rsocket-backpressure-example

An example of backpressure between an RSocket client and service.

In this example the count-client requests a stream of integers from the count-service and specifies that it can only handle 10 requests at a time.

Building the Example

Run the following command to build the example:

./gradlew clean build

Running the Example

Follow the steps below to run the example:

1. Run the following command to start the count-service:

    ./gradlew :count-service:run
   

   If the service has started successfully you will see the following in the terminal:

    > Task :count-service:run
    [main] INFO example.count.service.CountService - RSocket server started on port: 7000
   

2. In a new terminal, run the following command to start streaming integers with the count-client:

    ./gradlew :count-client:run
   

   If successful, you will see in the terminal that it processes 10,000 integers:

    [reactor-tcp-nio-1] INFO example.count.client.CountClient - Received: 9995
    [reactor-tcp-nio-1] INFO example.count.client.CountClient - Received: 9996
    [reactor-tcp-nio-1] INFO example.count.client.CountClient - Received: 9997
    [reactor-tcp-nio-1] INFO example.count.client.CountClient - Received: 9998
    [reactor-tcp-nio-1] INFO example.count.client.CountClient - Received: 9999
    [reactor-tcp-nio-1] INFO example.count.client.CountClient - Received: 10000
    [reactor-tcp-nio-1] INFO example.count.client.CountClient - Done
   

   In the count-service terminal, notice that it is receiving requests for 8 numbers at a time:

    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9984
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9985
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9986
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Received Request For: 8
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9987
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9988
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9989
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9990
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9991
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9992
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9993
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9994
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Received Request For: 8
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9995
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9996
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9997
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9998
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 9999
    [reactor-tcp-nio-2] INFO example.count.service.CountService - Sending: 10000
   

   The 8 items comes from the limitRate(10) on the client. The limitRate algorithm proactively fills the buffer when it is 75% exhausted. That is why you are seeing it request 8 instead of 10.

Bugs and Feedback

For bugs, questions, and discussions please use the Github Issues.

License

MIT License

Copyright (c) 2020 Greg Whitaker

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.