CAP_*-abilities

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Syslogd2 CAP_* Reference

Contents:

Preface
Structural CAP_* Declarations
CAP_KERNELTHREADS	CAP_TAILFILES	CAP_WORKERTHREADS
CAP_OUTPUTTHREADS	CAP_USERTHREADS
CAP_* Enforced Limits
CAP_SINGLEPOOL	CAP_SINGLETHREAD	CAP_SINGLEPORT
Informational CAP_* Declarations
CAP_STATS	CAP_WHATIF	CAP_COMMAND
Operational Support
CAP_HOUSEKEEPING	CAP_FILEROTATE
Additional Features and Capabilities
CAP_STREAMIN	CAP_STREAMOUT	CAP_FILTERSIN
CAP_FILTERSOUT	CAP_CACHE	CAP_RECONFIG
CAP_SPOOLFILES

Preface

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The set of CAP_ symbols supported by Syslgod2 is expected to grow (slowly) over time. This is the current (initial) set. Instructions for configuring these CAP_*-abilities into actual binary images can be found here.

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Structural CAP_* entries define optional threadPool types

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CAP_TAILFILES

Provides the ability to poll ASCII text files as an additional form of syslog data input. Also supports kernel input by polling a text file (such as /proc/kmsg).

CAP_KERNELTHREADS

This code has not yet been implemented.

CAP_WORKERTHREADS

Creates a new worker-threadpool type to offload processing of the raw data read from assigned input-sources. This leaves reader threads less to do for each message and allows faster response to high volumes of incoming datagram traffic. High volume datagram traffic is often lost as unread data-buffers get ovewritten by incoming data in non-responsive applications. Worker-threadpools can effectively use higher threadcounts to focus CPU cycles on processing of data rather than get "stuck" waiting on input.

CAP_OUTPUTTHREADS

Creates a new output-threadpool type to offload output processing of events (especially output filters and spooling). Output threadpools allow grouping of destinations into threadpools where dedicated threads share the processing load while multiple threadpools process messages to their assigned destinations in parallel with other threadpools. Load on processor-threads is reduced because their "list of outputs' has been reduced to the "list of threadpools".

CAP_USERTHREADS

Creates a new output-threadpool sub-type to offload the time-intensive process of writing a message to a list of potentially-logged-in users. Use of this threadpol is optional, but can improve processing in some situations by providing dedicated threads to process all user-terminal output.

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CAP_* Enforced Limits

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CAP_SINGLEPOOL

Provides an enforced limitation that disallows multiple thread-pools of any given type. It forces all threadpool-id values to a value of 0 (zero). Any type of threadpool may still be declared, but only one instance (with the default id value) may be used.

CAP_SINGLETHREAD

Provides an enforced limitation that disallows more than one thread in any given threadpool. This capability does not limit the types or numbe of instances of threadpools declaed -- only the number of threads in each one.

CAP_SINGLEPORT

Provides an enforced limitation that prevents the specification of non-default IP or Linux input sockets. This limitation does not prevent the use of CAP_TAILFILES to define text-file inputs or to enable kernel input.

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Informational CAP_* Declarations

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CAP_STATS

Provides the ability to collect and display performance statistics. (Experimental)

CAP_WHATIF

Provides an ability to display a configuration summary for troubleshooting or diagnostic purposes or to wrtie that display to a file.

CAP_COMMAND

Provides an interactive command interface on designated Linux stream socket(s). (Reqiures CAP_STREAMIN and CAP_HOUSEKEEPING.)

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Operational Support

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CAP_HOUSEKEEPING

Provides the abiltiy to define and utilize housekeeping threads to offload background operations that would otherwise overwhelm the parent process.

CAP_FILEROTATE

Provides the ability for Syslogd2 to monitor and automatically rotate output files based on file-size.

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Additional Features & Capabilities

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CAP_STREAMIN

Provides the ability to read receive data via TCP or via streaming UNIX sockets.

CAP_STREAMOUT

Provides the ability to transmit data via TCP or to write to streaming UNIX sockets.

CAP_FILTERSIN

Provides the abiltiy to define and process input filters.

CAP_FILTERSOUT

Provides the abiltiy to define and process output filters.

CAP_CACHE

Provides an internal name-cache (optionally initialized from a specified cache-file) to resolve destination hostnames and incoming source IP-Addresses as an alternative (or complement) to DNS lookups.

CAP_RECONFIG

Provides the ability for Syslogd2 to reconfigure itself during operation to accommodate changes in either network state or in the primary configuration file.

CAP_SPOOLFILES

Provides the ability for stream outputs that may experience broken connections (TCP, Streaming Unix sockets and Named Pipe connections) to write data to a spool file in the event of primary connection failure. CAP_SPOOLFILES also provides code to flush accumulated (spooled) data when connections are re-established.

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