16.8. logging.handlers — Logging handlers — Python 3.5.4 documentation

class


logging.


StreamHandler

( stream=None ) ¶

返回新的实例化 StreamHandler 类。若 stream 有指定，实例将使用它为日志记录输出；否则， sys.stderr 会被使用。

class


logging.


FileHandler

( filename , mode='a' , encoding=None , delay=False ) ¶

返回新的实例化 FileHandler 类。打开指定文件并用作日志记录流。若 mode 未指定， 'a' 被使用。若 encoding 不是 None ，用于采用该编码打开文件。若 delay 为 True，则延迟打开文件直到首次调用 emit() . By default, the file grows indefinitely.

class


logging.


NullHandler

¶

返回新的实例化 NullHandler 类。

emit ( record ) ¶

handle ( record ) ¶

createLock ( ) ¶

class


logging.handlers.


WatchedFileHandler

( filename , mode='a' , encoding=None , delay=False ) ¶

返回新的实例化 WatchedFileHandler 类。打开指定文件并用作日志记录流。若 mode 未指定， 'a' 被使用。若 encoding 不是 None ，用于采用该编码打开文件。若 delay 为 True，则延迟打开文件直到首次调用 emit() . By default, the file grows indefinitely.

emit ( record ) ¶

class


logging.handlers.


BaseRotatingHandler

( filename , mode , encoding=None , delay=False ) ¶

The parameters are as for FileHandler . The attributes are:

namer ¶

If this attribute is set to a callable, the rotation_filename() method delegates to this callable. The parameters passed to the callable are those passed to rotation_filename() .

注意

The namer function is called quite a few times during rollover, so it should be as simple and as fast as possible. It should also return the same output every time for a given input, otherwise the rollover behaviour may not work as expected.

3.3 版新增。

rotator ¶

If this attribute is set to a callable, the rotate() method delegates to this callable. The parameters passed to the callable are those passed to rotate() .

3.3 版新增。

rotation_filename ( default_name ) ¶

Modify the filename of a log file when rotating.

This is provided so that a custom filename can be provided.

The default implementation calls the ‘namer’ attribute of the handler, if it’s callable, passing the default name to it. If the attribute isn’t callable (the default is None ), the name is returned unchanged.

参数：	default_name – The default name for the log file.

3.3 版新增。

rotate ( source , dest ) ¶

When rotating, rotate the current log.

The default implementation calls the ‘rotator’ attribute of the handler, if it’s callable, passing the source and dest arguments to it. If the attribute isn’t callable (the default is None ), the source is simply renamed to the destination.

参数：	source – The source filename. This is normally the base filename, e.g. ‘test.log’. dest – The destination filename. This is normally what the source is rotated to, e.g. ‘test.log.1’.

3.3 版新增。

class


logging.handlers.


RotatingFileHandler

( filename , mode='a' , maxBytes=0 , backupCount=0 , encoding=None , delay=False ) ¶

返回新的实例化 RotatingFileHandler 类。打开指定文件并用作日志记录流。若 mode 未指定， 'a' 被使用。若 encoding 不是 None ，用于采用该编码打开文件。若 delay 为 True，则延迟打开文件直到首次调用 emit() . By default, the file grows indefinitely.

可以使用 maxBytes and backupCount 值以允许文件 rollover 按预先确定大小。当大小即将超过时，关闭文件并为输出默默打开新文件。出现翻转每当当前日志文件接近 maxBytes in length; if either of maxBytes or backupCount is zero, rollover never occurs. If backupCount 非 0，系统将通过追加扩展名 .1、.2 等到文件名以保存旧日志文件。例如，采用 backupCount 5 和基文件名 app.log ，将获得 app.log , app.log.1 , app.log.2 ，直到 app.log.5 。正写入的文件始终是 app.log 。当填充此文被时，关闭它并重命名为 app.log.1 ，及若文件 app.log.1 , app.log.2 等存在，那么将它们重命名为 app.log.2 , app.log.3 等分别。

doRollover ( ) ¶: 进行翻转，如上所述。

emit ( record ) ¶: 将记录输出到文件，以迎合先前描述的翻转。

class


logging.handlers.


TimedRotatingFileHandler

( filename , when='h' , interval=1 , backupCount=0 , encoding=None , delay=False , utc=False , atTime=None ) ¶

返回新的实例化 TimedRotatingFileHandler class. The specified file is opened and used as the stream for logging. On rotating it also sets the filename suffix. Rotating happens based on the product of 当 and interval .

可以使用当 to specify the type of interval . The list of possible values is below. Note that they are not case sensitive.

