mirror of
https://codeberg.org/forgejo/forgejo.git
synced 2024-11-26 09:09:36 -05:00
337 lines
15 KiB
Markdown
337 lines
15 KiB
Markdown
|
# easyjson [](https://travis-ci.org/mailru/easyjson) [](https://goreportcard.com/report/github.com/mailru/easyjson)
|
||
|
|
|
||
|
|
Package easyjson provides a fast and easy way to marshal/unmarshal Go structs
|
||
|
|
to/from JSON without the use of reflection. In performance tests, easyjson
|
||
|
|
outperforms the standard `encoding/json` package by a factor of 4-5x, and other
|
||
|
|
JSON encoding packages by a factor of 2-3x.
|
||
|
|
|
||
|
|
easyjson aims to keep generated Go code simple enough so that it can be easily
|
||
|
|
optimized or fixed. Another goal is to provide users with the ability to
|
||
|
|
customize the generated code by providing options not available with the
|
||
|
|
standard `encoding/json` package, such as generating "snake_case" names or
|
||
|
|
enabling `omitempty` behavior by default.
|
||
|
|
|
||
|
|
## Usage
|
||
|
|
```sh
|
||
|
|
# install
|
||
|
|
go get -u github.com/mailru/easyjson/...
|
||
|
|
|
||
|
|
# run
|
||
|
|
easyjson -all <file>.go
|
||
|
|
```
|
||
|
|
|
||
|
|
The above will generate `<file>_easyjson.go` containing the appropriate marshaler and
|
||
|
|
unmarshaler funcs for all structs contained in `<file>.go`.
|
||
|
|
|
||
|
|
Please note that easyjson requires a full Go build environment and the `GOPATH`
|
||
|
|
environment variable to be set. This is because easyjson code generation
|
||
|
|
invokes `go run` on a temporary file (an approach to code generation borrowed
|
||
|
|
from [ffjson](https://github.com/pquerna/ffjson)).
|
||
|
|
|
||
|
|
## Options
|
||
|
|
```txt
|
||
|
|
Usage of easyjson:
|
||
|
|
-all
|
||
|
|
generate marshaler/unmarshalers for all structs in a file
|
||
|
|
-build_tags string
|
||
|
|
build tags to add to generated file
|
||
|
|
-leave_temps
|
||
|
|
do not delete temporary files
|
||
|
|
-no_std_marshalers
|
||
|
|
don't generate MarshalJSON/UnmarshalJSON funcs
|
||
|
|
-noformat
|
||
|
|
do not run 'gofmt -w' on output file
|
||
|
|
-omit_empty
|
||
|
|
omit empty fields by default
|
||
|
|
-output_filename string
|
||
|
|
specify the filename of the output
|
||
|
|
-pkg
|
||
|
|
process the whole package instead of just the given file
|
||
|
|
-snake_case
|
||
|
|
use snake_case names instead of CamelCase by default
|
||
|
|
-lower_camel_case
|
||
|
|
use lowerCamelCase instead of CamelCase by default
|
||
|
|
-stubs
|
||
|
|
only generate stubs for marshaler/unmarshaler funcs
|
||
|
|
-disallow_unknown_fields
|
||
|
|
return error if some unknown field in json appeared
|
||
|
|
```
|
||
|
|
|
||
|
|
Using `-all` will generate marshalers/unmarshalers for all Go structs in the
|
||
|
|
file. If `-all` is not provided, then only those structs whose preceding
|
||
|
|
comment starts with `easyjson:json` will have marshalers/unmarshalers
|
||
|
|
generated. For example:
|
||
|
|
|
||
|
|
```go
|
||
|
|
//easyjson:json
|
||
|
|
type A struct {}
|
||
|
|
```
|
||
|
|
|
||
|
|
Additional option notes:
|
||
|
|
|
||
|
|
* `-snake_case` tells easyjson to generate snake\_case field names by default
|
||
|
|
(unless overridden by a field tag). The CamelCase to snake\_case conversion
|
||
|
|
algorithm should work in most cases (ie, HTTPVersion will be converted to
|
||
|
|
"http_version").
