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// Copyright 2015 Light Code Labs, LLC
//
// 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 expvar
import (
"expvar"
"runtime"
"sync"
"github.com/mholt/caddy"
"github.com/mholt/caddy/caddyhttp/httpserver"
)
func init() {
caddy.RegisterPlugin("expvar", caddy.Plugin{
ServerType: "http",
Action: setup,
})
}
// setup configures a new ExpVar middleware instance.
func setup(c *caddy.Controller) error {
resource, err := expVarParse(c)
if err != nil {
return err
}
// publish any extra information/metrics we may want to capture
publishExtraVars()
ev := ExpVar{Resource: resource}
httpserver.GetConfig(c).AddMiddleware(func(next httpserver.Handler) httpserver.Handler {
ev.Next = next
return ev
})
return nil
}
func expVarParse(c *caddy.Controller) (Resource, error) {
var resource Resource
var err error
for c.Next() {
args := c.RemainingArgs()
switch len(args) {
case 0:
resource = Resource(defaultExpvarPath)
case 1:
resource = Resource(args[0])
default:
return resource, c.ArgErr()
}
}
return resource, err
}
func publishExtraVars() {
// By using sync.Once instead of an init() function, we don't clutter
// the app's expvar export unnecessarily, or risk colliding with it.
publishOnce.Do(func() {
expvar.Publish("Goroutines", expvar.Func(func() interface{} {
return runtime.NumGoroutine()
}))
})
}
var publishOnce sync.Once // publishing variables should only be done once
var defaultExpvarPath = "/debug/vars"
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