btrdb

package module
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 Go to latest Published: Feb 1, 2017 License: BSD-2-Clause Imports: 8 Imported by: 7

README

BTrDB golang bindings

GoDoc

These are the go BTrDB bindings. This branch is compatible with version 3, the most widely deployed version of BTrDB.

You can read the API documentation and code examples by clicking the godoc button above. To import this package in your code, add

import "gopkg.in/btrdb.v3"

Documentation

Overview

Package btrdb implements bindings to interface with a running instance of the Berkeley Tree Database (BTrDB).

The main abstraction provided is a BTrDBConnection, which represents a single connection to a BTrDB.

Example usage: 

import (
	"gopkg.in/btrdb.v3"
	"github.com/pborman/uuid"
)

func main() {
	var myuuid uuid.UUID
	var err error
	var bc *btrdb.BTrDBConnection
	var version uint64
	var versionchan chan uint64
	var svchan chan btrdb.StandardValue
	var sv btrdb.StandardValue
	var points []btrdb.StandardValue
	var statcode chan string
	var strstatcode string
	var asyncerr chan string

	bc, err = btrdb.NewBTrDBConnection("localhost:4410")
	if err != nil {
		/* Fatal error */
	}

	/* UUID of the stream into which to insert/query */
	myuuid = uuid.NewRandom()

	/* Points to insert */
	points = []btrdb.StandardValue{
		btrdb.StandardValue{Time: 1, Value: 2.0},
		btrdb.StandardValue{Time: 4, Value: 7.5},
		btrdb.StandardValue{Time: 6, Value: 2.5},
		btrdb.StandardValue{Time: 13, Value: 8.0},
		btrdb.StandardValue{Time: 15, Value: 6.0},
	}

	/* Insert */
	statcode, err = bc.InsertValues(myuuid, points, true)
	strstatcode = <- statcode
	if err != nil || "ok" != strstatcode {
		/* Error */
	}

	/* Standard Values Query */
	svchan, versionchan, asyncerr, err = bc.QueryStandardValues(myuuid, 0, 16, 0)
	if err != nil {
		/* Error */
	}

	for sv = range svchan {
		/* Handle Point */
	}

	/* Get the version used to satisfy the query */
	version = <- versionchan
}

Index

Constants

View Source 
const BUFFER_LEN = 1024

Variables

View Source 
var ERR_CLOSED = errors.New("Connection closed")

Error if the connection to BTrDB is lost

Functions

This section is empty.

Types

type BTrDBConnection 

type BTrDBConnection struct {
	// contains filtered or unexported fields
}

BTrDBConnection abstracts a single connection to a BTrDB. A single BTrDBConnection supports multiple concurrent requests to BTrDB.

func NewBTrDBConnection 

func NewBTrDBConnection(addr string) (*BTrDBConnection, error)

Creates a connection to the BTrDB at the provided address, and returns a BTrDBConnection to represent the connection.

func (*BTrDBConnection) Close 

func (bc *BTrDBConnection) Close() error

Releases the resources associated with this BTrDBConnection. It is undefined behavior to call this while there are outstanding requests on the connection.

func (*BTrDBConnection) DeleteValues 

func (bc *BTrDBConnection) DeleteValues(uuid uuid.UUID, start_time int64, end_time int64) (chan string, error)

Delete values from the specified stream in the specified time range.

Return values are the same as in InsertValues.

func (*BTrDBConnection) InsertValues 

func (bc *BTrDBConnection) InsertValues(uuid uuid.UUID, points []StandardValue, sync bool) (chan string, error)

Inserts the points specified in the points slice into the stream corresponding to the specified UUID. If the sync parameter is true, then the BTrDB will commit the points to disk, before sending an acknowledgment; otherwise, it will return an acknowledgment and an OK will be received immediately, but the data will not be immediately queryable.

Returns a channel with the status code of the operation, and an error in case the request could not be sent. When the acknowledgment is received from the BTrDB, the status code will appear on the channel as a string; 'ok' is the value corresponding to success.

func (*BTrDBConnection) QueryChangedRanges 

func (bc *BTrDBConnection) QueryChangedRanges(uuid uuid.UUID, from_generation uint64, to_generation uint64, resolution uint8) (chan TimeRange, chan uint64, chan string, error)

Makes a Changed Ranges Query for ranges of time at the specified resolution that correspond to data that changed between the specified versions in the specified stream.

