16.8. "logging.handlers" — Gestionnaires de journalisation
**********************************************************

**Code source :** Lib/logging/handlers.py


Important
^^^^^^^^^

Cette page contient uniquement des informations de référence. Pour des
tutoriels, veuillez consulter

* Tutoriel basique

* Tutoriel avancé

* Recettes pour la journalisation

======================================================================

Les gestionnaires suivants, très utiles, sont fournis dans le paquet.
Notez que trois des gestionnaires ("StreamHandler", "FileHandler" et
"NullHandler") sont en réalité définis dans le module "logging" lui-
même, mais qu’ils sont documentés ici avec les autres gestionnaires.


16.8.1. Gestionnaire à flux — *StreamHandler*
=============================================

La classe "StreamHandler", du paquet "logging", envoie les sorties de
journalisation dans des flux tels que *sys.stdout*, *sys.stderr* ou
n’importe quel objet fichier-compatible (ou, plus précisément, tout
objet qui gère les méthodes "write()" et "flush()").

class logging.StreamHandler(stream=None)

   Renvoie une nouvelle instance de la classe "StreamHandler". Si
   *stream* est spécifié, l’instance l’utilise pour les sorties de
   journalisation ; autrement elle utilise *sys.stderr*.

   emit(record)

      If a formatter is specified, it is used to format the record.
      The record is then written to the stream with a terminator. If
      exception information is present, it is formatted using
      "traceback.print_exception()" and appended to the stream.

   flush()

      Purge le flux en appelant sa méthode "flush()". Notez que la
      méthode "close()" est héritée de "Handler" donc elle n'écrit
      rien. Par conséquent, un appel explicite à "flush()" peut
      parfois s'avérer nécessaire.

Modifié dans la version 3.2: The "StreamHandler" class now has a
"terminator" attribute, default value "'\n'", which is used as the
terminator when writing a formatted record to a stream. If you don't
want this newline termination, you can set the handler instance's
"terminator" attribute to the empty string. In earlier versions, the
terminator was hardcoded as "'\n'".


16.8.2. Gestionnaire à fichier — *FileHandler*
==============================================

La classe "FileHandler", du paquet "logging", envoie les sorties de
journalisation dans un fichier. Elle hérite des fonctionnalités de
sortie de "StreamHandler".

class logging.FileHandler(filename, mode='a', encoding=None, delay=False)

   Returns a new instance of the "FileHandler" class. The specified
   file is opened and used as the stream for logging. If *mode* is not
   specified, "'a'" is used.  If *encoding* is not "None", it is used
   to open the file with that encoding.  If *delay* is true, then file
   opening is deferred until the first call to "emit()". By default,
   the file grows indefinitely.

   Modifié dans la version 3.6: L'argument *filename* accepte les
   objets "Path" aussi bien que les chaînes de caractères.

   close()

      Ferme le fichier.

   emit(record)

      Écrit l’enregistrement dans le fichier.


16.8.3. Gestionnaire à puits sans fond — *NullHandler*
======================================================

Nouveau dans la version 3.1.

La classe "NullHandler", située dans le paquet principal "logging", ne
produit aucun formatage ni sortie. C’est essentiellement un
gestionnaire « fantôme » destiné aux développeurs de bibliothèques.

class logging.NullHandler

   Renvoie une nouvelle instance de la classe "NullHandler".

   emit(record)

      Cette méthode ne fait rien.

   handle(record)

      Cette méthode ne fait rien.

   createLock()

      Cette méthode renvoie "None" pour le verrou, étant donné qu’il
      n’y a aucun flux d'entrée-sortie sous-jacent dont l’accès doit
      être sérialisé.

Voir Configuration de la journalisation pour une bibliothèque pour
plus d’information sur l'utilisation de "NullHandler".


