Feat/new metrics

[Catharsis68]

Add New Metrics for Call Outcomes and ACK Timeouts

Overview

This PR introduces several new metric counters to improve observability around SIP call processing. The added metrics track:

• Failed Calls: drachtio_calls_failed
• Successful Calls: drachtio_calls_successful
• ACK Timeouts: drachtio_ack_timeout

These metrics help us monitor and diagnose issues with SIP transactions, including cases where the final ACK is not received after a 200 OK response.

Changes

1. New Metric Definitions in src/drachtio.h

• Added three new string constants:
  • STATS_COUNTER_FAILED_CALLS – tracks the number of calls that failed.
  • STATS_COUNTER_SUCCESSFUL_CALLS – tracks the number of successfully completed calls.
  • STATS_COUNTER_ACK_TIMEOUT – tracks instances of ACK timeouts.

These constants are used with our stats macros (like STATS_COUNTER_INCREMENT, etc.) throughout the codebase.

2. Metrics Increment for ACK Timeouts in src/sip-dialog-controller.cpp

• In the SIP dialog controller, when an ACK timeout is detected (for example, during retransmission of a 200 OK response without receiving an ACK), the STATS_COUNTER_ACK_TIMEOUT metric is incremented.
• This helps in flagging potential network issues or application delays affecting SIP transactions.

3. Monitoring and Diagnostics Enhancements

• Call Outcome Metrics: The new counters provide a clear view of successful versus failed calls, enabling more detailed performance analysis.
• ACK Timeout Visibility: Real-time data on ACK timeouts aids in proactive troubleshooting and ensures that potential issues are not overlooked.

Testing and Verification

• Local Testing: Confirmed that the new constants are correctly defined and that ACK timeouts are being properly incremented.
• Integration Testing: Observed the updated metrics in our monitoring dashboard during stress tests, verifying that the new data points (including any added contextual metadata) appear correctly in logs.
• Logging: Enhanced logging in the relevant sections confirms that the metrics calls execute as expected during timeout scenarios.

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By merging this PR, we gain improved visibility into SIP call performance and can quickly pinpoint issues related to ACK timeouts and call failures, thereby enhancing overall system reliability.