fluidb-old/http/service.go

// Package http provides the HTTP server for accessing the distributed database.
// It also provides the endpoint for other nodes to join an existing cluster.
package http

import (
	"encoding/json"
	"io/ioutil"
	"net"
	"net/http"
	"strings"
	"time"

	sql "github.com/otoolep/rqlite/db"
)

// Store is the interface the Raft-driven database must implement.
type Store interface {
	// Execute executes a slice of queries, each of which doesn't
	// return rows. It tx is true, then all queries will be executed
	// successfully or none will be.
	Execute(queries []string, tx bool) ([]*sql.Result, error)

	// Query executes a slice of queries, each of which returns rows.
	// If tx is true, then the query will take place while a read
	// transaction is held on the database.
	Query(queries []string, tx, leader, verify bool) ([]*sql.Rows, error)

	// Join joins the node, reachable at addr, to this node.
	Join(addr string) error

	// Leader returns the leader of the cluster.
	Leader() string

	// Stats returns stats on the Store.
	Stats() (map[string]interface{}, error)

	// Backup returns the byte stream of the backup file.
	Backup(leader bool) ([]byte, error)
}

// Response represents a response from the HTTP service.
type Response struct {
	Results interface{} `json:"results,omitempty"`
	Error   string      `json:"error,omitempty"`
	Time    float64     `json:"time,omitempty"`

	start time.Time
}

// NewResponse returns a new instance of response.
func NewResponse() *Response {
	return &Response{
		start: time.Now(),
	}
}

// Service provides HTTP service.
type Service struct {
	addr string       // Bind address of the HTTP service.
	ln   net.Listener // Service listener

	store Store // The Raft-backed database store.

	lastBackup time.Time // Time of last successful backup.
}

// New returns an uninitialized HTTP service.
func New(addr string, store Store) *Service {
	return &Service{
		addr:  addr,
		store: store,
	}
}

// Start starts the service.
func (s *Service) Start() error {
	server := http.Server{
		Handler: s,
	}

	ln, err := net.Listen("tcp", s.addr)
	if err != nil {
		return err
	}
	s.ln = ln

	go func() {
		err := server.Serve(s.ln)
		if err != nil {
			return
		}
	}()

	return nil
}

// Close closes the service.
func (s *Service) Close() {
	s.ln.Close()
	return
}

// ServeHTTP allows Service to serve HTTP requests.
func (s *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	switch {
	case strings.HasPrefix(r.URL.Path, "/db/execute"):
		s.handleExecute(w, r)
	case strings.HasPrefix(r.URL.Path, "/db/query"):
		s.handleQuery(w, r)
	case strings.HasPrefix(r.URL.Path, "/db/backup"):
		s.handleBackup(w, r)
	case strings.HasPrefix(r.URL.Path, "/join"):
		s.handleJoin(w, r)
	case strings.HasPrefix(r.URL.Path, "/status"):
		s.handleStatus(w, r)
	default:
		w.WriteHeader(http.StatusNotFound)
	}
}

// handleJoin handles cluster-join requests from other nodes.
func (s *Service) handleJoin(w http.ResponseWriter, r *http.Request) {
	b, err := ioutil.ReadAll(r.Body)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	m := map[string]string{}
	if err := json.Unmarshal(b, &m); err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}

	if len(m) != 1 {
		w.WriteHeader(http.StatusBadRequest)
		return
	}

	remoteAddr, ok := m["addr"]
	if !ok {
		w.WriteHeader(http.StatusBadRequest)
		return
	}

	if err := s.store.Join(remoteAddr); err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		return
	}
}

// handleBackup returns the consistent database snapshot.
func (s *Service) handleBackup(w http.ResponseWriter, r *http.Request) {
	if r.Method != "GET" {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}

	noLeader, err := noLeader(r)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	b, err := s.store.Backup(!noLeader)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		return
	}

	_, err = w.Write(b)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	s.lastBackup = time.Now()
}

