Maintaining persistence of a messaging system

摘要

Methods, systems, and apparatus, including computer programs for receiving, from a first client device, a request for messages of a first channel of a plurality of channels starting at a position in the first channel, wherein each channel comprises a respective ordered plurality of messages stored in one or more respective buffers according to the order, each buffer having a respective time-to-live; receiving, from one of the second client devices, a response message comprising one or more messages of the first channel that are at or after the position in the order; and sending the messages to the first client device.

主权项

1. A method comprising:
performing by one or more computers:
receiving, from a first client device, a request for messages of a first channel of a plurality of channels starting at a position in the first channel, wherein each channel comprises a respective ordered plurality of messages stored in one or more respective buffers according to the order, each buffer having a respective time-to-live;identifying a first message in the first channel corresponding to the position in the order, wherein the first message is stored in a buffer having a time-to-live that has expired;sending to one or more second client devices that subscribe to the first channel a request for messages beginning at the position in the order;receiving, from one of the second client devices, a response message comprising one or more messages of the first channel that are at or after the position in the order;retrieving messages for the first channel from one or more buffers of the first channel having time-to-lives that have not expired and according to the order;combining the retrieved messages and the messages from the response message according to the order; andsending the combined messages to the first client device.