@@ -0,0 +1,241 @@
.. _ruby-csot:

===========================
Limit Server Execution Time
===========================

.. contents:: On this page
:local:
:backlinks: none
:depth: 2
:class: singlecol

.. facet::
:name: genre
:values: reference

.. meta::
:keywords: error, blocking, thread, task, code example

Overview
--------

In this guide, you can learn how to use the ``timeout_ms`` option to set a
timeout for server operations.

When you use the {+driver-short+} to perform a server operation, you can
limit the duration allowed for the server to finish the operation. To do so,
specify a **client-side operation timeout (CSOT)**. The timeout applies to all
steps needed to complete the operation, including server selection, connection
checkout, and server-side execution. If the timeout expires before the operation
completes, the {+driver-short+} raises a timeout exception.

timeout_ms Option
-----------------

To specify a timeout when connecting to a MongoDB deployment, set the
``timeout_ms`` connection option to the timeout length in milliseconds. You can
specify a timeout value in the following ways:

- Pass the ``timeout_ms`` client option to the ``Mongo::Client`` constructor.
- Pass the ``timeoutMS`` connection string option as a parameter to your connection string.

Select from the following tabs to view examples for how to use the ``timeout_ms`` client
option or the ``timeoutMS`` connection string option to specify a timeout of 30 seconds:

.. tabs::

.. tab:: Mongo::Client
:tabid: mongoclient

.. code-block:: ruby
:emphasize-lines: 2

uri = "<connection string>"
options = { timeout_ms: 30000 }

client = Mongo::Client.new(uri, options)

.. tab:: Connection String
:tabid: connection-string

.. code-block:: ruby
:emphasize-lines: 1

uri = "mongodb://<hostname>:<port>?timeoutMS=30000"
client = Mongo::Client.new(uri)

If you specify the ``timeout_ms`` option, the driver automatically applies the
specified timeout for each server operation.

.. note::

The ``timeout_ms`` connection option unifies most timeout related options.
The following timeout options are deprecated:

- ``socket_timeout``
- ``wait_queue_timeout``
- ``wtimeout``
- ``max_time_ms``
- ``max_commit_time_ms``

The ``timeout_ms`` connection option takes precedence over these
deprecated timeout options.

Timeout Inheritance
~~~~~~~~~~~~~~~~~~~

When you specify a ``timeout_ms`` option, the driver applies the timeout
according to the same inheritance behaviors as the other {+driver-short+} options.
The following table describes how the timeout value is inherited at each level:

.. list-table::
:header-rows: 1
:widths: 30 70

* - Level
- Inheritance Description

* - Operation
- Takes the highest precedence and overrides ``timeout_ms``
options set at any other level.

* - Transaction
- Takes precedence over ``timeout_ms`` set at the session,
collection, database, or client level.

* - Session
- Applies to all transactions and operations within
that session, unless the option is overridden by options set at those levels.

* - Database
- Applies to all sessions and operations within that
database, unless the option is overridden by options set at those levels.

* - Collection
- Applies to all sessions and operations on that
collection, unless the option is overridden by options set at those levels.

* - Client
- Applies to all databases, collections, sessions, transactions, and
operations within that client that do not otherwise specify
``timeout_ms``.

To learn more about overriding the timeout option and setting other options, see the
following :ref:`ruby-csot-overrides` section.

.. _ruby-csot-overrides:

Overrides
---------

You can specify a ``timeout_ms`` option at the operation level to override the
client-level configuration for a specific operation. This allows you to
customize timeouts based on the needs of individual queries.

The following example demonstrates how an operation-level ``timeout_ms``
configuration can override a client-level ``timeout_ms`` configuration:

.. literalinclude:: /includes/connect/csot.rb
:language: ruby
:start-after: start-csot-overrides
:end-before: end-csot-overrides

Transactions
~~~~~~~~~~~~

You can set a timeout for transactions by using the ``default_timeout_ms`` client option.

When you create a new ``Mongo::Session`` instance to implement a transaction,
you can set the ``default_timeout_ms`` client option to specify the
``timeout_ms`` values for the following methods:

- `commit_transaction <{+api-root+}/Mongo/Session.html#commit_transaction-instance_method>`__
- `abort_transaction <{+api-root+}/Mongo/Session.html#abort_transaction-instance_method>`__
- `with_transaction <{+api-root+}/Mongo/Session.html#with_transaction-instance_method>`__
- `end_session <{+api-root+}/Mongo/Session.html#end_session-instance_method>`__

If you do not specify ``default_timeout_ms``, the driver uses the ``timeout_ms``
value set on the parent ``Mongo::Client``.

You cannot override the ``timeout_ms`` value of the ``Mongo::Client`` for a
call to ``start_session``.