|
||
|
|
|
||
|
|
* `-build_tags` will add the specified build tags to generated Go sources.
|
||
|
|
|
||
|
|
## Generated Marshaler/Unmarshaler Funcs
|
||
|
|
|
||
|
|
For Go struct types, easyjson generates the funcs `MarshalEasyJSON` /
|
||
|
|
`UnmarshalEasyJSON` for marshaling/unmarshaling JSON. In turn, these satisify
|
||
|
|
the `easyjson.Marshaler` and `easyjson.Unmarshaler` interfaces and when used in
|
||
|
|
conjunction with `easyjson.Marshal` / `easyjson.Unmarshal` avoid unnecessary
|
||
|
|
reflection / type assertions during marshaling/unmarshaling to/from JSON for Go
|
||
|
|
structs.
|
||
|
|
|
||
|
|
easyjson also generates `MarshalJSON` and `UnmarshalJSON` funcs for Go struct
|
||
|
|
types compatible with the standard `json.Marshaler` and `json.Unmarshaler`
|
||
|
|
interfaces. Please be aware that using the standard `json.Marshal` /
|
||
|
|
`json.Unmarshal` for marshaling/unmarshaling will incur a significant
|
||
|
|
performance penalty when compared to using `easyjson.Marshal` /
|
||
|
|
`easyjson.Unmarshal`.
|
||
|
|
|
||
|
|
Additionally, easyjson exposes utility funcs that use the `MarshalEasyJSON` and
|
||
|
|
`UnmarshalEasyJSON` for marshaling/unmarshaling to and from standard readers
|
||
|
|
and writers. For example, easyjson provides `easyjson.MarshalToHTTPResponseWriter`
|
||
|
|
which marshals to the standard `http.ResponseWriter`. Please see the [GoDoc
|
||
|
|
listing](https://godoc.org/github.com/mailru/easyjson) for the full listing of
|
||
|
|
utility funcs that are available.
|
||
|
|
|
||
|
|
## Controlling easyjson Marshaling and Unmarshaling Behavior
|
||
|
|
|
||
|
|
Go types can provide their own `MarshalEasyJSON` and `UnmarshalEasyJSON` funcs
|
||
|
|
that satisify the `easyjson.Marshaler` / `easyjson.Unmarshaler` interfaces.
|
||
|
|
These will be used by `easyjson.Marshal` and `easyjson.Unmarshal` when defined
|
||
|
|
for a Go type.
|
||
|
|
|
||
|
|
Go types can also satisify the `easyjson.Optional` interface, which allows the
|
||
|
|
type to define its own `omitempty` logic.
|
||
|
|
|
||
|
|
## Type Wrappers
|
||
|
|
|
||
|
|
easyjson provides additional type wrappers defined in the `easyjson/opt`
|
||
|
|
package. These wrap the standard Go primitives and in turn satisify the
|
||
|
|
easyjson interfaces.
|
||
|
|
|
||
|
|
The `easyjson/opt` type wrappers are useful when needing to distinguish between
|
||
|
|
a missing value and/or when needing to specifying a default value. Type
|
||
|
|
wrappers allow easyjson to avoid additional pointers and heap allocations and
|
||
|
|
can significantly increase performance when used properly.
|
||
|
|
|
||
|
|
## Memory Pooling
|
||
|
|
|
||
|
|
easyjson uses a buffer pool that allocates data in increasing chunks from 128
|
||
|
|
to 32768 bytes. Chunks of 512 bytes and larger will be reused with the help of
|
||
|
|
`sync.Pool`. The maximum size of a chunk is bounded to reduce redundant memory
|
||
|
|
allocation and to allow larger reusable buffers.
|
||
|
|
|
||
|
|
easyjson's custom allocation buffer pool is defined in the `easyjson/buffer`
|
||
|
|
package, and the default behavior pool behavior can be modified (if necessary)
|
||
|
|
through a call to `buffer.Init()` prior to any marshaling or unmarshaling.
|
||
|
|
Please see the [GoDoc listing](https://godoc.org/github.com/mailru/easyjson/buffer)
|
||
|
|
for more information.
