Move gaelogging from luci/luci-go to luci/gae

impl/prod/logger.go

Index: impl/prod/logger.go
diff --git a/impl/prod/logger.go b/impl/prod/logger.go
new file mode 100644
index 0000000000000000000000000000000000000000..2b8d9712fdf2cc2fbe35811a3ffea27883ac66a2
--- /dev/null
+++ b/impl/prod/logger.go
@@ -0,0 +1,67 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package prod
+
+import (
+	"fmt"
+
+	"github.com/luci/luci-go/common/logging"
+	"golang.org/x/net/context"
+	"google.golang.org/appengine/log"
+)
+
+// useLogging adds a logging.Logger implementation to the context which logs to
+// appengine's log handler.
+func useLogging(c context.Context) context.Context {
+	return logging.SetFactory(c, func(ic context.Context) logging.Logger {
+		return &loggerImpl{AEContext(ic)}
+	})
+}
+
+type loggerImpl struct {
+	aeCtx context.Context
+}
+
+func (gl *loggerImpl) Debugf(format string, args ...interface{}) {
+	gl.LogCall(logging.Debug, 1, format, args)
+}
+func (gl *loggerImpl) Infof(format string, args ...interface{}) {
+	gl.LogCall(logging.Info, 1, format, args)
+}
+func (gl *loggerImpl) Warningf(format string, args ...interface{}) {
+	gl.LogCall(logging.Warning, 1, format, args)
+}
+func (gl *loggerImpl) Errorf(format string, args ...interface{}) {
+	gl.LogCall(logging.Error, 1, format, args)
+}
+
+// TODO(riannucci): prefix with caller's code location.
+func (gl *loggerImpl) LogCall(l logging.Level, calldepth int, format string, args []interface{}) {
+	if gl.aeCtx == nil || !logging.IsLogging(gl.aeCtx, l) {
+		return
+	}
+
+	var logf func(context.Context, string, ...interface{})
+	switch l {
+	case logging.Debug:
+		logf = log.Debugf
+	case logging.Info:
+		logf = log.Infof
+	case logging.Warning:
+		logf = log.Warningf
+
+	case logging.Error:
+		fallthrough
+	default:
+		logf = log.Errorf
+	}
+
+	fields := logging.GetFields(gl.aeCtx)
+	if len(fields) > 0 {
+		logf(gl.aeCtx, "%s :: %s", fmt.Sprintf(format, args...), fields.FieldString(true))
+	} else {
+		logf(gl.aeCtx, format, args...)
+	}
+}