7/3/2023 0 Comments Golang json comparereq is a k8s.io/api/admission/v1.AdmissionRequest object jsondiff. ![]() Comparing between the unmarshaled and copied versions can generate add and change patches below a path not in the original JSON, and the API server will reject your patch.Ī realistic usage would be similar to the following snippet: These will exist when you unmarshal from JSON, because of how Go structs work, but are not in the original JSON. Optional fields being ones that are a struct type, but are not pointers to those structs. Below is a quote of the original comment: As pointed out by user /u/terinjokes on Reddit, due to the nature of Go structs, the "hydrated" corev1.Pod object may contain "optional fields", resulting in a patch that state added/changed values that the Kubernetes API server doesn't know about. Note that the above example is used for simplicity, but in a real-world admission controller, you should create the diff from the raw bytes of the field. The JSON patch can then be used in the response payload of you Kubernetes webhook. holds the string passed to the decoderĬursor : int64 type variable."path": "/spec/volumes/0/emptyDir/medium " In order to decode, you have to traverse the input buffer character by position.Īt that time, if you check whether the buffer has reached the end, it will be very slow.īuf : byte type variable. Faster termination character inspection using NUL character Like the encoder, the decoder also uses typeptr to call the dedicated process. If you want to know more, please refer to the implementation here Decoder Dispatch by typeptr from map to slice If this approach is not available, it will fall back to the atomic based process described above. However, if there is too much type information, it will use a lot of memory, so by default we will only use this optimization if the slice size fits within 2Mib. The fact that all type information can be acquired means that by constructing slices in advance with the acquired total number of type information, it is possible to look up with the value of typeptr without worrying about out-of-range access. This allows you to get all the type information defined in the binary at runtime. There is an API named typelinks defined in the runtime package that the reflect package uses internally. So I thought if I could change the lookup from map to slice. However, as a result of profiling, I noticed that runtime.mapaccess2 accounts for a significant percentage of the execution time. This implementation slows down the set instead of speeding up the get, but it works well because of the nature of the library, it encodes much more for the same type. However, this is slow, so it's a good idea to use the atomic package for exclusive control as implemented by segmentio/encoding/json ( ). Map requires exclusive control, so use sync.Map for a naive implementation. When retrieving the data cached from the type information by typeptr, we usually use map. The technique of implementing recursive processing with the JMP operation while avoiding the CALL operation is a famous technique for implementing a high-speed virtual machine.įor more details, please refer to the article ( but Japanese only ). In this operation, after acquiring the opcode sequence used for recursive processing, the function is not called recursively as it is, but the necessary values are saved by itself and implemented by moving to the next operation. In go-json, recursive processing is processed by the operation type of opStructFieldRecursive. Since the only value required for the result of json.Marshal(interface The techniques listed here are the ones used by most of the libraries listed above. Here, we explain the various speed-up techniques implemented by go-json. Despite this, we are developing with the aim of being the fastest library. It's easier to implement by using automatic code generation for performance or by using a dedicated interface, but go-json dares to stick to compatibility with encoding/json and is the simple interface. Go-json is very fast in both encoding and decoding compared to other libraries. ![]() If you run the test in this repository and find a bug, please commit to corpus to go-json-fuzz and report the issue to go-json. ![]() Go-json-fuzz is the repository for fuzzing tests.
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