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server.go
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server.go
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package skyd
import (
"bytes"
"encoding/json"
"errors"
"fmt"
"github.com/gorilla/mux"
"github.com/jmhodges/levigo"
"hash/fnv"
"io"
"io/ioutil"
"log"
"net"
"net/http"
"net/http/pprof"
"os"
"regexp"
"runtime"
"time"
)
//------------------------------------------------------------------------------
//
// Typedefs
//
//------------------------------------------------------------------------------
// A Server is the front end that controls access to tables.
type Server struct {
httpServer *http.Server
router *mux.Router
logger *log.Logger
path string
listener net.Listener
servlets []*Servlet
tables map[string]*Table
factors *Factors
shutdownChannel chan bool
}
//------------------------------------------------------------------------------
//
// Errors
//
//------------------------------------------------------------------------------
//--------------------------------------
// Alternate Content Type
//--------------------------------------
// Hackish way to return plain text for query codegen. Might fix later but
// it's rarely used.
type TextPlainContentTypeError struct {
}
func (e *TextPlainContentTypeError) Error() string {
return ""
}
//------------------------------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------------------------------
// NewServer returns a new Server.
func NewServer(port uint, path string) *Server {
r := mux.NewRouter()
s := &Server{
httpServer: &http.Server{Addr: fmt.Sprintf(":%d", port), Handler: r},
router: r,
logger: log.New(os.Stdout, "", log.LstdFlags),
path: path,
tables: make(map[string]*Table),
}
s.router.HandleFunc("/debug/pprof", pprof.Index)
s.router.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
s.router.HandleFunc("/debug/pprof/profile", pprof.Profile)
s.router.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
s.addHandlers()
s.addTableHandlers()
s.addPropertyHandlers()
s.addEventHandlers()
s.addQueryHandlers()
return s
}
//------------------------------------------------------------------------------
//
// Properties
//
//------------------------------------------------------------------------------
// The root server path.
func (s *Server) Path() string {
return s.path
}
// The path to the data directory.
func (s *Server) DataPath() string {
return fmt.Sprintf("%v/data", s.path)
}
// The path to the table metadata directory.
func (s *Server) TablesPath() string {
return fmt.Sprintf("%v/tables", s.path)
}
// Generates the path for a table attached to the server.
func (s *Server) TablePath(name string) string {
return fmt.Sprintf("%v/%v", s.TablesPath(), name)
}
// The path to the factors database.
func (s *Server) FactorsPath() string {
return fmt.Sprintf("%v/factors", s.path)
}
//------------------------------------------------------------------------------
//
// Methods
//
//------------------------------------------------------------------------------
//--------------------------------------
// Lifecycle
//--------------------------------------
// Runs the server.
func (s *Server) ListenAndServe(shutdownChannel chan bool) error {
s.shutdownChannel = shutdownChannel
err := s.open()
if err != nil {
return err
}
listener, err := net.Listen("tcp", s.httpServer.Addr)
if err != nil {
s.close()
return err
}
s.listener = listener
go s.httpServer.Serve(s.listener)
s.logger.Printf("Sky v%s is now listening on http://localhost%s\n", Version, s.httpServer.Addr)
return nil
}
// Stops the server.
func (s *Server) Shutdown() error {
// Close servlets.
s.close()
// Close socket.
if s.listener != nil {
// Then stop the server.
err := s.listener.Close()
s.listener = nil
if err != nil {
return err
}
}
// Notify that the server is shutdown.
if s.shutdownChannel != nil {
s.shutdownChannel <- true
}
return nil
}
// Checks if the server is listening for new connections.
func (s *Server) Running() bool {
return (s.listener != nil)
}
// Opens the data directory and servlets.
func (s *Server) open() error {
s.close()
// Setup the file system if it doesn't exist.
err := s.createIfNotExists()
if err != nil {
return fmt.Errorf("skyd.Server: Unable to create server folders: %v", err)
}
// Open factors database.
s.factors = NewFactors(s.FactorsPath())
err = s.factors.Open()
if err != nil {
s.close()
return err
}
// Create servlets from child directories with numeric names.
infos, err := ioutil.ReadDir(s.DataPath())
if err != nil {
return err
}
for _, info := range infos {
match, _ := regexp.MatchString("^\\d$", info.Name())
if info.IsDir() && match {
s.servlets = append(s.servlets, NewServlet(fmt.Sprintf("%s/%s", s.DataPath(), info.Name()), s.factors))
}
}
// If none exist then build them based on the number of logical CPUs available.
