53 lines
2 KiB
Text
53 lines
2 KiB
Text
= nng_log_set_logger(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_set_logger - set logging handler
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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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typedef void (*nng_logger)(nng_log_level level, nng_log_facility facility,
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const char *msgid, const char *msg);
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void nng_null_logger(nng_log_level, nng_log_facility, const char *, const char *);
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void nng_stderr_logger(nng_log_level, nng_log_facility, const char *, const char *);
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void nng_system_logger(nng_log_level, nng_log_facility, const char *, const char *);
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void nng_log_set_logger(nng_logger logger);
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----
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== DESCRIPTION
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The `nng_log_set_logger` is used to set the base logging function to _logger_.
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The _logger_ may be a user defined function to process log messages.
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Only a single logger may be registered at a time.
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If needed, the logger should make copies of either _msgid_ or _msg_, as those may not be valid once the logger function returns.
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The `nng_null_logger` function is an implementation of `nng_logger` that simply discards the content.
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This is the default logger, so logging is disabled by default.
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The `nng_stderr_logger` function is an implementation that logs messages to the standard error stream.
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It will attempt to colorize messages by the severity, if the standard error is a terminal device.
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This can be supressed by setting either the `NO_COLOR` or `NNG_LOG_NO_COLOR` environment variables.
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The `nng_system_logger` attempts to use an appropriate system facility to log messages.
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For POSIX systems, this means using `syslog` to process the messages.
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For other the `nng_stderr_log` may be used as a fallback.
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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.3.adoc[nng_log(3)]
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