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Convert README to template (#343)
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Use Go's templating to remove the drudgery from updating the benchmarks in the README.
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bufdev authored and akshayjshah committed Mar 6, 2017
1 parent 3e4a6c3 commit 1d90273
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89 changes: 89 additions & 0 deletions .readme.tmpl
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# :zap: zap [![GoDoc][doc-img]][doc] [![Build Status][ci-img]][ci] [![Coverage Status][cov-img]][cov]

Blazing fast, structured, leveled logging in Go.

## Installation

`go get -u go.uber.org/zap`

## Quick Start

In contexts where performance is nice, but not critical, use the
`SugaredLogger`. It's 4-10x faster than than other structured logging libraries
and includes both structured and `printf`-style APIs.

```go
logger, _ := NewProduction()
sugar := logger.Sugar()
sugar.Infow("Failed to fetch URL.",
// Structured context as loosely-typed key-value pairs.
"url", url,
"attempt", retryNum,
"backoff", time.Second,
)
sugar.Infof("Failed to fetch URL: %s", url)
```

When performance and type safety are critical, use the `Logger`. It's even faster than
the `SugaredLogger` and allocates far less, but it only supports structured logging.

```go
logger, _ := NewProduction()
logger.Info("Failed to fetch URL.",
// Structured context as strongly-typed Field values.
zap.String("url", url),
zap.Int("attempt", tryNum),
zap.Duration("backoff", time.Second),
)
```

## Performance

For applications that log in the hot path, reflection-based serialization and
string formatting are prohibitively expensive — they're CPU-intensive and
make many small allocations. Put differently, using `encoding/json` and
`fmt.Fprintf` to log tons of `interface{}`s makes your application slow.

Zap takes a different approach. It includes a reflection-free, zero-allocation
JSON encoder, and the base `Logger` strives to avoid serialization overhead and
allocations wherever possible. By building the high-level `SugaredLogger` on
that foundation, zap lets users *choose* when they need to count every
allocation and when they'd prefer a more familiar, loosely-typed API.

As measured by its own [benchmarking suite][], not only is zap more performant
than comparable structured logging libraries — it's also faster than the
standard library. Like all benchmarks, take these with a grain of salt.<sup
id="anchor-versions">[1](#footnote-versions)</sup>

Log a message and 10 fields:

{{.BenchmarkAddingFields}}

Log a message with a logger that already has 10 fields of context:

{{.BenchmarkAccumulatedContext}}

Log a static string, without any context or `printf`-style templating:

{{.BenchmarkWithoutFields}}

## Development Status: Release Candidate 2
The current release is `v1.0.0-rc.2`. No further breaking changes are *planned*
unless wider use reveals critical bugs or usability issues, but users who need
absolute stability should wait for the 1.0.0 release.

<hr>
Released under the [MIT License](LICENSE.txt).

<sup id="footnote-versions">1</sup> In particular, keep in mind that we may be
benchmarking against slightly older versions of other libraries. Versions are
pinned in zap's [glide.lock][] file. [↩](#anchor-versions)

[doc-img]: https://godoc.org/go.uber.org/zap?status.svg
[doc]: https://godoc.org/go.uber.org/zap
[ci-img]: https://travis-ci.org/uber-go/zap.svg?branch=master
[ci]: https://travis-ci.org/uber-go/zap
[cov-img]: https://coveralls.io/repos/github/uber-go/zap/badge.svg?branch=master
[cov]: https://coveralls.io/github/uber-go/zap?branch=master
[benchmarking suite]: https://github.com/uber-go/zap/tree/master/benchmarks
[glide.lock]: https://github.com/uber-go/zap/blob/master/glide.lock
9 changes: 8 additions & 1 deletion Makefile
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Expand Up @@ -5,6 +5,8 @@ PKGS ?= $(shell glide novendor)
# Many Go tools take file globs or directories as arguments instead of packages.
PKG_FILES ?= *.go zapcore benchmarks buffer testutils internal/bufferpool internal/exit internal/multierror internal/observer internal/color

COVERALLS_IGNORE := internal/readme/readme.go

# The linting tools evolve with each Go version, so run them only on the latest
# stable release.
GO_VERSION := $(shell go version | cut -d " " -f 3)
Expand Down Expand Up @@ -63,9 +65,14 @@ test:

.PHONY: coveralls
coveralls:
goveralls -service=travis-ci
goveralls -ignore=$(COVERALLS_IGNORE) -service=travis-ci

.PHONY: bench
BENCH ?= .
bench:
@$(foreach pkg,$(PKGS),go test -bench=$(BENCH) -run="^$$" $(BENCH_FLAGS) $(pkg);)

.PHONY: updatereadme
updatereadme:
rm -f README.md
cat .readme.tmpl | go run internal/readme/readme.go > README.md
41 changes: 22 additions & 19 deletions README.md
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Expand Up @@ -59,35 +59,38 @@ Log a message and 10 fields:

| Library | Time | Bytes Allocated | Objects Allocated |
| :--- | :---: | :---: | :---: |
| :zap: zap | 1436 ns/op | 705 B/op | 2 allocs/op |
| :zap: zap (sugared) | 2436 ns/op | 1931 B/op | 21 allocs/op |
| logrus | 9393 ns/op | 5783 B/op | 77 allocs/op |
| go-kit | 6929 ns/op | 3119 B/op | 65 allocs/op |
| log15 | 25004 ns/op | 5535 B/op | 91 allocs/op |
| apex/log | 18450 ns/op | 4025 B/op | 64 allocs/op |
| :zap: zap | 694 ns/op | 705 B/op | 2 allocs/op |
| :zap: zap (sugared) | 1174 ns/op | 1613 B/op | 20 allocs/op |
| logrus | 6824 ns/op | 6100 B/op | 78 allocs/op |
| go-kit | 3830 ns/op | 2897 B/op | 66 allocs/op |
| log15 | 16650 ns/op | 5632 B/op | 93 allocs/op |
| apex/log | 13381 ns/op | 3834 B/op | 65 allocs/op |
| lion | 5807 ns/op | 5811 B/op | 63 allocs/op |

Log a message with a logger that already has 10 fields of context:

| Library | Time | Bytes Allocated | Objects Allocated |
| :--- | :---: | :---: | :---: |
| :zap: zap | 368 ns/op | 0 B/op | 0 allocs/op |
| :zap: zap (sugared) | 388 ns/op | 0 B/op | 0 allocs/op |
| logrus | 8420 ns/op | 3967 B/op | 61 allocs/op |
| go-kit | 7288 ns/op | 2950 B/op | 50 allocs/op |
| log15 | 17678 ns/op | 2546 B/op | 42 allocs/op |
| apex/log | 16126 ns/op | 2801 B/op | 49 allocs/op |
| :zap: zap | 233 ns/op | 0 B/op | 0 allocs/op |
| :zap: zap (sugared) | 356 ns/op | 80 B/op | 2 allocs/op |
| logrus | 5647 ns/op | 4568 B/op | 63 allocs/op |
| go-kit | 4416 ns/op | 3048 B/op | 52 allocs/op |
| log15 | 14623 ns/op | 2643 B/op | 44 allocs/op |
| apex/log | 11730 ns/op | 2898 B/op | 51 allocs/op |
| lion | 3553 ns/op | 4076 B/op | 38 allocs/op |

Log a static string, without any context or `printf`-style templating:

| Library | Time | Bytes Allocated | Objects Allocated |
| :--- | :---: | :---: | :---: |
| :zap: zap | 398 ns/op | 0 B/op | 0 allocs/op |
| :zap: zap (sugared) | 400 ns/op | 80 B/op | 2 allocs/op |
| standard library | 678 ns/op | 80 B/op | 2 allocs/op |
| logrus | 2778 ns/op | 1409 B/op | 25 allocs/op |
| go-kit | 1318 ns/op | 656 B/op | 13 allocs/op |
| log15 | 5720 ns/op | 1496 B/op | 24 allocs/op |
| apex/log | 3282 ns/op | 584 B/op | 11 allocs/op |
| :zap: zap | 266 ns/op | 0 B/op | 0 allocs/op |
| :zap: zap (sugared) | 367 ns/op | 80 B/op | 2 allocs/op |
| standard library | 584 ns/op | 80 B/op | 2 allocs/op |
| logrus | 1586 ns/op | 1507 B/op | 27 allocs/op |
| go-kit | 612 ns/op | 656 B/op | 13 allocs/op |
| log15 | 4911 ns/op | 1592 B/op | 26 allocs/op |
| apex/log | 2557 ns/op | 584 B/op | 11 allocs/op |
| lion | 914 ns/op | 1225 B/op | 10 allocs/op |