|
||
|
|
|
||
|
|
## Issues, Notes, and Limitations
|
||
|
|
|
||
|
|
* easyjson is still early in its development. As such, there are likely to be
|
||
|
|
bugs and missing features when compared to `encoding/json`. In the case of a
|
||
|
|
missing feature or bug, please create a GitHub issue. Pull requests are
|
||
|
|
welcome!
|
||
|
|
|
||
|
|
* Unlike `encoding/json`, object keys are case-sensitive. Case-insensitive
|
||
|
|
matching is not currently provided due to the significant performance hit
|
||
|
|
when doing case-insensitive key matching. In the future, case-insensitive
|
||
|
|
object key matching may be provided via an option to the generator.
|
||
|
|
|
||
|
|
* easyjson makes use of `unsafe`, which simplifies the code and
|
||
|
|
provides significant performance benefits by allowing no-copy
|
||
|
|
conversion from `[]byte` to `string`. That said, `unsafe` is used
|
||
|
|
only when unmarshaling and parsing JSON, and any `unsafe` operations
|
||
|
|
/ memory allocations done will be safely deallocated by
|
||
|
|
easyjson. Set the build tag `easyjson_nounsafe` to compile it
|
||
|
|
without `unsafe`.
|
||
|
|
|
||
|
|
* easyjson is compatible with Google App Engine. The `appengine` build
|
||
|
|
tag (set by App Engine's environment) will automatically disable the
|
||
|
|
use of `unsafe`, which is not allowed in App Engine's Standard
|
||
|
|
Environment. Note that the use with App Engine is still experimental.
|
||
|
|
|
||
|
|
* Floats are formatted using the default precision from Go's `strconv` package.
|
||
|
|
As such, easyjson will not correctly handle high precision floats when
|
||
|
|
marshaling/unmarshaling JSON. Note, however, that there are very few/limited
|
||
|
|
uses where this behavior is not sufficient for general use. That said, a
|
||
|
|
different package may be needed if precise marshaling/unmarshaling of high
|
||
|
|
precision floats to/from JSON is required.
|
||
|
|
|
||
|
|
* While unmarshaling, the JSON parser does the minimal amount of work needed to
|
||
|
|
skip over unmatching parens, and as such full validation is not done for the
|
||
|
|
entire JSON value being unmarshaled/parsed.
|
||
|
|
|
||
|
|
* Currently there is no true streaming support for encoding/decoding as
|
||
|
|
typically for many uses/protocols the final, marshaled length of the JSON
|
||
|
|
needs to be known prior to sending the data. Currently this is not possible
|
||
|
|
with easyjson's architecture.
|
||
|
|
|
||
|
|
* easyjson parser and codegen based on reflection, so it wont works on `package main`
|
||
|
|
files, because they cant be imported by parser.
|
||
|
|
|
||
|
|
## Benchmarks
|
||
|
|
|
||
|
|
Most benchmarks were done using the example
|
||
|
|
[13kB example JSON](https://dev.twitter.com/rest/reference/get/search/tweets)
|
||
|
|
(9k after eliminating whitespace). This example is similar to real-world data,
|
||
|
|
is well-structured, and contains a healthy variety of different types, making
|
||
|
|
it ideal for JSON serialization benchmarks.
|
||
|
|
|
||
|
|
Note:
|
||
|
|
|
||
|
|
* For small request benchmarks, an 80 byte portion of the above example was
|
||
|
|
used.
|
||
|
|
|
||
|
|
* For large request marshaling benchmarks, a struct containing 50 regular
|
||
|
|
samples was used, making a ~500kB output JSON.
|
||
|
|
|
||
|
|
* Benchmarks are showing the results of easyjson's default behaviour,
|
||
|
|
which makes use of `unsafe`.
|
||
|
|
|
||
|
|
Benchmarks are available in the repository and can be run by invoking `make`.
|
||
|
|
|
||
|
|
### easyjson vs. encoding/json
|
||
|
|
|
||
|
|
easyjson is roughly 5-6 times faster than the standard `encoding/json` for
|
||
|
|
unmarshaling, and 3-4 times faster for non-concurrent marshaling. Concurrent
|
||
|
|
marshaling is 6-7x faster if marshaling to a writer.
