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logging (package)
Logging package for Python. Based on PEP 282 and comments thereto in
comp.lang.python.
Copyright (C) 2001-2019 Vinay Sajip. All Rights Reserved.
To use, simply 'import logging' and log away!
Classes
BufferingFormatter
A formatter suitable for formatting a number of records.
format(self, records)
Format the specified records and return the result as a string.
formatFooter(self, records)
Return the footer string for the specified records.
formatHeader(self, records)
Return the header string for the specified records.
FileHandler
A handler class which writes formatted logging records to disk files.
acquire(self)
Acquire the I/O thread lock.
addFilter(self, filter)
Add the specified filter to this handler.
close(self)
Closes the stream.
createLock(self)
Acquire a thread lock for serializing access to the underlying I/O.
emit(self, record)
Emit a record.
If the stream was not opened because 'delay' was specified in the
constructor, open it before calling the superclass's emit.
filter(self, record)
Determine if a record is loggable by consulting all the filters.
The default is to allow the record to be logged; any filter can veto
this and the record is then dropped. Returns a zero value if a record
is to be dropped, else non-zero.
.. versionchanged:: 3.2
Allow filters to be just callables.
flush(self)
Flushes the stream.
format(self, record)
Format the specified record.
If a formatter is set, use it. Otherwise, use the default formatter
for the module.
get_name(self)
handle(self, record)
Conditionally emit the specified logging record.
Emission depends on filters which may have been added to the handler.
Wrap the actual emission of the record with acquisition/release of
the I/O thread lock. Returns whether the filter passed the record for
emission.
handleError(self, record)
Handle errors which occur during an emit() call.
This method should be called from handlers when an exception is
encountered during an emit() call. If raiseExceptions is false,
exceptions get silently ignored. This is what is mostly wanted
for a logging system - most users will not care about errors in
the logging system, they are more interested in application errors.
You could, however, replace this with a custom handler if you wish.
The record which was being processed is passed in to this method.
release(self)
Release the I/O thread lock.
removeFilter(self, filter)
Remove the specified filter from this handler.
setFormatter(self, fmt)
Set the formatter for this handler.
setLevel(self, level)
Set the logging level of this handler. level must be an int or a str.
setStream(self, stream)
Sets the StreamHandler's stream to the specified value,
if it is different.
Returns the old stream, if the stream was changed, or None
if it wasn't.
set_name(self, name)
name = <property object at 0x7f02273a1e00>
terminator = '\n'
Filter
Filter instances are used to perform arbitrary filtering of LogRecords.
Loggers and Handlers can optionally use Filter instances to filter
records as desired. The base filter class only allows events which are
below a certain point in the logger hierarchy. For example, a filter
initialized with "A.B" will allow events logged by loggers "A.B",
"A.B.C", "A.B.C.D", "A.B.D" etc. but not "A.BB", "B.A.B" etc. If
initialized with the empty string, all events are passed.
filter(self, record)
Determine if the specified record is to be logged.
Returns True if the record should be logged, or False otherwise.
If deemed appropriate, the record may be modified in-place.
Filterer
A base class for loggers and handlers which allows them to share
common code.
addFilter(self, filter)
Add the specified filter to this handler.
filter(self, record)
Determine if a record is loggable by consulting all the filters.
The default is to allow the record to be logged; any filter can veto
this and the record is then dropped. Returns a zero value if a record
is to be dropped, else non-zero.
.. versionchanged:: 3.2
Allow filters to be just callables.
removeFilter(self, filter)
Remove the specified filter from this handler.
Formatter
Formatter instances are used to convert a LogRecord to text.
Formatters need to know how a LogRecord is constructed. They are
responsible for converting a LogRecord to (usually) a string which can
be interpreted by either a human or an external system. The base Formatter
allows a formatting string to be specified. If none is supplied, the
style-dependent default value, "%(message)s", "{message}", or
"${message}", is used.
