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diff --git a/vendor/github.com/mailru/easyjson/README.md b/vendor/github.com/mailru/easyjson/README.md new file mode 100644 index 000000000..7fd768654 --- /dev/null +++ b/vendor/github.com/mailru/easyjson/README.md @@ -0,0 +1,333 @@ +# 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. + +## 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 |