Provided by: spamassassin_3.4.4-1ubuntu1_all bug

NAME

       Mail::SpamAssassin::BayesStore::Redis - Redis Bayesian Storage Module Implementation

DESCRIPTION

       This module implements a Redis based bayesian storage module.

       Apache SpamAssassin v3.4.0 introduces support for keeping a Bayes database on a Redis
       server, either running locally, or accessed over network. Similar to SQL backends, the
       database may be concurrently used by several hosts running SpamAssassin.

       The current implementation only supports a global Bayes database, i.e.  per-recipient sub-
       databases are not supported. The Redis 2.6.* server supports access over IPv4 or over a
       Unix socket, starting with Redis version 2.8.0 also IPv6 is supported. Bear in mind that
       Redis server only offers limited access controls, so it is advisable to let the Redis
       server bind to a loopback interface only, or to use other mechanisms to limit access, such
       as local firewall rules.

       The Redis backend for Bayes can put a Lua scripting support in a Redis server to good use,
       improving performance. The Lua support is available in Redis server since version 2.6.  In
       absence of a Lua support, the Redis backend uses batched (pipelined) traditional Redis
       commands, so it should work with a Redis server version 2.4 (untested), although this is
       not recommended for busy sites.

       Expiration of token and 'seen' message id entries is left to the Redis server. There is no
       provision for manually expiring a database, so it is highly recommended to leave the
       setting bayes_auto_expire to its default value 1 (i.e. enabled).

       Example configuration:

         bayes_store_module  Mail::SpamAssassin::BayesStore::Redis
         bayes_sql_dsn       server=127.0.0.1:6379;password=foo;database=2
         bayes_token_ttl 21d
         bayes_seen_ttl   8d
         bayes_auto_expire 1

       A redis server with a Lua support (2.6 or higher) is recommended for performance reasons.

       The bayes_sql_dsn config variable has been hijacked for our purposes:

         bayes_sql_dsn

           Optional config parameters affecting a connection to a redis server.

           This is a semicolon-separated list of option=value pairs, where an option
           can be: server, password, database. Unrecognized options are silently
           ignored.

           The 'server' option specifies a socket on which a redis server is
           listening. It can be an absolute path of a Unix socket, or a host:port
           pair, where a host can be an IPv4 or IPv6 address or a host name.
           An IPv6 address must be enclosed in brackets, e.g. [::1]:6379
           (IPv6 support in a redis server is available since version 2.8.0).
           A default is to connect to an INET socket at 127.0.0.1, port 6379.

           The value of a 'password' option is sent in an AUTH command to a redis
           server on connecting if a server requests authentication. A password is
           sent in plain text and a redis server only offers an optional rudimentary
           authentication. To limit access to a redis server use its 'bind' option
           to bind to a specific interface (typically to a loopback interface),
           or use a host-based firewall.

           The value of a 'database' option can be an non-negative (small) integer,
           which is passed to a redis server with a SELECT command on connecting,
           and chooses a sub-database index. A default database index is 0.

           Example: server=localhost:6379;password=foo;database=2

         bayes_token_ttl

           Controls token expiry (ttl value in SECONDS, sent as-is to Redis)
           when bayes_auto_expire is true. Default value is 3 weeks (but check
           Mail::SpamAssassin::Conf.pm to make sure).

         bayes_seen_ttl

           Controls 'seen' expiry (ttl value in SECONDS, sent as-is to Redis)
           when bayes_auto_expire is true. Default value is 8 days (but check
           Mail::SpamAssassin::Conf.pm to make sure).

       Expiry is done internally in Redis using *_ttl settings mentioned above, but only if
       bayes_auto_expire is true (which is a default).  This is why --force-expire etc does
       nothing, and token counts and atime values are shown as zero in statistics.

       LIMITATIONS: Only global bayes storage is implemented, per-user bayes is not currently
       available. Dumping (sa-learn --backup, or --dump) of a huge database may not be possible
       if all keys do not fit into process memory.

METHODS

   new
       public class (Mail::SpamAssassin::BayesStore::Redis) new
       (Mail::Spamassassin::Plugin::Bayes $bayes)

       Description: This methods creates a new instance of the
       Mail::SpamAssassin::BayesStore::Redis object.  It expects to be passed an instance of the
       Mail::SpamAssassin:Bayes object which is passed into the Mail::SpamAssassin::BayesStore
       parent object.

   prefork_init
       public instance (Boolean) prefork_init ();

       Description: This optional method is called in the parent process shortly before forking
       off child processes.

   spamd_child_init
       public instance (Boolean) spamd_child_init ();

       Description: This optional method is called in a child process shortly after being
       spawned.

   tie_db_readonly
       public instance (Boolean) tie_db_readonly ();

       Description: This method ensures that the database connection is properly setup and
       working.

   tie_db_writable
       public instance (Boolean) tie_db_writable ()

       Description: This method ensures that the database connection is properly setup and
       working. If necessary it will initialize the database so that they can begin using the
       database immediately.