The Formatter can be initialized with a format string which makes use of
knowledge of the LogRecord attributes - e.g. the default value mentioned
above makes use of the fact that the user's message and arguments are pre-
formatted into a LogRecord's message attribute. Currently, the useful
attributes in a LogRecord are described by:
%(name)s Name of the logger (logging channel)
%(levelno)s Numeric logging level for the message (DEBUG, INFO,
WARNING, ERROR, CRITICAL)
%(levelname)s Text logging level for the message ("DEBUG", "INFO",
"WARNING", "ERROR", "CRITICAL")
%(pathname)s Full pathname of the source file where the logging
call was issued (if available)
%(filename)s Filename portion of pathname
%(module)s Module (name portion of filename)
%(lineno)d Source line number where the logging call was issued
(if available)
%(funcName)s Function name
%(created)f Time when the LogRecord was created (time.time()
return value)
%(asctime)s Textual time when the LogRecord was created
%(msecs)d Millisecond portion of the creation time
%(relativeCreated)d Time in milliseconds when the LogRecord was created,
relative to the time the logging module was loaded
(typically at application startup time)
%(thread)d Thread ID (if available)
%(threadName)s Thread name (if available)
%(process)d Process ID (if available)
%(message)s The result of record.getMessage(), computed just as
the record is emitted
localtime(...)
localtime([seconds]) -> (tm_year,tm_mon,tm_mday,tm_hour,tm_min,
tm_sec,tm_wday,tm_yday,tm_isdst)
Convert seconds since the Epoch to a time tuple expressing local time.
When 'seconds' is not passed in, convert the current time instead.
format(self, record)
Format the specified record as text.
The record's attribute dictionary is used as the operand to a
string formatting operation which yields the returned string.
Before formatting the dictionary, a couple of preparatory steps
are carried out. The message attribute of the record is computed
using LogRecord.getMessage(). If the formatting string uses the
time (as determined by a call to usesTime(), formatTime() is
called to format the event time. If there is exception information,
it is formatted using formatException() and appended to the message.
formatException(self, ei)
Format and return the specified exception information as a string.
This default implementation just uses
traceback.print_exception()
formatMessage(self, record)
formatStack(self, stack_info)
This method is provided as an extension point for specialized
formatting of stack information.
The input data is a string as returned from a call to
:func:`traceback.print_stack`, but with the last trailing newline
removed.
The base implementation just returns the value passed in.
formatTime(self, record, datefmt=None)
Return the creation time of the specified LogRecord as formatted text.
This method should be called from format() by a formatter which
wants to make use of a formatted time. This method can be overridden
in formatters to provide for any specific requirement, but the
basic behaviour is as follows: if datefmt (a string) is specified,
it is used with time.strftime() to format the creation time of the
record. Otherwise, an ISO8601-like (or RFC 3339-like) format is used.
The resulting string is returned. This function uses a user-configurable
function to convert the creation time to a tuple. By default,
time.localtime() is used; to change this for a particular formatter
instance, set the 'converter' attribute to a function with the same
signature as time.localtime() or time.gmtime(). To change it for all
formatters, for example if you want all logging times to be shown in GMT,
set the 'converter' attribute in the Formatter class.
usesTime(self)
Check if the format uses the creation time of the record.
default_msec_format = '%s,%03d'
default_time_format = '%Y-%m-%d %H:%M:%S'
Handler
Handler instances dispatch logging events to specific destinations.
The base handler class. Acts as a placeholder which defines the Handler
interface. Handlers can optionally use Formatter instances to format
records as desired. By default, no formatter is specified; in this case,
the 'raw' message as determined by record.message is logged.
acquire(self)
Acquire the I/O thread lock.
addFilter(self, filter)
Add the specified filter to this handler.
close(self)
Tidy up any resources used by the handler.
This version removes the handler from an internal map of handlers,
_handlers, which is used for handler lookup by name. Subclasses
should ensure that this gets called from overridden close()
methods.
createLock(self)
Acquire a thread lock for serializing access to the underlying I/O.
emit(self, record)
Do whatever it takes to actually log the specified logging record.
This version is intended to be implemented by subclasses and so
raises a NotImplementedError.
filter(self, record)
Determine if a record is loggable by consulting all the filters.
The default is to allow the record to be logged; any filter can veto
this and the record is then dropped. Returns a zero value if a record
is to be dropped, else non-zero.
.. versionchanged:: 3.2
Allow filters to be just callables.
flush(self)
Ensure all logging output has been flushed.
This version does nothing and is intended to be implemented by
subclasses.
format(self, record)
Format the specified record.
If a formatter is set, use it. Otherwise, use the default formatter
for the module.
get_name(self)
handle(self, record)
Conditionally emit the specified logging record.
Emission depends on filters which may have been added to the handler.
Wrap the actual emission of the record with acquisition/release of
the I/O thread lock. Returns whether the filter passed the record for
emission.
handleError(self, record)
Handle errors which occur during an emit() call.
This method should be called from handlers when an exception is
encountered during an emit() call. If raiseExceptions is false,
exceptions get silently ignored. This is what is mostly wanted
for a logging system - most users will not care about errors in
the logging system, they are more interested in application errors.
