Chapter 5. Working with Counters


Counters provide atomic increment and decrement operations that record the count of objects.

Prerequisites

  • Start the Data Grid CLI.
  • Connect to a running Data Grid cluster.

5.1. Creating Counters

Create strong and weak counters with the Data Grid CLI.

Procedure

  1. Create a CLI connection to Data Grid.
  2. Run the create counter command with the appropriate arguments.

    1. Create my-weak-counter.

      [//containers/default]> create counter --concurrency-level=1 --initial-value=5 --storage=PERSISTENT --type=weak my-weak-counter
    2. Create my-strong-counter.

      [//containers/default]> create counter --initial-value=3 --storage=PERSISTENT --type=strong my-strong-counter
  3. List available counters.

    [//containers/default]> ls counters
    my-strong-counter
    my-weak-counter
  4. Verify counter configurations.

    1. Describe my-weak-counter.

      [//containers/default]> describe counters/my-weak-counter
      
      {
          "weak-counter":{
              "initial-value":5,
              "storage":"PERSISTENT",
              "concurrency-level":1
          }
      }
    2. Describe my-strong-counter.

      [//containers/default]> describe counters/my-strong-counter
      
      {
          "strong-counter":{
              "initial-value":3,
              "storage":"PERSISTENT",
              "upper-bound":5
          }
      }

5.2. Adding Deltas to Counters

Increment or decrement counters with arbitrary values.

Procedure

  1. Select a counter.

    [//containers/default]> counter my-weak-counter
  2. List the current count.

    [//containers/default/counters/my-weak-counter]> ls
    5
  3. Increment the counter value by 2.

    [//containers/default/counters/my-weak-counter]> add --delta=2
  4. Decrement the counter value by -4.

    [//containers/default/counters/my-weak-counter]> add --delta=-4
Note

Strong counters return values after the operation is applied. Use --quiet=true to hide the return value.

For example, my-strong-counter]> add --delta=3 --quiet=true.

Weak counters return empty responses.

Red Hat logoGithubRedditYoutubeTwitter

Learn

Try, buy, & sell

Communities

About Red Hat Documentation

We help Red Hat users innovate and achieve their goals with our products and services with content they can trust.

Making open source more inclusive

Red Hat is committed to replacing problematic language in our code, documentation, and web properties. For more details, see the Red Hat Blog.

About Red Hat

We deliver hardened solutions that make it easier for enterprises to work across platforms and environments, from the core datacenter to the network edge.

© 2024 Red Hat, Inc.