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x.go
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/*
* Copyright (C) 2017 Dgraph Labs, Inc. and Contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package x
import (
"bufio"
"bytes"
"context"
"encoding/json"
"fmt"
"net"
"net/http"
"regexp"
"sort"
"strconv"
"strings"
"time"
"golang.org/x/net/trace"
)
// Error constants representing different types of errors.
const (
Success = "Success"
ErrorUnauthorized = "ErrorUnauthorized"
ErrorInvalidMethod = "ErrorInvalidMethod"
ErrorInvalidRequest = "ErrorInvalidRequest"
ErrorMissingRequired = "ErrorMissingRequired"
Error = "Error"
ErrorNoData = "ErrorNoData"
ErrorUptodate = "ErrorUptodate"
ErrorNoPermission = "ErrorNoPermission"
ErrorInvalidMutation = "ErrorInvalidMutation"
ErrorServiceUnavailable = "ErrorServiceUnavailable"
ValidHostnameRegex = "^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\\-]*[a-zA-Z0-9])\\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\\-]*[A-Za-z0-9])$"
Star = "_STAR_ALL"
GrpcMaxSize = 256 << 20
)
var (
// Useful for running multiple servers on the same machine.
regExpHostName = regexp.MustCompile(ValidHostnameRegex)
)
// WhiteSpace Replacer removes spaces and tabs from a string.
var WhiteSpace = strings.NewReplacer(" ", "", "\t", "")
type errRes struct {
Code string `json:"code"`
Message string `json:"message"`
}
type queryRes struct {
Errors []errRes `json:"errors"`
}
// SetError sets the error logged in this package.
func SetError(prev *error, n error) {
if prev == nil {
prev = &n
}
}
// SetStatus sets the error code, message and the newly assigned uids
// in the http response.
func SetStatus(w http.ResponseWriter, code, msg string) {
var qr queryRes
qr.Errors = append(qr.Errors, errRes{Code: code, Message: msg})
if js, err := json.Marshal(qr); err == nil {
w.Write(js)
} else {
panic(fmt.Sprintf("Unable to marshal: %+v", qr))
}
}
type QueryResWithData struct {
Errors []errRes `json:"errors"`
Data *string `json:"data"`
}
// In case an error was encountered after the query execution started, we have to return data
// key with null value according to GraphQL spec.
func SetStatusWithData(w http.ResponseWriter, code, msg string) {
var qr QueryResWithData
qr.Errors = append(qr.Errors, errRes{Code: code, Message: msg})
// This would ensure that data key is present with value null.
if js, err := json.Marshal(qr); err == nil {
w.Write(js)
} else {
panic(fmt.Sprintf("Unable to marshal: %+v", qr))
}
}
func Reply(w http.ResponseWriter, rep interface{}) {
if js, err := json.Marshal(rep); err == nil {
w.Header().Set("Content-Type", "application/json")
fmt.Fprint(w, string(js))
} else {
SetStatus(w, Error, "Internal server error")
}
}
func ParseRequest(w http.ResponseWriter, r *http.Request, data interface{}) bool {
defer r.Body.Close()
decoder := json.NewDecoder(r.Body)
if err := decoder.Decode(&data); err != nil {
SetStatus(w, Error, fmt.Sprintf("While parsing request: %v", err))
return false
}
return true
}
var Nilbyte []byte
// Reads a single line from a buffered reader. The line is read into the
// passed in buffer to minimize allocations. This is the preferred
// method for loading long lines which could be longer than the buffer
// size of bufio.Scanner.
func ReadLine(r *bufio.Reader, buf *bytes.Buffer) error {
isPrefix := true
var err error
buf.Reset()
for isPrefix && err == nil {
var line []byte
// The returned line is an internal buffer in bufio and is only
// valid until the next call to ReadLine. It needs to be copied
// over to our own buffer.
line, isPrefix, err = r.ReadLine()
if err == nil {
buf.Write(line)
}
}
return err
}
// Go doesn't have a round function for Duration and the duration value can be a
// bit ugly to look at sometimes. This is an attempt to round the value.
func Round(d time.Duration) time.Duration {
var denominator time.Duration
if d > time.Minute {
denominator = 0.1e12 // So that it has one digit after the decimal.
