Provided by: libmongoc-doc_1.30.4-1ubuntu1_all 
SYNOPSIS
typedef struct mongoc_structured_log_opts_t mongoc_structured_log_opts_t;
mongoc_structured_log_opts_t is an opaque type that contains options for the structured logging
subsystem: per-component log levels, a maximum logged document length, and a handler function.
Create a mongoc_structured_log_opts_t with mongoc_structured_log_opts_new(), set options and a callback
on it, then pass it to mongoc_client_set_structured_log_opts() or
mongoc_client_pool_set_structured_log_opts(). Must be destroyed by calling
mongoc_structured_log_opts_destroy().
FUNCTIONS
mongoc_structured_log_opts_new()
Synopsis
mongoc_structured_log_opts_t *
mongoc_structured_log_opts_new (void);
Creates a new mongoc_structured_log_opts_t, filled with defaults captured from the current environment.
Sets a default log handler which would write a text representation of each log message to stderr, stdout,
or another file configurable using MONGODB_LOG_PATH. This setting has no effect if the default handler
is replaced using mongoc_structured_log_opts_set_handler().
Environment variable errors are non-fatal, and result in one-time warnings delivered as an unstructured
log.
Per-component maximum levels are initialized equivalently to:
mongoc_structured_log_opts_set_max_level_for_all_components(opts, MONGOC_STRUCTURED_LOG_LEVEL_WARNING);
mongoc_structured_log_opts_set_max_levels_from_env(opts);
Environment Variables
This is a full list of the captured environment variables.
• MONGODB_LOG_MAX_DOCUMENT_LENGTH: Maximum length for JSON-serialized documents that appear within a log
message. It may be a number, in bytes, or unlimited (case insensitive) to choose an
implementation-specific value near the maximum representable length. By default, the limit is 1000
bytes. This limit affects interior documents like commands and replies, not the total length of a
structured log message.
• MONGODB_LOG_PATH: A file path or one of the special strings stderr or stdout (case insensitive)
specifying the destination for structured logs seen by the default handler. By default, it writes to
stderr. This path will be captured during mongoc_structured_log_opts_new(), but it will not
immediately be opened. If the file can't be opened, a warning is then written to the unstructured log
and the handler writes structured logs to stderr instead.
WARNING:
When a file path is given for MONGODB_LOG_PATH, each log instance (one stand-alone client or pool)
will separately open this file for append. The results are operating system specific. On UNIX-like
platforms each instance's output will be interleaved, in most cases without splitting individual log
messages. Notably on Windows the file will be opened in exclusive mode by the first instance and
subsequent instances will fail, falling back on the default of stderr. Applications that use
multiple processes or multiple client pools will likely want to supply a log handler that annotates
each message with information about its originating log instance.
• MONGODB_LOG_COMMAND: A log level name to set as the maximum for
MONGOC_STRUCTURED_LOG_COMPONENT_COMMAND.
• MONGODB_LOG_TOPOLOGY: A log level name to set as the maximum for
MONGOC_STRUCTURED_LOG_COMPONENT_TOPOLOGY.
• MONGODB_LOG_SERVER_SELECTION: A log level name to set as the maximum for
MONGOC_STRUCTURED_LOG_COMPONENT_SERVER_SELECTION.
• MONGODB_LOG_CONNECTION: A log level name to set as the maximum for
MONGOC_STRUCTURED_LOG_COMPONENT_CONNECTION.
• MONGODB_LOG_ALL: A log level name applied to all components not otherwise specified.
Note that log level names are always case insensitive. This is a full list of recognized names,
including allowed aliases:
• emergency, off
• alert
• critical
• error
• warning, warn
• notice
• informational, info
• debug
• trace
Returns
A newly allocated mongoc_structured_log_opts_t.
mongoc_structured_log_opts_destroy()
Synopsis
void
mongoc_structured_log_opts_destroy (mongoc_structured_log_opts_t *opts);
Parameters
• opts: Pointer to a mongoc_structured_log_opts_t allocated with mongoc_structured_log_opts_new(), or
NULL.
