doc: logging function documentation

doc/Makefile

@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: BSD-3-Clause
-# Copyright 2014-2023, Intel Corporation
+# Copyright 2014-2024, Intel Corporation
 #
 
 #
@@ -18,6 +18,7 @@ MANPAGES_3_MD = libpmem/pmem_flush.3.md libpmem/pmem_is_pmem.3.md libpmem/pmem_m
 		libpmemobj/pmemobj_list_insert.3.md libpmemobj/pmemobj_memcpy_persist.3.md libpmemobj/pmemobj_mutex_zero.3.md \
 		libpmemobj/pmemobj_open.3.md libpmemobj/pmemobj_root.3.md libpmemobj/pmemobj_tx_begin.3.md libpmemobj/pmemobj_tx_add_range.3.md \
 		libpmemobj/pmemobj_tx_alloc.3.md libpmemobj/pobj_layout_begin.3.md libpmemobj/pobj_list_head.3.md libpmemobj/toid_declare.3.md \
+		libpmemobj/pmemobj_log_get_threshold.3.md libpmemobj/pmemobj_log_set_function.3.md libpmemobj/pmemobj_log_set_threshold.3.md \
 		libpmempool/pmempool_check_init.3.md libpmempool/pmempool_feature_query.3.md libpmempool/pmempool_rm.3.md libpmempool/pmempool_sync.3.md
 
 MANPAGES_1_MD = pmempool/pmempool.1.md pmempool/pmempool-info.1.md pmempool/pmempool-create.1.md \

doc/libpmemobj/.gitignore

@@ -5,6 +5,9 @@ pmemobj_alloc.3
 pmemobj_ctl_get.3
 pmemobj_first.3
 pmemobj_list_insert.3
+pmemobj_log_get_threshold.3
+pmemobj_log_set_function.3
+pmemobj_log_set_threshold.3
 pmemobj_memcpy_persist.3
 pmemobj_mutex_zero.3
 pmemobj_open.3

doc/libpmemobj/pmemobj_log_get_threshold.3.md

@@ -0,0 +1,52 @@
+---
+draft: false
+slider_enable: true
+description: ""
+disclaimer: "The contents of this web site and the associated <a href=\"https://github.com/pmem\">GitHub repositories</a> are BSD-licensed open source."
+aliases: ["pmemobj_log_get_threshold.3.html"]
+title: "libpmemobj | PMDK"
+header: "pmemobj API version 2.3"
+---
+
+[comment]: <> (SPDX-License-Identifier: BSD-3-Clause)
+[comment]: <> (Copyright 2024, Intel Corporation)
+
+[comment]: <> (pmemobj_log_get_threshold.3 -- get the logging threshold level)
+
+[NAME](#name)<br />
+[SYNOPSIS](#synopsis)<br />
+[DESCRIPTION](#description)<br />
+[RETURN VALUE](#return-value)<br />
+[ERRORS](#errors)<br />
+[SEE ALSO](#see-also)<br />
+
+# NAME #
+
+**pmemobj_log_get_threshold** - get the logging threshold level
+
+# SYNOPSIS #
+
+```c
+	int pmemobj_log_get_threshold(enum pmemobj_log_threshold threshold,
+              enum pmemobj_log_level level);
+```
+
+# DESCRIPTION #
+
+**pmemobj_log_get_threshold**() gets the current level of the threshold.
+See **pmemobj_log_set_threshold**(3) for available thresholds and levels.
+
+# RETURN VALUE #
+
+**pmemobj_log_get_threshold**() function returns 0 on success or returns
+a non-zero value and sets errno on failure.
+
+# ERRORS #
+
+**pmemobj_log_get_threshold**() can fail with the following errors:
+ - EINVAL - threshold is not **CORE_LOG_THRESHOLD** nor **CORE_LOG_THRESHOLD_AUX**
+ - EINVAL - *level is NULL
+
+# SEE ALSO #
+
+**pmemobj_log_set_function**(3), **pmemobj_log_set_threshold**(3).