16.8.4. Gestionnaire à fichier avec surveillance — *WatchedFileHandler*
=======================================================================

La classe "WatchedFileHandler", située dans le module
"logging.handlers", est un "FileHandler" qui surveille le fichier dans
lequel il journalise. Si le fichier change, il est fermé et rouvert en
utilisant le nom du fichier.

Un changement du fichier peut arriver à cause de l’utilisation de
programmes tels que *newsyslog* ou *logrotate* qui assurent le
roulement des fichiers de journalisation. Ce gestionnaire, destiné à
une utilisation sous Unix/Linux, surveille le fichier pour voir s’il a
changé depuis la dernière écriture (un fichier est réputé avoir changé
si son nœud d’index ou le périphérique auquel il est rattaché a
changé). Si le fichier a changé, l’ancien flux vers ce fichier est
fermé, et le fichier est ouvert pour établir un nouveau flux.

Ce gestionnaire n’est pas approprié pour une utilisation sous
*Windows*, car sous *Windows* les fichiers de journalisation ouverts
ne peuvent être ni déplacés, ni renommés — la journalisation ouvre les
fichiers avec des verrous exclusifs — de telle sorte qu’il n’y a pas
besoin d’un tel gestionnaire. En outre, *ST_INO* n’est pas géré par
*Windows* ; "stat()" renvoie toujours zéro pour cette valeur.

class logging.handlers.WatchedFileHandler(filename, mode='a', encoding=None, delay=False)

   Returns a new instance of the "WatchedFileHandler" class. The
   specified file is opened and used as the stream for logging. If
   *mode* is not specified, "'a'" is used.  If *encoding* is not
   "None", it is used to open the file with that encoding.  If *delay*
   is true, then file opening is deferred until the first call to
   "emit()".  By default, the file grows indefinitely.

   Modifié dans la version 3.6: L'argument *filename* accepte les
   objets "Path" aussi bien que les chaînes de caractères.

   reopenIfNeeded()

      Vérifie si le fichier a changé. Si c’est le cas, le flux
      existant est purgé et fermé et le fichier est rouvert,
      généralement avant d'effectuer l’écriture de l'enregistrement
      dans le fichier.

      Nouveau dans la version 3.6.

   emit(record)

      Écrit l’enregistrement dans le fichier, mais appelle d’abord
      "reopenIfNeeded()" pour rouvrir le fichier s’il a changé.


16.8.5. Base des gestionnaires à roulement *BaseRotatingHandler*
================================================================

La classe "BaseRotatingHandler", située dans le module
"logging.handlers", est la classe de base pour les gestionnaires à
roulement, "RotatingFileHandler" et "TimedRotatingFileHandler". Vous
ne devez pas initialiser cette classe, mais elle a des attributs et
des méthodes que vous devrez peut-être surcharger.

class logging.handlers.BaseRotatingHandler(filename, mode, encoding=None, delay=False)

   Les paramètres sont les mêmes que pour "FileHandler". Les attributs
   sont :

   namer

      Si cet attribut est défini en tant qu’appelable, la méthode
      "rotation_filename()" se rapporte à cet appelable. Les
      paramètres passés à l’appelable sont ceux passés à
      "rotation_filename()".

      Note:

        La fonction *namer* est appelée pas mal de fois durant le
        roulement, de telle sorte qu’elle doit être aussi simple et
        rapide que possible. Elle doit aussi renvoyer toujours la même
        sortie pour une entrée donnée, autrement le comportement du
        roulement pourrait être différent de celui attendu.

      Nouveau dans la version 3.3.

   rotator

      Si cet attribut est défini en tant qu’appelable, cet appelable
      se substitue à la méthode "rotate()". Les paramètres passés à
      l’appelable sont ceux passés à "rotate()".

      Nouveau dans la version 3.3.

   rotation_filename(default_name)

      Modifie le nom du fichier d’un fichier de journalisation lors du
      roulement.

      Cette méthode sert à pouvoir produire un nom de fichier
      personnalisé.

