/
server.go
244 lines (212 loc) · 5.94 KB
/
server.go
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package server
import (
"context"
"fmt"
"net/http"
"strings"
"github.com/gin-gonic/gin"
"github.com/gorilla/websocket"
"github.com/hasura/pgdeltastream/db"
"github.com/hasura/pgdeltastream/types"
log "github.com/sirupsen/logrus"
)
var wsupgrader = websocket.Upgrader{
ReadBufferSize: 1024,
WriteBufferSize: 1024,
}
func StartServer(host string, port int) {
var err error
session := &types.Session{}
r := gin.Default()
v1 := r.Group("/v1")
{
v1.GET("/init", func(c *gin.Context) {
err = initDB(session)
if err != nil {
e := fmt.Sprintf("unable to init session")
log.WithError(err).Error(e)
c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{
"error": e,
})
return
}
c.JSON(http.StatusOK, gin.H{
"slotName": session.SlotName,
})
})
snapshotRoute := v1.Group("/snapshot")
{
snapshotRoute.POST("/data", func(c *gin.Context) {
if session.SnapshotName == "" {
e := fmt.Sprintf("snapshot not available: call /init to initialize a new slot and snapshot")
log.Error(e)
c.AbortWithStatusJSON(http.StatusServiceUnavailable, gin.H{
"error": e,
})
return
}
// get data with table, offset, limits
var postData types.SnapshotDataJSON
//err = c.MustBindWith(&postData, binding.JSON)
err = c.ShouldBindJSON(&postData)
if err != nil {
e := fmt.Sprintf("invalid input JSON")
log.WithError(err).Error(e)
c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{
"error": e,
})
return
}
err = validateSnapshotDataJSON(&postData)
if err != nil {
e := err.Error()
log.WithError(err).Error(e)
c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{
"error": e,
})
return
}
log.Infof("Snapshot data requested for table: %s, offset: %d, limit: %d", postData.Table, *postData.Offset, *postData.Limit)
data, err := snapshotData(session, &postData)
if err != nil {
e := fmt.Sprintf("unable to get snapshot data")
log.WithError(err).Error(e)
c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{
"error": e,
})
return
}
c.JSON(http.StatusOK, data)
})
/*
snapshotRoute.GET("/end", func(c *gin.Context) {
// end snapshot
c.String(200, "end") // TODO
})
*/
}
lrRoute := v1.Group("/lr")
{
lrRoute.GET("/stream", func(c *gin.Context) { // /stream?slotName=my_slot
slotName := c.Query("slotName")
if slotName == "" {
e := fmt.Sprintf("no slotName provided")
log.WithError(err).Error(e)
c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{
"error": e,
})
return
}
log.Info("LR Stream requested for slot ", slotName)
session.SlotName = slotName
// now upgrade the HTTP connection to a websocket connection
wsConn, err := wsupgrader.Upgrade(c.Writer, c.Request, nil)
if err != nil {
e := fmt.Sprintf("could not upgrade to websocket connection")
log.WithError(err).Error(e)
c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{
"error": e,
})
return
}
session.WSConn = wsConn
// begin streaming
err = lrStream(session)
if err != nil {
e := fmt.Sprintf("could not create stream")
log.WithError(err).Error(e)
c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{
"error": e,
})
return
}
})
}
}
r.Run(fmt.Sprintf("%s:%d", host, port))
}
// create replication slot ex and get snapshot name, consistent point
// return slotname
func initDB(session *types.Session) error {
var err error
// initilize the connections for the session
resetSession(session)
err = db.Init(session)
if err != nil {
return err
}
return nil
}
// validate fields in the snapshot data request JSON
func validateSnapshotDataJSON(requestData *types.SnapshotDataJSON) error {
ob := requestData.OrderBy
if ob != nil {
if ob.Column == "" {
return fmt.Errorf("required field 'column' missing in 'order_by'")
}
if !(strings.EqualFold(ob.Order, "asc") || strings.EqualFold(ob.Order, "desc")) {
return fmt.Errorf("order_by order direction can only be either 'ASC' or 'DESC'")
}
}
return nil
}
func snapshotData(session *types.Session, requestData *types.SnapshotDataJSON) ([]map[string]interface{}, error) {
return db.SnapshotData(session, requestData)
}
func lrStream(session *types.Session) error {
// reset the connections
err := resetSession(session)
if err != nil {
log.WithError(err).Error("Could not create replication connection")
return fmt.Errorf("Could not create replication connection")
}
wsErr := make(chan error, 1)
go db.LRListenAck(session, wsErr) // concurrently listen on the ws for ack messages
go db.LRStream(session) // listen for WAL messages and send them over ws
select {
/*case <-c.Writer.CloseNotify(): // ws closed // ?this doesn't work?
log.Warn("Websocket connection closed. Cancelling context.")
cancelFunc()
*/
case <-wsErr: // ws closed
log.Warn("Websocket connection closed. Cancelling context.")
// cancel session context
session.CancelFunc()
// close connections
err = session.WSConn.Close()
if err != nil {
log.WithError(err).Error("Could not close websocket connection")
}
err = session.ReplConn.Close()
if err != nil {
log.WithError(err).Error("Could not close replication connection")
}
}
return nil
}
// Cancel the currently running session
// Recreate replication connection
func resetSession(session *types.Session) error {
var err error
// cancel the currently running session
if session.CancelFunc != nil {
session.CancelFunc()
}
// close websocket connection
if session.WSConn != nil {
//err = session.WSConn.Close()
if err != nil {
return err
}
}
// create new context
ctx, cancelFunc := context.WithCancel(context.Background())
session.Ctx = ctx
session.CancelFunc = cancelFunc
// create the replication connection
err = db.CheckAndCreateReplConn(session)
if err != nil {
return err
}
return nil
}