Zabbix

/*

** Copyright (C) 2001-2025 Zabbix SIA

**

** This program is free software: you can redistribute it and/or modify it under the terms of

** the GNU Affero General Public License as published by the Free Software Foundation, version 3.

**

** This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;

** without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

** See the GNU Affero General Public License for more details.

**

** You should have received a copy of the GNU Affero General Public License along with this program.

** If not, see <https://www.gnu.org/licenses/>.

**/

​

// watch package provides utility functionality for easier Watcher plugin implementation.

// Watcher plugin listens for events specified by the item requests and comnverts those

// events to item values. This package handles event source initialization/deinitialization,

// event filtering and conversion to item values/errors.

package watch

​

import (

    "sync"

    "time"

​

    "golang.zabbix.com/sdk/plugin"

)

​

// EventSource generates events by calling Manager.Notify() method and passing arbitrary

// data. The data is converted to string values by event filter that was created by the

// event source during Manager update.

type EventSource interface {

    // initialize event source and start generating events

    Initialize() error

    // stop generating events and release internal resources allocated by event source

    Release()

    // create new event filter based on item key

    NewFilter(key string) (filter EventFilter, err error)

}

​

// EventProvider interface provides methods to get event source by item key. An new or existing

// event source can be returned. EventProvider is required to create Manager instance.

type EventProvider interface {

    EventSourceByKey(key string) (EventSource, error)

}

​

// EventFilter has two responsibilities. The first is to convert data to a string value.

// The second is optional - based on internal filter parameters (item key for example)

// it can make the data to be ignored by returning nil value.

type EventFilter interface {

    // Process processes data from event source and returns:

    //   value - data is valid and matches filter

    //   error - invalid data

    //   nothing - data is valid, but does not match the filter

    Process(data interface{}) (value *string, err error)

}

​

// eventWriter links event filter to output sink where the filtered results must be written

type eventWriter struct {

    output plugin.ResultWriter

    filter EventFilter

}

​

// Item to monitor