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https://github.com/protocolbuffers/protobuf-go.git
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b0d217f664
Implementations of the legacy Marshaler type have no way to efficiently compute the size of the message. Rather than generating an inefficient fast-path Size method which marshals the message and examines the length of the result, don't generate a fast-path at all. Drop the requirement that a fast-path MarshalAppend requires a corresponding Size. Avoids O(N^2) behavior when marshaling a legacy Marshaler that recursively calls proto.Marshal. Change-Id: I4793cf32275d08f29c8e1a1a44a193d9a5724058 Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/213443 Reviewed-by: Joe Tsai <joetsai@google.com>
85 lines
2.5 KiB
Go
85 lines
2.5 KiB
Go
// Copyright 2019 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package proto
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import (
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"google.golang.org/protobuf/internal/encoding/messageset"
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"google.golang.org/protobuf/internal/encoding/wire"
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"google.golang.org/protobuf/reflect/protoreflect"
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"google.golang.org/protobuf/runtime/protoiface"
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)
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// Size returns the size in bytes of the wire-format encoding of m.
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func Size(m Message) int {
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return MarshalOptions{}.Size(m)
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}
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// Size returns the size in bytes of the wire-format encoding of m.
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func (o MarshalOptions) Size(m Message) int {
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return sizeMessage(m.ProtoReflect())
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}
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func sizeMessage(m protoreflect.Message) (size int) {
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methods := protoMethods(m)
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if methods != nil && methods.Size != nil {
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return methods.Size(m, protoiface.MarshalOptions{})
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}
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if methods != nil && methods.MarshalAppend != nil {
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// This is not efficient, but we don't have any choice.
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// This case is mainly used for legacy types with a Marshal method.
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b, _ := methods.MarshalAppend(nil, m, protoiface.MarshalOptions{})
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return len(b)
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}
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return sizeMessageSlow(m)
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}
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func sizeMessageSlow(m protoreflect.Message) (size int) {
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if messageset.IsMessageSet(m.Descriptor()) {
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return sizeMessageSet(m)
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}
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m.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
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size += sizeField(fd, v)
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return true
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})
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size += len(m.GetUnknown())
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return size
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}
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func sizeField(fd protoreflect.FieldDescriptor, value protoreflect.Value) (size int) {
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num := fd.Number()
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switch {
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case fd.IsList():
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return sizeList(num, fd, value.List())
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case fd.IsMap():
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return sizeMap(num, fd, value.Map())
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default:
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return wire.SizeTag(num) + sizeSingular(num, fd.Kind(), value)
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}
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}
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func sizeList(num wire.Number, fd protoreflect.FieldDescriptor, list protoreflect.List) (size int) {
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if fd.IsPacked() && list.Len() > 0 {
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content := 0
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for i, llen := 0, list.Len(); i < llen; i++ {
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content += sizeSingular(num, fd.Kind(), list.Get(i))
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}
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return wire.SizeTag(num) + wire.SizeBytes(content)
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}
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for i, llen := 0, list.Len(); i < llen; i++ {
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size += wire.SizeTag(num) + sizeSingular(num, fd.Kind(), list.Get(i))
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}
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return size
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}
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func sizeMap(num wire.Number, fd protoreflect.FieldDescriptor, mapv protoreflect.Map) (size int) {
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mapv.Range(func(key protoreflect.MapKey, value protoreflect.Value) bool {
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size += wire.SizeTag(num)
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size += wire.SizeBytes(sizeField(fd.MapKey(), key.Value()) + sizeField(fd.MapValue(), value))
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return true
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})
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return size
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}
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