First Commit

Author: Sri Krishna Paritala

.gitignore

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+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, build with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# IDE preferences
+.idea/
+.vscode/

.travis.yml

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+language: go
+
+go:
+  - 1.10.x
+  - 1.11.x
+  - tip
+
+install:
+  - go get -u golang.org/x/tools/cmd/goimports
+  - go get -u github.com/golang/lint/golint
+
+script:
+  - go get -d -t ./...
+  - go vet ./...
+  - golint ./...
+  - go test ./...
+  - >
+    goimports -d -e ./ | grep '.*' && { echo; echo "Aborting due to non-empty goimports output."; exit 1; } || :

README.md

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+# idgen
+
+Generates url safe lexically sorted random ids with a prefix in go. Inspired from Stripe.
+
+## Usage
+
+```go
+package main
+
+import (
+	"fmt"
+	
+	"github.com/srikrsna/idgen"
+)
+
+func main()  {
+    id := idgen.New("cus")
+    fmt.Println(id)
+    // Output: cus_0000XSNJG0MQJHBF4QX1EFD6Y3
+}    
+``` 
+
+### Depends on
+
+[oklog/ulid](https://github.com/oklog/ulid)

go.mod

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+module github.com/srikrsna/idgen
+
+require github.com/oklog/ulid v1.3.1

go.sum

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+github.com/oklog/ulid v1.3.1 h1:EGfNDEx6MqHz8B3uNV6QAib1UR2Lm97sHi3ocA6ESJ4=
+github.com/oklog/ulid v1.3.1/go.mod h1:CirwcVhetQ6Lv90oh/F+FBtV6XMibvdAFo93nm5qn4U=

id.go

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+package idgen
+
+import (
+	"io"
+	"math/rand"
+	"sync"
+	"time"
+
+	"github.com/oklog/ulid"
+)
+
+// New generates a lexically sorted, url safe Id with a prefix.
+// Eg: cus_JSfjkdjf333j46, i.e. {prefix}-{ulid}
+func New(prefix string) string {
+	ent := getEntropy()
+	res := prefix + "_" + ulid.MustNew(ulid.Now(), ent).String()
+	putEntropy(ent)
+	return res
+}
+
+var entropyPool = sync.Pool{
+	New: func() interface{} {
+		return ulid.Monotonic(rand.New(rand.NewSource(time.Now().UnixNano())), 0)
+	},
+}
+
+func getEntropy() io.Reader {
+	return entropyPool.Get().(io.Reader)
+}
+
+func putEntropy(r io.Reader) {
+	entropyPool.Put(r)
+}
+
+// PrefixGenerator generates a new id with the given prefix
+type PrefixGenerator struct {
+	Prefix string
+}
+
+func (p PrefixGenerator) New() string {
+	return New(p.Prefix)
+}

id_test.go

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+package idgen_test
+
+import (
+	"fmt"
+	"net/url"
+	"strings"
+	"testing"
+
+	"github.com/oklog/ulid"
+
+	"github.com/srikrsna/idgen"
+)
+
+func TestPrefix(t *testing.T) {
+	prefix := "cus"
+	testPrefix(t, idgen.New(prefix), prefix)
+}
+
+func TestULID(t *testing.T) {
+	id := idgen.New("cus")
+	if _, err := ulid.Parse(id[len("cus_"):]); err != nil {
+		t.Errorf("func New not generating ulids: %v", err)
+	}
+}
+
+func TestURLSafe(t *testing.T) {
+	for range [20]struct{}{} {
+		id := idgen.New("cus")
+
+		if url.PathEscape(id) != id {
+			t.Errorf("value generated by New is not url path safe, expected: %s, got: %s", url.PathEscape(id), id)
+		}
+
+		if url.QueryEscape(id) != id {
+			t.Errorf("value generated by New is not url query safe, expected: %s, got: %s", url.QueryEscape(id), id)
+		}
+	}
+}
+
+func TestPrefixGenerator_New(t *testing.T) {
+	const prefix = "cus"
+	pg := idgen.PrefixGenerator{
+		Prefix: prefix,
+	}
+	testPrefix(t, pg.New() ,prefix)
+}
+
+func testPrefix(t *testing.T, id, prefix string) {
+	t.Helper()
+	if !strings.HasPrefix(id, prefix+"_") {
+		t.Errorf("New should return a ulid with the given prefix, expected: cus, got: %s", id)
+	}
+}
+
+func ExampleNew() {
+	id := idgen.New("cus")
+
+	fmt.Println(id[:4])
+
+	// Output: cus_
+}
+
+func BenchmarkNew(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_ = idgen.New("cus")
+	}
+}
+
+func BenchmarkNewParallel(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			_ = idgen.New("cus")
+		}
+	})
+}