值	Type of interval
`'S'`	Seconds
`'M'`	Minutes
`'H'`	Hours
`'D'`	Days
`'W0'-'W6'`	Weekday (0=Monday)
`'midnight'`	Roll over at midnight

When using weekday-based rotation, specify ‘W0’ for Monday, ‘W1’ for Tuesday, and so on up to ‘W6’ for Sunday. In this case, the value passed for interval isn’t used.

The system will save old log files by appending extensions to the filename. The extensions are date-and-time based, using the strftime format %Y-%m-%d_%H-%M-%S or a leading portion thereof, depending on the rollover interval.

When computing the next rollover time for the first time (when the handler is created), the last modification time of an existing log file, or else the current time, is used to compute when the next rotation will occur.

若 utc argument is true, times in UTC will be used; otherwise local time is used.

若 backupCount is nonzero, at most backupCount files will be kept, and if more would be created when rollover occurs, the oldest one is deleted. The deletion logic uses the interval to determine which files to delete, so changing the interval may leave old files lying around.

若 delay 为 True，则延迟打开文件直到首次调用 emit() .

若 atTime 不是 None ，它必须是 datetime.time instance which specifies the time of day when rollover occurs, for the cases where rollover is set to happen “at midnight” or “on a particular weekday”.

3.4 版改变： atTime 参数被添加。

doRollover ( ) ¶: 进行翻转，如上所述。

emit ( record ) ¶: Outputs the record to the file, catering for rollover as described above.

class


logging.handlers.


SocketHandler

( host , port ) ¶

返回新的实例化 SocketHandler class intended to communicate with a remote machine whose address is given by host and port .

3.4 版改变：若 port is specified as None , a Unix domain socket is created using the value in host - otherwise, a TCP socket is created.

close ( ) ¶: 关闭套接字。

emit ( ) ¶: Pickles the record’s attribute dictionary and writes it to the socket in binary format. If there is an error with the socket, silently drops the packet. If the connection was previously lost, re-establishes the connection. To unpickle the record at the receiving end into a LogRecord ，使用 makeLogRecord() 函数。

handleError ( ) ¶: Handles an error which has occurred during emit() . The most likely cause is a lost connection. Closes the socket so that we can retry on the next event.

makeSocket ( ) ¶: This is a factory method which allows subclasses to define the precise type of socket they want. The default implementation creates a TCP socket ( socket.SOCK_STREAM ).

makePickle ( record ) ¶

Pickles the record’s attribute dictionary in binary format with a length prefix, and returns it ready for transmission across the socket.

Note that pickles aren’t completely secure. If you are concerned about security, you may want to override this method to implement a more secure mechanism. For example, you can sign pickles using HMAC and then verify them on the receiving end, or alternatively you can disable unpickling of global objects on the receiving end.

send ( packet ) ¶: Send a pickled string packet to the socket. This function allows for partial sends which can happen when the network is busy.

createSocket ( ) ¶

Tries to create a socket; on failure, uses an exponential back-off algorithm. On initial failure, the handler will drop the message it was trying to send. When subsequent messages are handled by the same instance, it will not try connecting until some time has passed. The default parameters are such that the initial delay is one second, and if after that delay the connection still can’t be made, the handler will double the delay each time up to a maximum of 30 seconds.

This behaviour is controlled by the following handler attributes:

retryStart (initial delay, defaulting to 1.0 seconds).
retryFactor (multiplier, defaulting to 2.0).
retryMax (maximum delay, defaulting to 30.0 seconds).

This means that if the remote listener starts up after the handler has been used, you could lose messages (since the handler won’t even attempt a connection until the delay has elapsed, but just silently drop messages during the delay period).

class


logging.handlers.


DatagramHandler

( host , port ) ¶

返回新的实例化 DatagramHandler class intended to communicate with a remote machine whose address is given by host and port .

3.4 版改变：若 port is specified as None , a Unix domain socket is created using the value in host - otherwise, a TCP socket is created.

emit ( ) ¶: Pickles the record’s attribute dictionary and writes it to the socket in binary format. If there is an error with the socket, silently drops the packet. To unpickle the record at the receiving end into a LogRecord ，使用 makeLogRecord() 函数。

makeSocket ( ) ¶: The factory method of SocketHandler is here overridden to create a UDP socket ( socket.SOCK_DGRAM ).

send ( s ) ¶: Send a pickled string to a socket.

class


logging.handlers.