      L’implémentation par défaut appelle l’attribut *namer* du
      gestionnaire, si c’est un appelable, lui passant le nom par
      défaut. Si l’attribut n’est pas un appelable (le défaut est
      "None"), le nom est renvoyé tel quel.

      Paramètres:
         **default_name** -- Le nom par défaut du fichier de
         journalisation.

      Nouveau dans la version 3.3.

   rotate(source, dest)

      Lors du roulement, effectue le roulement du journal courant.

      L’implémentation par défaut appelle l’attribut *rotator* du
      gestionnaire, si c’est un appelable, lui passant les arguments
      *source* et *dest*. Si l’attribut n’est pas un appelable (le
      défaut est "None"), le nom de la source est simplement renommé
      avec la destination.

      Paramètres:
         * **source** -- Le nom du fichier source. Il s’agit
           normalement du nom du fichier, par exemple ""test.log"".

         * **dest** -- Le nom du fichier de destination. Il s’agit
           normalement du nom donné à la source après le roulement,
           par exemple ""test.log.1"".

      Nouveau dans la version 3.3.

La raison d’être de ces attributs est de vous épargner la création
d’une sous-classe — vous pouvez utiliser les mêmes appels pour des
instances de "RotatingFileHandler" et "TimedRotatingFileHandler". Si
le *namer* ou le *rotator* appelable lève une exception, ce sera géré
de la même manière que n’importe quelle exception durant un appel
"emit()", c'est-à-dire par la méthode "handleError()" du gestionnaire.

Si vous avez besoin de faire d’importantes modifications au processus
de roulement, surchargez les méthodes.

Pour un exemple, voir Using a rotator and namer to customize log
rotation processing.


16.8.6. Gestionnaire à roulement de fichiers — *RotatingFileHandler*
====================================================================

La classe "RotatingFileHandler", située dans le module
"logging.handlers", gère le roulement des fichiers de journalisation
sur disque.

class logging.handlers.RotatingFileHandler(filename, mode='a', maxBytes=0, backupCount=0, encoding=None, delay=False)

   Returns a new instance of the "RotatingFileHandler" class. The
   specified file is opened and used as the stream for logging. If
   *mode* is not specified, "'a'" is used.  If *encoding* is not
   "None", it is used to open the file with that encoding.  If *delay*
   is true, then file opening is deferred until the first call to
   "emit()".  By default, the file grows indefinitely.

   Utilisez les valeurs *maxBytes* et *backupCount* pour autoriser le
   roulement du fichier (*rollover*) à une taille prédéterminée. Quand
   la taille limite est sur le point d’être dépassée, le fichier est
   fermé et un nouveau fichier est discrètement ouvert en tant que
   sortie. Un roulement se produit dès que le fichier de
   journalisation actuel atteint presque une taille de *maxBytes* ; si
   *maxBytes* ou *backupCount* est à 0, le roulement ne se produit
   jamais, donc en temps normal il convient de définir *backupCount* à
   au moins 1, et avoir une valeur de *maxBytes* non nulle. Quand
   *backupCount* est non nul, le système sauvegarde les anciens
   fichiers de journalisation en leur ajoutant au nom du fichier, les
   suffixes "".1"", "".2"" et ainsi de suite. Par exemple, avec un
   *backupCount* de 5 et "app.log" comme radical du fichier, vous
   obtiendrez "app.log", "app.log.1", "app.log.2", jusqu’à
   "app.log.5". Le fichier dans lequel on écrit est toujours
   "app.log". Quand ce fichier est rempli, il est fermé et renommé en
   "app.log.1", et si les fichiers "app.log.1", "app.log.2", etc.
   existent, alors ils sont renommés respectivement en "app.log.2",
   "app.log.3" etc.

   Modifié dans la version 3.6: L'argument *filename* accepte les
   objets "Path" aussi bien que les chaînes de caractères.

   doRollover()

      Effectue un roulement, comme décrit au-dessus.

   emit(record)

      Écrit l'enregistrement dans le fichier, effectuant un roulement
      au besoin comme décrit précédemment.


