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exchange_manager.go
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exchange_manager.go
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package engine
import (
"errors"
"fmt"
"strings"
"sync"
"time"
exchange "github.com/thrasher-corp/gocryptotrader/exchanges"
"github.com/thrasher-corp/gocryptotrader/log"
)
// vars related to exchange functions
var (
ErrNoExchangesLoaded = errors.New("no exchanges have been loaded")
ErrExchangeNotFound = errors.New("exchange not found")
ErrExchangeAlreadyLoaded = errors.New("exchange already loaded")
ErrExchangeFailedToLoad = errors.New("exchange failed to load")
ErrExchangeNameIsEmpty = errors.New("exchange name is empty")
errExchangeIsNil = errors.New("exchange is nil")
)
// CustomExchangeBuilder interface allows external applications to create
// custom/unsupported exchanges that satisfy the IBotExchange interface.
type CustomExchangeBuilder interface {
NewExchangeByName(name string) (exchange.IBotExchange, error)
}
// ExchangeManager manages what exchanges are loaded
type ExchangeManager struct {
mtx sync.Mutex
exchanges map[string]exchange.IBotExchange
Builder CustomExchangeBuilder
}
// NewExchangeManager creates a new exchange manager
func NewExchangeManager() *ExchangeManager {
return &ExchangeManager{
exchanges: make(map[string]exchange.IBotExchange),
}
}
// Add adds an exchange
func (m *ExchangeManager) Add(exch exchange.IBotExchange) error {
if m == nil {
return fmt.Errorf("exchange manager: %w", ErrNilSubsystem)
}
if exch == nil {
return fmt.Errorf("exchange manager: %w", errExchangeIsNil)
}
m.mtx.Lock()
defer m.mtx.Unlock()
_, ok := m.exchanges[strings.ToLower(exch.GetName())]
if ok {
return fmt.Errorf("exchange manager: %s %w", exch.GetName(), ErrExchangeAlreadyLoaded)
}
m.exchanges[strings.ToLower(exch.GetName())] = exch
return nil
}
// GetExchanges returns all stored exchanges
func (m *ExchangeManager) GetExchanges() ([]exchange.IBotExchange, error) {
if m == nil {
return nil, fmt.Errorf("exchange manager: %w", ErrNilSubsystem)
}
m.mtx.Lock()
defer m.mtx.Unlock()
exchs := make([]exchange.IBotExchange, 0, len(m.exchanges))
for _, exch := range m.exchanges {
exchs = append(exchs, exch)
}
return exchs, nil
}
// RemoveExchange removes an exchange from the manager
func (m *ExchangeManager) RemoveExchange(exchangeName string) error {
if m == nil {
return fmt.Errorf("exchange manager: %w", ErrNilSubsystem)
}
if exchangeName == "" {
return fmt.Errorf("exchange manager: %w", ErrExchangeNameIsEmpty)
}
m.mtx.Lock()
defer m.mtx.Unlock()
exch, ok := m.exchanges[strings.ToLower(exchangeName)]
if !ok {
return fmt.Errorf("exchange manager: %s %w", exchangeName, ErrExchangeNotFound)
}
err := exch.Shutdown()
if err != nil {
return fmt.Errorf("exchange manager: %w", err)
}
delete(m.exchanges, strings.ToLower(exchangeName))
log.Infof(log.ExchangeSys, "%s exchange unloaded successfully.\n", exchangeName)
return nil
}
// GetExchangeByName returns an exchange by its name if it exists
func (m *ExchangeManager) GetExchangeByName(exchangeName string) (exchange.IBotExchange, error) {
if m == nil {
return nil, fmt.Errorf("exchange manager: %w", ErrNilSubsystem)
}
if exchangeName == "" {
return nil, fmt.Errorf("exchange manager: %w", ErrExchangeNameIsEmpty)
}
m.mtx.Lock()
defer m.mtx.Unlock()
exch, ok := m.exchanges[strings.ToLower(exchangeName)]
if !ok {
return nil, fmt.Errorf("exchange manager: %s %w", exchangeName, ErrExchangeNotFound)
}
return exch, nil
}
// NewExchangeByName helps create a new exchange to be loaded
func (m *ExchangeManager) NewExchangeByName(name string) (exchange.IBotExchange, error) {
nameLower := strings.ToLower(name)
_, err := m.GetExchangeByName(nameLower)
if err != nil {
if !errors.Is(err, ErrExchangeNotFound) {
return nil, fmt.Errorf("exchange manager: %s %w", name, err)
}
} else {
return nil, fmt.Errorf("exchange manager: %s %w", name, ErrExchangeAlreadyLoaded)
}
if m.Builder != nil {
return m.Builder.NewExchangeByName(nameLower)
}
return NewSupportedExchangeByName(nameLower)
}
// Shutdown shuts down all exchanges and unloads them
func (m *ExchangeManager) Shutdown(shutdownTimeout time.Duration) error {
if m == nil {
return fmt.Errorf("exchange manager: %w", ErrNilSubsystem)
}
if shutdownTimeout < 0 {
shutdownTimeout = 0
}
var lockout sync.Mutex
timer := time.NewTimer(shutdownTimeout)
var wg sync.WaitGroup
m.mtx.Lock()
defer m.mtx.Unlock()
lockout.Lock()
for _, exch := range m.exchanges {
wg.Add(1)
go func(wg *sync.WaitGroup, mtx *sync.Mutex, exch exchange.IBotExchange) {
err := exch.Shutdown()
if err != nil {
log.Errorf(log.ExchangeSys, "%s failed to shutdown %v.\n", exch.GetName(), err)
} else {
mtx.Lock()
delete(m.exchanges, strings.ToLower(exch.GetName()))
mtx.Unlock()
}
wg.Done()
}(&wg, &lockout, exch)
}
lockout.Unlock()
ch := make(chan struct{})
go func(wg *sync.WaitGroup, finish chan<- struct{}) {
wg.Wait()
finish <- struct{}{}
}(&wg, ch)
select {
case <-timer.C:
// Possible deadlock in a number of operating exchanges.
lockout.Lock()
for name := range m.exchanges {
log.Warnf(log.ExchangeSys, "%s has failed to shutdown within %s, please review.\n", name, shutdownTimeout)
}
lockout.Unlock()
case <-ch:
// Every exchange has finished their shutdown call.
lockout.Lock()
for name := range m.exchanges {
log.Errorf(log.ExchangeSys, "%s has failed to shutdown due to error, please review.\n", name)
}
lockout.Unlock()
}
return nil
}