65 lines
2.5 KiB
Text
65 lines
2.5 KiB
Text
= nng_log(3)
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//
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// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
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//
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// This document is supplied under the terms of the MIT License, a
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// copy of which should be located in the distribution where this
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// file was obtained (LICENSE.txt). A copy of the license may also be
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// found online at https://opensource.org/licenses/MIT.
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//
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== NAME
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nng_log - log messages
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== SYNOPSIS
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[source, c]
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----
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#include <nng/nng.h>
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void nng_log_err(const char *msgid, const char *msg, ...);
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void nng_log_warn(const char *msgid, const char *msg, ...);
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void nng_log_notice(const char *msgid, const char *msg, ...);
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void nng_log_info(const char *msgid, const char *msg, ...);
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void nng_log_debug(const char *msgid, const char *msg, ...);
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void nng_log_auth(nng_log_level level, const char *msgid, const char *msg, ...);
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----
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== DESCRIPTION
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These functions are used to post a message to system or application logs.
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The first five forms all post a message at the severity indicated by the function name.
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The _msgid_ should be a short message identifier that should indicate the message in question.
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A `NULL` value for _msgid_ canbe used as well.
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Message identifiers can be used to assist in filtering logs.
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These should uniquely identify the nature of the problem, whe possible, to assist in trouble-shooting.
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They should also be short.
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Eight characters or less is ideal, and more than sixteen is strongly discouraged.
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The message is formatting as if by `sprintf`, using `msg` as the format, and remaining arguments as arguments to the format.
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The final function, `nng_log_auth`, is used for posting authentication related messages which might be treated specially, such as be storing them in a separate secured log file.
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It takes the severity as a level in _level_.
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The severity can be one of the following values:
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* `NNG_LOG_ERR`
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* `NNG_LOG_WARN`
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* `NNG_LOG_NOTICE`
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* `NNG_LOG_INFO`
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* `NNG_LOG_DEBUG`
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The message itself is handled according to the logging facility set up with xref:nng_mg_set_logger.3.adoc[`nng_log_set_logger`].
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Message delivery is best effort, and messages may be suppressed based on the priority set with xref:nng_log_set_level.3.adoc[`nng_log_set_level`].
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Note that in order to get log messages, a suitable logger must be set using `nng_log_set_logger`.
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The default logger, `nng_null_logger` simply discards logged content.
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== SEE ALSO
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xref:nng_log_set_facility.3.adoc[nng_log_set_facility(3)],
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xref:nng_log_set_level.3.adoc[nng_log_set_level(3)],
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xref:nng_log_set_logger.3.adoc[nng_log_set_logger(3)]
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