A blazingly fast JSON serializing & deserializing library, accelerated by JIT (just-in-time compiling) and SIMD (single-instruction-multiple-data).
Default behaviors are mostly consistent with `encoding/json`, except HTML escaping form (see [Escape HTML](https://github.com/bytedance/sonic/blob/main/README.md#escape-html)) and `SortKeys` feature (optional support see [Sort Keys](https://github.com/bytedance/sonic/blob/main/README.md#sort-keys)) that is **NOT** in conformity to [RFC8259](https://datatracker.ietf.org/doc/html/rfc8259).
Sonic supports decoding json from `io.Reader` or encoding objects into `io.Writer`, aims at handling multiple values as well as reducing memory consumption.
On account of the performance loss from sorting (roughly 10%), sonic doesn't enable this feature by default. If your component depends on it to work (like [zstd](https://github.com/facebook/zstd)), Use it like this:
On account of the performance loss (roughly 15%), sonic doesn't enable this feature by default. You can use `encoder.EscapeHTML` option to open this feature (align with `encoding/json.HTMLEscape`).
Sonic encodes primitive objects (struct/map...) as compact-format JSON by default, except marshaling `json.RawMessage` or `json.Marshaler`: sonic ensures validating their output JSON but **DONOT** compacting them for performance concerns. We provide the option `encoder.CompactMarshaler` to add compacting process.
If there a **mismatch-typed** value for a given key, sonic will report `decoder.MismatchTypeError` (if there are many, report the last one), but still skip wrong the value and keep decoding next JSON.
Sonic/ast.Node is a completely self-contained AST for JSON. It implements serialization and deserialization both and provides robust APIs for obtaining and modification of generic data.
**Tip**: since `Index()` uses offset to locate data, which is much faster than scanning like `Get()`, we suggest you use it as much as possible. And sonic also provides another API `IndexOrGet()` to underlying use offset as well as ensure the key is matched.
Sonic provides an advanced API for fully parsing JSON into non-standard types (neither `struct` not `map[string]interface{}`) without using any intermediate representation (`ast.Node` or `interface{}`). For example, you might have the following types which are like `interface{}` but actually not `interface{}`:
```go
type UserNode interface {}
// the following types implement the UserNode interface.
type (
UserNull struct{}
UserBool struct{ Value bool }
UserInt64 struct{ Value int64 }
UserFloat64 struct{ Value float64 }
UserString struct{ Value string }
UserObject struct{ Value map[string]UserNode }
UserArray struct{ Value []UserNode }
)
```
Sonic provides the following API to return **the preorder traversal of a JSON AST**. The `ast.Visitor` is a SAX style interface which is used in some C++ JSON library. You should implement `ast.Visitor` by yourself and pass it to `ast.Preorder()` method. In your visitor you can make your custom types to represent JSON values. There may be an O(n) space container (such as stack) in your visitor to record the object / array hierarchy.
See [ast/visitor.go](https://github.com/bytedance/sonic/blob/main/ast/visitor.go) for detailed usage. We also implement a demo visitor for `UserNode` in [ast/visitor_test.go](https://github.com/bytedance/sonic/blob/main/ast/visitor_test.go).
Sonic **DOES NOT** ensure to support all environments, due to the difficulty of developing high-performance codes. For developers who use sonic to build their applications in different environments, we have the following suggestions:
- Developing on **Mac M1**: Make sure you have Rosetta 2 installed on your machine, and set `GOARCH=amd64` when building your application. Rosetta 2 can automatically translate x86 binaries to arm64 binaries and run x86 applications on Mac M1.
- Developing on **Linux arm64**: You can install qemu and use the `qemu-x86_64 -cpu max` command to convert x86 binaries to amr64 binaries for applications built with sonic. The qemu can achieve a similar transfer effect to Rosetta 2 on Mac M1.
For developers who want to use sonic on Linux arm64 without qemu, or those who want to handle JSON strictly consistent with `encoding/json`, we provide some compatible APIs as `sonic.API`
-`ConfigDefault`: the sonic's default config (`EscapeHTML=false`,`SortKeys=false`...) to run on sonic-supporting environment. It will fall back to `encoding/json` with the corresponding config, and some options like `SortKeys=false` will be invalid.