You could, however, replace this with a custom handler if you wish.
The record which was being processed is passed in to this method.
release(self)
Release the I/O thread lock.
removeFilter(self, filter)
Remove the specified filter from this handler.
setFormatter(self, fmt)
Set the formatter for this handler.
setLevel(self, level)
Set the logging level of this handler. level must be an int or a str.
set_name(self, name)
name = <property object at 0x7f02273a1e00>
LogRecord
A LogRecord instance represents an event being logged.
LogRecord instances are created every time something is logged. They
contain all the information pertinent to the event being logged. The
main information passed in is in msg and args, which are combined
using str(msg) % args to create the message field of the record. The
record also includes information such as when the record was created,
the source line where the logging call was made, and any exception
information to be logged.
getMessage(self)
Return the message for this LogRecord.
Return the message for this LogRecord after merging any user-supplied
arguments with the message.
Logger
Instances of the Logger class represent a single logging channel. A
"logging channel" indicates an area of an application. Exactly how an
"area" is defined is up to the application developer. Since an
application can have any number of areas, logging channels are identified
by a unique string. Application areas can be nested (e.g. an area
of "input processing" might include sub-areas "read CSV files", "read
XLS files" and "read Gnumeric files"). To cater for this natural nesting,
channel names are organized into a namespace hierarchy where levels are
separated by periods, much like the Java or Python package namespace. So
in the instance given above, channel names might be "input" for the upper
level, and "input.csv", "input.xls" and "input.gnu" for the sub-levels.
There is no arbitrary limit to the depth of nesting.
addFilter(self, filter)
Add the specified filter to this handler.
addHandler(self, hdlr)
Add the specified handler to this logger.
callHandlers(self, record)
Pass a record to all relevant handlers.
Loop through all handlers for this logger and its parents in the
logger hierarchy. If no handler was found, output a one-off error
message to sys.stderr. Stop searching up the hierarchy whenever a
logger with the "propagate" attribute set to zero is found - that
will be the last logger whose handlers are called.
critical(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'CRITICAL'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.critical("Houston, we have a %s", "major disaster", exc_info=1)
debug(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'DEBUG'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.debug("Houston, we have a %s", "thorny problem", exc_info=1)
error(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'ERROR'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.error("Houston, we have a %s", "major problem", exc_info=1)
exception(self, msg, *args, exc_info=True, **kwargs)
Convenience method for logging an ERROR with exception information.
critical(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'CRITICAL'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.critical("Houston, we have a %s", "major disaster", exc_info=1)
filter(self, record)
Determine if a record is loggable by consulting all the filters.
The default is to allow the record to be logged; any filter can veto
this and the record is then dropped. Returns a zero value if a record
is to be dropped, else non-zero.
.. versionchanged:: 3.2
Allow filters to be just callables.
findCaller(self, stack_info=False, stacklevel=1)
Find the stack frame of the caller so that we can note the source
file name, line number and function name.
getChild(self, suffix)
Get a logger which is a descendant to this one.
This is a convenience method, such that
logging.getLogger('abc').getChild('def.ghi')
is the same as
logging.getLogger('abc.def.ghi')
It's useful, for example, when the parent logger is named using
__name__ rather than a literal string.
getEffectiveLevel(self)
Get the effective level for this logger.
Loop through this logger and its parents in the logger hierarchy,
looking for a non-zero logging level. Return the first one found.
handle(self, record)
Call the handlers for the specified record.
This method is used for unpickled records received from a socket, as
well as those created locally. Logger-level filtering is applied.
hasHandlers(self)
See if this logger has any handlers configured.
Loop through all handlers for this logger and its parents in the
logger hierarchy. Return True if a handler was found, else False.
Stop searching up the hierarchy whenever a logger with the "propagate"
attribute set to zero is found - that will be the last logger which
is checked for the existence of handlers.
info(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'INFO'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.info("Houston, we have a %s", "interesting problem", exc_info=1)
isEnabledFor(self, level)
Is this logger enabled for level 'level'?
log(self, level, msg, *args, **kwargs)
Log 'msg % args' with the integer severity 'level'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.log(level, "We have a %s", "mysterious problem", exc_info=1)
makeRecord(self, name, level, fn, lno, msg, args, exc_info, func=None, extra=None, sinfo=None)
A factory method which can be overridden in subclasses to create
specialized LogRecords.
removeFilter(self, filter)
Remove the specified filter from this handler.
removeHandler(self, hdlr)
Remove the specified handler from this logger.
