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83 lines
1.7 KiB
Go
83 lines
1.7 KiB
Go
package main
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import (
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"encoding/json"
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"fmt"
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"io"
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)
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var requestTypes = make(map[string]func() request, 32)
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func registerRequestType(fn func() request) {
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r := fn()
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if _, ok := requestTypes[r.Kind()]; ok {
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panic("request type already registered")
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}
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requestTypes[r.Kind()] = fn
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}
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type Envelope struct {
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Id int `json:"id"`
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Kind string `json:"kind"`
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Body json.RawMessage `json:"body"`
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}
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func (e Envelope) Open() (request, error) {
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fn, ok := requestTypes[e.Kind]
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if !ok {
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return nil, fmt.Errorf("unknown request type: %s", e.Kind)
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}
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r := fn()
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if err := json.Unmarshal(e.Body, r); err != nil {
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return nil, fmt.Errorf("failed to unmarshal json in note open: %v", err)
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}
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return r, nil
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}
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// Bool is used to acknowledge that a request has been received and that there
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// is no useful information for the user.
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type Bool bool
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func (b Bool) Kind() string {
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return "bool"
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}
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func init() { registerRequestType(func() request { return new(Bool) }) }
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type request interface {
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Kind() string
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}
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func wrapRequest(id int, r request) (*Envelope, error) {
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b, err := json.Marshal(r)
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if err != nil {
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return nil, fmt.Errorf("unable to wrap request: %v", err)
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}
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return &Envelope{
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Id: id,
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Kind: r.Kind(),
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Body: b,
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}, nil
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}
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func writeRequest(w io.Writer, id int, r request) error {
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b, err := json.Marshal(r)
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if err != nil {
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return fmt.Errorf("unable to marshal request: %v", err)
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}
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msg := json.RawMessage(b)
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e := &Envelope{
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Id: id,
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Kind: r.Kind(),
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Body: msg,
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}
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raw, err := json.Marshal(e)
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if err != nil {
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return fmt.Errorf("unable to marshal request envelope: %v", err)
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}
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if _, err := w.Write(raw); err != nil {
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return fmt.Errorf("unable to write request: %v", err)
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}
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return nil
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}
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