if len(s.servlets) == 0 {
cpuCount := runtime.NumCPU()
for i := 0; i < cpuCount; i++ {
s.servlets = append(s.servlets, NewServlet(fmt.Sprintf("%s/%v", s.DataPath(), i), s.factors))
}
}
// Open servlets.
for _, servlet := range s.servlets {
err = servlet.Open()
if err != nil {
s.close()
return err
}
}
return nil
}
// Closes the data directory and servlets.
func (s *Server) close() {
// Close servlets.
if s.servlets != nil {
for _, servlet := range s.servlets {
servlet.Close()
}
s.servlets = nil
}
// Close factors database.
if s.factors != nil {
s.factors.Close()
s.factors = nil
}
}
// Creates the appropriate directory structure if one does not exist.
func (s *Server) createIfNotExists() error {
// Create root directory.
err := os.MkdirAll(s.path, 0700)
if err != nil {
return err
}
// Create data directory and one directory for each servlet.
err = os.MkdirAll(s.DataPath(), 0700)
if err != nil {
return err
}
// Create tables directory.
err = os.MkdirAll(s.TablesPath(), 0700)
if err != nil {
return err
}
return nil
}
//--------------------------------------
// Logging
//--------------------------------------
// Silences the log.
func (s *Server) Silence() {
s.logger = log.New(ioutil.Discard, "", log.LstdFlags)
}
//--------------------------------------
// Routing
//--------------------------------------
// Parses incoming JSON objects and converts outgoing responses to JSON.
func (s *Server) ApiHandleFunc(route string, handlerFunction func(http.ResponseWriter, *http.Request, map[string]interface{}) (interface{}, error)) *mux.Route {
wrappedFunction := func(w http.ResponseWriter, req *http.Request) {
// warn("%s \"%s %s %s\"", req.RemoteAddr, req.Method, req.RequestURI, req.Proto)
t0 := time.Now()
var ret interface{}
params, err := s.decodeParams(w, req)
if err == nil {
ret, err = handlerFunction(w, req, params)
}
// If we're returning plain text then just dump out what's returned.
if _, ok := err.(*TextPlainContentTypeError); ok {
w.Header().Set("Content-Type", "text/plain")
w.WriteHeader(http.StatusOK)
if str, ok := ret.(string); ok {
w.Write([]byte(str))
}
return
}
// If there is an error then replace the return value.
if err != nil {
ret = map[string]interface{}{"message": err.Error()}
}
// Write header status.
w.Header().Set("Content-Type", "application/json")
var status int
if err == nil {
status = http.StatusOK
} else {
status = http.StatusInternalServerError
}
w.WriteHeader(status)
// Write to access log.
s.logger.Printf("%s \"%s %s %s\" %d %0.3f", req.RemoteAddr, req.Method, req.RequestURI, req.Proto, status, time.Since(t0).Seconds())
if status != http.StatusOK {
s.logger.Printf("ERROR %v", err)
}
// Encode the return value appropriately.
if ret != nil {
encoder := json.NewEncoder(w)
err := encoder.Encode(ConvertToStringKeys(ret))
if err != nil {
fmt.Printf("skyd.Server: Encoding error: %v\n", err.Error())
return
}
}
}
return s.router.HandleFunc(route, wrappedFunction)
}
// Decodes the body of the message into parameters.
func (s *Server) decodeParams(w http.ResponseWriter, req *http.Request) (map[string]interface{}, error) {
// Parses body parameters.
params := make(map[string]interface{})
decoder := json.NewDecoder(req.Body)
err := decoder.Decode(¶ms)
if err != nil && err != io.EOF {
return nil, errors.New("Malformed json request.")
}
return params, nil
}
//--------------------------------------
// Servlet Management
//--------------------------------------
// Executes a function through a single-threaded servlet context.
func (s *Server) GetObjectContext(tableName string, objectId string) (*Table, *Servlet, error) {
// Return an error if the table already exists.
table, err := s.OpenTable(tableName)
if err != nil {
return nil, nil, err
}
// Determine servlet index.
index, err := s.GetObjectServletIndex(table, objectId)
if err != nil {
return nil, nil, err
}
servlet := s.servlets[index]
return table, servlet, nil
}
// Calculates a tablet index based on the object identifier even hash.
func (s *Server) GetObjectServletIndex(t *Table, objectId string) (uint32, error) {
// Encode object identifier.
encodedObjectId, err := t.EncodeObjectId(objectId)
if err != nil {
return 0, err
}
// Calculate the even bits of the FNV1a hash.
h := fnv.New64a()
h.Reset()
h.Write(encodedObjectId)
hashcode := h.Sum64()
index := CondenseUint64Even(hashcode) % uint32(len(s.servlets))
return index, nil
}
//--------------------------------------
// Table Management
//--------------------------------------
// Retrieves a table that has already been opened.
func (s *Server) GetTable(name string) *Table {
return s.tables[name]
}
// Retrieves a list of all tables in the database but does not open them.