SysLogHandler

( address=('localhost' , SYSLOG_UDP_PORT) , facility=LOG_USER , socktype=socket.SOCK_DGRAM ) ¶

返回新的实例化 SysLogHandler class intended to communicate with a remote Unix machine whose address is given by address in the form of a (host, port) tuple. If address 未指定， ('localhost', 514) is used. The address is used to open a socket. An alternative to providing a (host, port) tuple is providing an address as a string, for example ‘/dev/log’. In this case, a Unix domain socket is used to send the message to the syslog. If facility 未指定， LOG_USER is used. The type of socket opened depends on the socktype argument, which defaults to socket.SOCK_DGRAM and thus opens a UDP socket. To open a TCP socket (for use with the newer syslog daemons such as rsyslog), specify a value of socket.SOCK_STREAM .

Note that if your server is not listening on UDP port 514, SysLogHandler may appear not to work. In that case, check what address you should be using for a domain socket - it’s system dependent. For example, on Linux it’s usually ‘/dev/log’ but on OS/X it’s ‘/var/run/syslog’. You’ll need to check your platform and use the appropriate address (you may need to do this check at runtime if your application needs to run on several platforms). On Windows, you pretty much have to use the UDP option.

3.2 版改变： socktype 被添加。

close ( ) ¶: 关闭到远程主机的套接字。

emit ( record ) ¶

The record is formatted, and then sent to the syslog server. If exception information is present, it is not sent to the server.

3.2.1 版改变： (见： bpo-12168 .) In earlier versions, the message sent to the syslog daemons was always terminated with a NUL byte, because early versions of these daemons expected a NUL terminated message - even though it’s not in the relevant specification (RFC 5424). More recent versions of these daemons don’t expect the NUL byte but strip it off if it’s there, and even more recent daemons (which adhere more closely to RFC 5424) pass the NUL byte on as part of the message.

To enable easier handling of syslog messages in the face of all these differing daemon behaviours, the appending of the NUL byte has been made configurable, through the use of a class-level attribute, append_nul . This defaults to True (preserving the existing behaviour) but can be set to False 在 SysLogHandler instance in order for that instance to not append the NUL terminator.

3.3 版改变： (见： bpo-12419 .) In earlier versions, there was no facility for an “ident” or “tag” prefix to identify the source of the message. This can now be specified using a class-level attribute, defaulting to "" to preserve existing behaviour, but which can be overridden on a SysLogHandler instance in order for that instance to prepend the ident to every message handled. Note that the provided ident must be text, not bytes, and is prepended to the message exactly as is.

encodePriority ( facility , priority ) ¶

Encodes the facility and priority into an integer. You can pass in strings or integers - if strings are passed, internal mapping dictionaries are used to convert them to integers.

The symbolic LOG_ values are defined in SysLogHandler and mirror the values defined in the sys/syslog.h 头文件。

Priorities

Name (string)	Symbolic value
`alert`	LOG_ALERT
`crit` or `critical`	LOG_CRIT
`debug`	LOG_DEBUG
`emerg` or `panic`	LOG_EMERG
`err` or `error`	LOG_ERR
`info`	LOG_INFO
`notice`	LOG_NOTICE
`warn` or `warning`	LOG_WARNING

Facilities

Name (string)	Symbolic value
`auth`	LOG_AUTH
`authpriv`	LOG_AUTHPRIV
`cron`	LOG_CRON
`daemon`	LOG_DAEMON
`ftp`	LOG_FTP
`kern`	LOG_KERN
`lpr`	LOG_LPR
`mail`	LOG_MAIL
`news`	LOG_NEWS
`syslog`	LOG_SYSLOG
`user`	LOG_USER
`uucp`	LOG_UUCP
`local0`	LOG_LOCAL0
`local1`	LOG_LOCAL1
`local2`	LOG_LOCAL2
`local3`	LOG_LOCAL3
`local4`	LOG_LOCAL4
`local5`	LOG_LOCAL5
`local6`	LOG_LOCAL6
`local7`	LOG_LOCAL7

mapPriority ( levelname ) ¶: Maps a logging level name to a syslog priority name. You may need to override this if you are using custom levels, or if the default algorithm is not suitable for your needs. The default algorithm maps DEBUG , INFO , WARNING , ERROR and CRITICAL to the equivalent syslog names, and all other level names to ‘warning’.

class


logging.handlers.


