Development: Fix hazelcast issue on server shutdown

[BBesrour]

Checklist

General

• This is a small issue that I tested locally and was confirmed by another developer on a test server.
• Language: I followed the guidelines for inclusive, diversity-sensitive, and appreciative language.
• I chose a title conforming to the naming conventions for pull requests.

Server

• Important: I implemented the changes with a very good performance and prevented too many (unnecessary) and too complex database calls.
• I strictly followed the principle of data economy for all database calls.
• I strictly followed the server coding and design guidelines.
• I added multiple integration tests (Spring) related to the features (with a high test coverage).
• I added pre-authorization annotations according to the guidelines and checked the course groups for all new REST Calls (security).
• I documented the Java code using JavaDoc style.

Motivation and Context

This PR fixes an issue that happens at server shutdown

Oct 24 09:34:35 artemis-production-node1.artemis.in.tum.de java[607710]: com.hazelcast.core.HazelcastInstanceNotActiveException: Hazelcast instance is not active!
...
Oct 24 09:34:35 artemis-production-node1.artemis.in.tum.de java[607710]:         at de.tum.cit.aet.artemis.core.service.feature.FeatureToggleService.enabledFeatures(FeatureToggleService.java:112)

Steps for Testing

Prerequisites:

• 1 Instructor

1. Navigate through artemis and make sure no error occurs (visiting a course and submitting should be enough)

Testserver States

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Review Progress

Performance Review

• I (as a reviewer) confirm that the client changes (in particular related to REST calls and UI responsiveness) are implemented with a very good performance even for very large courses with more than 2000 students.
• I (as a reviewer) confirm that the server changes (in particular related to database calls) are implemented with a very good performance even for very large courses with more than 2000 students.

Code Review

• Code Review 1
• Code Review 2

Manual Tests

• Test 1
• Test 2

Performance Tests

• Test 1
• Test 2

Test Coverage

Screenshots

Summary by CodeRabbit

• New Features

  • Enhanced error handling and control flow for feature toggles.
  • Introduced a safer method for accessing feature states.

• Improvements

  • Updated initialization to occur after application readiness.
  • Added lifecycle checks for feature status methods to ensure operations are performed only when the system is active.

• Bug Fixes

  • Improved logging and error handling for inactive Hazelcast instances.

[coderabbitai]

Walkthrough

The FeatureToggleService class has been modified to improve error handling and control flow concerning the lifecycle of the Hazelcast instance. Key changes include the introduction of a new method getFeatures() for safer access to the features map, updates to the init() method to use @EventListener, and revisions to several methods to ensure operations are only performed when the Hazelcast instance is active. These modifications aim to reduce exceptions related to the instance's state.

Changes

File

Change Summary

src/main/java/de/tum/cit/aet/artemis/core/service/feature/FeatureToggleService.java

- Added method private Optional<Map<Feature, Boolean>> getFeatures(). - Updated method signature of updateFeatureToggles(final Map<Feature, Boolean> features) to updateFeatureToggles(final Map<Feature, Boolean> updatedFeatures). - Modified init() to use @EventListener(ApplicationReadyEvent.class). - Updated enableFeature(), disableFeature(), updateFeatureToggles(), sendUpdate(), isFeatureEnabled(), enabledFeatures(), and disabledFeatures() to incorporate lifecycle checks for the Hazelcast instance.

Possibly related PRs

• Development: Improve boundary cases with Hazelcast #9387: This PR modifies the lifecycle management of services related to Hazelcast, similar to the changes in the FeatureToggleService that also enhance error handling and lifecycle checks for the Hazelcast instance.
• Development: Set unique hazelcast instance name for each abstract server test setup to reduce flakiness #9416: This PR addresses the configuration of Hazelcast instances in test setups, which relates to ensuring that the Hazelcast instance is correctly managed and isolated, similar to the lifecycle management improvements in the main PR.

Suggested labels

tests, bugfix

Suggested reviewers

• krusche
• ole-ve
• dfuchss

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[coderabbitai]

Actionable comments posted: 2

🧹 Outside diff range and nitpick comments (1)

src/main/java/de/tum/cit/aet/artemis/core/service/feature/FeatureToggleService.java (1)

19-19: Ensure consistent and appropriate logging levels for Hazelcast inactivity.

Currently, the code logs an error message when the Hazelcast instance is inactive in several methods. If Hazelcast being inactive can occur during normal shutdown or expected scenarios, consider logging at a WARN level instead of ERROR to reflect the severity appropriately.

Apply this diff to adjust the logging level:

-    log.error("Failed to get features in FeatureToggleService as Hazelcast instance is not active any more.");
+    log.warn("Hazelcast instance is inactive; cannot retrieve features.");

Repeat for other similar log statements.

Also applies to: 51-53, 122-123, 140-141, 157-158, 174-175

📜 Review details

Configuration used: .coderabbit.yaml
Review profile: CHILL

📥 Commits

Files that changed from the base of the PR and between 6e1c562 and 95645e3.

📒 Files selected for processing (1)

• src/main/java/de/tum/cit/aet/artemis/core/service/feature/FeatureToggleService.java (7 hunks)

🧰 Additional context used

📓 Path-based instructions (1)

src/main/java/de/tum/cit/aet/artemis/core/service/feature/FeatureToggleService.java (1)

Pattern src/main/java/**/*.java: naming:CamelCase; principles:{single_responsibility,small_methods,no_duplication}; db:{perf_queries,datetime_not_timestamp}; rest:{stateless,singleton,delegate_logic,http_only,minimal_dtos}; dtos:{java_records,no_entities,min_data,single_resp}; di:constructor_injection; kiss:simple_code; file_handling:os_indep_paths; practices:{least_access,avoid_transactions,code_reuse,static_member_ref,prefer_primitives}; sql:{param_annotation,uppercase,avoid_subqueries};java:avoid_star_imports

🔇 Additional comments (3)

src/main/java/de/tum/cit/aet/artemis/core/service/feature/FeatureToggleService.java (3)

60-60: Verify the use of @EventListener(ApplicationReadyEvent.class) for the init() method.

