Logging

Logging

Use the Aerospike libevent client to configure logging.

By default, the Aerospike libevent client logs messages to stderr, which provides basic information about the client.

Setting the Log Level

Applications can change the verbosity level of these log messages using cf_set_log_level(). The function is thread-safe and can be called any time.

// Use internal client logging, but set a filter.
cf_set_log_level(CF_WARN);

Valid log levels are:

• CF_NO_LOGGING
• CF_ERROR
• CF_WARN
• CF_INFO (default)
• CF_DEBUG

Setting a Custom Log Callback

To provide a custom log callback using cf_set_log_callback():

cf_set_log_callback(my_log_cb);

This directs log messages to the callback instead of to stderr to allow the application to format and filter the messages.

The signature of the log callback is:

typedef void (*cf_log_callback)(cf_log_level level, const char* fmt, ...);

Where,

• level — The level of the log message.
• fmt — The format string for the log message (cannot end with \n).
• ... — The parameters for fmt.

This example custom log callback adds a prefix and newline:

void
my_log_cb(cf_log_level level, const char* fmt_no_newline, ...)
{
	// Add a prefix to show it's a client log statement, and to show the level.
	const char* prefix;

	switch (level) {
	case CF_DEBUG: prefix = "Aerospike Client - DEBUG: "; break;
	case CF_INFO:  prefix = "Aerospike Client - INFO: ";  break;
	case CF_WARN:  prefix = "Aerospike Client - WARN: ";  break;
	default: // Should not get here - just fall-through to error case.
	case CF_ERROR: prefix = "Aerospike Client - ERROR: "; break;
	}

	// New format string length is:
	// prefix length + format parameter length + 1 (for newline).
	size_t prefix_len = strlen(prefix);
	size_t fmt_len = prefix_len + strlen(fmt_no_newline) + 1;

	// Generate the new format string.
	char fmt[fmt_len + 1];

	strcpy(fmt, prefix);
	strcpy(fmt + prefix_len, fmt_no_newline);
	fmt[fmt_len - 1] = '\n';
	fmt[fmt_len] = 0;

	// Using the new format string, write the log message to stdout.
	va_list ap;

	va_start(ap, fmt_no_newline);
	vfprintf(stdout, fmt, ap);
	va_end(ap);

	fflush(stdout);
}