Chapter 5. Working with Counters
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 Create a CLI connection to Data Grid. Run the create counter command with the appropriate arguments. Create my-weak-counter . Create my-strong-counter . List available counters. Verify counter configurations. Describe my-weak-counter . { "weak-counter":{ "initial-value":5, "storage":"PERSISTENT", "concurrency-level":1 } } Describe 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 Select a counter. List the current count. Increment the counter value by 2 . Decrement the counter value by -4 . Note Strong counters return values after the operation is applied. Use --quiet=true to hide the return value. For example, add --delta=3 --quiet=true . Weak counters return empty responses.
create counter --concurrency-level=1 --initial-value=5 --storage=PERSISTENT --type=weak my-weak-counter create counter --initial-value=3 --storage=PERSISTENT --type=strong my-strong-counter ls counters describe counters/my-weak-counter { "weak-counter":{ "initial-value":5, "storage":"PERSISTENT", "concurrency-level":1 } } describe counters/my-strong-counter { "strong-counter":{ "initial-value":3, "storage":"PERSISTENT", "upper-bound":5 } } counter my-weak-counter [//containers/default/counters/my-weak-counter]> ls 5 [//containers/default/counters/my-weak-counter]> add --delta=2 [//containers/default/counters/my-weak-counter]> add --delta=-4