Merge pull request #75 from kortschak/parse

Use error returns and interface type for parsing

appengine/appengine.go

@@ -15,14 +15,12 @@
 package cayleyappengine
 
 import (
-	"os"
-
 	"github.com/barakmich/glog"
 
 	"github.com/google/cayley/config"
+	"github.com/google/cayley/db"
 	"github.com/google/cayley/graph"
 	"github.com/google/cayley/http"
-	"github.com/google/cayley/nquads"
 
 	_ "github.com/google/cayley/graph/memstore"
 )
@@ -32,37 +30,6 @@ func init() {
 	cfg := config.ParseConfigFromFile("cayley_appengine.cfg")
 	ts, _ := graph.NewTripleStore("memstore", "", nil)
 	glog.Errorln(cfg)
-	LoadTriplesFromFileInto(ts, cfg.DatabasePath, cfg.LoadSize)
+	db.Load(ts, cfg, cfg.DatabasePath)
 	http.SetupRoutes(ts, cfg)
 }
-
-func ReadTriplesFromFile(c chan *graph.Triple, tripleFile string) {
-	f, err := os.Open(tripleFile)
-	if err != nil {
-		glog.Fatalln("Couldn't open file", tripleFile)
-	}
-
-	defer func() {
-		if err := f.Close(); err != nil {
-			glog.Fatalln(err)
-		}
-	}()
-
-	nquads.ReadNQuadsFromReader(c, f)
-}
-
-func LoadTriplesFromFileInto(ts graph.TripleStore, filename string, loadSize int) {
-	tChan := make(chan *graph.Triple)
-	go ReadTriplesFromFile(tChan, filename)
-	tripleblock := make([]*graph.Triple, loadSize)
-	i := 0
-	for t := range tChan {
-		tripleblock[i] = t
-		i++
-		if i == loadSize {
-			ts.AddTripleSet(tripleblock)
-			i = 0
-		}
-	}
-	ts.AddTripleSet(tripleblock[0:i])
-}

cayley.go

@@ -58,37 +58,62 @@ func main() {
 		Usage()
 		os.Exit(1)
 	}
+
 	cmd := os.Args[1]
 	newargs := make([]string, 0)
 	newargs = append(newargs, os.Args[0])
 	newargs = append(newargs, os.Args[2:]...)
 	os.Args = newargs
 	flag.Parse()
-	var ts graph.TripleStore
+
 	cfg := config.ParseConfigFromFlagsAndFile(*configFile)
+
 	if os.Getenv("GOMAXPROCS") == "" {
 		runtime.GOMAXPROCS(runtime.NumCPU())
 		glog.Infoln("Setting GOMAXPROCS to", runtime.NumCPU())
 	} else {
 		glog.Infoln("GOMAXPROCS currently", os.Getenv("GOMAXPROCS"), " -- not adjusting")
 	}
+
+	var (
+		ts  graph.TripleStore
+		err error
+	)
 	switch cmd {
 	case "init":
-		db.Init(cfg, *tripleFile)
+		err = db.Init(cfg, *tripleFile)
 	case "load":
-		ts = db.Open(cfg)
-		db.Load(ts, cfg, *tripleFile)
+		ts, err = db.Open(cfg)
+		if err != nil {
+			break
+		}
+		err = db.Load(ts, cfg, *tripleFile)
+		if err != nil {
+			break
+		}
 		ts.Close()
 	case "repl":
-		ts = db.Open(cfg)
-		db.Repl(ts, *queryLanguage, cfg)
+		ts, err = db.Open(cfg)
+		if err != nil {
+			break
+		}
+		err = db.Repl(ts, *queryLanguage, cfg)
+		if err != nil {
+			break
+		}
 		ts.Close()
 	case "http":
-		ts = db.Open(cfg)
+		ts, err = db.Open(cfg)
+		if err != nil {
+			break
+		}
 		http.Serve(ts, cfg)
 		ts.Close()
 	default:
 		fmt.Println("No command", cmd)
 		flag.Usage()
 	}
+	if err != nil {
+		glog.Fatalln(err)
+	}
 }

db/init.go

@@ -19,16 +19,21 @@ import (
 	"github.com/google/cayley/graph"
 )
 