-`ConfigStd`: the std-compatible config (`EscapeHTML=true`,`SortKeys=true`...) to run on sonic-supporting environment. It will fall back to `encoding/json`.
-`ConfigFastest`: the fastest config (`NoQuoteTextMarshaler=true`) to run on sonic-supporting environment. It will fall back to `encoding/json` with the corresponding config, and some options will be invalid.
Since Sonic uses [golang-asm](https://github.com/twitchyliquid64/golang-asm) as a JIT assembler, which is NOT very suitable for runtime compiling, first-hit running of a huge schema may cause request-timeout or even process-OOM. For better stability, we advise **using `Pretouch()` for huge-schema or compact-memory applications** before `Marshal()/Unmarshal()`.
When decoding **string values without any escaped characters**, sonic references them from the origin JSON buffer instead of mallocing a new buffer to copy. This helps a lot for CPU performance but may leave the whole JSON buffer in memory as long as the decoded objects are being used. In practice, we found the extra memory introduced by referring JSON buffer is usually 20% ~ 80% of decoded objects. Once an application holds these objects for a long time (for example, cache the decoded objects for reusing), its in-use memory on the server may go up. - `Config.CopyString`/`decoder.CopyString()`: We provide the option for `Decode()` / `Unmarshal()` users to choose not to reference the JSON buffer, which may cause a decline in CPU performance to some degree.
-`GetFromStringNoCopy()`: For memory safety, `sonic.Get()` / `sonic.GetFromString()` now copies return JSON. If users want to get json more quickly and not care about memory usage, you can use `GetFromStringNoCopy()` to return a JSON directly referenced from source.
For alignment to `encoding/json`, we provide API to pass `[]byte` as an argument, but the string-to-bytes copy is conducted at the same time considering safety, which may lose performance when the origin JSON is huge. Therefore, you can use `UnmarshalString()` and `GetFromString()` to pass a string, as long as your origin data is a string or **nocopy-cast** is safe for your []byte. We also provide API `MarshalString()` for convenient **nocopy-cast** of encoded JSON []byte, which is safe since sonic's output bytes is always duplicated and unique.
To ensure data security, sonic.Encoder quotes and escapes string values from `encoding.TextMarshaler` interfaces by default, which may degrade performance much if most of your data is in form of them. We provide `encoder.NoQuoteTextMarshaler` to skip these operations, which means you **MUST** ensure their output string escaped and quoted following [RFC8259](https://datatracker.ietf.org/doc/html/rfc8259).
In **fully-parsed** scenario, `Unmarshal()` performs better than `Get()`+`Node.Interface()`. But if you only have a part of the schema for specific json, you can combine `Get()` and `Unmarshal()` together:
-`Array`'s performance is **much better** than `Map` when Inserting (Deserialize) and Scanning (Serialize) data;
- **Hashing** (`map[x]`) is not as efficient as **Indexing** (`array[x]`), which `ast.Node` can conduct on **both array and object**;
- Using `Interface()`/`Map()` means Sonic must parse all the underlying values, while `ast.Node` can parse them **on demand**.
**CAUTION:** `ast.Node`**DOESN'T** ensure concurrent security directly, due to its **lazy-load** design. However, you can call `Node.Load()`/`Node.LoadAll()` to achieve that, which may bring performance reduction while it still works faster than converting to `map` or `interface{}`
For generic data, `ast.Node` should be enough for your needs in most cases.
However, `ast.Node` is designed for partially processing JSON string. It has some special designs such as lazy-load which might not be suitable for directly parsing the whole JSON string like `Unmarshal()`. Although `ast.Node` is better then `map` or `interface{}`, it's also a kind of intermediate representation after all if your final types are customized and you have to convert the above types to your custom types after parsing.
For better performance, in previous case the `ast.Visitor` will be the better choice. It performs JSON decoding like `Unmarshal()` and you can directly use your final types to represents a JSON AST without any intermediate representations.
But `ast.Visitor` is not a very handy API. You might need to write a lot of code to implement your visitor and carefully maintain the tree hierarchy during decoding. Please read the comments in [ast/visitor.go](https://github.com/bytedance/sonic/blob/main/ast/visitor.go) carefully if you decide to use this API.
