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 countercommand with the appropriate arguments.- Create - my-weak-counter.- [//containers/default]> create counter --concurrency-level=1 --initial-value=5 --storage=PERSISTENT --type=weak my-weak-counter - [//containers/default]> create counter --concurrency-level=1 --initial-value=5 --storage=PERSISTENT --type=weak my-weak-counter- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Create - my-strong-counter.- [//containers/default]> create counter --initial-value=3 --storage=PERSISTENT --type=strong my-strong-counter - [//containers/default]> create counter --initial-value=3 --storage=PERSISTENT --type=strong my-strong-counter- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
 
- List available counters. - [//containers/default]> ls counters my-strong-counter my-weak-counter - [//containers/default]> ls counters my-strong-counter my-weak-counter- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Verify counter configurations. - Describe - my-weak-counter.- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Describe - my-strong-counter.- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
 
5.2. Adding Deltas to Counters
Increment or decrement counters with arbitrary values.
Procedure
- Select a counter. - [//containers/default]> counter my-weak-counter - [//containers/default]> counter my-weak-counter- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- List the current count. - [//containers/default/counters/my-weak-counter]> ls 5 - [//containers/default/counters/my-weak-counter]> ls 5- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Increment the counter value by - 2.- [//containers/default/counters/my-weak-counter]> add --delta=2 - [//containers/default/counters/my-weak-counter]> add --delta=2- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Decrement the counter value by - -4.- [//containers/default/counters/my-weak-counter]> add --delta=-4 - [//containers/default/counters/my-weak-counter]> add --delta=-4- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
					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.