-func Init(cfg *config.Config, triplePath string) bool {
+func Init(cfg *config.Config, triplePath string) error {
 	err := graph.InitTripleStore(cfg.DatabaseType, cfg.DatabasePath, cfg.DatabaseOptions)
 	if err != nil {
-		return false
+		return err
 	}
-
 	if triplePath != "" {
-		ts := Open(cfg)
-		Load(ts, cfg, triplePath)
+		ts, err := Open(cfg)
+		if err != nil {
+			return err
+		}
+		err = Load(ts, cfg, triplePath)
+		if err != nil {
+			return err
+		}
 		ts.Close()
 	}
-	return true
+	return err
 }

db/load.go

@@ -18,52 +18,62 @@ import (
 	"bytes"
 	"compress/bzip2"
 	"compress/gzip"
+	"fmt"
 	"io"
 	"os"
 
 	"github.com/barakmich/glog"
-
 	"github.com/google/cayley/config"
 	"github.com/google/cayley/graph"
 	"github.com/google/cayley/nquads"
 )
 
-func Load(ts graph.TripleStore, cfg *config.Config, triplePath string) {
-	tChan := make(chan *graph.Triple)
-	go ReadTriplesFromFile(tChan, triplePath)
-
-	bulker, canBulk := ts.(graph.BulkLoader)
-	if canBulk {
-		err := bulker.BulkLoad(tChan)
-		if err == nil {
-			return
-		}
-		if err != graph.ErrCannotBulkLoad {
-			glog.Errorln("Error attempting to bulk load: ", err)
-		}
-	}
-
-	LoadTriplesInto(tChan, ts, cfg.LoadSize)
-}
-
-func ReadTriplesFromFile(c chan *graph.Triple, tripleFile string) {
-	f, err := os.Open(tripleFile)
+func Load(ts graph.TripleStore, cfg *config.Config, path string) error {
+	f, err := os.Open(path)
 	if err != nil {
-		glog.Fatalln("Couldn't open file", tripleFile)
+		return fmt.Errorf("could not open file %q: %v", path, err)
 	}
-
-	defer func() {
-		if err := f.Close(); err != nil {
-			glog.Fatalln(err)
-		}
-	}()
+	defer f.Close()
 
 	r, err := decompressor(f)
 	if err != nil {
 		glog.Fatalln(err)
 	}
 
-	nquads.ReadNQuadsFromReader(c, r)
+	dec := nquads.NewDecoder(r)
+
+	bulker, canBulk := ts.(graph.BulkLoader)
+	if canBulk {
+		err = bulker.BulkLoad(dec)
+		if err == nil {
+			return nil
+		}
+		if err == graph.ErrCannotBulkLoad {
+			err = nil
+		}
+	}
+	if err != nil {
+		return err
+	}
+
+	block := make([]*graph.Triple, 0, cfg.LoadSize)
+	for {
+		t, err := dec.Unmarshal()
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			return err
+		}
+		block = append(block, t)
+		if len(block) == cap(block) {
+			ts.AddTripleSet(block)
+			block = block[:0]
+		}
+	}
+	ts.AddTripleSet(block)
+
+	return nil
 }
 
 const (
@@ -91,17 +101,3 @@ func decompressor(r readAtReader) (io.Reader, error) {
 		return r, nil
 	}
 }
-
-func LoadTriplesInto(tChan chan *graph.Triple, ts graph.TripleStore, loadSize int) {
-	tripleblock := make([]*graph.Triple, loadSize)
-	i := 0
-	for t := range tChan {
-		tripleblock[i] = t
-		i++
-		if i == loadSize {
-			ts.AddTripleSet(tripleblock)
-			i = 0
-		}
-	}
-	ts.AddTripleSet(tripleblock[0:i])
-}

db/open.go

@@ -21,17 +21,20 @@ import (
 	"github.com/google/cayley/graph"
 )
 
