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server.go
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server.go
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package main
import (
"context"
"encoding/json"
"errors"
"fmt"
"log"
"net"
"net/http"
"pitchlake-backend/db"
"pitchlake-backend/models"
"sync"
"time"
"github.com/coder/websocket"
)
// dbServer enables broadcasting to a set of subscribers.
type dbServer struct {
// subscriberMessageBuffer controls the max number
// of messages that can be queued for a subscriber
// before it is kicked.
//
// Defaults to 16.
subscriberMessageBuffer int
db *db.DB
// publishLimiter controls the rate limit applied to the publish endpoint.
//
// Defaults to one publish every 100ms with a burst of 8.
// logf controls where logs are sent.
// Defaults to log.Printf.
logf func(f string, v ...interface{})
// serveMux routes the various endpoints to the appropriate handler.
serveMux http.ServeMux
subscribersVaultMu sync.Mutex
subscribersVault map[string]map[*subscriber]struct{}
subscribersHomeMu sync.Mutex
subscribersHome map[*subscriber]struct{}
}
// subscriber represents a subscriber.
// Messages are sent on the msgs channel and if the client
// cannot keep up with the messages, closeSlow is called.
type subscriber struct {
msgs chan []byte
address string
userType string
optionRound uint64
closeSlow func()
}
type subscriberMessage struct {
Address string `json:"address"`
UserType string `json:"user_type"`
View string `json:"view"`
OptionRound uint64 `json:"option_round"`
}
// newdbServer constructs a dbServer with the defaults.
// Create a custom context for the server here and pass it to the db package
func newDBServer() *dbServer {
db := &db.DB{}
connString := ""
db.Init(connString)
dbs := &dbServer{
subscriberMessageBuffer: 16,
logf: log.Printf,
subscribersVault: make(map[string]map[*subscriber]struct{}),
subscribersHome: make(map[*subscriber]struct{}),
db: db,
}
dbs.serveMux.Handle("/", http.FileServer(http.Dir(".")))
dbs.serveMux.HandleFunc("/subscribeHome", dbs.subscribeHomeHandler)
dbs.serveMux.HandleFunc("/subscribeVault", dbs.subscribeVaultHandler)
dbs.listener()
return dbs
}
func (dbs *dbServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
dbs.serveMux.ServeHTTP(w, r)
}
func (dbs *dbServer) subscribeHomeHandler(w http.ResponseWriter, r *http.Request) {
err := dbs.subscribeHome(r.Context(), w, r)
if errors.Is(err, context.Canceled) {
return
}
if websocket.CloseStatus(err) == websocket.StatusNormalClosure ||
websocket.CloseStatus(err) == websocket.StatusGoingAway {
return
}
if err != nil {
dbs.logf("%v", err)
return
}
}
// subscribeHandler accepts the WebSocket connection and then subscribes
// it to all future messages.
func (dbs *dbServer) subscribeVaultHandler(w http.ResponseWriter, r *http.Request) {
err := dbs.subscribeVault(r.Context(), w, r)
if errors.Is(err, context.Canceled) {
return
}
if websocket.CloseStatus(err) == websocket.StatusNormalClosure ||
websocket.CloseStatus(err) == websocket.StatusGoingAway {
return
}
if err != nil {
dbs.logf("%v", err)
return
}
}
// subscribe subscribes the given WebSocket to all broadcast messages.
// It creates a subscriber with a buffered msgs chan to give some room to slower
// connections and then registers the subscriber. It then listens for all messages
// and writes them to the WebSocket. If the context is cancelled or
// an error occurs, it returns and deletes the subscription.
//
// It uses CloseRead to keep reading from the connection to process control
// messages and cancel the context if the connection drops.
func (dbs *dbServer) subscribeVault(ctx context.Context, w http.ResponseWriter, r *http.Request) error {
var mu sync.Mutex
var c *websocket.Conn
var closed bool
//Extract address from the request and add here
decoder := json.NewDecoder(r.Body)
var sm subscriberMessage
decoder.Decode(&sm)
s := &subscriber{
address: sm.Address,
userType: sm.UserType,
msgs: make(chan []byte, dbs.subscriberMessageBuffer),
closeSlow: func() {
mu.Lock()
defer mu.Unlock()
closed = true
if c != nil {
c.Close(websocket.StatusPolicyViolation, "connection too slow to keep up with messages")
}
},
}
dbs.addSubscriber(s, "Vault")
defer dbs.deleteSubscriber(s, "Vault")
c2, err := websocket.Accept(w, r, nil)
if err != nil {
return err
}
mu.Lock()
if closed {
mu.Unlock()
return net.ErrClosed
}
c = c2
mu.Unlock()
defer c.CloseNow()
ctx = c.CloseRead(ctx)
//Send initial payload here
var vaultSubscription models.VaultSubscription
vaultState, err := dbs.db.GetVaultStateByID(s.address)
if sm.OptionRound != 0 {
optionRoundState, err := dbs.db.GetOptionRoundByID(sm.OptionRound)
if err != nil {
return err
}
vaultSubscription.OptionRoundState = *optionRoundState
} else {
optionRoundState, err := dbs.db.GetOptionRoundByAddress(vaultState.CurrentRoundAddress)
if err != nil {
return err
}