// handleStatus returns status on the system.
func (s *Service) handleStatus(w http.ResponseWriter, r *http.Request) {
	if r.Method != "GET" {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}

	results, err := s.store.Stats()
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		return
	}

	httpStatus := map[string]interface{}{
		"addr": s.Addr().String(),
	}

	// Build the status response.
	status := map[string]interface{}{
		"store": results,
		"http":  httpStatus,
	}
	if !s.lastBackup.IsZero() {
		status["last_backup"] = s.lastBackup
	}

	pretty, _ := isPretty(r)
	var b []byte
	if pretty {
		b, err = json.MarshalIndent(status, "", "    ")
	} else {
		b, err = json.Marshal(status)
	}
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError) // Internal error actually
	} else {
		_, err = w.Write([]byte(b))
		if err != nil {
			w.WriteHeader(http.StatusInternalServerError)
		}
	}
}

// handleExecute handles queries that modify the database.
func (s *Service) handleExecute(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}

	resp := NewResponse()

	isTx, err := isTx(r)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	b, err := ioutil.ReadAll(r.Body)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	r.Body.Close()

	queries := []string{}
	if err := json.Unmarshal(b, &queries); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	results, err := s.store.Execute(queries, isTx)
	if err != nil {
		resp.Error = err.Error()

	} else {
		resp.Results = results
	}
	resp.Time = time.Now().Sub(resp.start).Seconds()
	writeResponse(w, r, resp)
}

// handleQuery handles queries that do not modify the database.
func (s *Service) handleQuery(w http.ResponseWriter, r *http.Request) {
	if r.Method != "GET" && r.Method != "POST" {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}

	resp := NewResponse()

	isTx, err := isTx(r)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	noLeader, err := noLeader(r)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	verify, err := verify(r)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Get the query statement(s), and do tx if necessary.
	queries := []string{}

	if r.Method == "GET" {
		query, err := stmtParam(r)
		if err != nil {
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		queries = []string{query}
	} else {
		b, err := ioutil.ReadAll(r.Body)
		if err != nil {
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		r.Body.Close()
		if err := json.Unmarshal(b, &queries); err != nil {
			w.WriteHeader(http.StatusBadRequest)
			return
		}
	}

	results, err := s.store.Query(queries, isTx, !noLeader, verify)
	if err != nil {
		resp.Error = err.Error()

	} else {
		resp.Results = results
	}
	resp.Time = time.Now().Sub(resp.start).Seconds()
	writeResponse(w, r, resp)
}

// Addr returns the address on which the Service is listening
func (s *Service) Addr() net.Addr {
	return s.ln.Addr()
}

func writeResponse(w http.ResponseWriter, r *http.Request, j *Response) {
	var b []byte
	var err error
	pretty, _ := isPretty(r)

	if pretty {
		b, err = json.MarshalIndent(j, "", "    ")
	} else {
		b, err = json.Marshal(j)
	}
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	_, err = w.Write(b)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
}

// queryParam returns whether the given query param is set to true.
func queryParam(req *http.Request, param string) (bool, error) {
	err := req.ParseForm()
	if err != nil {
		return false, err
	}
	if _, ok := req.Form[param]; ok {
		return true, nil
	}
	return false, nil
}

// stmtParam returns the value for URL param 'q', if present.
func stmtParam(req *http.Request) (string, error) {
	q := req.URL.Query()
	stmt := strings.TrimSpace(q.Get("q"))
	return stmt, nil
}

// isPretty returns whether the HTTP response body should be pretty-printed.
func isPretty(req *http.Request) (bool, error) {
	return queryParam(req, "pretty")
}

// isTx returns whether the HTTP request is requesting a transaction.
func isTx(req *http.Request) (bool, error) {
	return queryParam(req, "transaction")
}

// isExplain returns whether the HTTP request is requesting a explanation.
func isExplain(req *http.Request) (bool, error) {
	return queryParam(req, "explain")
}

// noLeader returns whether processing should skip the leader check.
func noLeader(req *http.Request) (bool, error) {
	return queryParam(req, "noleader")
}

// verify returns whether processing should perform a leader check on the cluster
func verify(req *http.Request) (bool, error) {
	return queryParam(req, "verify")
}