-func Open(cfg *config.Config) graph.TripleStore {
+func Open(cfg *config.Config) (graph.TripleStore, error) {
 	glog.Infof("Opening database \"%s\" at %s", cfg.DatabaseType, cfg.DatabasePath)
 	ts, err := graph.NewTripleStore(cfg.DatabaseType, cfg.DatabasePath, cfg.DatabaseOptions)
 	if err != nil {
-		glog.Fatalln(err.Error())
+		return nil, err
 	}
 
 	// Memstore is not persistent, so it MUST be loaded.
 	if cfg.DatabaseType == "memstore" {
-		Load(ts, cfg, cfg.DatabasePath)
+		err = Load(ts, cfg, cfg.DatabasePath)
+		if err != nil {
+			return nil, err
+		}
 	}
 
-	return ts
+	return ts, nil
 }

db/repl.go

@@ -16,10 +16,11 @@ package db
 
 import (
 	"bufio"
+	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"os"
-	"strings"
 	"time"
 
 	"github.com/google/cayley/config"
@@ -60,7 +61,7 @@ func Run(query string, ses graph.Session) {
 	}
 }
 
-func Repl(ts graph.TripleStore, queryLanguage string, cfg *config.Config) {
+func Repl(ts graph.TripleStore, queryLanguage string, cfg *config.Config) error {
 	var ses graph.Session
 	switch queryLanguage {
 	case "sexp":
@@ -72,72 +73,75 @@ func Repl(ts graph.TripleStore, queryLanguage string, cfg *config.Config) {
 	default:
 		ses = gremlin.NewSession(ts, cfg.GremlinTimeout, true)
 	}
-	inputBf := bufio.NewReader(os.Stdin)
-	line := ""
+	buf := bufio.NewReader(os.Stdin)
+	var line []byte
 	for {
-		if line == "" {
+		if len(line) == 0 {
 			fmt.Print("cayley> ")
 		} else {
 			fmt.Print("...       ")
 		}
-		l, pre, err := inputBf.ReadLine()
+		l, prefix, err := buf.ReadLine()
 		if err == io.EOF {
-			if line != "" {
-				line = ""
+			if len(line) != 0 {
+				line = line[:0]
 			} else {
-				break
+				return nil
 			}
 		}
 		if err != nil {
-			line = ""
+			line = line[:0]
 		}
-		if pre {
-			panic("Line too long")
+		if prefix {
+			return errors.New("line too long")
 		}
-		line += string(l)
-		if line == "" {
+		line = append(line, l...)
+		if len(line) == 0 {
 			continue
 		}
-		if strings.HasPrefix(line, ":debug") {
+		if bytes.HasPrefix(line, []byte(":debug")) {
 			ses.ToggleDebug()
 			fmt.Println("Debug Toggled")
-			line = ""
+			line = line[:0]
 			continue
 		}
-		if strings.HasPrefix(line, ":a") {
+		if bytes.HasPrefix(line, []byte(":a")) {
 			var tripleStmt = line[3:]
-			triple := nquads.Parse(tripleStmt)
+			triple, err := nquads.Parse(string(tripleStmt))
 			if triple == nil {
-				fmt.Println("Not a valid triple.")
-				line = ""
+				if err != nil {
+					fmt.Printf("not a valid triple: %v\n", err)
+				}
+				line = line[:0]
 				continue
 			}
 			ts.AddTriple(triple)
-			line = ""
+			line = line[:0]
 			continue
 		}
-		if strings.HasPrefix(line, ":d") {
+		if bytes.HasPrefix(line, []byte(":d")) {
 			var tripleStmt = line[3:]
-			triple := nquads.Parse(tripleStmt)
+			triple, err := nquads.Parse(string(tripleStmt))
 			if triple == nil {
-				fmt.Println("Not a valid triple.")
-				line = ""
+				if err != nil {
+					fmt.Printf("not a valid triple: %v\n", err)
+				}
+				line = line[:0]
 				continue
 			}
 			ts.RemoveTriple(triple)
-			line = ""
+			line = line[:0]
 			continue
 		}
-		result, err := ses.InputParses(line)
+		result, err := ses.InputParses(string(line))
 		switch result {
 		case graph.Parsed:
-			Run(line, ses)
-			line = ""
+			Run(string(line), ses)
+			line = line[:0]
 		case graph.ParseFail:
 			fmt.Println("Error: ", err)
-			line = ""
+			line = line[:0]
 		case graph.ParseMore:
-		default:
 		}
 	}
 }