doc/libpmemobj/pmemobj_log_set_function.3.md

@@ -0,0 +1,84 @@
+---
+draft: false
+slider_enable: true
+description: ""
+disclaimer: "The contents of this web site and the associated <a href=\"https://github.com/pmem\">GitHub repositories</a> are BSD-licensed open source."
+aliases: ["pmemobj_log_set_function.3.html"]
+title: "libpmemobj | PMDK"
+header: "pmemobj API version 2.3"
+---
+
+[comment]: <> (SPDX-License-Identifier: BSD-3-Clause)
+[comment]: <> (Copyright 2024, Intel Corporation)
+
+[comment]: <> (pmemobj_log_set_function.3 -- set the logging function)
+
+[NAME](#name)<br />
+[SYNOPSIS](#synopsis)<br />
+[DESCRIPTION](#description)<br />
+[RETURN VALUE](#return-value)<br />
+[ERRORS](#errors)<br />
+[NOTE](#note)<br />
+[SEE ALSO](#see-also)<br />
+
+# NAME #
+
+**pmemobj_log_set_function**() - set the logging function
+
+# SYNOPSIS #
+
+```c
+#include <libpmemobj.h>
+
+	typedef void pmemobj_log_function(
+		enum pmemobj_log_level level,
+		const char *file_name,
+		const int line_no,
+		const char *function_name,
+		const char *message_format,
+		...);
+
+	int pmemobj_log_set_function(pmemobj_log_function *log_function);
+```
+
+# DESCRIPTION #
+
+**pmemobj_log_set_function**() allows choosing the function which will get all
+the generated logging messages. The log_function can be either
+**PMEMOBJ_LOG_USE_DEFAULT_FUNCTION** which will use the default logging function
+(built into the library) or a pointer to a user-defined function.
+
+Parameters of a user-defined log function are as follow:
+- **level** - the log level of the message (see **pmemobj_log_set_threshold**(3))
+- **file_name** - name of the source file where the message coming from. It could
+              be set to NULL and
+  in such case neither line_no nor function_name are provided.
+ - **line_no** - the source file line where the message coming from
+ - **function_name** - the function name where the message coming from
+ - **message_format** - **printf**(3)-like format string of the message
+ - "..." - additional arguments of the message format string
+
+THE DEFAULT LOGGING FUNCTION
+The initial value of the logging function is **CORE_LOG_USE_DEFAULT_FUNCTION**.
+This function writes messages to **syslog**(3) (the primary destination) and to
+**stderr**(3) (the secondary destination).
+
+# RETURN VALUE #
+
+**pmemobj_log_set_function**() function returns 0 on success or returns
+a non-zero value and sets errno on failure.
+
+# ERRORS #
+
+ - EAGAIN - a temporary error occurred, the retry may fix the problem
+
+# NOTE #
+
+The logging messages on the levels above the CORE_LOG_THRESHOLD level won't
+trigger the logging function.
+
+The user defined function must be thread-safe.
+
+# SEE ALSO #
+
+**pmemobj_log_get_threshold**(3), **pmemobj_log_set_threshold**(3).