16.8.7. Gestionnaire à roulement de fichiers périodique — *TimedRotatingFileHandler*
====================================================================================

La classe "TimedRotatingFileHandler", située dans le module
"logging.handlers", gère le roulement des fichiers de journalisation
sur le disque à un intervalle de temps spécifié.

class logging.handlers.TimedRotatingFileHandler(filename, when='h', interval=1, backupCount=0, encoding=None, delay=False, utc=False, atTime=None)

   Renvoie une nouvelle instance de la classe
   "TimedRotatingFileHandler". Le fichier spécifié est ouvert et
   utilisé en tant que flux de sortie pour la journalisation. Au
   moment du roulement, il met également à jour le suffixe du nom du
   fichier. Le roulement se produit sur la base combinée de *when* et
   *interval*.

   Utilisez le *when* pour spécifier le type de l’*interval*. La liste
   des valeurs possibles est ci-dessous. Notez qu’elles sont sensibles
   à la casse.

   +------------------+------------------------------+---------------------------+
   | Valeur           | Type d’intervalle            | Si/comment *atTime* est   |
   |                  |                              | utilisé                   |
   |==================|==============================|===========================|
   | "'S'"            | Secondes                     | Ignoré                    |
   +------------------+------------------------------+---------------------------+
   | "'M'"            | Minutes                      | Ignoré                    |
   +------------------+------------------------------+---------------------------+
   | "'H'"            | Heures                       | Ignoré                    |
   +------------------+------------------------------+---------------------------+
   | "'D'"            | Jours                        | Ignoré                    |
   +------------------+------------------------------+---------------------------+
   | "'W0'-'W6'"      | Jour de la semaine (0=lundi) | Utilisé pour calculer le  |
   |                  |                              | moment du roulement       |
   +------------------+------------------------------+---------------------------+
   | "'midnight'"     | Roulement du fichier à       | Utilisé pour calculer le  |
   |                  | minuit, si *atTime* n’est    | moment du roulement       |
   |                  | pas spécifié, sinon à        |                           |
   |                  | l’heure *atTime*             |                           |
   +------------------+------------------------------+---------------------------+

   Lors de l’utilisation d’un roulement basé sur les jours de la
   semaine, définir *W0* pour lundi, *W1* pour mardi, et ainsi de
   suite jusqu’à *W6* pour dimanche. Dans ce cas, la valeur indiquée
   pour *interval* n’est pas utilisée.

   Le système sauvegarde les anciens fichiers de journalisation en
   ajoutant une extension au nom du fichier. Les extensions sont
   basées sur la date et l’heure, en utilisation le format *strftime*
   "%Y-%m-%d_%H-%M-%S" ou le début de celui-ci, selon l’intervalle du
   roulement.

   Lors du premier calcul du roulement suivant (quand le gestionnaire
   est créé), la dernière date de modification d’un fichier de
   journalisation existant, ou sinon la date actuelle, est utilisée
   pour calculer la date du prochain roulement.

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

   If *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.

   If *delay* is true, then file opening is deferred until the first
   call to "emit()".

   If *atTime* is not "None", it must be a "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". Note that in these cases, the *atTime* value is
   effectively used to compute the *initial* rollover, and subsequent
   rollovers would be calculated via the normal interval calculation.

   Note:

     Calculation of the initial rollover time is done when the handler
     is initialised. Calculation of subsequent rollover times is done
     only when rollover occurs, and rollover occurs only when emitting
     output. If this is not kept in mind, it might lead to some
     confusion. For example, if an interval of "every minute" is set,
     that does not mean you will always see log files with times (in
     the filename) separated by a minute; if, during application
     execution, logging output is generated more frequently than once
     a minute, *then* you can expect to see log files with times
     separated by a minute. If, on the other hand, logging messages
     are only output once every five minutes (say), then there will be
     gaps in the file times corresponding to the minutes where no
     output (and hence no rollover) occurred.

