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traverse.go
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traverse.go
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package iokit
import (
"bytes"
"io"
"math"
"strings"
)
func LimitOfReader(r io.Reader) int64 {
_, n := traverseLimitReaders(r, math.MaxInt64)
return n
}
func LimitOfWriter(w io.Writer) int64 {
_, n := traverseLimitWriters(w, math.MaxInt64)
return n
}
func LimitOfWriterTo(w io.WriterTo) int64 {
switch ww := w.(type) {
case interface{ FixedByteSize() int }:
return int64(ww.FixedByteSize())
case interface{ ProtoSize() int }:
return int64(ww.ProtoSize())
case interface{ Size() int }:
return int64(ww.Size())
case io.Reader:
if n := sizeOfReader(ww); n >= 0 {
return n
}
}
return math.MaxInt64
}
func sizeOfReader(r io.Reader) int64 {
switch rr := r.(type) {
case *bytes.Buffer:
return int64(rr.Len())
case *strings.Reader:
return int64(rr.Len())
case interface{ PhysicalRemaining() int64 }:
return rr.PhysicalRemaining()
//case interface{ Len() int }:
// return int64(rr.Len())
default:
return -1
}
}
func traverseLimitReaders(r io.Reader, min int64) (io.Reader, int64) {
for r != nil {
if min <= 0 {
return r, 0
}
var n int64
switch v := r.(type) {
case *RateLimitedReader:
_, min = traverseLimitReaders(v.R, min)
return r, min
case *TeeReader:
if v.CopyTo == nil {
r = v.R
continue
}
_, min = traverseLimitReaders(v.R, min)
return v, min
case *io.LimitedReader:
n = v.N
r = v.R
case *LimitedTriggerReader:
r = &v.hLimitedReader
continue
case *LimitedReader:
n = v.n
r = &v.r
default:
switch n = sizeOfReader(r); {
case n >= 0 && n < min:
return r, n
default:
return r, min
}
}
if n < min {
min = n
}
}
return nil, 0
}
func updatedLimitReaders(r io.Reader, delta int64) {
if delta <= 0 {
return
}
for r != nil {
switch v := r.(type) {
case *TeeReader:
if v.CopyTo == nil {
r = v.R
continue
}
return
case *io.LimitedReader:
v.N -= delta
r = v.R
case *LimitedTriggerReader:
v.n -= delta
r = &v.hLimitedReader.r
if v.n <= 0 {
// this ensures proper sequence of triggering when there are
// multiple instances of LimitedTriggerReader on the read chain
updatedLimitReaders(r, delta)
v.trigger()
return
}
case *LimitedReader:
v.n -= delta
r = &v.r
default:
return
}
}
}
func traverseLimitWriters(w io.Writer, min int64) (io.Writer, int64) {
for w != nil {
if min <= 0 {
return w, 0
}
var n int64
switch v := w.(type) {
case *RateLimitedWriter:
_, min = traverseLimitWriters(v.W, min)
return w, min
case *TeeWriter:
if v.CopyTo == nil {
w = v.W
continue
}
_, min = traverseLimitWriters(v.W, min)
return v, min
case *LimitedWriter:
n = v.n
w = &v.w
default:
return w, min
}
if n < min {
min = n
}
}
return nil, 0
}
func updatedLimitWriters(w io.Writer, delta int64) {
if delta <= 0 {
return
}
for w != nil {
switch v := w.(type) {
case *TeeWriter:
if v.CopyTo == nil {
w = v.W
continue
}
return
case *LimitedWriter:
v.n -= delta
w = &v.w
default:
return
}
}
}