   _open_db
       private instance (Boolean) _open_db (Boolean $writable)

       Description: This method ensures that the database connection is properly setup and
       working.  It will initialize bayes variables so that they can begin using the database
       immediately.

   untie_db
       public instance () untie_db ()

       Description: Closes any open db handles.  You can safely call this at any time.

   sync_due
       public instance (Boolean) sync_due ()

       Description: This method determines if a database sync is currently required.

       Unused for Redis implementation.

   expiry_due
       public instance (Boolean) expiry_due ()

       Description: This methods determines if an expire is due.

       Unused for Redis implementation.

   seen_get
       public instance (String) seen_get (string $msgid)

       Description: This method retrieves the stored value, if any, for $msgid.  The return value
       is the stored string ('s' for spam and 'h' for ham) or undef if $msgid is not found.

   seen_put
       public (Boolean) seen_put (string $msgid, char $flag)

       Description: This method records $msgid as the type given by $flag.  $flag is one of two
       values 's' for spam and 'h' for ham.

   seen_delete
       public instance (Boolean) seen_delete (string $msgid)

       Description: This method removes $msgid from the database.

   get_storage_variables
       public instance (@) get_storage_variables ()

       Description: This method retrieves the various administrative variables used by the Bayes
       process and database.

       The values returned in the array are in the following order:

       0: scan count base 1: number of spam 2: number of ham 3: number of tokens in db 4: last
       expire atime 5: oldest token in db atime 6: db version value 7: last journal sync 8: last
       atime delta 9: last expire reduction count 10: newest token in db atime

       Only 1,2,6 are used with Redis, others return zero always.

   get_running_expire_tok
       public instance (String $time) get_running_expire_tok ()

       Description: This method determines if an expire is currently running and returns the last
       time set.

   set_running_expire_tok
       public instance (String $time) set_running_expire_tok ()

       Description: This method sets the time that an expire starts running.

   remove_running_expire_tok
       public instance (Boolean) remove_running_expire_tok ()

       Description: This method removes the row in the database that indicates that and expire is
       currently running.

   tok_get
       public instance (Integer, Integer, Integer) tok_get (String $token)

       Description: This method retrieves a specified token ($token) from the database and
       returns its spam_count, ham_count and last access time.

   tok_get_all
       public instance (\@) tok_get (@ $tokens)

       Description: This method retrieves the specified tokens ($tokens) from storage and returns
       a ref to arrays spam count, ham count and last access time.

   tok_count_change
       public instance (Boolean) tok_count_change (
         Integer $dspam, Integer $dham, String $token, String $newatime)

       Description: This method takes a $spam_count and $ham_count and adds it to $tok along with
       updating $toks atime with $atime.

   multi_tok_count_change
       public instance (Boolean) multi_tok_count_change (
         Integer $dspam, Integer $dham, \% $tokens, String $newatime)

       Description: This method takes a $dspam and $dham and adds it to all of the tokens in the
       $tokens hash ref along with updating each token's atime with $atime.

   nspam_nham_get
       public instance ($spam_count, $ham_count) nspam_nham_get ()

       Description: This method retrieves the total number of spam and the total number of ham
       learned.

   nspam_nham_change
       public instance (Boolean) nspam_nham_change (Integer $num_spam,
                                                    Integer $num_ham)

       Description: This method updates the number of spam and the number of ham in the database.

   tok_touch
       public instance (Boolean) tok_touch (String $token,
                                            String $atime)

       Description: This method updates the given tokens ($token) atime.

       The assumption is that the token already exists in the database.

       We will never update to an older atime

   tok_touch_all
       public instance (Boolean) tok_touch (\@ $tokens
                                            String $atime)

       Description: This method does a mass update of the given list of tokens $tokens, if the
       existing token atime is < $atime.

   cleanup
       public instance (Boolean) cleanup ()

       Description: This method performs any cleanup necessary before moving onto the next
       operation.

   get_magic_re
       public instance (String) get_magic_re ()

       Description: This method returns a regexp which indicates a magic token.

   sync
       public instance (Boolean) sync (\% $opts)

       Description: This method performs a sync of the database

   perform_upgrade
       public instance (Boolean) perform_upgrade (\% $opts);

       Description: Performs an upgrade of the database from one version to another, not
       currently used in this implementation.

   clear_database
       public instance (Boolean) clear_database ()

       Description: This method deletes all records for a particular user.

       Callers should be aware that any errors returned by this method could causes the database
       to be inconsistent for the given user.

   dump_db_toks
       public instance () dump_db_toks (String $template, String $regex, Array @vars)

       Description: This method loops over all tokens, computing the probability for the token
       and then printing it out according to the passed in token.

   backup_database
       public instance (Boolean) backup_database ()

       Description: This method will dump the users database in a machine readable format.

   restore_database
       public instance (Boolean) restore_database (String $filename, Boolean $showdots)

       Description: This method restores a database from the given filename, $filename.

       Callers should be aware that any errors returned by this method could causes the database
       to be inconsistent for the given user.

   db_readable
       public instance (Boolean) db_readable()

       Description: This method returns a boolean value indicating if the database is in a
       readable state.

   db_writable
       public instance (Boolean) db_writable()

       Description: This method returns a boolean value indicating if the database is in a
       writable state.