   Modifié dans la version 3.4: *atTime* parameter was added.

   Modifié dans la version 3.6: L'argument *filename* accepte les
   objets "Path" aussi bien que les chaînes de caractères.

   doRollover()

      Effectue un roulement, comme décrit au-dessus.

   emit(record)

      Outputs the record to the file, catering for rollover as
      described above.


16.8.8. SocketHandler
=====================

The "SocketHandler" class, located in the "logging.handlers" module,
sends logging output to a network socket. The base class uses a TCP
socket.

class logging.handlers.SocketHandler(host, port)

   Returns a new instance of the "SocketHandler" class intended to
   communicate with a remote machine whose address is given by *host*
   and *port*.

   Modifié dans la version 3.4: If "port" is specified as "None", a
   Unix domain socket is created using the value in "host" -
   otherwise, a TCP socket is created.

   close()

      Closes the socket.

   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", use the "makeLogRecord()"
      function.

   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).


16.8.9. DatagramHandler
=======================

The "DatagramHandler" class, located in the "logging.handlers" module,
inherits from "SocketHandler" to support sending logging messages over
UDP sockets.

class logging.handlers.DatagramHandler(host, port)

   Returns a new instance of the "DatagramHandler" class intended to
   communicate with a remote machine whose address is given by *host*
   and *port*.

   Modifié dans la version 3.4: If "port" is specified as "None", a
   Unix domain socket is created using the value in "host" -
   otherwise, a UDP 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", use the "makeLogRecord()"
      function.

   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.


16.8.10. SysLogHandler
======================

The "SysLogHandler" class, located in the "logging.handlers" module,
supports sending logging messages to a remote or local Unix syslog.

class logging.handlers.SysLogHandler(address=('localhost', SYSLOG_UDP_PORT), facility=LOG_USER, socktype=socket.SOCK_DGRAM)

   Returns a new instance of the "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* is
   not specified, "('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* is not specified, "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.

   Modifié dans la version 3.2: *socktype* was added.

   close()

      Closes the socket to the remote host.

   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.

      Modifié dans la version 3.2.1: (See: 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" on
      a "SysLogHandler" instance in order for that instance to *not*
      append the NUL terminator.

      Modifié dans la version 3.3: (See: 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" header file.

      **Priorities**

      +----------------------------+-----------------+
      | Name (string)              | Symbolic value  |
      |============================|=================|
      | "alert"                    | LOG_ALERT       |
      +----------------------------+-----------------+
      | "crit" ou "critical"       | LOG_CRIT        |
      +----------------------------+-----------------+
      | "debug"                    | LOG_DEBUG       |
      +----------------------------+-----------------+
      | "emerg" ou "panic"         | LOG_EMERG       |
      +----------------------------+-----------------+
      | "err" ou "error"           | LOG_ERR         |
      +----------------------------+-----------------+
      | "info"                     | LOG_INFO        |
      +----------------------------+-----------------+
      | "notice"                   | LOG_NOTICE      |
      +----------------------------+-----------------+
      | "warn" ou "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'.


16.8.11. NTEventLogHandler
==========================

The "NTEventLogHandler" class, located in the "logging.handlers"
module, supports sending logging messages to a local Windows NT,
Windows 2000 or Windows XP event log. Before you can use it, you need
Mark Hammond's Win32 extensions for Python installed.

class logging.handlers.NTEventLogHandler(appname, dllname=None, logtype='Application')

   Returns a new instance of the "NTEventLogHandler" class. The
   *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* is one of "'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* attribute.

   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".


16.8.12. SMTPHandler
====================

The "SMTPHandler" class, located in the "logging.handlers" module,
supports sending logging messages to an email address via SMTP.

class logging.handlers.SMTPHandler(mailhost, fromaddr, toaddrs, subject, credentials=None, secure=None, timeout=1.0)

   Returns a new instance of the "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* argument.

