Add zero-copy serialization APIs. #357
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buffer.go
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| // Keep the buffer alive during the write, to prevent the GC from | ||
| // collecting the memory while it's being used. | ||
| n, err := w.Write(unsafe.Slice((*byte)(cbuffer), writeSize)) | ||
| runtime.KeepAlive(b) |
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I think since b is the object that implements this method the keepalive isn't needed
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Removed. I was being extra cautious, but if we call b.WriteTo(w), it becomes clear that b is being kept somewhere reachable.
serialize.go
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| return &buffer, nil | ||
| } | ||
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| // SerializeArrayNonEmptyDomainToBuffer gets and serializes the array nonempty domain and returns a Buffer object containing the payload. |
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| // SerializeArrayNonEmptyDomainToBuffer gets and serializes the array nonempty domain and returns a Buffer object containing the payload. | |
| // SerializeArrayNonEmptyDomain gets and serializes the array nonempty domain. |
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Fixed, thanks for catching it.
| } | ||
| assert.NotEmpty(t, bytes.Bytes()) | ||
| runtime.GC() | ||
| runtime.GC() |
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I don't understand the purpose of the last few lines in this test, but I see there was one like it just below so I'm probably missing something.
Should there be a check here that buffer was garbage collected, or is the test verifying something else with the explicit calls to runtime.GC()?
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I copied the GC calls from the existing test, I don't know what their purpose was.
buffer_list.go
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| @@ -44,6 +45,36 @@ func (b *BufferList) Context() *Context { | |||
| return b.context | |||
| } | |||
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| // WriteTo writes the contents of a BufferList to an io.Writer. | |||
| func (b *BufferList) WriteTo(w io.Writer) (n int64, err error) { | |||
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Were the named return values intentional? Feel free to disregard, just pointing it out since I don't see these names being directly used in the function body.
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Must have been from a previous iteration of the code. Removed.
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Thanks for this very useful optimization, great job! One question, is this Core PR a prerequisite? If yes let's mark this one as Draft so that we don't accidentally merge it before Go has bundled to a Core version that includes that change.
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Strictly speaking no, this PR can be merged without waiting for the Core PR. The Core PR is a prerequisite for fully taking advantage of the APIs added in this PR in the REST server (and even this might not be true, I have thought of a potential workaround). |
It will make some stuff easier in the REST server.
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SC-58009
This PR updates the
BufferandBufferListtypes to implement theio.WriterTointerface, by writing the data directly to anio.Writerwithout an intermediate copy to Go-backed memory. ForBufferwe do that with theUnsafe.Slicefunction (it is safe as long as theWriterfollows the contract and does not retain the slice after the call toWrite), and forBufferListwe callWriteTofor each buffer.In order to take advantage of this, new serialization APIs were added that return a
Bufferinstead of abyte[](and unavoidably had to make a copy to Go-managed memory). The old serialization APIs, as well as theBuffer.Serialize()andBufferList.Flatten()functions were deprecated.