vaultSubscription.OptionRoundState = *optionRoundState
}
vaultSubscription.VaultState = *vaultState
if err != nil {
return err
}
if sm.UserType == "lp" {
lpState, err := dbs.db.GetLiquidityProviderStateByAddress(s.address)
if err != nil {
return err
}
vaultSubscription.LiquidityProviderState = *lpState
} else if sm.UserType == "ob" {
obState, err := dbs.db.GetOptionBuyerByAddress(s.address)
if err != nil {
return err
}
vaultSubscription.OptionBuyerState = *obState
} else {
return errors.New("invalid user type")
}
// Marshal the VaultState to a JSON byte array
jsonPayload, err := json.Marshal(vaultSubscription)
if err != nil {
return err
}
writeTimeout(ctx, time.Second*5, c, jsonPayload)
for {
select {
case msg := <-s.msgs:
err := writeTimeout(ctx, time.Second*5, c, msg)
if err != nil {
return err
}
case <-ctx.Done():
return ctx.Err()
}
}
}
func (dbs *dbServer) subscribeHome(ctx context.Context, w http.ResponseWriter, r *http.Request) error {
var mu sync.Mutex
var c *websocket.Conn
var closed bool
//Extract address from the request and add here
decoder := json.NewDecoder(r.Body)
var sm subscriberMessage
decoder.Decode(&sm)
s := &subscriber{
msgs: make(chan []byte, dbs.subscriberMessageBuffer),
closeSlow: func() {
mu.Lock()
defer mu.Unlock()
closed = true
if c != nil {
c.Close(websocket.StatusPolicyViolation, "connection too slow to keep up with messages")
}
},
}
dbs.addSubscriber(s, "Vault")
defer dbs.deleteSubscriber(s, "Vault")
c2, err := websocket.Accept(w, r, nil)
if err != nil {
return err
}
mu.Lock()
if closed {
mu.Unlock()
return net.ErrClosed
}
c = c2
mu.Unlock()
defer c.CloseNow()
ctx = c.CloseRead(ctx)
//Send initial payload here
writeTimeout(ctx, time.Second*5, c, []byte("subscribed"))
for {
select {
case msg := <-s.msgs:
err := writeTimeout(ctx, time.Second*5, c, msg)
if err != nil {
return err
}
case <-ctx.Done():
return ctx.Err()
}
}
}
func (dbs *dbServer) listener() {
_, err := dbs.db.Conn.Exec(context.Background(), "LISTEN lp_update")
if err != nil {
log.Fatal(err)
}
_, err = dbs.db.Conn.Exec(context.Background(), "LISTEN vault_update")
if err != nil {
log.Fatal(err)
}
_, err = dbs.db.Conn.Exec(context.Background(), "LISTEN state_transition")
if err != nil {
log.Fatal(err)
}
_, err = dbs.db.Conn.Exec(context.Background(), "LISTEN ob_update")
if err != nil {
log.Fatal(err)
}
_, err = dbs.db.Conn.Exec(context.Background(), "LISTEN or_update")
if err != nil {
log.Fatal(err)
}
fmt.Println("Waiting for notifications...")
for {
// Wait for a notification
notification, err := dbs.db.Conn.WaitForNotification(context.Background())
if err != nil {
log.Fatal(err)
}
//Process notification here
switch notification.Channel {
case "lp_update":
fmt.Println("Received an update on lp_row_update")
case "vault_update":
fmt.Println("Received an update on vault_update")
case "state_transition":
//Push this to all channels (without address as well)
fmt.Println("Received an update on state_transition")
case "ob_update":
fmt.Println("Received an update on ob_update")
case "or_update":
fmt.Println("Received an update on or_update")
}
dbs.publishAddress(notification.Channel, []byte(notification.Payload))
dbs.publishAll([]byte(notification.Payload))
}
}
// publishUser sends a message to all subscribers of a specific address.
func (dbs *dbServer) publishAddress(address string, msg []byte) {
dbs.subscribersVaultMu.Lock()
defer dbs.subscribersVaultMu.Unlock()
for s := range dbs.subscribersVault[address] {
select {
case s.msgs <- msg:
default:
go s.closeSlow()
}
}
}
// publishAll sends a message to all subscribers of all addresses.
func (dbs *dbServer) publishAll(msg []byte) {
dbs.subscribersVaultMu.Lock()
defer dbs.subscribersVaultMu.Unlock()
for address := range dbs.subscribersVault {
for s := range dbs.subscribersVault[address] {
select {
case s.msgs <- msg:
default:
go s.closeSlow()
}
}
}
}
// addSubscriber registers a subscriber.
func (dbs *dbServer) addSubscriber(s *subscriber, subscriptionType string) {
if subscriptionType == "Vault" {
dbs.subscribersVaultMu.Lock()
dbs.subscribersVault[s.address][s] = struct{}{}
dbs.subscribersVaultMu.Unlock()
} else if subscriptionType == "Home" {
dbs.subscribersHomeMu.Lock()
dbs.subscribersHome[s] = struct{}{}
dbs.subscribersHomeMu.Unlock()
}
}
// deleteSubscriber deletes the given subscriber.
func (dbs *dbServer) deleteSubscriber(s *subscriber, subscriptionType string) {
if subscriptionType == "Vault" {
dbs.subscribersVaultMu.Lock()
delete(dbs.subscribersVault[s.address], s)
dbs.subscribersVaultMu.Unlock()
} else if subscriptionType == "Home" {
dbs.subscribersHomeMu.Lock()
delete(dbs.subscribersHome, s)
dbs.subscribersHomeMu.Unlock()
}
}
func writeTimeout(ctx context.Context, timeout time.Duration, c *websocket.Conn, msg []byte) error {
ctx, cancel := context.WithTimeout(ctx, timeout)
defer cancel()
return c.Write(ctx, websocket.MessageText, msg)
}