NTEventLogHandler

( appname , dllname=None , logtype='Application' ) ¶

返回新的实例化 NTEventLogHandler 类。 appname is used to define the application name as it appears in the event log. An appropriate registry entry is created using this name. The dllname should give the fully qualified pathname of a .dll or .exe which contains message definitions to hold in the log (if not specified, 'win32service.pyd' is used - this is installed with the Win32 extensions and contains some basic placeholder message definitions. Note that use of these placeholders will make your event logs big, as the entire message source is held in the log. If you want slimmer logs, you have to pass in the name of your own .dll or .exe which contains the message definitions you want to use in the event log). The logtype 是某一 'Application' , 'System' or 'Security' , and defaults to 'Application' .

close ( ) ¶: At this point, you can remove the application name from the registry as a source of event log entries. However, if you do this, you will not be able to see the events as you intended in the Event Log Viewer - it needs to be able to access the registry to get the .dll name. The current version does not do this.

emit ( record ) ¶: Determines the message ID, event category and event type, and then logs the message in the NT event log.

getEventCategory ( record ) ¶: Returns the event category for the record. Override this if you want to specify your own categories. This version returns 0.

getEventType ( record ) ¶: Returns the event type for the record. Override this if you want to specify your own types. This version does a mapping using the handler’s typemap attribute, which is set up in __init__() to a dictionary which contains mappings for DEBUG , INFO , WARNING , ERROR and CRITICAL . If you are using your own levels, you will either need to override this method or place a suitable dictionary in the handler’s typemap 属性。

getMessageID ( record ) ¶: Returns the message ID for the record. If you are using your own messages, you could do this by having the msg passed to the logger being an ID rather than a format string. Then, in here, you could use a dictionary lookup to get the message ID. This version returns 1, which is the base message ID in win32service.pyd .

class


logging.handlers.


SMTPHandler

( mailhost , fromaddr , toaddrs , subject , credentials=None , secure=None , timeout=1.0 ) ¶

返回新的实例化 SMTPHandler class. The instance is initialized with the from and to addresses and subject line of the email. The toaddrs should be a list of strings. To specify a non-standard SMTP port, use the (host, port) tuple format for the mailhost argument. If you use a string, the standard SMTP port is used. If your SMTP server requires authentication, you can specify a (username, password) tuple for the credentials 自变量。

To specify the use of a secure protocol (TLS), pass in a tuple to the secure argument. This will only be used when authentication credentials are supplied. The tuple should be either an empty tuple, or a single-value tuple with the name of a keyfile, or a 2-value tuple with the names of the keyfile and certificate file. (This tuple is passed to the smtplib.SMTP.starttls() method.)

A timeout can be specified for communication with the SMTP server using the timeout 自变量。

3.3 版新增： The timeout 自变量被添加。

emit ( record ) ¶: Formats the record and sends it to the specified addressees.

getSubject ( record ) ¶: If you want to specify a subject line which is record-dependent, override this method.

class


logging.handlers.


BufferingHandler

( capacity ) ¶

Initializes the handler with a buffer of the specified capacity.

emit ( record ) ¶: Appends the record to the buffer. If shouldFlush() returns true, calls flush() to process the buffer.

flush ( ) ¶: You can override this to implement custom flushing behavior. This version just zaps the buffer to empty.

shouldFlush ( record ) ¶: Returns true if the buffer is up to capacity. This method can be overridden to implement custom flushing strategies.

class


logging.handlers.


MemoryHandler

( capacity , flushLevel=ERROR , target=None ) ¶

返回新的实例化 MemoryHandler class. The instance is initialized with a buffer size of capacity 。若 flushLevel 未指定， ERROR 源于使用。若无 target is specified, the target will need to be set using setTarget() before this handler does anything useful.

close ( ) ¶: 调用 flush() , sets the target to None and clears the buffer.

flush ( ) ¶: 对于 MemoryHandler , flushing means just sending the buffered records to the target, if there is one. The buffer is also cleared when this happens. Override if you want different behavior.

setTarget ( target ) ¶: Sets the target handler for this handler.

shouldFlush ( record ) ¶: Checks for buffer full or a record at the flushLevel or higher.

class


logging.handlers.


HTTPHandler

( host , url , method='GET' , secure=False , credentials=None , context=None ) ¶

返回新的实例化 HTTPHandler 类。 host can be of the form host:port , should you need to use a specific port number. If no 方法被指定， GET 被使用。若 secure is true, a HTTPS connection will be used. The context parameter may be set to a ssl.SSLContext instance to configure the SSL settings used for the HTTPS connection. If credentials is specified, it should be a 2-tuple consisting of userid and password, which will be placed in a HTTP ‘Authorization’ header using Basic authentication. If you specify credentials, you should also specify secure=True so that your userid and password are not passed in cleartext across the wire.

