Issues/224 atomic counter attribute #3809

irina-herciu · 2025-05-13T07:43:31Z

Introduce support for the [DynamoDBAtomicCounter] attribute in the DynamoDB Object Persistence Model for the AWS SDK for .NET. This feature brings parity with the Java SDK V2, which supports atomic counters via @DynamoDbAtomicCounter.

java DynamoDbAtomicCounter
Using atomic counters

Description

New attribute: DynamoDBAtomicCounterAttribute, to mark numeric properties for auto-increment behavior
Updates to DynamoDBContext and internal mapping to detect and apply counter increment behavior during save item operation

class Session {
    [DynamoDBHashKey]
    public string Id { get; set; }

    [DynamoDBAtomicCounter]
    public int RetryCount { get; set; }

    // This field starts from 100 and increments by 5 on each save
    [DynamoDBAtomicCounter(delta:5, startValue:100)] 
    public long Views { get; set; }
}

On context.SaveAsync(session), it will automatically be incremented in DynamoDB using the appropriate SET operation.

Motivation and Context

Testing

Integration test added
Unit test to be added for internal methods

Screenshots (if appropriate)

Types of changes

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to change)

Checklist

My code follows the code style of this project
My change requires a change to the documentation
I have updated the documentation accordingly
I have read the README document
I have added tests to cover my changes
All new and existing tests passed

License

I confirm that this pull request can be released under the Apache 2 license

add new atribute and update internal config

normj · 2025-05-20T01:22:50Z

sdk/src/Services/DynamoDBv2/Custom/DataModel/ContextInternal.cs

+            foreach (var propertyStorage in counterPropertyStorages)
+            {
+                Primitive counter;
+                string versionAttributeName = propertyStorage.AttributeName;


Shouldn't this be called counterAttributeName?

normj · 2025-05-20T01:29:52Z

sdk/src/Services/DynamoDBv2/Custom/DataModel/ContextInternal.cs

+                string startValueName = $":{propertyStorage.AttributeName}Start";
+                string deltaValueName = $":{propertyStorage.AttributeName}Delta";
+                string counterAttributeName = Common.GetAttributeReference(propertyStorage.AttributeName);
+                asserts += $"{counterAttributeName} = " +


Curious how this compares to Java V2. But if I set the StartValue to 3 and Delta to 5 when I save my first version of the object I get 8. I would expect 3 after the first save and 8 with the second save. If this is consistent with Java we need to make sure the docs on the StartValue and Delta are clear this is how it works.

first save will be 3 as the value in ExpressionAttributeValues is CounterStartValue-CounterDelta so that the increment can be done correctly. This is the same behavior as in Java V2.

Okay, can you add a comment by the propertyStorage.CounterStartValue - propertyStorage.CounterDelta; line that the propertyStorage.CounterDelta is being subtracted from the initial value to compensate it being added back to the starting value via the delta? Since I missed that detail reviewing the code others in the future will likely miss that as well.

sdk/src/Services/DynamoDBv2/Custom/DataModel/ContextInternal.cs

normj · 2025-05-21T00:13:07Z

sdk/src/Services/DynamoDBv2/Custom/DataModel/Context.cs

-                await table.UpdateHelperAsync(storage.Document, table.MakeKey(storage.Document), null, cancellationToken).ConfigureAwait(false);
+                updateDocument = await table.UpdateHelperAsync(storage.Document, table.MakeKey(storage.Document), new UpdateItemOperationConfig
+                {
+                    ReturnValues = ReturnValues.AllNewAttributes


To avoid change in behavior should we set AllNewAttributes only if there is a counter condition expression?

normj · 2025-05-21T00:13:32Z

sdk/src/Services/DynamoDBv2/Custom/DataModel/Context.cs

                var updateItemOperationConfig = new UpdateItemOperationConfig
                {
-                    Expected = expectedDocument,
-                    ReturnValues = ReturnValues.None,
+                    ReturnValues = ReturnValues.AllNewAttributes,


To avoid change in behavior should we set AllNewAttributes only if there is a counter condition expression?

