128 lines
3.2 KiB
Go
128 lines
3.2 KiB
Go
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package server
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import (
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"encoding/json"
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"fmt"
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"time"
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)
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// ----------------
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// Discovery struct
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// ----------------
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const TimeToLife = 60 // when server won't occur in the discovery channel longer than this, it should be considered as not-alive
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// Discovery contains information about a single server and is used for server discovery
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type Discovery struct {
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Hostname string `json:"hostname"`
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Labels []string `json:"labels"`
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// For internal use to check if the server is still alive.
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// Contains timestamp of the last check.
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LastCheck int64 `json:"last_check"`
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}
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// Validate checks all values in the struct if the content is valid
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func (d *Discovery) Validate() error {
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// TODO: implement
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return nil
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}
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// IsAlive return true if the server should be considered as alive
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func (d *Discovery) IsAlive() bool {
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return time.Now().Unix()-d.LastCheck < TimeToLife
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}
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func (d *Discovery) Bytes() ([]byte, error) {
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data, err := json.Marshal(d)
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return data, err
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}
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// -----------------
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// Discovery storage
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// -----------------
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// Discoveries helps to store instances of Discovery struct and access them in thread safe mode
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type Discoveries struct {
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activeServers []Discovery
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LogChannel chan string
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}
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// Add appends a new discovery/server to the storage
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func (d *Discoveries) Add(discovery Discovery) {
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if d.Exist(discovery.Hostname) {
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d.Refresh(discovery.Hostname)
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return
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}
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discovery.LastCheck = time.Now().Unix()
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d.activeServers = append(d.activeServers, discovery)
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if d.LogChannel != nil {
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d.LogChannel <- fmt.Sprintf("%s registered", discovery.Hostname)
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}
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}
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// Refresh updates
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func (d *Discoveries) Refresh(hostname string) {
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for idx, discovery := range d.activeServers {
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if discovery.Hostname == hostname {
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d.activeServers[idx].LastCheck = time.Now().Unix()
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}
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}
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}
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// Delete removes server identified by hostname from the storage
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func (d *Discoveries) Delete(hostname string) {
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if d.LogChannel != nil {
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d.LogChannel <- fmt.Sprintf("removing %s", hostname)
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}
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newSet := []Discovery{}
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for _, server := range d.activeServers {
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if server.Hostname != hostname {
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newSet = append(newSet, server)
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}
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}
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d.activeServers = newSet
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}
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// Exist returns true if server with given hostname exists
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func (d *Discoveries) Exist(hostname string) bool {
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for _, server := range d.activeServers {
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if server.Hostname == hostname {
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return true
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}
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}
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return false
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}
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// Get returns Discovery struct with the given hostname but it can be also an empty struct if it's not found. Check if hostname is empty or use Exist first to be sure.
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func (d *Discoveries) Get(hostname string) Discovery {
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for _, server := range d.activeServers {
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if server.Hostname == hostname {
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return server
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}
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}
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return Discovery{}
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}
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// GetAll returns copy of the internal storage
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func (d *Discoveries) GetAll() []Discovery {
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return d.activeServers
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}
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// Clean checks loops over last check values for each discovery object and removes it if it's passed
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func (d *Discoveries) Clean() {
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newSet := []Discovery{}
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for _, server := range d.activeServers {
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if server.IsAlive() {
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newSet = append(newSet, server)
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} else {
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if d.LogChannel != nil {
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d.LogChannel <- fmt.Sprintf("%s not alive anymore", server.Hostname)
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}
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}
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}
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d.activeServers = newSet
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}
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