Overview

Module glc

• Description
• Function Index
• Function Details

Description

Event filter implementation.

An event query is constructed using the built in operators exported from this module. The filtering operators are used to specify which events should be included in the output of the query. The default output action is to copy all events matching the input filters associated with a query to the output. This makes it possible to construct and compose multiple queries at runtime.

Examples of built in filters

  %% Select all events where 'a' exists and is greater than 0.
  glc:gt(a, 0).
  %% Select all events where 'a' exists and is equal to 0.
  glc:eq(a, 0).
  %% Select all events where 'a' exists and is not equal to 0.
  glc:neq(a, 0).
  %% Select all events where 'a' exists and is less than 0.
  glc:lt(a, 0).
  %% Select all events where 'a' exists and is anything.
  glc:wc(a).
 
  %% Select no input events. Used as black hole query.
  glc:null(false).
  %% Select all input events. Used as passthrough query.
  glc:null(true).

Examples of combining filters

  %% Select all events where both 'a' and 'b' exists and are greater than 0.
  glc:all([glc:gt(a, 0), glc:gt(b, 0)]).
  %% Select all events where 'a' or 'b' exists and are greater than 0.
  glc:any([glc:gt(a, 0), glc:gt(b, 0)]).

Handling output events

Once a query has been composed it is possible to override the output action with an erlang function. The function will be applied to each output event from the query. The return value from the function will be ignored.

  %% Write all input events as info reports to the error logger.
  glc:with(glc:null(true), fun(E) ->
      error_logger:info_report(gre:pairs(E)) end).

Function Index

Function Details

all/1

Filter the input using multiple filters.

any/1

Filter the input using one of multiple filters.

compile/2

Compile a query to a module.

compile/3

compile/4

delete/1

Release a compiled query.

eq/2

filter/1

The number of filtered events for this query module.

get/2

gt/2

gte/2

handle/2

Handle an event using a compiled query.

info/1

input/1

The number of input events for this query module.

job_error/1

The number of job errors for this query module.

job_input/1

The number of job inputs for this query module.

job_run/1

The number of job runs for this query module.

job_time/1

The amount of time jobs took for this query module.

lt/2

lte/2

neq/2

nf/1

null/1

Always return true or false.

output/1

The number of output events for this query module.

reset_counters/1

Reset all counters

reset_counters/2

Reset a specific counter

run/3

start/0

union/1

Return a union of multiple queries.

The union of multiple queries is the equivalent of executing multiple queries separately on the same input event. The advantage is that filter conditions that are common to all or some of the queries only need to be tested once.

wc/1

with/2

Apply a function to each output of a query.

Overview

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