|
||
|
|
|
||
|
|
### easyjson vs. ffjson
|
||
|
|
|
||
|
|
easyjson uses the same approach for JSON marshaling as
|
||
|
|
[ffjson](https://github.com/pquerna/ffjson), but takes a significantly
|
||
|
|
different approach to lexing and parsing JSON during unmarshaling. This means
|
||
|
|
easyjson is roughly 2-3x faster for unmarshaling and 1.5-2x faster for
|
||
|
|
non-concurrent unmarshaling.
|
||
|
|
|
||
|
|
As of this writing, `ffjson` seems to have issues when used concurrently:
|
||
|
|
specifically, large request pooling hurts `ffjson`'s performance and causes
|
||
|
|
scalability issues. These issues with `ffjson` can likely be fixed, but as of
|
||
|
|
writing remain outstanding/known issues with `ffjson`.
|
||
|
|
|
||
|
|
easyjson and `ffjson` have similar performance for small requests, however
|
||
|
|
easyjson outperforms `ffjson` by roughly 2-5x times for large requests when
|
||
|
|
used with a writer.
|
||
|
|
|
||
|
|
### easyjson vs. go/codec
|
||
|
|
|
||
|
|
[go/codec](https://github.com/ugorji/go) provides
|
||
|
|
compile-time helpers for JSON generation. In this case, helpers do not work
|
||
|
|
like marshalers as they are encoding-independent.
|
||
|
|
|
||
|
|
easyjson is generally 2x faster than `go/codec` for non-concurrent benchmarks
|
||
|
|
and about 3x faster for concurrent encoding (without marshaling to a writer).
|
||
|
|
|
||
|
|
In an attempt to measure marshaling performance of `go/codec` (as opposed to
|
||
|
|
allocations/memcpy/writer interface invocations), a benchmark was done with
|
||
|
|
resetting length of a byte slice rather than resetting the whole slice to nil.
|
||
|
|
However, the optimization in this exact form may not be applicable in practice,
|
||
|
|
since the memory is not freed between marshaling operations.
|
||
|
|
|
||
|
|
### easyjson vs 'ujson' python module
|
||
|
|
|
||
|
|
[ujson](https://github.com/esnme/ultrajson) is using C code for parsing, so it
|
||
|
|
is interesting to see how plain golang compares to that. It is imporant to note
|
||
|
|
that the resulting object for python is slower to access, since the library
|
||
|
|
parses JSON object into dictionaries.
|
||
|
|
|
||
|
|
easyjson is slightly faster for unmarshaling and 2-3x faster than `ujson` for
|
||
|
|
marshaling.
|
||
|
|
|
||
|
|
### Benchmark Results
|
||
|
|
|
||
|
|
`ffjson` results are from February 4th, 2016, using the latest `ffjson` and go1.6.
|
||
|
|
`go/codec` results are from March 4th, 2016, using the latest `go/codec` and go1.6.
