wings/server/state.go

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package server
import (
"encoding/json"
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"fmt"
"github.com/pkg/errors"
"github.com/pterodactyl/wings/config"
"github.com/pterodactyl/wings/environment"
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"io"
"io/ioutil"
"os"
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"sync"
)
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var stateMutex sync.Mutex
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// Returns the state of the servers.
func CachedServerStates() (map[string]string, error) {
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// Request a lock after we check if the file exists.
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stateMutex.Lock()
defer stateMutex.Unlock()
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// Open the states file.
f, err := os.OpenFile(config.Get().System.GetStatesPath(), os.O_RDONLY|os.O_CREATE, 0644)
if err != nil {
return nil, errors.WithStack(err)
}
defer f.Close()
// Convert the json object to a map.
states := map[string]string{}
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if err := json.NewDecoder(f).Decode(&states); err != nil && err != io.EOF {
return nil, errors.WithStack(err)
}
return states, nil
}
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// saveServerStates .
func saveServerStates() error {
// Get the states of all servers on the daemon.
states := map[string]string{}
for _, s := range GetServers().All() {
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states[s.Id()] = s.GetState()
}
// Convert the map to a json object.
data, err := json.Marshal(states)
if err != nil {
return errors.WithStack(err)
}
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stateMutex.Lock()
defer stateMutex.Unlock()
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// Write the data to the file
if err := ioutil.WriteFile(config.Get().System.GetStatesPath(), data, 0644); err != nil {
return errors.WithStack(err)
}
return nil
}
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// Sets the state of the server internally. This function handles crash detection as
// well as reporting to event listeners for the server.
func (s *Server) SetState(state string) error {
if state != environment.ProcessOfflineState &&
state != environment.ProcessStartingState &&
state != environment.ProcessRunningState &&
state != environment.ProcessStoppingState {
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return errors.New(fmt.Sprintf("invalid server state received: %s", state))
}
prevState := s.GetState()
// Update the currently tracked state for the server.
s.Proc().setInternalState(state)
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// Emit the event to any listeners that are currently registered.
if prevState != state {
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s.Log().WithField("status", s.Proc().getInternalState()).Debug("saw server status change event")
s.Events().Publish(StatusEvent, s.Proc().getInternalState())
}
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// Persist this change to the disk immediately so that should the Daemon be stopped or
// crash we can immediately restore the server state.
//
// This really only makes a difference if all of the Docker containers are also stopped,
// but this was a highly requested feature and isn't hard to work with, so lets do it.
//
// We also get the benefit of server status changes always propagating corrected configurations
// to the disk should we forget to do it elsewhere.
go func() {
if err := saveServerStates(); err != nil {
s.Log().WithField("error", err).Warn("failed to write server states to disk")
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}
}()
// Reset the resource usage to 0 when the process fully stops so that all of the UI
// views in the Panel correctly display 0.
if state == environment.ProcessOfflineState {
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s.resources.mu.Lock()
s.resources.Empty()
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s.resources.mu.Unlock()
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s.emitProcUsage()
}
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// If server was in an online state, and is now in an offline state we should handle
// that as a crash event. In that scenario, check the last crash time, and the crash
// counter.
//
// In the event that we have passed the thresholds, don't do anything, otherwise
// automatically attempt to start the process back up for the user. This is done in a
// separate thread as to not block any actions currently taking place in the flow
// that called this function.
if (prevState == environment.ProcessStartingState || prevState == environment.ProcessRunningState) && s.GetState() == environment.ProcessOfflineState {
s.Log().Info("detected server as entering a crashed state; running crash handler")
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go func(server *Server) {
if err := server.handleServerCrash(); err != nil {
if IsTooFrequentCrashError(err) {
server.Log().Info("did not restart server after crash; occurred too soon after the last")
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} else {
server.Log().WithField("error", err).Error("failed to handle server crash")
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}
}
}(s)
}
return nil
}
// Returns the current state of the server in a race-safe manner.
func (s *Server) GetState() string {
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return s.Proc().getInternalState()
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}
// Determines if the server state is running or not. This is different than the
// environment state, it is simply the tracked state from this daemon instance, and
// not the response from Docker.
func (s *Server) IsRunning() bool {
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st := s.GetState()
return st == environment.ProcessRunningState || st == environment.ProcessStartingState
}