// Do not use these table references for anything but informational purposes!
func (s *Server) GetAllTables() ([]*Table, error) {
// Create a table object for each directory in the tables path.
infos, err := ioutil.ReadDir(s.TablesPath())
if err != nil {
return nil, err
}
tables := []*Table{}
for _, info := range infos {
if info.IsDir() {
tables = append(tables, NewTable(info.Name(), s.TablePath(info.Name())))
}
}
return tables, nil
}
// Opens a table and returns a reference to it.
func (s *Server) OpenTable(name string) (*Table, error) {
// If table already exists then use it.
table := s.GetTable(name)
if table != nil {
return table, nil
}
// Otherwise open it and save the reference.
table = NewTable(name, s.TablePath(name))
err := table.Open()
if err != nil {
table.Close()
return nil, err
}
s.tables[name] = table
return table, nil
}
// Deletes a table.
func (s *Server) DeleteTable(name string) error {
// Return an error if the table doesn't exist.
table := s.GetTable(name)
if table == nil {
table = NewTable(name, s.TablePath(name))
}
if !table.Exists() {
return fmt.Errorf("Table does not exist: %s", name)
}
// Determine table prefix.
prefix, err := TablePrefix(table.Name)
if err != nil {
return err
}
// Delete data from each servlet.
for _, servlet := range s.servlets {
servlet.Lock()
defer servlet.Unlock()
// Delete the data from disk.
ro := levigo.NewReadOptions()
defer ro.Close()
wo := levigo.NewWriteOptions()
defer wo.Close()
iterator := servlet.db.NewIterator(ro)
defer iterator.Close()
iterator.Seek(prefix)
for iterator = iterator; iterator.Valid(); iterator.Next() {
key := iterator.Key()
if bytes.HasPrefix(key, prefix) {
err := servlet.db.Delete(wo, key)
if err != nil {
return err
}
} else {
break
}
}
}
// Remove the table from the lookup and remove it's schema.
delete(s.tables, name)
return table.Delete()
}
//--------------------------------------
// Query
//--------------------------------------
// Runs a query against a table.
func (s *Server) RunQuery(table *Table, query *Query) (interface{}, error) {
var engine *ExecutionEngine
engines := make([]*ExecutionEngine, 0)
// Create a channel to receive aggregate responses.
rchannel := make(chan interface{}, len(s.servlets))
// Generate the query source code.
source, err := query.Codegen()
if err != nil {
return nil, err
}
// Create an engine for merging results.
engine, err = NewExecutionEngine(table, source)
if err != nil {
return nil, err
}
defer engine.Destroy()
//fmt.Println(engine.FullAnnotatedSource())
// Initialize one execution engine for each servlet.
for _, servlet := range s.servlets {
// Create an engine for each servlet.
e, err := NewExecutionEngine(table, source)
if err != nil {
return nil, err
}
// Initialize iterator.
ro := levigo.NewReadOptions()
iterator := servlet.db.NewIterator(ro)
err = e.SetIterator(iterator)
if err != nil {
return nil, err
}
engines = append(engines, e)
}
// Execute servlets asynchronously and retrieve responses outside
// of the server context.
for index, _ := range s.servlets {
e := engines[index]
go func() {
if result, err := e.Aggregate(); err != nil {
rchannel <- err
} else {
rchannel <- result
}
}()
}
// Wait for each servlet to complete and then merge the results.
var servletError error
var result interface{}
result = make(map[interface{}]interface{})
for i := 0; i < len(s.servlets); i++ {
ret := <-rchannel
if err, ok := ret.(error); ok {
fmt.Printf("skyd.Server: Aggregate error: %v", err)
servletError = err
} else {
// Defactorize aggregate results.
err = query.Defactorize(ret)
if err != nil {
return nil, err
}
// Merge results.
if ret != nil {
result, err = engine.Merge(result, ret)
if err != nil {
fmt.Printf("skyd.Server: Merge error: %v", err)
servletError = err
}
}
}
}
err = servletError
// Clean up engines.
// TODO: Defer clean up earlier on in case of failure.
for _, e := range engines {
e.Destroy()
}
return result, err
}