Add Duration-Based Testing and Enhanced TLS Logging

[Ankith-Confluent]

Duration-based testing for rdkafka_performance

New -E <seconds> flag allows running producer tests for a specified duration (in seconds) instead of message count. Includes mutual exclusivity validation with -c flag with real-time countdown display.

Example
./rdkafka_performance -P -t anl-1 -p 0 -s 1000 -E 600 -X file=test.conf -X compression.type=none -X linger.ms=5 -l -A latency_L2-long.txt

TLS connection visibility

Added logger callback to display TLS version information during connection establishment, improving observability for SSL/TLS debugging.

[confluent-cla-assistant]

🎉 All Contributor License Agreements have been signed. Ready to merge.
_{Please push an empty commit if you would like to re-run the checks to verify CLA status for all contributors.}

[Copilot]

Pull Request Overview

This PR adds duration-based testing capability to the rdkafka_performance tool and enhances TLS connection logging for better observability.

Key Changes:

• Introduces a new -E <seconds> flag for running producer tests for a specified duration instead of message count, with mutual exclusivity validation against the -c flag
• Adds a logger callback to display TLS version and cipher information during SSL/TLS connection establishment
• Implements real-time countdown display showing remaining test time during duration-based tests

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/rdkafka_ssl.c	Added debug logging to display TLS version and cipher information after successful SSL certificate verification
examples/rdkafka_performance.c	Implemented duration-based testing with -E flag, added logger callback for TLS info display, and integrated countdown timer in stats output

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

The logger callback always prints all log messages to stderr, which will produce excessive output. This should be conditional based on log level or verbosity settings to avoid flooding the console with debug messages. Consider adding a level check (e.g., if (level <= LOG_WARNING)) or respecting the global verbosity setting.

Suggested change

	/* Print warnings and errors to stderr */
	fprintf(stderr, "%%%d|%s|%s: %s\n", level, rd_kafka_name(rk), fac, buf);
	/* Only print warnings and errors by default, or more if verbosity is high */
	/* Map verbosity: 1 = warnings/errors, 2 = info, 3 = debug, 4+ = all */
	int min_level;
	if (verbosity >= 4)
	min_level = 7; /* RD_KAFKA_LOG_PRINT, print all */
	else if (verbosity == 3)
	min_level = 6; /* RD_KAFKA_LOG_DEBUG */
	else if (verbosity == 2)
	min_level = 5; /* RD_KAFKA_LOG_INFO */
	else
	min_level = 4; /* RD_KAFKA_LOG_WARNING */
	if (level <= min_level)
	fprintf(stderr, "%%%d|%s|%s: %s\n", level, rd_kafka_name(rk), fac, buf);

[Copilot]

Using atoi() for parsing user input doesn't detect invalid input. If the user provides non-numeric input, atoi() returns 0, which will pass the <= 0 check but gives a misleading error message. Use strtol() with error checking to properly validate numeric input and provide accurate error messages for malformed input.

Suggested change

	case 'E':
	test_duration = atoi(optarg);
	if (test_duration <= 0) {
	fprintf(stderr,
	"%% Invalid test duration: %s "
	"(must be > 0)\n",
	optarg);
	exit(1);
	}
	break;
	case 'E': {
	char *endptr = NULL;
	long val;
	errno = 0;
	val = strtol(optarg, &endptr, 10);
	if (errno == ERANGE || val > INT_MAX || val <= 0 || endptr == optarg || *endptr != '\0') {
	fprintf(stderr,
	"%% Invalid test duration: %s "
	"(must be a positive integer)\n",
	optarg);
	exit(1);
	}
	test_duration = (int)val;
	break;
	}

[Copilot]

[nitpick] The 5-second flush timeout is hardcoded with no explanation of why this specific duration was chosen. Consider documenting the rationale for this timeout value or making it configurable, especially since duration-based tests might involve different message volumes that could require different flush timeouts.