doc/libpmemobj/pmemobj_log_set_threshold.3.md

@@ -0,0 +1,101 @@
+---
+draft: false
+slider_enable: true
+description: ""
+disclaimer: "The contents of this web site and the associated <a href=\"https://github.com/pmem\">GitHub repositories</a> are BSD-licensed open source."
+aliases: ["pmemobj_log_set_threshold.3.html"]
+title: "libpmemobj | PMDK"
+header: "pmemobj API version 2.3"
+---
+
+[comment]: <> (SPDX-License-Identifier: BSD-3-Clause)
+[comment]: <> (Copyright 2024, Intel Corporation)
+
+[comment]: <> (pmemobj_log_set_threshold.3 -- set the logging threshold level)
+
+[NAME](#name)<br />
+[SYNOPSIS](#synopsis)<br />
+[DESCRIPTION](#description)<br />
+[RETURN VALUE](#return-value)<br />
+[ERRORS](#errors)<br />
+[SEE ALSO](#see-also)<br />
+
+# NAME #
+
+**pmemobj_log_set_threshold** - set the logging threshold level
+
+ # SYNOPSIS #
+
+```c
+#include <libpmemobj.h>
+
+	int pmemobj_log_set_threshold(enum pmemobj_log_threshold threshold,
+              enum pmemobj_log_level level);
+
+	enum log_level {
+		PMEMOBJ_LOG_LEVEL_HARK,
+		PMEMOBJ_LOG_LEVEL_FATAL,
+		PMEMOBJ_LOG_LEVEL_ERROR,
+		PMEMOBJ_LOG_LEVEL_WARNING,
+		PMEMOBJ_LOG_LEVEL_NOTICE,
+		PMEMOBJ_LOG_LEVEL_INFO,
+		PMEMOBJ_LOG_LEVEL_DEBUG,
+	};
+
+	enum log_threshold {
+		PMEMOBJ_LOG_THRESHOLD,
+		PMEMOBJ_LOG_THRESHOLD_AUX,
+		PMEMOBJ_LOG_THRESHOLD_MAX
+	};
+```
+
+# DESCRIPTION #
+
+**pmemobj_log_set_threshold**() sets the logging threshold level.
+
+Available thresholds are:
+ - **PMEMOBJ_LOG_THRESHOLD** - the main threshold used to filter out undesired
+  logging messages. Messages on a higher level than the primary threshold
+  level are ignored. **PMEMOBJ_LOG_LEVEL_HARK** shall be used to suppress
+ logging.
+ The default value is **PMEMOBJ_LOG_WARNING**.
+ - **PMEMOBJ_LOG_THRESHOLD_AUX** - the auxiliary threshold intended for use inside
+  the logging function (please see **log_get_threshold**(3)). The logging
+  function may or may not take this threshold into consideration. The default
+  value is **PMEMOBJ_LOG_LEVEL_HARK**.
+
+Available threshold levels are defined by enum log_level:
+ - **PMEMOBJ_LOG_LEVEL_HARK** - only basic library info
+ - **PMEMOBJ_LOG_LEVEL_FATAL** - an error that causes the library to stop working
+   immediately
+ - **PMEMOBJ_LOG_LEVEL_ERROR** - an error that causes the library to stop working
+   properly
+ - **PMEMOBJ_LOG_LEVEL_WARNING** - an error that could be handled in the upper
+   level
+ - **PMEMOBJ_LOG_LEVEL_NOTICE** - non-massive info mainly related to public API
+   function completions
+ - **PMEMOBJ_LOG_LEVEL_INFO** - massive info e.g. every write operation indication
+ - **PMEMOBJ_LOG_LEVEL_DEBUG** - debug info e.g. write operation dump
+
+THE DEFAULT LOGGING FUNCTION
+The default logging function writes messages to **syslog**(3) and to **stderr**(3),
+where **syslog**(3) is the primary destination (**PMEMOBJ_LOG_THRESHOLD** applies)
+whereas **stderr**(3) is the secondary destination (**PMEMOBJ_LOG_THRESHOLD_AUX**
+applies).
+
+# RETURN VALUE #
+
+**pmemobj_log_set_threshold**() function returns 0 on success or returns
+a non-zero value and sets errno on failure.
+
+# ERRORS #
+
+**pmemobj_log_set_threshold**() can set the following errno values on fail:
+ - EINVAL - threshold is not **PMEMOBJ_LOG_THRESHOLD** nor
+   **PMEMOBJ_LOG_THRESHOLD_AUX**
+ - EINVAL - level is not a value defined by enum log_level type
+ - EAGAIN - a temporary error occurred, the retry may fix the problem
+
+# SEE ALSO #
+
+**pmemobj_log_get_threshold**(3), **pmemobj_log_set_function**(3).