You can only set a timeout value for the
`start_transaction <{+api-root+}/Mongo/Session.html#start_transaction-instance_method>`__
method by using the ``timeout_ms`` option.
Comment on lines +164 to +166
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For tech reviewer, can you confirm that this statement is true? Thank you!

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Are you asking to confirm that default_timeout_ms is not applied to start_transaction? If so, yes, that is true. Note that start_transaction doesn't actually perform any operations on the server, but only applies any options given to it, to subsequent transaction-related commands.


You cannot override ``default_timeout_ms`` by setting the ``timeout_ms`` option on an
operation in a transaction session provided by the ``with_transaction`` callback,
or the driver throws an error.

Client Encryption
~~~~~~~~~~~~~~~~~

When you use Client-Side Field Level Encryption (CSFLE), the driver uses the
``timeout_ms`` option to limit the time allowed for encryption and decryption
operations.

If you specify the ``timeout_ms`` option when you construct a
``ClientEncryption`` instance, it controls the lifetime of all operations
performed on that instance. If you do not provide ``timeout_ms``, the instance
inherits the ``timeout_ms`` setting from the ``Mongo::Client`` used in the
``ClientEncryption`` constructor.

If you set ``timeout_ms`` on both the client and directly in
``ClientEncryption``, the value provided to ``ClientEncryption`` takes
precedence.

Cursors
-------

Cursors offer configurable timeout settings when using the CSOT feature. You can
adjust cursor handling by configuring either the cursor lifetime or cursor
iteration mode if needed. To configure the mode, set the ``timeoutMode`` option
to ``cursorLifetime``, which is the default, or ``iteration``.

Cursor Lifetime Mode
~~~~~~~~~~~~~~~~~~~~

The cursor lifetime mode uses ``timeout_ms`` to limit the entire lifetime of a
cursor. In this mode, the initialization of the cursor and all subsequent calls
to the cursor methods must complete within the limit specified by the
``timeout_ms`` option. All documents must be returned within this limit.
Otherwise, the cursor's lifetime expires and a timeout error occurs.

When you close a cursor by calling the ``to_a`` or ``close`` method, the
timeout resets to ensure server-side resources are cleaned up.

The following example shows how to set the ``timeout_ms`` option to ensure that
the cursor is initialized and all documents are retrieved within 10 seconds:

.. code-block:: ruby

docs = collection.find({}, timeout_ms:10000).to_a

Cursor Iteration Mode
~~~~~~~~~~~~~~~~~~~~~

The cursor iteration mode uses the ``timeout_ms`` option to limit each call to
the ``try_next`` method. The timeout refreshes after each call completes.
This is the default mode for all tailable cursors,
such as the tailable cursors returned by the ``find`` method on capped
collections or change streams.

The following code example iterates over documents in a sample collection
by using an iterable cursor, and then fetches and logs the ``title`` information for
each movie document:

.. literalinclude:: /includes/connect/csot.rb
:language: ruby
:start-after: start-csot-iterable
:end-before: end-csot-iterable

API Documentation
-----------------

To learn more about using timeouts with the {+driver-short+}, see the following
API documentation:

- `Mongo::Client <{+api-root+}/Mongo/Client.html>`__
- `Mongo::Session <{+api-root+}/Mongo/Session.html>`__
28 changes: 28 additions & 0 deletions source/includes/connect/csot.rb
Original file line number Diff line number Diff line change
@@ -0,0 +1,28 @@
# start-csot-overrides
require 'mongo'

# Replace the placeholder with your connection string
uri = "<connection string>"

# Sets a client-level timeout configuration
options = { timeout_ms: 30000 }

Mongo::Client.new(uri, options) do |client|
db = client.use('test-db')
collection = db[:test-collection]

# Performs a query with an operation-level timeout configuration,
# overriding the client-level configuration
docs = collection.find({}, timeout_ms: 10000).to_a

docs.each { |doc| puts doc }
end
# end-csot-overrides

# start-csot-iterable
cursor = collection.find()

cursor.each do |movie|
puts movie['title']
end
# end-csot-iterable
9 changes: 9 additions & 0 deletions source/indexes/atlas-search-index.txt
Original file line number Diff line number Diff line change
@@ -119,3 +119,12 @@ Additional Information

To learn more about MongoDB Atlas Search, see the
:atlas:`Atlas Search </atlas-search/atlas-search-overview/>` documentation.

API Documentation
~~~~~~~~~~~~~~~~~

To learn more about any of the methods discussed in this guide, see the
following API documentation:

- `search_indexes <{+api-root+}/Mongo/Collection.html#search_indexes-instance_method>`__
- `SearchIndex <{+api-root+}/Mongo/SearchIndex/View.html>`__
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