setLevel(self, level)
Set the logging level of this logger. level must be an int or a str.
warn(self, msg, *args, **kwargs)
warning(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'WARNING'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.warning("Houston, we have a %s", "bit of a problem", exc_info=1)
manager = <logging.Manager object at 0x7f02273a49a0>
root = <RootLogger root (INFO)>
LoggerAdapter
An adapter for loggers which makes it easier to specify contextual
information in logging output.
critical(self, msg, *args, **kwargs)
Delegate a critical call to the underlying logger.
debug(self, msg, *args, **kwargs)
Delegate a debug call to the underlying logger.
error(self, msg, *args, **kwargs)
Delegate an error call to the underlying logger.
exception(self, msg, *args, exc_info=True, **kwargs)
Delegate an exception call to the underlying logger.
getEffectiveLevel(self)
Get the effective level for the underlying logger.
hasHandlers(self)
See if the underlying logger has any handlers.
info(self, msg, *args, **kwargs)
Delegate an info call to the underlying logger.
isEnabledFor(self, level)
Is this logger enabled for level 'level'?
log(self, level, msg, *args, **kwargs)
Delegate a log call to the underlying logger, after adding
contextual information from this adapter instance.
process(self, msg, kwargs)
Process the logging message and keyword arguments passed in to
a logging call to insert contextual information. You can either
manipulate the message itself, the keyword args or both. Return
the message and kwargs modified (or not) to suit your needs.
Normally, you'll only need to override this one method in a
LoggerAdapter subclass for your specific needs.
setLevel(self, level)
Set the specified level on the underlying logger.
warn(self, msg, *args, **kwargs)
warning(self, msg, *args, **kwargs)
Delegate a warning call to the underlying logger.
manager = <property object at 0x7f02273b33b0>
name = <property object at 0x7f02273b3310>
Manager
There is [under normal circumstances] just one Manager instance, which
holds the hierarchy of loggers.
getLogger(self, name)
Get a logger with the specified name (channel name), creating it
if it doesn't yet exist. This name is a dot-separated hierarchical
name, such as "a", "a.b", "a.b.c" or similar.
If a PlaceHolder existed for the specified name [i.e. the logger
didn't exist but a child of it did], replace it with the created
logger and fix up the parent/child references which pointed to the
placeholder to now point to the logger.
setLogRecordFactory(self, factory)
Set the factory to be used when instantiating a log record with this
Manager.
setLoggerClass(self, klass)
Set the class to be used when instantiating a logger with this Manager.
disable = <property object at 0x7f02273b3270>
NullHandler
This handler does nothing. It's intended to be used to avoid the
"No handlers could be found for logger XXX" one-off warning. This is
important for library code, which may contain code to log events. If a user
of the library does not configure logging, the one-off warning might be
produced; to avoid this, the library developer simply needs to instantiate
a NullHandler and add it to the top-level logger of the library module or
package.
acquire(self)
Acquire the I/O thread lock.
addFilter(self, filter)
Add the specified filter to this handler.
close(self)
Tidy up any resources used by the handler.
This version removes the handler from an internal map of handlers,
_handlers, which is used for handler lookup by name. Subclasses
should ensure that this gets called from overridden close()
methods.
createLock(self)
emit(self, record)
Stub.
filter(self, record)
Determine if a record is loggable by consulting all the filters.
The default is to allow the record to be logged; any filter can veto
this and the record is then dropped. Returns a zero value if a record
is to be dropped, else non-zero.
.. versionchanged:: 3.2
Allow filters to be just callables.
flush(self)
Ensure all logging output has been flushed.
This version does nothing and is intended to be implemented by
subclasses.
format(self, record)
Format the specified record.
If a formatter is set, use it. Otherwise, use the default formatter
for the module.
get_name(self)
handle(self, record)
Stub.
handleError(self, record)
Handle errors which occur during an emit() call.
This method should be called from handlers when an exception is
encountered during an emit() call. If raiseExceptions is false,
exceptions get silently ignored. This is what is mostly wanted
for a logging system - most users will not care about errors in
the logging system, they are more interested in application errors.
You could, however, replace this with a custom handler if you wish.
