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https://github.com/codemodus/chain
Composable chains of nested http.Handler instances.
https://github.com/codemodus/chain
Last synced: about 1 month ago
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Composable chains of nested http.Handler instances.
- Host: GitHub
- URL: https://github.com/codemodus/chain
- Owner: codemodus
- License: mit
- Created: 2015-05-14T19:52:58.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2018-08-25T20:35:40.000Z (over 6 years ago)
- Last Synced: 2024-08-03T15:06:15.780Z (5 months ago)
- Language: Go
- Homepage:
- Size: 40 KB
- Stars: 63
- Watchers: 7
- Forks: 3
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-go - chain - Composable chains of nested http.Handler instances. - ★ 63 (Web Frameworks)
- awesome-go-extra - chain - 05-14T19:52:58Z|2018-08-25T20:35:40Z| (Web Frameworks / Fail injection)
README
# chain
go get github.com/codemodus/chain
Package chain aids the composition of nested http.Handler instances.
Nesting functions is a simple concept. If your nested handler order does not
need to be composable, please do not use this or any similar package and avoid
adding a dependency to your project.
## Usage
```go
type Chain
func New(handlers ...func(http.Handler) http.Handler) *Chain
func (c *Chain) Append(handlers ...func(http.Handler) http.Handler) *Chain
func (c *Chain) Copy(chain *Chain)
func (c *Chain) End(handler http.Handler) http.Handler
func (c *Chain) EndFn(handlerFunc http.HandlerFunc) http.Handler
func (c *Chain) Merge(chains ...*Chain) *Chain
```
### Setup
```go
import (
// ...
"github.com/codemodus/chain"
)
func main() {
// ...
// Nested handlers write either "0" or "1" to the response body before
// and after ServeHTTP() is called.
//
// endHandler writes "_END_" to the response body.
ch00 := New(nestedHandler0, nestedHandler0)
ch001 := ch00.Append(nestedHandler1)
ch1 := New(nestedHandler1)
ch1001 := ch1.Merge(ch001)
mux := http.NewServeMux()
mux.Handle("/00_End", ch00.EndFn(endHandler)) // Resp Body: "00_END_00"
mux.Handle("/001_End", ch001.EndFn(endHandler)) // Resp Body: "001_END_100"
mux.Handle("/1001_End", ch1001.EndFn(endHandler)) // Resp Body: "1001_END_1001"
// ...
}
```
### Nestable http.Handler
```go
func nestableHandler(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// ...
next.ServeHTTP(w, r)
// ...
})
}
```
## More Info
### Changes in go1.7+/chain2.0+
As of Go 1.7, the http package's Request type includes a field (accessed via
the Context() method) which holds an implementation of context.Context. Further,
the context package has been added to the standard library. There is now no need
for the custom Handler defined in previous versions of chain. Please refer to
the following command to ease the process of updating your source.
sed -r -e 's/chain\.Handler/http.Handler/g' \
-e 's/[a-zA-Z0-9]+ context\.Context, ([a-zA-Z0-9]+) (http\.ResponseWriter)/\1 \2/' \
-e 's/ServeHTTPContext\([a-zA-Z0-9]+, /ServeHTTP(/'
Beyond this, any usage of chain.Set(context.Context) will need to be modified
manually. Adding the affected logic as a nested handler is a simple and
effective alternative. Don't forget to run gofmt/goimports.
## Documentation
View the [GoDoc](http://godoc.org/github.com/codemodus/chain)
## Benchmarks
These results are for comparison of normally nested functions, and chained
functions. Each benchmark includes 10 functions prior to the final handler.
go1.7
benchmark iter time/iter bytes alloc allocs
--------- ---- --------- ----------- ------
BenchmarkChain10 20000 61.01 μs/op 3684 B/op 51 allocs/op
BenchmarkChain10-4 20000 68.62 μs/op 3691 B/op 51 allocs/op
BenchmarkChain10-8 20000 69.33 μs/op 3696 B/op 51 allocs/op
BenchmarkNest10 20000 60.36 μs/op 3684 B/op 51 allocs/op
BenchmarkNest10-4 20000 70.82 μs/op 3692 B/op 51 allocs/op
BenchmarkNest10-8 20000 71.03 μs/op 3697 B/op 51 allocs/op