This package critically depends on reading/writing single bytes. Since
arguments to interface methods io.Reader.Read / io.Writer.Write escape, a naive
implementation would heap-allocate a one-byte array per read/write.
Prior to cl/625167495, the wire package provided custom Reader/Writer
interfaces, implementations of which were required to provide their own
ReadByte/WriteByte methods that did not take any escaping arguments.
cl/625167495 eliminated these interfaces and made the wire package use
sync.Pool to allocate one-byte arrays instead, simplifying the pipelining of
readers and writers but introducing non-trivial overhead. This CL re-introduces
wire.Reader/Writer, but as structs combining an io.Reader/Writer and a one-byte
array; this preserves the relative ease of using arbitrary io.Readers/Writers,
while eliminating sync.Pool overhead by essentially having callers of the wire
package provide the persistent buffer.
PiperOrigin-RevId: 666946511
These interfaces only existed to add ReadByte() and WriteByte() methods. There
were only 4 implementors of these methods: compressio.{Simple}{Reader/Writer}.
And there were only 2 users of this.
Using io.{Reader/Writer} is more extendible. For instance, it allows using
*os.File with the `wire` package without any wrappers.
Updated the 2 users to implement their own {read/write}Byte(). To avoid heap
allocation of the [1]byte storage during call to io.Reader.Read or
io.Writer.Write due to interface call, used sync.Pool. Earlier, calls to
compressio.Simple{Reader/Writer}'s implementation of {Read/Write}Byte would
cause a heap allocation.
PiperOrigin-RevId: 625167495
- When encodeState.resolve() determines that the resolved reflect.Value is
contained by a previously-resolved object, set wire.Ref.Type to the
containing object's type (existing.obj.Type()) rather than the contained
value's type (obj.Type()).
- When encodeState.resolve() determines that the resolved reflect.Value
contains a previously-resolved object, handle cases where the new object
contains *multiple* previously-resolved objects. (This may cause
previously-allocated object IDs to become unused; to facilitate this, change
encodeState.pending to a map, and change the wire format to prefix each
object with its object ID.)
- Add encodeState.encodedStructs to avoid redundant encoding of structs, since
deduplication of objects via encodeState.resolve() doesn't work for objects
instantiated by StateSave() and passed to SaveValue() (i.e. fields tagged
`state:".(whatever)"`).
- Make unexported array fields deserializable via slices that refer to them by
casting away their unexportedness in decodeState.decodeObject().
Updates #1663
PiperOrigin-RevId: 338727687
Previously, it was not possible to encode/decode an object graph which
contained a pointer to a field within another type. This was because the
encoder was previously unable to disambiguate a pointer to an object and a
pointer within the object.
This CL remedies this by constructing an address map tracking the full memory
range object occupy. The encoded Refvalue message has been extended to allow
references to children objects within another object. Because the encoding
process may learn about object structure over time, we cannot encode any
objects under the entire graph has been generated.
This CL also updates the state package to use standard interfaces intead of
reflection-based dispatch in order to improve performance overall. This
includes a custom wire protocol to significantly reduce the number of
allocations and take advantage of structure packing.
As part of these changes, there are a small number of minor changes in other
places of the code base:
* The lists used during encoding are changed to use intrusive lists with the
objectEncodeState directly, which required that the ilist Len() method is
updated to work properly with the ElementMapper mechanism.
* A bug is fixed in the list code wherein Remove() called on an element that is
already removed can corrupt the list (removing the element if there's only a
single element). Now the behavior is correct.
* Standard error wrapping is introduced.
* Compressio was updated to implement the new wire.Reader and wire.Writer
inteface methods directly. The lack of a ReadByte and WriteByte caused issues
not due to interface dispatch, but because underlying slices for a Read or
Write call through an interface would always escape to the heap!
* Statify has been updated to support the new APIs.
See README.md for a description of how the new mechanism works.
PiperOrigin-RevId: 318010298
Koichi Shiraishi
Jamie LiuandgVisor bot
Ayush RanjanandgVisor bot
Adin ScannellandgVisor bot
Ting-Yu WangandgVisor bot