|
||
|
|
|
||
|
|
#### Unmarshaling
|
||
|
|
|
||
|
|
| lib | json size | MB/s | allocs/op | B/op |
|
||
|
|
|:---------|:----------|-----:|----------:|------:|
|
||
|
|
| standard | regular | 22 | 218 | 10229 |
|
||
|
|
| standard | small | 9.7 | 14 | 720 |
|
||
|
|
| | | | | |
|
||
|
|
| easyjson | regular | 125 | 128 | 9794 |
|
||
|
|
| easyjson | small | 67 | 3 | 128 |
|
||
|
|
| | | | | |
|
||
|
|
| ffjson | regular | 66 | 141 | 9985 |
|
||
|
|
| ffjson | small | 17.6 | 10 | 488 |
|
||
|
|
| | | | | |
|
||
|
|
| codec | regular | 55 | 434 | 19299 |
|
||
|
|
| codec | small | 29 | 7 | 336 |
|
||
|
|
| | | | | |
|
||
|
|
| ujson | regular | 103 | N/A | N/A |
|
||
|
|
|
||
|
|
#### Marshaling, one goroutine.
|
||
|
|
|
||
|
|
| lib | json size | MB/s | allocs/op | B/op |
|
||
|
|
|:----------|:----------|-----:|----------:|------:|
|
||
|
|
| standard | regular | 75 | 9 | 23256 |
|
||
|
|
| standard | small | 32 | 3 | 328 |
|
||
|
|
| standard | large | 80 | 17 | 1.2M |
|
||
|
|
| | | | | |
|
||
|
|
| easyjson | regular | 213 | 9 | 10260 |
|
||
|
|
| easyjson* | regular | 263 | 8 | 742 |
|
||
|
|
| easyjson | small | 125 | 1 | 128 |
|
||
|
|
| easyjson | large | 212 | 33 | 490k |
|
||
|
|
| easyjson* | large | 262 | 25 | 2879 |
|
||
|
|
| | | | | |
|
||
|
|
| ffjson | regular | 122 | 153 | 21340 |
|
||
|
|
| ffjson** | regular | 146 | 152 | 4897 |
|
||
|
|
| ffjson | small | 36 | 5 | 384 |
|
||
|
|
| ffjson** | small | 64 | 4 | 128 |
|
||
|
|
| ffjson | large | 134 | 7317 | 818k |
|
||
|
|
| ffjson** | large | 125 | 7320 | 827k |
|
||
|
|
| | | | | |
|
||
|
|
| codec | regular | 80 | 17 | 33601 |
|
||
|
|
| codec*** | regular | 108 | 9 | 1153 |
|
||
|
|
| codec | small | 42 | 3 | 304 |
|
||
|
|
| codec*** | small | 56 | 1 | 48 |
|
||
|
|
| codec | large | 73 | 483 | 2.5M |
|
||
|
|
| codec*** | large | 103 | 451 | 66007 |
|
||
|
|
| | | | | |
|
||
|
|
| ujson | regular | 92 | N/A | N/A |
|
||
|
|
|
||
|
|
\* marshaling to a writer,
|
||
|
|
\*\* using `ffjson.Pool()`,
|
||
|
|
\*\*\* reusing output slice instead of resetting it to nil
|
||
|
|
|
||
|
|
#### Marshaling, concurrent.
|
||
|
|
|
||
|
|
| lib | json size | MB/s | allocs/op | B/op |
|
||
|
|
|:----------|:----------|-----:|----------:|------:|
|
||
|
|
| standard | regular | 252 | 9 | 23257 |
|
||
|
|
| standard | small | 124 | 3 | 328 |
|
||
|
|
| standard | large | 289 | 17 | 1.2M |
|
||
|
|
| | | | | |
|
||
|
|
| easyjson | regular | 792 | 9 | 10597 |
|
||
|
|
| easyjson* | regular | 1748 | 8 | 779 |
|
||
|
|
| easyjson | small | 333 | 1 | 128 |
|
||
|
|
| easyjson | large | 718 | 36 | 548k |
|
||
|
|
| easyjson* | large | 2134 | 25 | 4957 |
|
||
|
|
| | | | | |
|
||
|
|
| ffjson | regular | 301 | 153 | 21629 |
|
||
|
|
| ffjson** | regular | 707 | 152 | 5148 |
|
||
|
|
| ffjson | small | 62 | 5 | 384 |
|
||
|
|
| ffjson** | small | 282 | 4 | 128 |
|
||
|
|
| ffjson | large | 438 | 7330 | 1.0M |
|
||
|
|
| ffjson** | large | 131 | 7319 | 820k |
|
||
|
|
| | | | | |
|
||
|
|
| codec | regular | 183 | 17 | 33603 |
|
||
|
|
| codec*** | regular | 671 | 9 | 1157 |
|
||
|
|
| codec | small | 147 | 3 | 304 |
|
||
|
|
| codec*** | small | 299 | 1 | 48 |
|
||
|
|
| codec | large | 190 | 483 | 2.5M |
|
||
|
|
| codec*** | large | 752 | 451 | 77574 |
|
||
|
|
|
||
|
|
\* marshaling to a writer,
|
||
|
|
\*\* using `ffjson.Pool()`,
|
||
|
|
\*\*\* reusing output slice instead of resetting it to nil
|