graph/triplestore.go

@@ -122,10 +122,14 @@ func (d Options) StringKey(key string) (string, bool) {
 var ErrCannotBulkLoad = errors.New("triplestore: cannot bulk load")
 
 type BulkLoader interface {
-	// BulkLoad loads Triples from a channel in bulk to the TripleStore. It
-	// returns ErrCannotBulkLoad if bulk loading is not possible (i.e. if you
-	// cannot load in bulk to a non-empty database, and the db is non-empty)
-	BulkLoad(chan *Triple) error
+	// BulkLoad loads Triples from a TripleUnmarshaler in bulk to the TripleStore.
+	// It returns ErrCannotBulkLoad if bulk loading is not possible. For example if
+	// you cannot load in bulk to a non-empty database, and the db is non-empty.
+	BulkLoad(TripleUnmarshaler) error
+}
+
+type TripleUnmarshaler interface {
+	Unmarshal() (*Triple, error)
 }
 
 type NewStoreFunc func(string, Options) (TripleStore, error)

http/write.go

@@ -17,6 +17,7 @@ package http
 import (
 	"encoding/json"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"strconv"
@@ -77,22 +78,32 @@ func (api *Api) ServeV1WriteNQuad(w http.ResponseWriter, r *http.Request, params
 		blockSize = int64(api.config.LoadSize)
 	}
 
-	tChan := make(chan *graph.Triple)
-	go nquads.ReadNQuadsFromReader(tChan, formFile)
-	tripleblock := make([]*graph.Triple, blockSize)
-	nTriples := 0
-	i := int64(0)
-	for t := range tChan {
-		tripleblock[i] = t
-		i++
-		nTriples++
-		if i == blockSize {
-			api.ts.AddTripleSet(tripleblock)
-			i = 0
+	dec := nquads.NewDecoder(formFile)
+
+	var (
+		n int
+
+		block = make([]*graph.Triple, 0, blockSize)
+	)
+	for {
+		t, err := dec.Unmarshal()
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			panic("what can do this here?") // FIXME(kortschak)
+		}
+		block = append(block, t)
+		n++
+		if len(block) == cap(block) {
+			api.ts.AddTripleSet(block)
+			block = block[:0]
 		}
 	}
-	api.ts.AddTripleSet(tripleblock[0:i])
-	fmt.Fprintf(w, "{\"result\": \"Successfully wrote %d triples.\"}", nTriples)
+	api.ts.AddTripleSet(block)
+
+	fmt.Fprintf(w, "{\"result\": \"Successfully wrote %d triples.\"}", n)
+
 	return 200
 }
 

nquads/nquads.go

@@ -16,109 +16,112 @@ package nquads
 
 import (
 	"bufio"
+	"errors"
+	"fmt"
 	"io"
 	"strings"
 
-	"github.com/barakmich/glog"
-
 	"github.com/google/cayley/graph"
 )
 
