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| author | Nicolas Lacasse <nlacasse@google.com> | 2019-02-08 12:59:04 -0800 |
|---|---|---|
| committer | Shentubot <shentubot@google.com> | 2019-02-08 13:00:00 -0800 |
| commit | 9c9386d2a8c041f3c1f19469b47414c419f7d534 (patch) | |
| tree | 2cb0db5fcf8facb2b70da11812c67341cd3a39a3 | |
| parent | 5079b38a9af1d66ad720005d7487dd711a0cb713 (diff) | |
CopyObjectOut should allocate a byte slice the size of the encoded object.
This adds an extra Reflection call to CopyObjectOut, but avoids many small
slice allocations if the object is large, since without this we grow the
backing slice incrementally as we encode more data.
PiperOrigin-RevId: 233110960
Change-Id: I93569af55912391e5471277f779139c23f040147
| -rw-r--r-- | pkg/sentry/usermem/usermem.go | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/pkg/sentry/usermem/usermem.go b/pkg/sentry/usermem/usermem.go index 1d6c0b4d6..75ac4d22d 100644 --- a/pkg/sentry/usermem/usermem.go +++ b/pkg/sentry/usermem/usermem.go @@ -181,7 +181,11 @@ func CopyObjectOut(ctx context.Context, uio IO, addr Addr, src interface{}, opts Addr: addr, Opts: opts, } - return w.Write(binary.Marshal(nil, ByteOrder, src)) + // Allocate a byte slice the size of the object being marshaled. This + // adds an extra reflection call, but avoids needing to grow the slice + // during encoding, which can result in many heap-allocated slices. + b := make([]byte, 0, binary.Size(src)) + return w.Write(binary.Marshal(b, ByteOrder, src)) } // CopyObjectIn copies a fixed-size value or slice of fixed-size values from |