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local.go
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local.go
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// Copyright (C) 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package master
import (
"context"
"fmt"
"reflect"
"sync"
"time"
"github.com/google/gapid/core/app/crash"
"github.com/google/gapid/core/event"
"github.com/google/gapid/test/robot/search"
"github.com/google/gapid/test/robot/search/eval"
)
const masterName = "Master"
const keepaliveFrequency = time.Second * 10
var satelliteClass = reflect.TypeOf(&Satellite{})
type local struct {
satelliteLock sync.Mutex
satellites []*satellite
nextID int32
keepalive *time.Ticker
onChange event.Broadcast
}
// NewLocal creates a new local Master that manages it's own satellites.
func NewLocal(ctx context.Context) Master {
l := &local{
keepalive: time.NewTicker(keepaliveFrequency),
}
crash.Go(func() { l.run(ctx) })
return l
}
func (m *local) Close(ctx context.Context) {
m.keepalive.Stop()
}
// Search implements Master.Search
// It searches the set of active satellites, and supports monitoring of satellites as they start orbiting.
func (m *local) Search(ctx context.Context, query *search.Query, handler SatelliteHandler) error {
filter := eval.Filter(ctx, query, satelliteClass, event.AsHandler(ctx, handler))
initial := m.producer(ctx)
if query.Monitor {
return event.Monitor(ctx, &m.satelliteLock, m.onChange.Listen, initial, filter)
}
return event.Feed(ctx, filter, initial)
}
// Orbit implements Master.Orbit
// It will start orbiting the master, and will not return until it leaves orbit.
func (m *local) Orbit(ctx context.Context, services ServiceList, commands CommandHandler) error {
sat := m.addSatellite(ctx, services)
defer m.removeSatellite(ctx, sat)
crash.Go(func() {
sat.sendCommand(ctx, &Command{Do: &Command_Identify{Identify: &Identify{Name: sat.info.Name}}})
})
sat.processCommands(ctx, commands)
return nil
}
// Shutdown implements Master.Shutdown
// It broadcasts the shutdown message to all satellites currently orbiting the master.
func (m *local) Shutdown(ctx context.Context, request *ShutdownRequest) (*ShutdownResponse, error) {
command := &Command{Do: &Command_Shutdown{Shutdown: request.Shutdown}}
response := &ShutdownResponse{}
return response, m.broadcast(ctx, command, request.To)
}
func (m *local) getSatellites() []*satellite {
m.satelliteLock.Lock()
defer m.satelliteLock.Unlock()
return append([]*satellite(nil), m.satellites...)
}
func (m *local) producer(ctx context.Context) event.Producer {
i := 0
return func(ctx context.Context) interface{} {
if i >= len(m.satellites) {
return nil
}
res := m.satellites[i]
i++
return res
}
}
func (m *local) addSatellite(ctx context.Context, services ServiceList) *satellite {
m.satelliteLock.Lock()
defer m.satelliteLock.Unlock()
// generate the name and modify the list under the lock
name := ""
switch {
case services.Master:
name = fmt.Sprintf("Master_%d", m.nextID)
case services.Worker:
name = fmt.Sprintf("Worker_%d", m.nextID)
case services.Web:
name = fmt.Sprintf("Web_%d", m.nextID)
}
m.nextID++
sat := newSatellite(ctx, name, services)
m.satellites = append(m.satellites, sat)
return sat
}
func (m *local) removeSatellite(ctx context.Context, sat *satellite) error {
m.satelliteLock.Lock()
defer m.satelliteLock.Unlock()
// find and remove the satellite from the list
for i, e := range m.satellites {
if e == sat {
m.satellites = append(m.satellites[:i], m.satellites[i+1:]...)
break
}
}
return nil
}
func serverInList(name string, servers []string) bool {
if len(servers) == 0 {
return true
}
for _, s := range servers {
if s == name {
return true
}
}
return false
}
func (m *local) broadcast(ctx context.Context, command *Command, to []string) error {
// First send the command to all the registered services that match the to list
for _, sat := range m.getSatellites() {
if !serverInList(sat.info.Name, to) {
continue
}
sat.sendCommand(ctx, command)
}
return nil
}
func (m *local) run(ctx context.Context) {
ping := &Command{Do: &Command_Ping{Ping: &Ping{}}}
// each time a tick happens
for _ = range m.keepalive.C {
// ping all the satellites to see if they are still up
for _, sat := range m.getSatellites() {
sat.sendCommand(ctx, ping)
}
}
}