The record which was being processed is passed in to this method.
release(self)
Release the I/O thread lock.
removeFilter(self, filter)
Remove the specified filter from this handler.
setFormatter(self, fmt)
Set the formatter for this handler.
setLevel(self, level)
Set the logging level of this handler. level must be an int or a str.
set_name(self, name)
name = <property object at 0x7f02273a1e00>
PercentStyle
format(self, record)
usesTime(self)
validate(self)
Validate the input format, ensure it matches the correct style
asctime_format = '%(asctime)s'
asctime_search = '%(asctime)'
default_format = '%(message)s'
validation_pattern = re.compile('%\\(\\w+\\)[#0+ -]*(\\*|\\d+)?(\\.(\\*|\\d+))?[diouxefgcrsa%]', re.IGNORECASE)
PlaceHolder
PlaceHolder instances are used in the Manager logger hierarchy to take
the place of nodes for which no loggers have been defined. This class is
intended for internal use only and not as part of the public API.
append(self, alogger)
Add the specified logger as a child of this placeholder.
RootLogger
A root logger is not that different to any other logger, except that
it must have a logging level and there is only one instance of it in
the hierarchy.
addFilter(self, filter)
Add the specified filter to this handler.
addHandler(self, hdlr)
Add the specified handler to this logger.
callHandlers(self, record)
Pass a record to all relevant handlers.
Loop through all handlers for this logger and its parents in the
logger hierarchy. If no handler was found, output a one-off error
message to sys.stderr. Stop searching up the hierarchy whenever a
logger with the "propagate" attribute set to zero is found - that
will be the last logger whose handlers are called.
critical(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'CRITICAL'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.critical("Houston, we have a %s", "major disaster", exc_info=1)
debug(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'DEBUG'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.debug("Houston, we have a %s", "thorny problem", exc_info=1)
error(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'ERROR'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.error("Houston, we have a %s", "major problem", exc_info=1)
exception(self, msg, *args, exc_info=True, **kwargs)
Convenience method for logging an ERROR with exception information.
critical(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'CRITICAL'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.critical("Houston, we have a %s", "major disaster", exc_info=1)
filter(self, record)
Determine if a record is loggable by consulting all the filters.
The default is to allow the record to be logged; any filter can veto
this and the record is then dropped. Returns a zero value if a record
is to be dropped, else non-zero.
.. versionchanged:: 3.2
Allow filters to be just callables.
findCaller(self, stack_info=False, stacklevel=1)
Find the stack frame of the caller so that we can note the source
file name, line number and function name.
getChild(self, suffix)
Get a logger which is a descendant to this one.
This is a convenience method, such that
logging.getLogger('abc').getChild('def.ghi')
is the same as
logging.getLogger('abc.def.ghi')
It's useful, for example, when the parent logger is named using
__name__ rather than a literal string.
getEffectiveLevel(self)
Get the effective level for this logger.
Loop through this logger and its parents in the logger hierarchy,
looking for a non-zero logging level. Return the first one found.
handle(self, record)
Call the handlers for the specified record.
This method is used for unpickled records received from a socket, as
well as those created locally. Logger-level filtering is applied.
hasHandlers(self)
See if this logger has any handlers configured.
Loop through all handlers for this logger and its parents in the
logger hierarchy. Return True if a handler was found, else False.
Stop searching up the hierarchy whenever a logger with the "propagate"
attribute set to zero is found - that will be the last logger which
is checked for the existence of handlers.
info(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'INFO'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.info("Houston, we have a %s", "interesting problem", exc_info=1)
isEnabledFor(self, level)
Is this logger enabled for level 'level'?
log(self, level, msg, *args, **kwargs)
Log 'msg % args' with the integer severity 'level'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.log(level, "We have a %s", "mysterious problem", exc_info=1)
makeRecord(self, name, level, fn, lno, msg, args, exc_info, func=None, extra=None, sinfo=None)
A factory method which can be overridden in subclasses to create
specialized LogRecords.
removeFilter(self, filter)
Remove the specified filter from this handler.
removeHandler(self, hdlr)
Remove the specified handler from this logger.
setLevel(self, level)
Set the logging level of this logger. level must be an int or a str.
warn(self, msg, *args, **kwargs)
warning(self, msg, *args, **kwargs)
Log 'msg % args' with severity 'WARNING'.
To pass exception information, use the keyword argument exc_info with
a true value, e.g.
logger.warning("Houston, we have a %s", "bit of a problem", exc_info=1)
manager = <logging.Manager object at 0x7f02273a49a0>
root = <RootLogger root (INFO)>
StrFormatStyle
format(self, record)
usesTime(self)
validate(self)
Validate the input format, ensure it is the correct string formatting style
asctime_format = '{asctime}'
asctime_search = '{asctime'
default_format = '{message}'
field_spec = re.compile('^(\\d+|\\w+)(\\.\\w+|\\[[^]]+\\])*