issue: 4432879 Refactor event_handler_manager

[pasis]

Description

Avoid start_thread with each reg action.
Refactor destructor.

What

Avoid start_thread with each reg action.
Refactor destructor.

Why ?

Potential CPU improvement for CPS and code cleanup.

Change type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Tests
• Other

Check list

• Code follows the style de facto guidelines of this project
• Comments have been inserted in hard to understand places
• Documentation has been updated (if necessary)
• Test has been added (if possible)

[galnoam]

@pasis, can we keep this in your privare fork?

[galnoam]

bot:retest

[galnoam]

bot:retest

[galnoam]

bot:retest

[galnoam]

/review

[galnoam]

/improve

[pr-review-bot-app]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 4 🔵🔵🔵🔵⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Resource Cleanup Ensure that the m_epfd resource is properly closed and reset in the destructor to avoid resource leaks or undefined behavior. if (m_epfd >= 0) { SYSCALL(close, m_epfd); } m_epfd = -1; Thread Affinity Handling Validate the logic for setting thread affinity and fallback mechanisms in start_thread to ensure compatibility and robustness across different environments. bool affinity_requested = false; if (!m_b_continue_running) { errno = ECANCELED; return -1; } if (m_event_handler_tid != 0) { return 0; } ret = pthread_attr_init(&tattr); if (ret != 0) { return -1; } cpu_set = safe_mce_sys().internal_thread_affinity; if (strcmp(safe_mce_sys().internal_thread_affinity_str, "-1") && !strcmp(safe_mce_sys().internal_thread_cpuset, MCE_DEFAULT_INTERNAL_THREAD_CPUSET)) { ret = pthread_attr_setaffinity_np(&tattr, sizeof(cpu_set), &cpu_set); if (ret != 0) { evh_logwarn("Failed to set event handler thread affinity. (errno=%d)", errno); } affinity_requested = (ret == 0); } else { evh_logdbg("Internal thread affinity not set."); } ret = pthread_create(&m_event_handler_tid, &tattr, event_handler_thread, this); if (ret != 0 && affinity_requested) { // Try without affinity in case this is a cset issue. evh_logwarn("Failed to start event handler thread with a thread affinity. Trying default " "thread affinity. (errno=%d)", errno); pthread_attr_destroy(&tattr); ret = pthread_attr_init(&tattr) ?: pthread_create(&m_event_handler_tid, &tattr, event_handler_thread, this); } // Destroy will either succeed or return EINVAL if the init fails in the above block. pthread_attr_destroy(&tattr); if (ret == 0) { evh_logdbg("Started event handler thread."); } else { evh_logerr("Failed to start event handler thread. (errno=%d)", errno); } return ret; Exception Handling Confirm that throwing an exception when start_thread fails in do_global_ctors_helper is the appropriate behavior and won't cause unintended side effects during initialization. if (rc != 0) { BULLSEYE_EXCLUDE_BLOCK_START throw_xlio_exception("Failed to start event handler thread.\n"); BULLSEYE_EXCLUDE_BLOCK_END }

[pr-review-bot-app]

PR Code Suggestions ✨

Category	Suggestion	Impact
Possible issue	Add error handling for thread initialization Add error handling for the pthread_attr_init and pthread_create calls to ensure that any failure in these operations is logged or handled appropriately, avoiding potential undefined behavior. src/core/event/event_handler_manager.cpp [347-348] -ret = pthread_attr_init(&tattr) - ?: pthread_create(&m_event_handler_tid, &tattr, event_handler_thread, this); +ret = pthread_attr_init(&tattr); +if (ret != 0) { + evh_logerr("Failed to initialize thread attributes. (errno=%d)", errno); + return ret; +} +ret = pthread_create(&m_event_handler_tid, &tattr, event_handler_thread, this); +if (ret != 0) { + evh_logerr("Failed to create event handler thread. (errno=%d)", errno); + pthread_attr_destroy(&tattr); + return ret; +} Suggestion importance[1-10]: 8 __ Why: The suggestion improves robustness by adding error handling for pthread_attr_init and pthread_create. This ensures that failures in thread initialization are logged and handled properly, reducing the risk of undefined behavior.	Medium
	Add null check for pointer access Add a null check for m_p_reg_action_q_to_push_to before accessing it to prevent potential segmentation faults if the pointer is null. src/core/event/event_handler_manager.cpp [446] -is_empty = m_p_reg_action_q_to_push_to->empty(); +is_empty = (m_p_reg_action_q_to_push_to && m_p_reg_action_q_to_push_to->empty()); Suggestion importance[1-10]: 8 __ Why: Adding a null check for m_p_reg_action_q_to_push_to prevents potential segmentation faults, which is a significant improvement for code safety and stability.	Medium
	Prevent resource leaks in thread attributes Ensure that the pthread_attr_destroy is called after the second pthread_attr_init to avoid resource leaks in case of repeated initialization. src/core/event/event_handler_manager.cpp [341-349] if (ret != 0 && affinity_requested) { evh_logwarn("Failed to start event handler thread with a thread affinity. Trying default " "thread affinity. (errno=%d)", errno); pthread_attr_destroy(&tattr); - ret = pthread_attr_init(&tattr) - ?: pthread_create(&m_event_handler_tid, &tattr, event_handler_thread, this); + ret = pthread_attr_init(&tattr); + if (ret == 0) { + ret = pthread_create(&m_event_handler_tid, &tattr, event_handler_thread, this); + pthread_attr_destroy(&tattr); + } } Suggestion importance[1-10]: 7 __ Why: The suggestion ensures that pthread_attr_destroy is called after the second pthread_attr_init, preventing resource leaks. This is a good improvement for resource management and aligns with best practices.	Medium
General	Log error code before exception Log the error code before throwing the exception to provide more context for debugging failures in starting the event handler thread. src/core/main.cpp [1000-1003] rc = g_p_event_handler_manager->start_thread(); if (rc != 0) { + evh_logerr("Failed to start event handler thread. (rc=%d)", rc); BULLSEYE_EXCLUDE_BLOCK_START throw_xlio_exception("Failed to start event handler thread.\n"); BULLSEYE_EXCLUDE_BLOCK_END } Suggestion importance[1-10]: 6 __ Why: Logging the error code before throwing an exception provides valuable debugging information. While not critical, it enhances the ability to diagnose issues when the thread fails to start.	Low

[galnoam]

Hi @pasis , @AlexanderGrissik , please check pr agent review comments.