dqlite

package module
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Published: Dec 4, 2019 License: Apache-2.0 Imports: 6 Imported by: 0

README

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This repository provides the go-dqlite Go package, containing bindings for the dqlite C library and a pure-Go client for the dqlite wire protocol.

Usage

The best way to understand how to use the go-dqlite package is probably by looking at the source code of the demo program and use it as example.

Build

In order to use the go-dqlite package in your application, you'll need to have the dqlite C library installed on your system, along with its dependencies. You then need to pass the -tags argument to the Go tools when building or testing your packages, for example:

go build -tags libsqlite3
go test -tags libsqlite3

Documentation

The documentation for this package can be found on Godoc.

Demo

To see dqlite in action, either install the Debian package from the PPA:

sudo add-apt-repository -y ppa:dqlite/stable
sudo apt install dqlite libdqlite-dev

or build the dqlite C library and its dependencies from source, as described here, and then run:

go install -tags libsqlite3 ./cmd/dqlite-demo

from the top-level directory of this repository.

Once the dqlite-demo binary is installed, start three nodes of the demo application, respectively with IDs 1, 2, and 3:

dqlite-demo start 1 &
dqlite-demo start 2 &
dqlite-demo start 3 &

The node with ID 1 automatically becomes the leader of a single node cluster, while the nodes with IDs 2 and 3 are waiting to be notified what cluster they belong to. Let's make nodes 2 and 3 join the cluster:

dqlite-demo add 2
dqlite-demo add 3

Now we can start using the cluster. The demo application is just a simple key/value store that stores data in a SQLite table. Let's insert a key pair:

dqlite-demo update my-key my-value

and then retrive it from the database:

dqlite-demo query my-key

Currently node 1 is the leader. If we stop it and then try to query the key again we'll notice that the query command hangs for a bit waiting for the failover to occur and for another node to step up as leader:

kill -TERM %1; sleep 0.1; dqlite-demo query my-key; dqlite-demo cluster

Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func ConfigMultiThread added in v1.2.0

func ConfigMultiThread() error

ConfigMultiThread sets the threading mode of SQLite to Multi-thread.

By default go-dqlite configures SQLite to Single-thread mode, because the dqlite engine itself is single-threaded, and enabling Multi-thread or Serialized modes would incur in a performance penality.

If your Go process also uses SQLite directly (e.g. using the github.com/mattn/go-sqlite3 bindings) you might need to switch to Multi-thread mode in order to be thread-safe.

IMPORTANT: It's possible to successfully change SQLite's threading mode only if no SQLite APIs have been invoked yet (e.g. no database has been opened yet). Therefore you'll typically want to call ConfigMultiThread() very early in your process setup. Alternatively you can set the GO_DQLITE_MULTITHREAD environment variable to 1 at process startup, in order to prevent go-dqlite from setting Single-thread mode at all.

Types

type Node added in v1.0.0

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

Node runs a dqlite node.

func New added in v1.0.0

func New(id uint64, address string, dir string, options ...Option) (*Node, error)

New creates a new Node instance.

func (*Node) BindAddress added in v1.0.0

func (s *Node) BindAddress() string

BindAddress returns the network address the node is listening to.

func (*Node) Close added in v1.0.0

func (s *Node) Close() error

Close the server, releasing all resources it created.

func (*Node) Recover added in v1.1.0

func (s *Node) Recover(cluster []NodeInfo) error

Recover a node by forcing a new cluster configuration.

func (*Node) Start added in v1.0.0

func (s *Node) Start() error

Start serving requests.

type NodeInfo added in v1.0.0

type NodeInfo = client.NodeInfo

NodeInfo is a convenience alias for client.NodeInfo.

type Option added in v1.0.0

type Option func(*options)

Option can be used to tweak node parameters.

func WithBindAddress added in v1.0.0

func WithBindAddress(address string) Option

WithBindAddress sets a custom bind address for the server.

func WithDialFunc

func WithDialFunc(dial client.DialFunc) Option

WithDialFunc sets a custom dial function for the server.

func WithNetworkLatency added in v1.0.0

func WithNetworkLatency(latency time.Duration) Option

WithNetworkLatency sets the average one-way network latency.

Directories

Path Synopsis
cmd
internal

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