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 Copy linkLink copied to clipboard!
Create strong and weak counters with the Data Grid CLI.
Procedure
Run
create counter
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 Copy linkLink copied to clipboard!
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.