AllNewAttributes is conditional now

normj · 2025-05-21T00:17:05Z

sdk/src/Services/DynamoDBv2/Custom/DataModel/ContextInternal.cs

+                string startValueName = $":{propertyStorage.AttributeName}Start";
+                string deltaValueName = $":{propertyStorage.AttributeName}Delta";
+                string counterAttributeName = Common.GetAttributeReference(propertyStorage.AttributeName);
+                asserts += $"{counterAttributeName} = " +


Okay, can you add a comment by the propertyStorage.CounterStartValue - propertyStorage.CounterDelta; line that the propertyStorage.CounterDelta is being subtracted from the initial value to compensate it being added back to the starting value via the delta? Since I missed that detail reviewing the code others in the future will likely miss that as well.

normj · 2025-05-21T00:22:22Z

sdk/test/Services/DynamoDBv2/IntegrationTests/DataModelTests.cs

+        /// <returns></returns>
+        [TestMethod]
+        [TestCategory("DynamoDBv2")]
+        public async Task TestContext_AtomicCounterAnnotation()


Can you add a check for updating the counter value when the current read value is behind the current value in the table and confirm after the save the POCO has latest value.

integration test was updated

normj · 2025-05-21T22:19:07Z

Sent the PR through the internal build system.

normj · 2025-05-22T22:51:05Z

I'm getting the following DDB integ test failure. Can you take a look?


[xUnit.net 00:00:06.34]     Amazon.DNXCore.IntegrationTests.DynamoDB.DynamoDBTests.TestContext [FAIL]
--
3720 | Failed Amazon.DNXCore.IntegrationTests.DynamoDB.DynamoDBTests.TestContext [3 s]
3721 | Error Message:
3722 | System.ArgumentNullException : Value cannot be null. (Parameter 'target')
3723 | Stack Trace:
3724 | at Amazon.Util.CircularReferenceTracking.Track(Object target) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Core\Amazon.Util\ReferenceTracking.cs:line 104
3725 | at Amazon.DynamoDBv2.DataModel.DynamoDBFlatConfig.OperationState.Track(Object target) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Services\DynamoDBv2\Custom\DataModel\Configs.cs:line 621
3726 | at Amazon.DynamoDBv2.DataModel.DynamoDBContext.PopulateInstance(ItemStorage storage, Object instance, DynamoDBFlatConfig flatConfig, StorageConfig storageConfig) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Services\DynamoDBv2\Custom\DataModel\ContextInternal.cs:line 443
3727 | at Amazon.DynamoDBv2.DataModel.DynamoDBContext.SaveHelperAsync(Type valueType, Object value, DynamoDBFlatConfig flatConfig, CancellationToken cancellationToken) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Services\DynamoDBv2\Custom\DataModel\Context.cs:line 467
3728 | at Amazon.DynamoDBv2.DataModel.DynamoDBContext.SaveHelperAsync[T](T value, DynamoDBFlatConfig flatConfig, CancellationToken cancellationToken) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Services\DynamoDBv2\Custom\DataModel\Context.cs:line 417
3729 | at Amazon.DynamoDBv2.DataModel.DynamoDBContext.SaveAsync[T](T value, CancellationToken cancellationToken) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Services\DynamoDBv2\Custom\DataModel\_async\Context.Async.cs:line 40
3730 | at Amazon.DNXCore.IntegrationTests.DynamoDB.DynamoDBTests.TestHashObjects() in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\test\NetStandard\IntegrationTests\IntegrationTests\DynamoDB\DataModelTests.cs:line 508
3731 | at Amazon.DNXCore.IntegrationTests.DynamoDB.DynamoDBTests.TestHashObjects() in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\test\NetStandard\IntegrationTests\IntegrationTests\DynamoDB\DataModelTests.cs:line 524
3732 | at Amazon.DNXCore.IntegrationTests.DynamoDB.DynamoDBTests.TestContext() in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\test\NetStandard\IntegrationTests\IntegrationTests\DynamoDB\DataModelTests.cs:line 42
3733 | --- End of stack trace from previous location ---
3734 | Results File: C:\codebuild\tmp\output\src3842137447\src/aws-sdk-net/sdk\test\NetStandard\IntegrationTests\bin\Release\net8.0/TestResults\ContainerAdministrator_6997AF1862EC_2025-05-21_17_10_42.trx
3735 |  
3736 | Failed!  - Failed:     1, Passed:     0, Skipped:     0, Total:     1, Duration: < 1 ms - IntegrationTests.dll (net8.0

irina-herciu · 2025-05-23T06:41:17Z

I'm getting the following DDB integ test failure. Can you take a look?


