Ability to build logger with custom Sink (#572)

Using the same global-registry pattern that we're using for encoders, let users register new sinks (like the built-in `stdout` and `stderr`).

sink.go

@@ -0,0 +1,94 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+ "errors"
+ "fmt"
+ "io"
+ "os"
+ "sync"
+
+ "go.uber.org/zap/zapcore"
+)
+
+var (
+ _sinkMutex sync.RWMutex
+ _sinkFactories map[string]func() (Sink, error)
+)
+
+func init() {
+ resetSinkRegistry()
+}
+
+func resetSinkRegistry() {
+ _sinkMutex.Lock()
+ defer _sinkMutex.Unlock()
+ _sinkFactories = map[string]func() (Sink, error){
+ "stdout": func() (Sink, error) { return nopCloserSink{os.Stdout}, nil },
+ "stderr": func() (Sink, error) { return nopCloserSink{os.Stderr}, nil },
+ }
+}
+
+type errSinkNotFound struct {
+ key string
+}
+
+func (e *errSinkNotFound) Error() string {
+ return fmt.Sprintf("no sink found for %q", e.key)
+}
+
+// Sink defines the interface to write to and close logger destinations.
+type Sink interface {
+ zapcore.WriteSyncer
+ io.Closer
+}
+
+// RegisterSink adds a Sink at the given key so it can be referenced
+// in config OutputPaths.
+func RegisterSink(key string, sinkFactory func() (Sink, error)) error {
+ _sinkMutex.Lock()
+ defer _sinkMutex.Unlock()
+ if key == "" {
+ return errors.New("sink key cannot be blank")
+ }
+ if _, ok := _sinkFactories[key]; ok {
+ return fmt.Errorf("sink already registered for key %q", key)
+ }
+ _sinkFactories[key] = sinkFactory
+ return nil
+}
+
+// newSink invokes the registered sink factory to create and return the
+// sink for the given key. Returns errSinkNotFound if the key cannot be found.
+func newSink(key string) (Sink, error) {
+ _sinkMutex.RLock()
+ defer _sinkMutex.RUnlock()
+ sinkFactory, ok := _sinkFactories[key]
+ if !ok {
+ return nil, &errSinkNotFound{key}
+ }
+ return sinkFactory()
+}
+
+type nopCloserSink struct{ zapcore.WriteSyncer }
+
+func (nopCloserSink) Close() error { return nil }

sink_test.go

@@ -0,0 +1,76 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+ "errors"
+ "os"
+ "testing"
+
+ "github.com/stretchr/testify/assert"
+)
+
+func TestRegisterSink(t *testing.T) {
+ tests := []struct {
+ name string
+ key string
+ factory func() (Sink, error)
+ wantError bool
+ }{
+ {"valid", "valid", func() (Sink, error) { return nopCloserSink{os.Stdout}, nil }, false},
+ {"empty", "", func() (Sink, error) { return nopCloserSink{os.Stdout}, nil }, true},
+ {"stdout", "stdout", func() (Sink, error) { return nopCloserSink{os.Stdout}, nil }, true},
+ }
+
+ for _, tt := range tests {
+ t.Run(tt.name, func(t *testing.T) {
+ err := RegisterSink(tt.key, tt.factory)
+ if tt.wantError {
+ assert.NotNil(t, err)
+ } else {
+ assert.Nil(t, err)
+ assert.NotNil(t, _sinkFactories[tt.key], "expected the factory to be present")
+ }
+ })
+ }
+}
+
+func TestNewSink(t *testing.T) {
+ defer resetSinkRegistry()
+ errTestSink := errors.New("test erroring")
+ err := RegisterSink("errors", func() (Sink, error) { return nil, errTestSink })
+ assert.Nil(t, err)
+ tests := []struct {
+ key string
+ err error
+ }{
+ {"stdout", nil},
+ {"errors", errTestSink},
+ {"nonexistent", &errSinkNotFound{"nonexistent"}},
+ }
+
+ for _, tt := range tests {
+ t.Run(tt.key, func(t *testing.T) {
+ _, err := newSink(tt.key)
+ assert.Equal(t, tt.err, err)
+ })
+ }
+}

writer.go

@@ -21,6 +21,7 @@
 package zap
 
 import (
+ "io"
  "io/ioutil"
  "os"
 
@@ -49,29 +50,32 @@ func Open(paths ...string) (zapcore.WriteSyncer, func(), error) {
 func open(paths []string) ([]zapcore.WriteSyncer, func(), error) {
  var openErr error
  writers := make([]zapcore.WriteSyncer, 0, len(paths))
- files := make([]*os.File, 0, len(paths))
+ closers := make([]io.Closer, 0, len(paths))
  close := func() {
- for _, f := range files {
- f.Close()
+ for _, c := range closers {
+ c.Close()
  }
  }
  for _, path := range paths {
- switch path {
- case "stdout":
- writers = append(writers, os.Stdout)
- // Don't close standard out.
+ sink, err := newSink(path)
+ if err == nil {
+ // Using a registered sink constructor.
+ writers = append(writers, sink)
+ closers = append(closers, sink)
  continue
- case "stderr":
- writers = append(writers, os.Stderr)
- // Don't close standard error.
+ }
+ if _, ok := err.(*errSinkNotFound); ok {
+ // No named sink constructor, use key as path to log file.
+ f, e := os.OpenFile(path, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0644)
+ openErr = multierr.Append(openErr, e)
+ if e == nil {
+ writers = append(writers, f)
+ closers = append(closers, f)
+ }
  continue
  }
- f, err := os.OpenFile(path, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0644)
+ // Sink constructor failed.
  openErr = multierr.Append(openErr, err)
- if err == nil {
- writers = append(writers, f)
- files = append(files, f)
- }
  }
 