} else if d > time.Second {
denominator = 0.1e9 // 0.1 * time.Second
} else if d > time.Millisecond {
denominator = time.Millisecond
} else {
denominator = time.Microsecond
}
if remainder := d % denominator; 2*remainder < denominator {
// This means we have to round it down.
d = d - remainder
} else {
d = d + denominator - remainder
}
return d
}
// PageRange returns start and end indices given pagination params. Note that n
// is the size of the input list.
func PageRange(count, offset, n int) (int, int) {
if n == 0 {
return 0, 0
}
if count == 0 && offset == 0 {
return 0, n
}
if count < 0 {
// Items from the back of the array, like Python arrays. Do a positive mod n.
if count*-1 > n {
count = -n
}
return (((n + count) % n) + n) % n, n
}
start := offset
if start < 0 {
start = 0
}
if start > n {
return n, n
}
if count == 0 { // No count specified. Just take the offset parameter.
return start, n
}
end := start + count
if end > n {
end = n
}
return start, end
}
// ValidateAddress checks whether given address can be used with grpc dial function
func ValidateAddress(addr string) bool {
host, port, err := net.SplitHostPort(addr)
if err != nil {
return false
}
if p, err := strconv.Atoi(port); err != nil || p <= 0 || p >= 65536 {
return false
}
if err := net.ParseIP(host); err == nil {
return true
}
// try to parse as hostname as per hostname RFC
if len(strings.Replace(host, ".", "", -1)) > 255 {
return false
}
return regExpHostName.MatchString(host)
}
// sorts the slice of strings and removes duplicates. changes the input slice.
// this function should be called like: someSlice = x.RemoveDuplicates(someSlice)
func RemoveDuplicates(s []string) (out []string) {
sort.Strings(s)
out = s[:0]
for i := range s {
if i > 0 && s[i] == s[i-1] {
continue
}
out = append(out, s[i])
}
return
}
func NewTrace(title string, ctx context.Context) (trace.Trace, context.Context) {
tr := trace.New("Dgraph", title)
tr.SetMaxEvents(1000)
ctx = trace.NewContext(ctx, tr)
return tr, ctx
}
type BytesBuffer struct {
data [][]byte
off int
sz int
}
func (b *BytesBuffer) grow(n int) {
if n < 128 {
n = 128
}
if len(b.data) == 0 {
b.data = append(b.data, make([]byte, n, n))
}
last := len(b.data) - 1
// Return if we have sufficient space
if len(b.data[last])-b.off >= n {
return
}
sz := len(b.data[last]) * 2
if sz > 512<<10 {
sz = 512 << 10 // 512 KB
}
if sz < n {
sz = n
}
b.data[last] = b.data[last][:b.off]
b.sz += len(b.data[last])
b.data = append(b.data, make([]byte, sz, sz))
b.off = 0
}
// returns a slice of lenght n to be used to writing
func (b *BytesBuffer) Slice(n int) []byte {
b.grow(n)
last := len(b.data) - 1
b.off += n
b.sz += n
return b.data[last][b.off-n : b.off]
}
func (b *BytesBuffer) Length() int {
return b.sz
}
// Caller should ensure that o is of appropriate length
func (b *BytesBuffer) CopyTo(o []byte) int {
offset := 0
for i, d := range b.data {
if i == len(b.data)-1 {
copy(o[offset:], d[:b.off])
offset += b.off
} else {
copy(o[offset:], d)
offset += len(d)
}
}
return offset
}
// Always give back <= touched bytes
func (b *BytesBuffer) TruncateBy(n int) {
b.off -= n
b.sz -= n
AssertTrue(b.off >= 0 && b.sz >= 0)
}