48 lines
1.5 KiB
Go
48 lines
1.5 KiB
Go
package types
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import (
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"io"
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"github.com/cosmos/cosmos-sdk/codec"
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)
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// WriteListener interface for streaming data out from a listenkv.Store
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type WriteListener interface {
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// if value is nil then it was deleted
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// storeKey indicates the source KVStore, to facilitate using the the same WriteListener across separate KVStores
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// delete bool indicates if it was a delete; true: delete, false: set
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OnWrite(storeKey StoreKey, key []byte, value []byte, delete bool) error
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}
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// StoreKVPairWriteListener is used to configure listening to a KVStore by writing out length-prefixed
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// protobuf encoded StoreKVPairs to an underlying io.Writer
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type StoreKVPairWriteListener struct {
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writer io.Writer
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marshaller codec.BinaryCodec
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}
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// NewStoreKVPairWriteListener wraps creates a StoreKVPairWriteListener with a provdied io.Writer and codec.BinaryCodec
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func NewStoreKVPairWriteListener(w io.Writer, m codec.BinaryCodec) *StoreKVPairWriteListener {
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return &StoreKVPairWriteListener{
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writer: w,
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marshaller: m,
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}
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}
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// OnWrite satisfies the WriteListener interface by writing length-prefixed protobuf encoded StoreKVPairs
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func (wl *StoreKVPairWriteListener) OnWrite(storeKey StoreKey, key []byte, value []byte, delete bool) error {
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kvPair := new(StoreKVPair)
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kvPair.StoreKey = storeKey.Name()
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kvPair.Delete = delete
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kvPair.Key = key
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kvPair.Value = value
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by, err := wl.marshaller.MarshalLengthPrefixed(kvPair)
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if err != nil {
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return err
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}
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if _, err := wl.writer.Write(by); err != nil {
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return err
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}
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return nil
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}
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