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Introduce GobSink, a Sink using Gob encoding
Signed-off-by: Alejandro Mery <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,111 @@ | ||
| package cache | ||
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| import ( | ||
| "bytes" | ||
| "encoding/gob" | ||
| "time" | ||
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| "github.com/darvaza-proxy/core" | ||
| ) | ||
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| var ( | ||
| _ Sink = (*GobSink[any])(nil) | ||
| ) | ||
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| // GobSink is a Sink using generics for type safety and Gob | ||
| // for encoding | ||
| type GobSink[T any] struct { | ||
| out *T | ||
| e time.Time | ||
| bytes []byte | ||
| } | ||
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| // Bytes returns the Gob encoded representation of the object | ||
| // in the Sink | ||
| func (sink *GobSink[T]) Bytes() []byte { | ||
| // TODO: do we need to copy them? | ||
| return sink.bytes | ||
| } | ||
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| // Expire tells when this object will be evicted from the Cache | ||
| func (sink *GobSink[T]) Expire() time.Time { | ||
| return sink.e | ||
| } | ||
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| // SetBytes sets the object of the GobSink and its expiration time | ||
| // from a Gob encoded byte array | ||
| func (sink *GobSink[T]) SetBytes(v []byte, e time.Time) error { | ||
| buf := bytes.NewBuffer(v) | ||
| dec := gob.NewDecoder(buf) | ||
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| if err := dec.Decode(sink.out); err != nil { | ||
| // failed to decode | ||
| sink.Reset() | ||
| return err | ||
| } | ||
|
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| // store | ||
| sink.bytes = make([]byte, len(v)) | ||
| sink.e = e | ||
| copy(sink.bytes, v) | ||
| return nil | ||
| } | ||
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| // SetString isn't supported by GobSink, but its needed to satisfy | ||
| // the Sink interface | ||
| func (sink *GobSink[T]) SetString(string, time.Time) error { | ||
| sink.Reset() | ||
| return ErrInvalid | ||
| } | ||
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| // SetValue sets the object of the GobSink and its expiration time | ||
| func (sink *GobSink[T]) SetValue(v any, e time.Time) error { | ||
| var buf bytes.Buffer | ||
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| p, ok := v.(*T) | ||
| if !ok { | ||
| return ErrInvalid | ||
| } | ||
|
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| enc := gob.NewEncoder(&buf) | ||
| if err := enc.Encode(p); err != nil { | ||
| sink.Reset() | ||
| return err | ||
| } | ||
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| sink.bytes = buf.Bytes() | ||
| sink.e = e | ||
| *sink.out = *p | ||
| return nil | ||
| } | ||
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| // Value gives a copy of the stored object | ||
| func (sink *GobSink[T]) Value() T { | ||
| if sink.out == nil { | ||
| var zero T | ||
| return zero | ||
| } | ||
| return *sink.out | ||
| } | ||
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| // Reset clears everything but the type pointer | ||
| // assigned during creation | ||
| func (sink *GobSink[T]) Reset() { | ||
| sink.bytes = []byte{} | ||
| sink.e = time.Time{} | ||
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| if sink.out != nil { | ||
| var zero T | ||
| *sink.out = zero | ||
| } | ||
| } | ||
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| // NewGobSink creates a new Sink using Gob as encoding | ||
| // and stores the object in the provided pointer | ||
| func NewGobSink[T any](out *T) *GobSink[T] { | ||
| if out == nil { | ||
| var zero T | ||
| core.Panicf("NewGobSink[%T]: output can not be nil", zero) | ||
| } | ||
| return &GobSink[T]{out: out} | ||
| } |