Return values are the same as in QueryStandardValues.

func (*BTrDBConnection) QueryNearestValue 

func (bc *BTrDBConnection) QueryNearestValue(uuid uuid.UUID, time int64, backward bool, version uint64) (chan StandardValue, chan uint64, chan string, error)

Makes a Nearest Value Query for the nearest point in the specified stream, at the specified version, nearest to the specified time, in the specified direction. A version number of 0 means to use the latest version of the stream.

Return values are the same as in QueryStandardValues.

func (*BTrDBConnection) QueryStandardValues 

func (bc *BTrDBConnection) QueryStandardValues(uuid uuid.UUID, start_time int64, end_time int64, version uint64) (chan StandardValue, chan uint64, chan string, error)

Makes a Standard Values Query for data in the specified stream, at the specified version, in the specified time range. A version number of 0 means to use the latest version of the stream.

Returns three channels and an error. The first channel contains the points satisfying the query. The second channel contains a single value, which is the version of the stream used to satisfy the query. In case BTrDB returns an error code, the third channel will contain a string describing the error. If the operation completes successfully, nothing is sent on this channel; it remains open until all points are consumed from the first channel. The fourth value returned is an error, used if the request cannot be sent to the database.

func (*BTrDBConnection) QueryStatisticalValues 

func (bc *BTrDBConnection) QueryStatisticalValues(uuid uuid.UUID, start_time int64, end_time int64, point_width uint8, version uint64) (chan StatisticalValue, chan uint64, chan string, error)

Makes a Statistical Values Query. Data in the specified stream, at the specified version, in the specified time range, is broken up into time intervals, each 1 << point_width nanoseconds in size. For each time interval, a statistical aggregate of the data in the interval is generated containing the number of data points in the interval, and the minimum, mean, and maximum values of data in the interval. A version number of 0 means to use the latest version of the stream.

Should the start and end times not line up with the sizes of the intervals, they are rounded down before making the query. The point_width parameter must be an integer in the interval [0, 62].

Return values are the same as in QueryStandardValues.

func (*BTrDBConnection) QueryVersion 

func (bc *BTrDBConnection) QueryVersion(uuids []uuid.UUID) (chan uint64, chan string, error)

Makes a Version Query for the version corresponding to each of the streams specified by the provided UUIDs.

Returns two channels and an error. The first channel contains the version numbers of the streams, in the same order as they were queried. In case BTrDB returns an error code, the third channel will contain a string describing the error (if the operation completes successfully, nothing is sent on this channel). The fourth value returned is an error, used if the request cannot be sent to the database.

func (*BTrDBConnection) QueryWindowValues 

func (bc *BTrDBConnection) QueryWindowValues(uuid uuid.UUID, start_time int64, end_time int64, width uint64, depth uint8, version uint64) (chan StatisticalValue, chan uint64, chan string, error)

Makes a Statistical Values Query. Data in the specified stream, at the specified version, in the specified time range, is broken up into time intervals, of the specified width, in nanoseconds. For each time interval, a statistical aggregate of the data in the interval is generated containing the number of data points in the interval, and the minimum, mean, and maximum values of data in the interval. The endpoints of the intervals are precise up to 1 << depth nanoseconds; the query is more performant for larger values of depth. A version number of 0 means to use the latest version of the stream.

Should the start and end times not line up with the sizes of the intervals, they are rounded down before making the query. The depth parameter must be an integer in the interval [0, 62].

Return values are the same as in QueryStandardValues.

type StandardValue 

type StandardValue struct {
	Time  int64
	Value float64
}

Represents a single data point.

type StatisticalValue 

type StatisticalValue struct {
	Time  int64
	Count uint64
	Min   float64
	Mean  float64
	Max   float64
}

Represents statistics over a range of data.

type TimeRange 

type TimeRange struct {
	StartTime int64
	EndTime   int64
}

Represents an interval of time that is closed on the start and open on the end. In other words, represents [StartTime, EndTime).

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