-func isWhitespace(s uint8) bool {
-	return (s == '\t' || s == '\r' || s == ' ')
-}
-func Parse(str string) *graph.Triple {
+var (
+	ErrAbsentSubject   = errors.New("nqauds: absent subject")
+	ErrAbsentPredicate = errors.New("nqauds: absent predicate")
+	ErrAbsentObject    = errors.New("nqauds: absent object")
+	ErrUnterminated    = errors.New("nqauds: unterminated quad")
+)
+
+func Parse(str string) (*graph.Triple, error) {
 	// Skip leading whitespace.
-	str = skipWhitespace(str)
+	str = trimSpace(str)
 	// Check for a comment
 	if str != "" && str[0] == '#' {
-		return nil
+		return nil, nil
 	}
 	sub, remainder := getTripleComponent(str)
-	if sub == nil {
-		return nil
+	if sub == "" {
+		return nil, ErrAbsentSubject
 	}
-	str = skipWhitespace(remainder)
+	str = trimSpace(remainder)
 	pred, remainder := getTripleComponent(str)
-	if pred == nil {
-		return nil
+	if pred == "" {
+		return nil, ErrAbsentPredicate
 	}
-	str = skipWhitespace(remainder)
+	str = trimSpace(remainder)
 	obj, remainder := getTripleComponent(str)
-	if obj == nil {
-		return nil
+	if obj == "" {
+		return nil, ErrAbsentObject
 	}
-	str = skipWhitespace(remainder)
-	prov_ptr, remainder := getTripleComponent(str)
-	var prov string
-	if prov_ptr == nil {
-		prov = ""
-	} else {
-		prov = *prov_ptr
-	}
-	str = skipWhitespace(remainder)
+	str = trimSpace(remainder)
+	prov, remainder := getTripleComponent(str)
+	str = trimSpace(remainder)
 	if str != "" && str[0] == '.' {
-		return &graph.Triple{*sub, *pred, *obj, prov}
+		return &graph.Triple{sub, pred, obj, prov}, nil
 	}
-	return nil
+	return nil, ErrUnterminated
 }
 
-func skipWhitespace(str string) string {
+func isSpace(s uint8) bool {
+	return s == ' ' || s == '\t' || s == '\r'
+}
+
+func trimSpace(str string) string {
 	i := 0
-	for i < len(str) && isWhitespace(str[i]) {
+	for i < len(str) && isSpace(str[i]) {
 		i += 1
 	}
 	return str[i:]
 }
 
-func getTripleComponent(str string) (*string, string) {
+func getTripleComponent(str string) (head, tail string) {
 	if len(str) == 0 {
-		return nil, str
+		return "", str
 	}
 	if str[0] == '<' {
 		return getUriPart(str[1:])
 	} else if str[0] == '"' {
 		return getQuotedPart(str[1:])
 	} else if str[0] == '.' {
-		return nil, str
+		return "", str
 	} else {
 		// Technically not part of the spec. But we do it anyway for convenience.
 		return getUnquotedPart(str)
 	}
 }
 
-func getUriPart(str string) (*string, string) {
+func getUriPart(str string) (head, tail string) {
 	i := 0
 	for i < len(str) && str[i] != '>' {
 		i += 1
 	}
 	if i == len(str) {
-		return nil, str
+		return "", str
 	}
-	part := str[0:i]
-	return &part, str[i+1:]
+	head = str[0:i]
+	return head, str[i+1:]
 }
 
-func getQuotedPart(str string) (*string, string) {
-	i := 0
-	start := 0
-	out := ""
+func getQuotedPart(str string) (head, tail string) {
+	var (
+		i     int
+		start int
+	)
 	for i < len(str) && str[i] != '"' {
 		if str[i] == '\\' {
-			out += str[start:i]
+			head += str[start:i]
 			switch str[i+1] {
 			case '\\':
-				out += "\\"
+				head += "\\"
 			case 'r':
-				out += "\r"
+				head += "\r"
 			case 'n':
-				out += "\n"
+				head += "\n"
 			case 't':
-				out += "\t"
+				head += "\t"
 			case '"':
-				out += "\""
+				head += "\""
 			default:
-				return nil, str
+				return "", str
 			}
 			i += 2
 			start = i
@@ -127,70 +130,74 @@ func getQuotedPart(str string) (*string, string) {
 		i += 1
 	}
 	if i == len(str) {
-		return nil, str
+		return "", str
 	}
-	out += str[start:i]
+	head += str[start:i]
 	i += 1
-	var remainder string
-	if strings.HasPrefix(str[i:], "^^<") {
+	switch {
+	case strings.HasPrefix(str[i:], "^^<"):
 		// Ignore type, for now
-		_, remainder = getUriPart(str[i+3:])
-	} else if strings.HasPrefix(str[i:], "@") {
-		_, remainder = getUnquotedPart(str[i+1:])
-	} else {
-		remainder = str[i:]
+		_, tail = getUriPart(str[i+3:])
+	case str[i] == '@':
+		_, tail = getUnquotedPart(str[i+1:])
+	default:
+		tail = str[i:]
 	}
 