[xUnit.net 00:00:06.34]     Amazon.DNXCore.IntegrationTests.DynamoDB.DynamoDBTests.TestContext [FAIL]
--
3720 | Failed Amazon.DNXCore.IntegrationTests.DynamoDB.DynamoDBTests.TestContext [3 s]
3721 | Error Message:
3722 | System.ArgumentNullException : Value cannot be null. (Parameter 'target')
3723 | Stack Trace:
3724 | at Amazon.Util.CircularReferenceTracking.Track(Object target) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Core\Amazon.Util\ReferenceTracking.cs:line 104
3725 | at Amazon.DynamoDBv2.DataModel.DynamoDBFlatConfig.OperationState.Track(Object target) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Services\DynamoDBv2\Custom\DataModel\Configs.cs:line 621
3726 | at Amazon.DynamoDBv2.DataModel.DynamoDBContext.PopulateInstance(ItemStorage storage, Object instance, DynamoDBFlatConfig flatConfig, StorageConfig storageConfig) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Services\DynamoDBv2\Custom\DataModel\ContextInternal.cs:line 443
3727 | at Amazon.DynamoDBv2.DataModel.DynamoDBContext.SaveHelperAsync(Type valueType, Object value, DynamoDBFlatConfig flatConfig, CancellationToken cancellationToken) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Services\DynamoDBv2\Custom\DataModel\Context.cs:line 467
3728 | at Amazon.DynamoDBv2.DataModel.DynamoDBContext.SaveHelperAsync[T](T value, DynamoDBFlatConfig flatConfig, CancellationToken cancellationToken) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Services\DynamoDBv2\Custom\DataModel\Context.cs:line 417
3729 | at Amazon.DynamoDBv2.DataModel.DynamoDBContext.SaveAsync[T](T value, CancellationToken cancellationToken) in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\src\Services\DynamoDBv2\Custom\DataModel\_async\Context.Async.cs:line 40
3730 | at Amazon.DNXCore.IntegrationTests.DynamoDB.DynamoDBTests.TestHashObjects() in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\test\NetStandard\IntegrationTests\IntegrationTests\DynamoDB\DataModelTests.cs:line 508
3731 | at Amazon.DNXCore.IntegrationTests.DynamoDB.DynamoDBTests.TestHashObjects() in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\test\NetStandard\IntegrationTests\IntegrationTests\DynamoDB\DataModelTests.cs:line 524
3732 | at Amazon.DNXCore.IntegrationTests.DynamoDB.DynamoDBTests.TestContext() in C:\codebuild\tmp\output\src2690751361\src\aws-sdk-net\sdk\test\NetStandard\IntegrationTests\IntegrationTests\DynamoDB\DataModelTests.cs:line 42
3733 | --- End of stack trace from previous location ---
3734 | Results File: C:\codebuild\tmp\output\src3842137447\src/aws-sdk-net/sdk\test\NetStandard\IntegrationTests\bin\Release\net8.0/TestResults\ContainerAdministrator_6997AF1862EC_2025-05-21_17_10_42.trx
3735 |  
3736 | Failed!  - Failed:     1, Passed:     0, Skipped:     0, Total:     1, Duration: < 1 ms - IntegrationTests.dll (net8.0

fixed the failing test, can you please retrigger the internal build?

irina-herciu added 9 commits May 6, 2025 17:25

add new atribute and update internal config

6ab2dec

wip

a765788

wip

3a8374f

add new atribute and update internal config

16cbd53

add new atribute and update internal config

refactoring

575466c

merge

c40bf07

refactoring

820c5c0

unit tests and refactoring

42750b4

refactoring

97ee267

peterrsongg requested review from normj and GarrettBeatty May 14, 2025 17:32

normj reviewed May 20, 2025

View reviewed changes

map in memory value from DB

097589a

normj requested changes May 21, 2025

View reviewed changes

integrarion tests and pr feedback

ff5772c

fix async save issue

3f858d2

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Issues/224 atomic counter attribute #3809

Issues/224 atomic counter attribute #3809

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irina-herciu commented May 13, 2025

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normj commented May 21, 2025

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irina-herciu commented May 23, 2025

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Issues/224 atomic counter attribute #3809

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Issues/224 atomic counter attribute #3809

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irina-herciu commented May 13, 2025

Description

Motivation and Context

Testing

Screenshots (if appropriate)

Types of changes

Checklist

License

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normj commented May 21, 2025

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