## Development Status: Release Candidate 2
The current release is `v1.0.0-rc.2`. No further breaking changes are *planned*
Expand Down
175 changes: 175 additions & 0 deletions internal/readme/readme.go
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// 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 main

import (
"flag"
"fmt"
"io/ioutil"
"log"
"os"
"os/exec"
"strings"
"text/template"
)

var (
libraryNames = []string{
"Zap",
"Zap.Sugar",
"stdlib.Println",
"sirupsen/logrus",
"go-kit/kit/log",
"inconshreveable/log15",
"apex/log",
"go.pedge.io/lion",
}
libraryNameToMarkdownName = map[string]string{
"Zap": ":zap: zap",
"Zap.Sugar": ":zap: zap (sugared)",
"stdlib.Println": "standard library",
"sirupsen/logrus": "logrus",
"go-kit/kit/log": "go-kit",
"inconshreveable/log15": "log15",
"apex/log": "apex/log",
"go.pedge.io/lion": "lion",
}
)

func main() {
flag.Parse()
if err := do(); err != nil {
log.Fatal(err)
}
}

func do() error {
tmplData, err := getTmplData()
if err != nil {
return err
}
data, err := ioutil.ReadAll(os.Stdin)
if err != nil {
return err
}
t, err := template.New("tmpl").Parse(string(data))
if err != nil {
return err
}
if err := t.Execute(os.Stdout, tmplData); err != nil {
return err
}
return nil
}

type tmplData struct {
BenchmarkAddingFields string
BenchmarkAccumulatedContext string
BenchmarkWithoutFields string
}

func getTmplData() (*tmplData, error) {
tmplData := &tmplData{}
rows, err := getBenchmarkRows("BenchmarkAddingFields")
if err != nil {
return nil, err
}
tmplData.BenchmarkAddingFields = rows
rows, err = getBenchmarkRows("BenchmarkAccumulatedContext")
if err != nil {
return nil, err
}
tmplData.BenchmarkAccumulatedContext = rows
rows, err = getBenchmarkRows("BenchmarkWithoutFields")
if err != nil {
return nil, err
}
tmplData.BenchmarkWithoutFields = rows
return tmplData, nil
}

func getBenchmarkRows(benchmarkName string) (string, error) {
benchmarkOutput, err := getBenchmarkOutput(benchmarkName)
if err != nil {
return "", err
}
rows := []string{
"| Library | Time | Bytes Allocated | Objects Allocated |",
"| :--- | :---: | :---: | :---: |",
}
for _, libraryName := range libraryNames {
row, err := getBenchmarkRow(benchmarkOutput, benchmarkName, libraryName)
if err != nil {
return "", err
}
if row == "" {
continue
}
rows = append(rows, row)
}
return strings.Join(rows, "\n"), nil
}

func getBenchmarkRow(input []string, benchmarkName string, libraryName string) (string, error) {
line, err := findUniqueSubstring(input, fmt.Sprintf("%s/%s-", benchmarkName, libraryName))
if err != nil {
return "", err
}
if line == "" {
return "", nil
}
split := strings.Split(line, "\t")
if len(split) < 5 {
return "", fmt.Errorf("unknown benchmark line: %s", line)
}
return fmt.Sprintf(
"| %s | %s | %s | %s |",
libraryNameToMarkdownName[libraryName],
strings.TrimSpace(split[2]),
strings.TrimSpace(split[3]),
strings.TrimSpace(split[4]),
), nil
}

func findUniqueSubstring(input []string, substring string) (string, error) {
var output string
for _, line := range input {
if strings.Contains(line, substring) {
if output != "" {
return "", fmt.Errorf("input has duplicate substring %s", substring)
}
output = line
}
}
return output, nil
}

func getBenchmarkOutput(benchmarkName string) ([]string, error) {
return getOutput("go", "test", fmt.Sprintf("-bench=%s", benchmarkName), "-benchmem", "./benchmarks")
}

func getOutput(name string, arg ...string) ([]string, error) {
output, err := exec.Command(name, arg...).CombinedOutput()
if err != nil {
return nil, fmt.Errorf("error running %s %s: %v\n%s", name, strings.Join(arg, " "), err, string(output))
}
return strings.Split(string(output), "\n"), nil
}

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