feat: make transaction retry configurable

[olavloite]

[Do not merge, just a prototype]

[gemini-code-assist]

Summary of Changes

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This pull request enhances the Google Cloud Spanner client library by making transaction retry mechanisms configurable. It refactors the core retry logic into a dedicated, instance-based helper and integrates new options into SpannerOptions, providing greater control over how aborted transactions are handled and retried. This change aims to improve flexibility for developers managing transaction resilience.

Highlights

• Configurable Transaction Retries: Introduced the ability to configure retry settings for aborted transactions, allowing users to customize retry behavior through SpannerOptions.
• Refactored Retry Logic: The static SpannerRetryHelper class was renamed to TransactionRetryHelper and refactored into an instance-based class, enabling it to hold specific RetrySettings.
• Default Retry Settings: Defined DEFAULT_TRANSACTION_RETRY_SETTINGS in SpannerOptions, which links to the rollbackSettings of SpannerStubSettings and sets a 24-hour total timeout with no maximum attempts for transaction retries.
• Integration with Spanner Components: Updated SessionImpl and TransactionRunnerImpl to utilize the new instance-based TransactionRetryHelper obtained from SpannerImpl.

Changelog

• google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionImpl.java
  • Updated the writeAtLeastOnceWithOptions method to use the new instance-based TransactionRetryHelper from the spanner object instead of the static SpannerRetryHelper.
• google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
  • Added a new private field transactionRetryHelper of type TransactionRetryHelper.
  • Initialized transactionRetryHelper in the constructor using SpannerOptions.getDefaultTransactionRetrySettings().
  • Added a public getter method getTransactionRetryHelper() to expose the new helper instance.
• google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java
  • Added imports for com.google.cloud.spanner.v1.stub.SpannerStub and com.google.spanner.v1.RollbackRequest.
  • Defined a new public static final RetrySettings DEFAULT_TRANSACTION_RETRY_SETTINGS for transaction retries, configured with a 24-hour total timeout and no max attempts, referencing SpannerStubSettings.rollbackSettings().
  • Added a private final field defaultTransactionRetrySettings to the SpannerOptions class.
  • Updated the SpannerOptions constructor to initialize defaultTransactionRetrySettings from the builder.
  • Modified the Builder class to include defaultTransactionRetrySettings, defaulting to TransactionRetryHelper.DEFAULT_TRANSACTION_RETRY_SETTINGS.
  • Updated the Builder copy constructor to include defaultTransactionRetrySettings.
  • Added a public setter method setDefaultTransactionRetrySettings(RetrySettings retrySettings) to the Builder class.
  • Added a public getter method getDefaultTransactionRetrySettings() to the SpannerOptions class.
• google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerRetryHelper.java
  • Renamed the file from SpannerRetryHelper.java to TransactionRetryHelper.java.
  • Renamed the class from SpannerRetryHelper to TransactionRetryHelper.
  • Refactored the class from a static utility class to an instance-based class, requiring RetrySettings in its constructor.
  • Removed the static txRetrySettings field and its associated Javadoc.
  • Updated all runTxWithRetriesOnAborted methods to be instance methods and use the retrySettings field.
• google-cloud-spanner/src/main/java/com/google/cloud/spanner/TransactionRunnerImpl.java
  • Updated the runInternal method to use the new instance-based TransactionRetryHelper from session.getSpanner().
• google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerRetryHelperTest.java
  • Renamed the file from SpannerRetryHelperTest.java to TransactionRetryHelperTest.java.
  • Renamed the test class from SpannerRetryHelperTest to TransactionRetryHelperTest.
  • Instantiated TransactionRetryHelper as a field retryHelper using SpannerOptions.DEFAULT_TRANSACTION_RETRY_SETTINGS.
  • Updated all test methods to call retryHelper.runTxWithRetriesOnAborted instead of the static SpannerRetryHelper methods.

Activity

• The pull request is marked as a prototype and not intended for immediate merge, indicating it's an early draft or proof-of-concept.

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[gemini-code-assist]

Code Review

This pull request introduces configurability for transaction retry settings by refactoring the retry logic from a static helper class (SpannerRetryHelper) into a new TransactionRetryHelper instance that is configured via SpannerOptions. This is a good improvement for flexibility. The changes are mostly correct, but I found one compilation error that needs to be fixed.

[gemini-code-assist]

This line will cause a compilation error. The static field DEFAULT_TRANSACTION_RETRY_SETTINGS was moved from SpannerRetryHelper (now TransactionRetryHelper) to SpannerOptions. You should reference it directly from SpannerOptions.

Suggested change

	private RetrySettings defaultTransactionRetrySettings =
	private RetrySettings defaultTransactionRetrySettings = DEFAULT_TRANSACTION_RETRY_SETTINGS;