  if openErr != nil {

writer_test.go

@@ -21,8 +21,12 @@
 package zap
 
 import (
+ "encoding/hex"
+ "errors"
  "io/ioutil"
+ "math/rand"
  "os"
+ "path/filepath"
  "testing"
 
  "github.com/stretchr/testify/assert"
@@ -44,28 +48,25 @@ func TestOpenNoPaths(t *testing.T) {
 }
 
 func TestOpen(t *testing.T) {
- temp, err := ioutil.TempFile("", "zap-open-test")
- require.NoError(t, err, "Couldn't create a temporary file for test.")
- defer os.Remove(temp.Name())
+ tempName := tempFileName("", "zap-open-test")
+ assert.False(t, fileExists(tempName))
 
  tests := []struct {
- paths []string
- filenames []string
- error string
+ paths []string
+ error string
  }{
- {[]string{"stdout"}, []string{os.Stdout.Name()}, ""},
- {[]string{"stderr"}, []string{os.Stderr.Name()}, ""},
- {[]string{temp.Name()}, []string{temp.Name()}, ""},
- {[]string{"/foo/bar/baz"}, []string{}, "open /foo/bar/baz: no such file or directory"},
+ {[]string{"stdout"}, ""},
+ {[]string{"stderr"}, ""},
+ {[]string{tempName}, ""},
+ {[]string{"/foo/bar/baz"}, "open /foo/bar/baz: no such file or directory"},
  {
- paths: []string{"stdout", "/foo/bar/baz", temp.Name(), "/baz/quux"},
- filenames: []string{os.Stdout.Name(), temp.Name()},
- error: "open /foo/bar/baz: no such file or directory; open /baz/quux: no such file or directory",
+ paths: []string{"stdout", "/foo/bar/baz", tempName, "/baz/quux"},
+ error: "open /foo/bar/baz: no such file or directory; open /baz/quux: no such file or directory",
  },
  }
 
  for _, tt := range tests {
- wss, cleanup, err := open(tt.paths)
+ _, cleanup, err := Open(tt.paths...)
  if err == nil {
  defer cleanup()
  }
@@ -75,14 +76,10 @@ func TestOpen(t *testing.T) {
  } else {
  assert.Equal(t, tt.error, err.Error(), "Unexpected error opening paths %v.", tt.paths)
  }
- names := make([]string, len(wss))
- for i, ws := range wss {
- f, ok := ws.(*os.File)
- require.True(t, ok, "Expected all WriteSyncers returned from open() to be files.")
- names[i] = f.Name()
- }
- assert.Equal(t, tt.filenames, names, "Opened unexpected files given paths %v.", tt.paths)
  }
+
+ assert.True(t, fileExists(tempName))
+ os.Remove(tempName)
 }
 
 func TestOpenFails(t *testing.T) {
@@ -118,8 +115,41 @@ func (w *testWriter) Sync() error {
  return nil
 }
 
+func TestOpenWithCustomSink(t *testing.T) {
+ defer resetSinkRegistry()
+ tw := &testWriter{"test", t}
+ ctr := func() (Sink, error) { return nopCloserSink{tw}, nil }
+ assert.Nil(t, RegisterSink("TestOpenWithCustomSink", ctr))
+ w, cleanup, err := Open("TestOpenWithCustomSink")
+ assert.Nil(t, err)
+ defer cleanup()
+ w.Write([]byte("test"))
+}
+
+func TestOpenWithErroringSinkFactory(t *testing.T) {
+ defer resetSinkRegistry()
+ expectedErr := errors.New("expected factory error")
+ ctr := func() (Sink, error) { return nil, expectedErr }
+ assert.Nil(t, RegisterSink("TestOpenWithErroringSinkFactory", ctr))
+ _, _, err := Open("TestOpenWithErroringSinkFactory")
+ assert.Equal(t, expectedErr, err)
+}
+
 func TestCombineWriteSyncers(t *testing.T) {
  tw := &testWriter{"test", t}
  w := CombineWriteSyncers(tw)
  w.Write([]byte("test"))
 }
+
+func tempFileName(prefix, suffix string) string {
+ randBytes := make([]byte, 16)
+ rand.Read(randBytes)
+ return filepath.Join(os.TempDir(), prefix+hex.EncodeToString(randBytes)+suffix)
+}
+
+func fileExists(name string) bool {
+ if _, err := os.Stat(name); os.IsNotExist(err) {
+ return false
+ }
+ return true
+}