Description
This function releases all resources associated with a mongoc_structured_log_opts_t. Does nothing if
opts is NULL.
mongoc_structured_log_opts_set_handler()
Synopsis
void
mongoc_structured_log_opts_set_handler (mongoc_structured_log_opts_t *opts,
mongoc_structured_log_func_t log_func,
void *user_data);
Sets the function to be called to handle structured log messages, as a mongoc_structured_log_func_t.
The callback is given a mongoc_structured_log_entry_t as a handle for obtaining additional information
about the log message. This entry pointer is only valid during a callback, because it's a low cost
reference to temporary data.
Structured log handlers must be thread-safe if they will be used with mongoc_client_pool_t. Handlers
must avoid unbounded recursion, preferably by avoiding the use of any libmongoc client or pool which uses
the same handler.
This function always replaces the default log handler from mongoc_structured_log_opts_new(), if it was
still set. If the log_func is set to NULL, structured logging will be disabled.
Parameters
• opts: Structured log options, allocated with mongoc_structured_log_opts_new().
• log_func: The handler to install, a mongoc_structured_log_func_t, or NULL to disable structured
logging.
• user_data: Optional user data, passed on to the handler.
SEE ALSO:
Structured Logging
mongoc_structured_log_opts_set_max_level_for_component()
Synopsis
bool
mongoc_structured_log_opts_set_max_level_for_component (mongoc_structured_log_opts_t *opts,
mongoc_structured_log_component_t component,
mongoc_structured_log_level_t level);
Sets the maximum log level per-component. Only log messages at or below this severity level will be
passed to mongoc_structured_log_func_t.
By default, each component's log level may come from environment variables. See
mongoc_structured_log_opts_set_max_levels_from_env().
Parameters
• opts: Structured log options, allocated with mongoc_structured_log_opts_new().
• component: The component to set a max log level. for, as a mongoc_structured_log_component_t.
• level: The new max log level for this component, as a mongoc_structured_log_level_t.
Returns
Returns true on success, or false if the supplied parameters were incorrect.
SEE ALSO:
Structured Logging
mongoc_structured_log_opts_set_max_level_for_all_components()
Synopsis
bool
mongoc_structured_log_opts_set_max_level_for_all_components (mongoc_structured_log_opts_t *opts,
mongoc_structured_log_level_t level);
Sets all per-component maximum log levels to the same value. Only log messages at or below this severity
level will be passed to mongoc_structured_log_func_t. Effective even for logging components not known at
compile-time.
Parameters
• opts: Structured log options, allocated with mongoc_structured_log_opts_new().
• level: The max log level for all components, as a mongoc_structured_log_level_t.
Returns
Returns true on success, or false if the supplied parameters were incorrect.
SEE ALSO:
Structured Logging
mongoc_structured_log_opts_set_max_levels_from_env()
Synopsis
bool
mongoc_structured_log_opts_set_max_levels_from_env (mongoc_structured_log_opts_t *opts);
Sets any maximum log levels requested by environment variables: MONGODB_LOG_ALL for all components,
followed by per-component log levels MONGODB_LOG_COMMAND, MONGODB_LOG_CONNECTION, MONGODB_LOG_TOPOLOGY,
and MONGODB_LOG_SERVER_SELECTION.
Expects the value to be recognizable by mongoc_structured_log_get_named_level(). Parse errors may cause
a warning message, delivered via unstructured logging.
Component levels with no valid environment variable setting will be left unmodified.
This happens automatically when mongoc_structured_log_opts_new() establishes defaults. Any subsequent
programmatic modifications to the mongoc_structured_log_opts_t will override the environment variable
settings. For applications that desire the opposite behavior, where environment variables may override
programmatic settings, they may call mongoc_structured_log_opts_set_max_levels_from_env() after calling
mongoc_structured_log_opts_set_max_level_for_component() and
mongoc_structured_log_opts_set_max_level_for_all_components(). This will process the environment a
second time, allowing it to override customized defaults.
