Eventer

The libmtev eventer can be configured through a top-level <eventer> configuration block.

<application>
  <eventer [ implementation="..." ]>
    <key>value</key>
    ...
  </eventer>
</application>

The implementation attribute is optional and must be supported on the platform; it is recommended that one omit this from configurataions. Valid values are epoll, kqueue, and ports.

The keys and values supported are:

• debugging

  If this key is present and the value is anything other than "0", eventer debugging facilities will be enabled. This can be slow and should not be used in production.

• show_loop_callbacks_threshold

  Specify a millsecond threshold for logging of "slow" callbacks in eventer loops. The default is 0 (all are logged), -1 disables logging. Logging is sent to a log stream called debug/eventer/callbacks/loop/<loopname>.

• show_jobq_callbacks_threshold

  Like show_loop_callbacks_threshold, but for callbacks run in asynchronous job queues. Logging is sent to a log stream called debug/eventer/callbacks/jobq/<queuename>.

• rlim_nofiles

  Specified the number of file descriptors desired. libmtev will attempt to up the operating system limits to allow the application to open this many files. The specified value must be at least 256. If not specified, a default value of 1048576 will be used.

• default_queue_threads

  This specified the number of threads that should be used to manage the default asynchronous job queue. If not specified, a value of 10 is used.

• concurrency

  The number of event loop threads to start. This effects the concurrency of the default event loop and sets the default of any non-default event loops. If not specified or specified as 0, the library will attempt to make a reasonable guess as to a good concurrency level based on the number of CPU cores in the system.

• loop_<name>

  This establishes a new named event loop and sets its concurrency and watchdog timeout to the provided values. The format is: concurrency[,timeout_in_seconds]

  If a concurrency value of 0 is provided, then the named event loop will use the default concurrency specified by the concurrency key. Floating point notation can be used to specify subsecond or partial second timeouts. If unspecified or specified as 0, the timeout will default to the global setting (which defaults to 5.0 unless overriden by the application).

• jobq_<name>

  This establishes a new named jobq and sets parameters around concurrency and memory safety. The format of the value is: concurrency[,min[,max[,safety[,backlog[,lifo]]]]]. Concurrency, min, max, and backlog are all unsigned integers. Concurrency must be greater than zero. If minimum is omitted or zero, no minimum is set. If max is omitted, it is set to min. If max is zero, there is no maximum. Safety can be one of none , cs , or gc (default). For more information om memory settings see eventer_jobq.h and mtev_memory.h. Backlog sets the advisory queue length backlog limit for the queue. The lifo setting instructs the jobq to process jobs last-in-first-out. The values for this field is either lifo or fifo.

  Note that this merely creates the jobq. One must find and use it programmatically within the software. It is designed to have a code-free way of allowing operators to adjust parameters around jobqs used within an application.

• default_jobq_ordering

  Specifies the default job consumption order for jobqs that don't explicitly declare an ordering requirement. Valid values are lifo and fifo. If unspecified, the default for this setting is FIFO.

• default_ca_chain

  Specified the path to a file containing a PEM encoded set of certificate authorities to trust by default.

• ssl_ctx_cache_expiry

  Sets the default number of seconds after which cached SSL contexts will be released. The default is 5 seconds.

• ssl_dhparam<bits>_file & ssl_dhparam<bits>

  By default 2048 bit NIST DH paramaters will be used. If you would like to create new ones, you may specify a file name and a new set of parameters of bits bits will be generated and stored for reuse.