mirror of https://github.com/prometheus/prometheus
92 lines
2.7 KiB
Go
92 lines
2.7 KiB
Go
package runtime
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import (
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"errors"
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"net/http"
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)
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// MIMEWildcard is the fallback MIME type used for requests which do not match
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// a registered MIME type.
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const MIMEWildcard = "*"
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var (
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acceptHeader = http.CanonicalHeaderKey("Accept")
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contentTypeHeader = http.CanonicalHeaderKey("Content-Type")
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defaultMarshaler = &JSONPb{OrigName: true}
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)
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// MarshalerForRequest returns the inbound/outbound marshalers for this request.
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// It checks the registry on the ServeMux for the MIME type set by the Content-Type header.
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// If it isn't set (or the request Content-Type is empty), checks for "*".
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// If there are multiple Content-Type headers set, choose the first one that it can
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// exactly match in the registry.
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// Otherwise, it follows the above logic for "*"/InboundMarshaler/OutboundMarshaler.
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func MarshalerForRequest(mux *ServeMux, r *http.Request) (inbound Marshaler, outbound Marshaler) {
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for _, acceptVal := range r.Header[acceptHeader] {
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if m, ok := mux.marshalers.mimeMap[acceptVal]; ok {
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outbound = m
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break
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}
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}
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for _, contentTypeVal := range r.Header[contentTypeHeader] {
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if m, ok := mux.marshalers.mimeMap[contentTypeVal]; ok {
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inbound = m
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break
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}
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}
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if inbound == nil {
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inbound = mux.marshalers.mimeMap[MIMEWildcard]
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}
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if outbound == nil {
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outbound = inbound
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}
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return inbound, outbound
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}
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// marshalerRegistry is a mapping from MIME types to Marshalers.
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type marshalerRegistry struct {
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mimeMap map[string]Marshaler
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}
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// add adds a marshaler for a case-sensitive MIME type string ("*" to match any
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// MIME type).
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func (m marshalerRegistry) add(mime string, marshaler Marshaler) error {
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if len(mime) == 0 {
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return errors.New("empty MIME type")
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}
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m.mimeMap[mime] = marshaler
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return nil
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}
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// makeMarshalerMIMERegistry returns a new registry of marshalers.
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// It allows for a mapping of case-sensitive Content-Type MIME type string to runtime.Marshaler interfaces.
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//
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// For example, you could allow the client to specify the use of the runtime.JSONPb marshaler
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// with a "application/jsonpb" Content-Type and the use of the runtime.JSONBuiltin marshaler
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// with a "application/json" Content-Type.
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// "*" can be used to match any Content-Type.
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// This can be attached to a ServerMux with the marshaler option.
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func makeMarshalerMIMERegistry() marshalerRegistry {
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return marshalerRegistry{
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mimeMap: map[string]Marshaler{
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MIMEWildcard: defaultMarshaler,
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},
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}
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}
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// WithMarshalerOption returns a ServeMuxOption which associates inbound and outbound
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// Marshalers to a MIME type in mux.
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func WithMarshalerOption(mime string, marshaler Marshaler) ServeMuxOption {
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return func(mux *ServeMux) {
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if err := mux.marshalers.add(mime, marshaler); err != nil {
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panic(err)
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}
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}
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}
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