Returns
Returns true on success. If warnings are encountered in the environment, returns false and may log
additional information to the unstructured logging facility. Note that, by design, these errors are by
default non-fatal. When mongoc_structured_log_opts_new() internally calls this function, it ignores the
return value.
SEE ALSO:
Structured Logging
mongoc_structured_log_opts_get_max_level_for_component()
Synopsis
mongoc_structured_log_level_t
mongoc_structured_log_opts_get_max_level_for_component (const mongoc_structured_log_opts_t *opts,
mongoc_structured_log_component_t component);
Parameters
• opts: Structured log options, allocated with mongoc_structured_log_opts_new().
• component: Log component as a mongoc_structured_log_component_t.
Returns
Returns the configured maximum log level for a specific component, as a mongoc_structured_log_level_t.
This may be the last value set with mongoc_structured_log_opts_set_max_level_for_component() or
mongoc_structured_log_opts_set_max_level_for_all_components(), or it may be the default obtained from
environment variables. If an invalid or unknown component enum is given, returns the lowest log level.
SEE ALSO:
Structured Logging
mongoc_structured_log_opts_set_max_document_length()
Synopsis
bool
mongoc_structured_log_opts_set_max_document_length (mongoc_structured_log_opts_t *opts,
size_t max_document_length);
Sets a maximum length for BSON documents that appear serialized in JSON form as part of a structured log
message.
Serialized JSON will be truncated at this limit, interpreted as a count of UTF-8 encoded bytes.
Truncation will be indicated with a ... suffix, the length of which is not included in the max document
length. If truncation at the exact indicated length would split a valid UTF-8 sequence, we instead
truncate the document earlier at the nearest boundary between code points.
Parameters
• opts: Structured log options, allocated with mongoc_structured_log_opts_new().
• max_document_length: Maximum length for each embedded JSON document, in bytes, not including an
ellipsis (...) added to indicate truncation. Values near or above INT_MAX will be rejected.
Returns
Returns true on success, or false if the supplied maximum length is too large.
SEE ALSO:
Structured Logging
mongoc_structured_log_opts_set_max_document_length_from_env()
mongoc_structured_log_opts_set_max_document_length_from_env()
Synopsis
bool
mongoc_structured_log_opts_set_max_document_length_from_env (mongoc_structured_log_opts_t *opts);
Sets a maximum document length from the MONGODB_LOG_MAX_DOCUMENT_LENGTH environment variable, if a valid
setting is found. See mongoc_structured_log_opts_new() for a description of the supported environment
variable formats.
Parse errors may cause a warning message, delivered via unstructured logging.
This happens automatically when mongoc_structured_log_opts_new() establishes defaults. Any subsequent
programmatic modifications to the mongoc_structured_log_opts_t will override the environment variable
settings. For applications that desire the opposite behavior, where environment variables may override
programmatic settings, they may call mongoc_structured_log_opts_set_max_document_length_from_env() after
calling mongoc_structured_log_opts_set_max_document_length(). This will process the environment a second
time, allowing it to override customized defaults.
Returns
Returns true on success: either a valid environment setting was found, or the value is unset and opts
will not be modified. If warnings are encountered in the environment, returns false and may log
additional information to the unstructured logging facility. Note that, by design, these errors are by
default non-fatal. When mongoc_structured_log_opts_new() internally calls this function, it ignores the
return value.
SEE ALSO:
Structured Logging
mongoc_structured_log_opts_get_max_document_length()
Synopsis
size_t
mongoc_structured_log_opts_get_max_document_length (const mongoc_structured_log_opts_t *opts);
Parameters
• opts: Structured log options, allocated with mongoc_structured_log_opts_new().
Returns
Returns the current maximum document length set in opts, as a size_t.
SEE ALSO:
Structured Logging
SEE ALSO:
Structured Logging
AUTHOR
MongoDB, Inc
COPYRIGHT
2009-present, MongoDB, Inc.
1.30.4 Jun 08, 2025 MONGOC_STRUCTURED_LOG_OPTS_T(3)