-	return &out, remainder
+	return head, tail
 }
 
-func getUnquotedPart(str string) (*string, string) {
-	i := 0
-	initStr := str
-	out := ""
-	start := 0
-	for i < len(str) && !isWhitespace(str[i]) {
+func getUnquotedPart(str string) (head, tail string) {
+	var (
+		i       int
+		initStr = str
+		start   int
+	)
+	for i < len(str) && !isSpace(str[i]) {
 		if str[i] == '"' {
 			part, remainder := getQuotedPart(str[i+1:])
-			if part == nil {
+			if part == "" {
 				return part, initStr
 			}
-			out += str[start:i]
+			head += str[start:i]
 			str = remainder
 			i = 0
 			start = 0
-			out += *part
+			head += part
 		}
 		i += 1
 	}
-	out += str[start:i]
-	return &out, str[i:]
+	head += str[start:i]
+	return head, str[i:]
 }
 
-func ReadNQuadsFromReader(c chan *graph.Triple, reader io.Reader) {
-	bf := bufio.NewReader(reader)
+type Decoder struct {
+	r    *bufio.Reader
+	line []byte
+}
 
-	nTriples := 0
-	line := ""
+func NewDecoder(r io.Reader) *Decoder {
+	return &Decoder{r: bufio.NewReader(r)}
+}
+
+func (dec *Decoder) Unmarshal() (*graph.Triple, error) {
+	dec.line = dec.line[:0]
 	for {
-		l, pre, err := bf.ReadLine()
-		if err == io.EOF {
+		l, pre, err := dec.r.ReadLine()
+		if err != nil {
+			return nil, err
+		}
+		dec.line = append(dec.line, l...)
+		if !pre {
 			break
 		}
-		if err != nil {
-			glog.Fatalln("Something bad happened while reading file " + err.Error())
-		}
-		line += string(l)
-		if pre {
-			continue
-		}
-		triple := Parse(line)
-		line = ""
-		if triple != nil {
-			nTriples++
-			c <- triple
-		}
 	}
-	glog.Infoln("Read", nTriples, "triples")
-	close(c)
+	triple, err := Parse(string(dec.line))
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse %q: %v", dec.line, err)
+	}
+	if triple == nil {
+		return dec.Unmarshal()
+	}
+	return triple, nil
 }

nquads/nquads_test.go

@@ -25,17 +25,26 @@ var testNTriples = []struct {
 	message string
 	input   string
 	expect  *graph.Triple
+	err     error
 }{
 	// NTriple tests.
 	{
 		message: "not parse invalid triples",
 		input:   "invalid",
 		expect:  nil,
+		err:     ErrAbsentPredicate,
+	},
+	{
+		message: "invalid internal quote",
+		input:   `":103032" "/film/performance/character" "Walter "Teacher" Cole" .`,
+		expect:  nil,
+		err:     ErrUnterminated,
 	},
 	{
 		message: "not parse comments",
 		input:   "# nominally valid triple .",
 		expect:  nil,
+		err:     nil,
 	},
 	{
 		message: "parse simple triples",
@@ -110,7 +119,10 @@ var testNTriples = []struct {
 
 func TestParse(t *testing.T) {
 	for _, test := range testNTriples {
-		got := Parse(test.input)
+		got, err := Parse(test.input)
+		if err != test.err {
+			t.Errorf("Unexpected error when %s: got:%v expect:%v", test.message, err, test.err)
+		}
 		if !reflect.DeepEqual(got, test.expect) {
 			t.Errorf("Failed to %s, %q, got:%q expect:%q", test.message, test.input, got, test.expect)
 		}
@@ -121,6 +133,6 @@ var result *graph.Triple
 
 func BenchmarkParser(b *testing.B) {
 	for n := 0; n < b.N; n++ {
-		result = Parse("<http://example/s> <http://example/p> \"object of some real\\tlength\"@en . # comment")
+		result, _ = Parse("<http://example/s> <http://example/p> \"object of some real\\tlength\"@en . # comment")
 	}
 }