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package main
import (
"fmt"
"github.com/linkedin/goavro"
)
func main() {
codex := initCodex()
err := decode(codex, []byte("\xC3\x01"+"\x8F\x5C\x39\x3F\x1A\xD5\x75\x72"+"\x06"))
if err != nil {
panic(err)
}
err = decode(codex, []byte("\xC3\x01"+"\xC7\x03\x45\x63\x72\x48\x01\x8F"+"\x0ahello"))
if err != nil {
panic(err)
}
}
// initCodex returns a codex with a small handful of example Codec instances.
func initCodex() map[uint64]*goavro.Codec {
codex := make(map[uint64]*goavro.Codec)
for _, primitive := range []string{"int", "long", "boolean", "float", "double", "string"} {
codec, err := goavro.NewCodec(`"` + primitive + `"`)
if err != nil {
panic(err)
}
codex[codec.Rabin] = codec
}
return codex
}
// decode attempts to decode the bytes in buf using one of the Codec instances
// in codex. The buf must start with the single-object encoding prefix,
// followed by the unsigned 64-bit Rabin fingerprint of the canonical schema
// used to encode the datum, finally followed by the encoded bytes. This is a
// simplified example of fetching the fingerprint from the SOE buffer, using
// that fingerprint to select a Codec from a dictionary of Codec instances,
// called codex in this case, and finally sends the buf to be decoded by that
// Codec.
func decode(codex map[uint64]*goavro.Codec, buf []byte) error {
// Perform a sanity check on the buffer, then return the Rabin fingerprint
// of the schema used to encode the data.
fingerprint, newBuf, err := goavro.FingerprintFromSOE(buf)
if err != nil {
panic(err)
return err
}
// Get a previously stored Codec from the codex map.
codec, ok := codex[fingerprint]
if !ok {
return fmt.Errorf("unknown codec: %#x", fingerprint)
}
// Use the fetched Codec to decode the buffer as a SOE.
var datum interface{}
// Both of the following branches work, but provided to illustrate two
// use-cases.
if true {
// Faster because SOE magic prefix and schema fingerprint already
// checked and used to fetch the Codec. Just need to decode the binary
// bytes remaining after the prefix were removed.
datum, _, err = codec.NativeFromBinary(newBuf)
} else {
// This way re-checks the SOE magic prefix and Codec fingerprint, doing
// repetitive work, but provided as an example for cases when there is
// only a single schema, a single Codec, and you do not use
// the FingerprintFromSOE function above.
datum, _, err = codec.NativeFromSingle(buf)
}
if err != nil {
panic(err)
}
_, err = fmt.Println(datum)
return err
}
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