Changing the initialization from @PostConstruct to @EventListener(ApplicationReadyEvent.class) alters when the features map is initialized. Ensure that all dependencies on the features map are unaffected by this change and that no feature checks occur before the application is fully ready.

---

151-159: ⚠️ Potential issue

Assess the handling of empty results in enabledFeatures() method when Hazelcast is inactive.

Returning an empty list when the Hazelcast instance is inactive might lead callers to believe that no features are enabled, potentially causing unintended behavior. Consider whether it's appropriate to return an empty list or if an exception should be raised to alert the system of the Hazelcast state.

Use this script to identify how the returned list from enabledFeatures() is used:

#!/bin/bash
# Description: Find all usages of enabledFeatures and examine the handling of an empty list

# Search for all calls to enabledFeatures
rg -A 2 'enabledFeatures\('

---

133-142: ⚠️ Potential issue

Review the error handling and return values in isFeatureEnabled() method.

When the Hazelcast instance is not active, the method logs an error and returns false. Consider whether returning false accurately reflects the feature's status or if it might mask a deeper issue. You might want to throw an exception or notify the caller in a different way to handle this scenario appropriately.

Run the following script to check how isFeatureEnabled() is used across the codebase and whether callers handle a false value as an indication of Hazelcast being inactive:

[HawKhiem]

Went over some courses on Artemis on TS3. No problems were found!

[florian-glombik]

I think defining the logged name dynamically is a cleaner approach, but if you disagree I do not mind - I guess that is rather opinionated and does not need to be changed for my approve 🤷

A small change request: please generalize the check hazelcastInstance != null && hazelcastInstance.getLifecycleService().isRunning() in a simple method, so adjustments would be easier in the future :)

[coderabbitai]

Actionable comments posted: 1

🧹 Outside diff range and nitpick comments (1)

src/main/java/de/tum/cit/aet/artemis/core/service/feature/FeatureToggleService.java (1)

140-140: Standardize error message format across methods.

The error messages have slight inconsistencies in their format. Consider standardizing them:

-            log.error("Failed to check if feature is enabled in FeatureToggleService as Hazelcast instance is not active any more.");
+            log.error("Failed to check if feature is enabled in {} as Hazelcast instance is not active anymore.", FeatureToggleService.class.getSimpleName());
-            log.error("Failed to retrieve enabled features update in FeatureToggleService as Hazelcast instance is not active any more.");
+            log.error("Failed to retrieve enabled features in {} as Hazelcast instance is not active anymore.", FeatureToggleService.class.getSimpleName());
-            log.error("Failed to retrieve disabled features update in FeatureToggleService as Hazelcast instance is not active any more.");
+            log.error("Failed to retrieve disabled features in {} as Hazelcast instance is not active anymore.", FeatureToggleService.class.getSimpleName());

Also applies to: 157-157, 174-174

📜 Review details

Configuration used: .coderabbit.yaml
Review profile: CHILL

📥 Commits

Files that changed from the base of the PR and between 95645e3 and 52337bc.

📒 Files selected for processing (1)

• src/main/java/de/tum/cit/aet/artemis/core/service/feature/FeatureToggleService.java (7 hunks)

🧰 Additional context used

📓 Path-based instructions (1)

src/main/java/de/tum/cit/aet/artemis/core/service/feature/FeatureToggleService.java (1)

Pattern src/main/java/**/*.java: naming:CamelCase; principles:{single_responsibility,small_methods,no_duplication}; db:{perf_queries,datetime_not_timestamp}; rest:{stateless,singleton,delegate_logic,http_only,minimal_dtos}; dtos:{java_records,no_entities,min_data,single_resp}; di:constructor_injection; kiss:simple_code; file_handling:os_indep_paths; practices:{least_access,avoid_transactions,code_reuse,static_member_ref,prefer_primitives}; sql:{param_annotation,uppercase,avoid_subqueries};java:avoid_star_imports

🔇 Additional comments (4)

src/main/java/de/tum/cit/aet/artemis/core/service/feature/FeatureToggleService.java (4)

60-60: LGTM! Good improvement in initialization timing.

The change from @PostConstruct to @EventListener(ApplicationReadyEvent.class) ensures that initialization occurs after the application is fully ready, which is more appropriate for Hazelcast initialization.

---

84-87: LGTM! Well-structured feature management methods.

The changes improve safety through proper error handling and the use of Optional. The parameter rename in updateFeatureToggles enhances clarity by avoiding shadowing.

Also applies to: 96-99, 108-112

---

179-181: LGTM! Good extraction of Hazelcast state check.

The helper method effectively reduces code duplication and improves maintainability. It's used consistently throughout the class.

---

Line range hint 45-181: Consider implementing state recovery mechanism.

While the current implementation handles Hazelcast unavailability gracefully, consider implementing a state recovery mechanism when Hazelcast becomes available again. This could help maintain feature toggle consistency across service restarts or temporary network issues.

Let's check if there's any existing recovery mechanism:

[github-actions]

⚠️ Unable to deploy to test servers ⚠️

Testserver "artemis-test3.artemis.cit.tum.de" is already in use by PR #9603.

[florian-glombik]

Thanks for the changes, approve code

[asliayk]

tested on ts5 with different courses and faced no errors