3.5 版改变： The context 参数被添加。

mapLogRecord ( record ) ¶: Provides a dictionary, based on record , which is to be URL-encoded and sent to the web server. The default implementation just returns record.__dict__ . This method can be overridden if e.g. only a subset of LogRecord is to be sent to the web server, or if more specific customization of what’s sent to the server is required.

emit ( record ) ¶: Sends the record to the Web server as a URL-encoded dictionary. The mapLogRecord() method is used to convert the record to the dictionary to be sent.

注意

Since preparing a record for sending it to a Web server is not the same as a generic formatting operation, using setFormatter() to specify a Formatter 对于 HTTPHandler has no effect. Instead of calling format() , this handler calls mapLogRecord() and then urllib.parse.urlencode() to encode the dictionary in a form suitable for sending to a Web server.

class


logging.handlers.


QueueHandler

( queue ) ¶

返回新的实例化 QueueHandler class. The instance is initialized with the queue to send messages to. The queue can be any queue-like object; it’s used as-is by the enqueue() method, which needs to know how to send messages to it.

emit ( record ) ¶: Enqueues the result of preparing the LogRecord.

prepare ( record ) ¶

Prepares a record for queuing. The object returned by this method is enqueued.

The base implementation formats the record to merge the message and arguments, and removes unpickleable items from the record in-place.

You might want to override this method if you want to convert the record to a dict or JSON string, or send a modified copy of the record while leaving the original intact.

enqueue ( record ) ¶: Enqueues the record on the queue using put_nowait() ; you may want to override this if you want to use blocking behaviour, or a timeout, or a customized queue implementation.

class


logging.handlers.


QueueListener

( queue , *handlers , respect_handler_level=False ) ¶

返回新的实例化 QueueListener class. The instance is initialized with the queue to send messages to and a list of handlers which will handle entries placed on the queue. The queue can be any queue-like object; it’s passed as-is to the dequeue() method, which needs to know how to get messages from it. If respect_handler_level is True , a handler’s level is respected (compared with the level for the message) when deciding whether to pass messages to that handler; otherwise, the behaviour is as in previous Python versions - to always pass each message to each handler.

3.5 版改变： The respect_handler_levels 自变量被添加。

dequeue ( block ) ¶

Dequeues a record and return it, optionally blocking.

The base implementation uses get() . You may want to override this method if you want to use timeouts or work with custom queue implementations.

prepare ( record ) ¶

Prepare a record for handling.

This implementation just returns the passed-in record. You may want to override this method if you need to do any custom marshalling or manipulation of the record before passing it to the handlers.

handle ( record ) ¶

Handle a record.

This just loops through the handlers offering them the record to handle. The actual object passed to the handlers is that which is returned from prepare() .

start ( ) ¶

启动监听器。

This starts up a background thread to monitor the queue for LogRecords to process.

stop ( ) ¶

Stops the listener.

This asks the thread to terminate, and then waits for it to do so. Note that if you don’t call this before your application exits, there may be some records still left on the queue, which won’t be processed.

enqueue_sentinel ( ) ¶

Writes a sentinel to the queue to tell the listener to quit. This implementation uses put_nowait() . You may want to override this method if you want to use timeouts or work with custom queue implementations.

3.3 版新增。

16.8. `logging.handlers` — 日志处理程序 ¶

16.8.1. StreamHandler ¶

16.8.2. FileHandler ¶

16.8.3. NullHandler ¶

16.8.4. WatchedFileHandler ¶

16.8.5. BaseRotatingHandler ¶

16.8.6. RotatingFileHandler ¶

16.8.7. TimedRotatingFileHandler ¶

16.8.8. SocketHandler ¶

16.8.9. DatagramHandler ¶

16.8.10. SysLogHandler ¶

16.8.11. NTEventLogHandler ¶

16.8.12. SMTPHandler ¶

16.8.13. MemoryHandler ¶

16.8.14. HTTPHandler ¶

16.8.15. QueueHandler ¶

16.8.16. QueueListener ¶

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16.8. logging.handlers — 日志处理程序 ¶

16.8.1. StreamHandler ¶

16.8.2. FileHandler ¶

16.8.3. NullHandler ¶

16.8.4. WatchedFileHandler ¶

16.8.5. BaseRotatingHandler ¶

16.8.6. RotatingFileHandler ¶

16.8.7. TimedRotatingFileHandler ¶

16.8.8. SocketHandler ¶

16.8.9. DatagramHandler ¶

16.8.10. SysLogHandler ¶

16.8.11. NTEventLogHandler ¶

16.8.12. SMTPHandler ¶

16.8.13. MemoryHandler ¶

16.8.14. HTTPHandler ¶

16.8.15. QueueHandler ¶

16.8.16. QueueListener ¶

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16.8. `logging.handlers` — 日志处理程序 ¶