4.2.16. goldrush [1]¶

简介:

OTP的事件处理与监控
Small, Fast event processing and monitoring for Erlang/OTP applications.
Goldrush is a small Erlang app that provides fast event stream processing

基本语法:

glc:gt(a, 0).   => {Key, '>', Term}
glc:gte(a, 0).  => {Key, '>=', Term}
glc:eq(a, 0).   => {Key, '=', Term}
glc:neq(a, 0).  => {Key, '!=', Term}
glc:lt(a, 0).   => {Key, '<', Term}
glc:lte(a, 0).  => {Key, '=<', Term}
glc:wc(a).      => {Key, '*'}       % all events where ‘a’ exists
glc:nf(a).      => {Key, '!'}       % all events where ‘a’ does not exist.
glc:null(false).=> {null, false}    % no input events. User as a black hole query.
glc:null(true). => {null, true}     % all input events. Used as a passthrough query.

高级语法:

glc:all([_|_]=Conds) => {all, Conds}
glc:any([_|_]=Conds) => {any, Conds};

% 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)]).
% Select all events where ‘a’ AND ‘b’ exists where ‘a’ is greater than 1 and ‘b’ is less than 2.
glc:all([glc:gt(a, 1), glc:lt(b, 2)]).
% Select all events where ‘a’ OR ‘b’ exists where ‘a’ is greater than 1 and ‘b’ is less than 2.
glc:any([glc:gt(a, 1), glc:lt(b, 2)]).

Reduced语法:

% Select all events where
%   ‘a’ is equal to 1, ‘b’ is equal to 2 and ‘c’ is equal to 3
%   and collapse any duplicate logic.
glc_lib:reduce(
  glc:all([
      glc:any([glc:eq(a, 1), glc:eq(b, 2)]),
      glc:any([glc:eq(a, 1), glc:eq(c, 3)])])).

%等同于
glc:all([glc:eq(a, 1), glc:eq(b, 2), glc:eq(c, 3)]).