   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* argument.

   Nouveau dans la version 3.3: The *timeout* argument was added.

   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.


16.8.13. MemoryHandler
======================

The "MemoryHandler" class, located in the "logging.handlers" module,
supports buffering of logging records in memory, periodically flushing
them to a *target* handler. Flushing occurs whenever the buffer is
full, or when an event of a certain severity or greater is seen.

"MemoryHandler" is a subclass of the more general "BufferingHandler",
which is an abstract class. This buffers logging records in memory.
Whenever each record is added to the buffer, a check is made by
calling "shouldFlush()" to see if the buffer should be flushed.  If it
should, then "flush()" is expected to do the flushing.

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, flushOnClose=True)

   Returns a new instance of the "MemoryHandler" class. The instance
   is initialized with a buffer size of *capacity*. If *flushLevel* is
   not specified, "ERROR" is used. If no *target* is specified, the
   target will need to be set using "setTarget()" before this handler
   does anything useful. If *flushOnClose* is specified as "False",
   then the buffer is *not* flushed when the handler is closed. If not
   specified or specified as "True", the previous behaviour of
   flushing the buffer will occur when the handler is closed.

   Modifié dans la version 3.6: The *flushOnClose* parameter was
   added.

   close()

      Calls "flush()", sets the target to "None" and clears the
      buffer.

   flush()

      For a "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.


16.8.14. HTTPHandler
====================

The "HTTPHandler" class, located in the "logging.handlers" module,
supports sending logging messages to a Web server, using either "GET"
or "POST" semantics.

class logging.handlers.HTTPHandler(host, url, method='GET', secure=False, credentials=None, context=None)

   Returns a new instance of the "HTTPHandler" class. The *host* can
   be of the form "host:port", should you need to use a specific port
   number.  If no *method* is specified, "GET" is used. If *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.

   Modifié dans la version 3.5: The *context* parameter was added.

   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.

   Note:

     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" for a "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.


16.8.15. QueueHandler
=====================

Nouveau dans la version 3.2.

The "QueueHandler" class, located in the "logging.handlers" module,
supports sending logging messages to a queue, such as those
implemented in the "queue" or "multiprocessing" modules.

Along with the "QueueListener" class, "QueueHandler" can be used to
let handlers do their work on a separate thread from the one which
does the logging. This is important in Web applications and also other
service applications where threads servicing clients need to respond
as quickly as possible, while any potentially slow operations (such as
sending an email via "SMTPHandler") are done on a separate thread.

class logging.handlers.QueueHandler(queue)

   Returns a new instance of the "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.


16.8.16. QueueListener
======================

Nouveau dans la version 3.2.

The "QueueListener" class, located in the "logging.handlers" module,
supports receiving logging messages from a queue, such as those
implemented in the "queue" or "multiprocessing" modules. The messages
are received from a queue in an internal thread and passed, on the
same thread, to one or more handlers for processing. While
"QueueListener" is not itself a handler, it is documented here because
it works hand-in-hand with "QueueHandler".

Along with the "QueueHandler" class, "QueueListener" can be used to
let handlers do their work on a separate thread from the one which
does the logging. This is important in Web applications and also other
service applications where threads servicing clients need to respond
as quickly as possible, while any potentially slow operations (such as
sending an email via "SMTPHandler") are done on a separate thread.

class logging.handlers.QueueListener(queue, *handlers, respect_handler_level=False)

   Returns a new instance of the "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.

   Modifié dans la version 3.5: The "respect_handler_levels" argument
   was added.

   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()

      Starts the listener.

      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.

      Nouveau dans la version 3.3.

Voir aussi:

  Module "logging"
     Référence d'API pour le module de journalisation.

  Module "logging.config"
     API de configuration pour le module de journalisation.
