adding in logging

vendor/go.uber.org/zap/writer.go

@@ -0,0 +1,96 @@
+// 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 (
+	"io/ioutil"
+	"os"
+
+	"go.uber.org/zap/zapcore"
+
+	"go.uber.org/multierr"
+)
+
+// Open is a high-level wrapper that takes a variadic number of paths, opens or
+// creates each of the specified files, and combines them into a locked
+// WriteSyncer. It also returns any error encountered and a function to close
+// any opened files.
+//
+// Passing no paths returns a no-op WriteSyncer. The special paths "stdout" and
+// "stderr" are interpreted as os.Stdout and os.Stderr, respectively.
+func Open(paths ...string) (zapcore.WriteSyncer, func(), error) {
+	writers, close, err := open(paths)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	writer := CombineWriteSyncers(writers...)
+	return writer, close, nil
+}
+
+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))
+	close := func() {
+		for _, f := range files {
+			f.Close()
+		}
+	}
+	for _, path := range paths {
+		switch path {
+		case "stdout":
+			writers = append(writers, os.Stdout)
+			// Don't close standard out.
+			continue
+		case "stderr":
+			writers = append(writers, os.Stderr)
+			// Don't close standard error.
+			continue
+		}
+		f, err := os.OpenFile(path, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0644)
+		openErr = multierr.Append(openErr, err)
+		if err == nil {
+			writers = append(writers, f)
+			files = append(files, f)
+		}
+	}
+
+	if openErr != nil {
+		close()
+		return writers, nil, openErr
+	}
+
+	return writers, close, nil
+}
+
+// CombineWriteSyncers is a utility that combines multiple WriteSyncers into a
+// single, locked WriteSyncer. If no inputs are supplied, it returns a no-op
+// WriteSyncer.
+//
+// It's provided purely as a convenience; the result is no different from
+// using zapcore.NewMultiWriteSyncer and zapcore.Lock individually.
+func CombineWriteSyncers(writers ...zapcore.WriteSyncer) zapcore.WriteSyncer {
+	if len(writers) == 0 {
+		return zapcore.AddSync(ioutil.Discard)
+	}
+	return zapcore.Lock(zapcore.NewMultiWriteSyncer(writers...))
+}