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f1a7dd766e
Per the sync/atomic bug note:
> On ARM, x86-32, and 32-bit MIPS, it is the caller's
> responsibility to arrange for 64-bit alignment of 64-bit words
> accessed atomically. The first word in a variable or in an
> allocated struct, array, or slice can be relied upon to be
> 64-bit aligned.
All atomic accesses of 64-bit variables in syncthing code base are
currently ok (i.e they are all 64-bit aligned).
Generally, the bug is triggered because of incorrect alignement
of struct fields. Free variables (declared in a function) are
guaranteed to be 64-bit aligned by the Go compiler.
To ensure the code remains correct upon further addition/removal
of fields, which would change the currently correct alignment, I
added the following comment where required:
// atomic, must remain 64-bit aligned
See https://golang.org/pkg/sync/atomic/#pkg-note-BUG.
63 lines
1.4 KiB
Go
63 lines
1.4 KiB
Go
// Copyright (C) 2014 The Protocol Authors.
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package protocol
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import (
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"io"
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"sync/atomic"
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"time"
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)
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type countingReader struct {
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io.Reader
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tot int64 // bytes (atomic, must remain 64-bit aligned)
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last int64 // unix nanos (atomic, must remain 64-bit aligned)
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}
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var (
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totalIncoming int64
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totalOutgoing int64
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)
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func (c *countingReader) Read(bs []byte) (int, error) {
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n, err := c.Reader.Read(bs)
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atomic.AddInt64(&c.tot, int64(n))
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atomic.AddInt64(&totalIncoming, int64(n))
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atomic.StoreInt64(&c.last, time.Now().UnixNano())
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return n, err
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}
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func (c *countingReader) Tot() int64 {
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return atomic.LoadInt64(&c.tot)
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}
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func (c *countingReader) Last() time.Time {
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return time.Unix(0, atomic.LoadInt64(&c.last))
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}
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type countingWriter struct {
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io.Writer
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tot int64 // bytes (atomic, must remain 64-bit aligned)
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last int64 // unix nanos (atomic, must remain 64-bit aligned)
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}
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func (c *countingWriter) Write(bs []byte) (int, error) {
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n, err := c.Writer.Write(bs)
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atomic.AddInt64(&c.tot, int64(n))
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atomic.AddInt64(&totalOutgoing, int64(n))
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atomic.StoreInt64(&c.last, time.Now().UnixNano())
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return n, err
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}
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func (c *countingWriter) Tot() int64 {
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return atomic.LoadInt64(&c.tot)
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}
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func (c *countingWriter) Last() time.Time {
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return time.Unix(0, atomic.LoadInt64(&c.last))
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}
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func TotalInOut() (int64, int64) {
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return atomic.LoadInt64(&totalIncoming), atomic.LoadInt64(&totalOutgoing)
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}
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