Since the protocol encodes timestamps differently depending on the
message, the code currently decodes into a local variable and then
converts it to a time.Time. However, this causes an allocation due to
the local having to escape to the heap in order for the readElement
function to write to it.
So, in order to avoid that, this introduces two new types for a
timestamp named uint32Time and int64Time that are encoded as the
respective type on the read. When calling the readElements function,
the time.Time field in the message is cast to a pointer of the
appropriate type which effectively allows the allocations to be avoided.
The following is a before and after comparison of the allocations
with the benchmarks that did not change removed:
benchmark old allocs new allocs delta
----------------------------------------------------------------------
ReadBlockHeader 1 0 -100.00%
DecodeHeaders 4001 2001 -49.99%
DecodeAddr 4001 3001 -24.99%
DecodeMerkleBlock 108 107 -0.93%
This introduces a new binary free list which provides a concurrent safe
list of unused buffers for the purpose of serializing and deserializing
primitive integers to their raw binary bytes.
For convenience, the type also provides functions for each of the
primitive unsigned integers that automatically obtain a buffer from the
free list, perform the necessary binary conversion, read from or write
to the given io.Reader or io.Writer, and return the buffer to the free
list.
A global instance of the type has been introduced with a maximum number
of 1024 items. Since each buffer is 8 bytes, it will consume a maximum
of 8KB. Theoretically, this value would only allow up to 1024 peers
simultaneously reading and writing without having to resort to burdening
the garbage collector with additional allocations. However, due to the
fact the code is designed in such a way that the buffers are quickly
used and returned to the free list, in practice it can support much more
than 1024 peers without involving the garbage collector since it is
highly unlikely every peer would need a buffer at the exact same time.
The following is a before and after comparison of the allocations
with the benchmarks that did not change removed:
benchmark old allocs new allocs delta
-------------------------------------------------------------
WriteVarInt1 1 0 -100.00%
WriteVarInt3 1 0 -100.00%
WriteVarInt5 1 0 -100.00%
WriteVarInt9 1 0 -100.00%
ReadVarInt1 1 0 -100.00%
ReadVarInt3 1 0 -100.00%
ReadVarInt5 1 0 -100.00%
ReadVarInt9 1 0 -100.00%
ReadVarStr4 3 2 -33.33%
ReadVarStr10 3 2 -33.33%
WriteVarStr4 2 1 -50.00%
WriteVarStr10 2 1 -50.00%
ReadOutPoint 1 0 -100.00%
WriteOutPoint 1 0 -100.00%
ReadTxOut 3 1 -66.67%
WriteTxOut 2 0 -100.00%
ReadTxIn 5 2 -60.00%
WriteTxIn 3 0 -100.00%
DeserializeTxSmall 15 7 -53.33%
DeserializeTxLarge 33428 16715 -50.00%
SerializeTx 8 0 -100.00%
ReadBlockHeader 7 1 -85.71%
WriteBlockHeader 10 4 -60.00%
DecodeGetHeaders 1004 501 -50.10%
DecodeHeaders 18002 4001 -77.77%
DecodeGetBlocks 1004 501 -50.10%
DecodeAddr 9002 4001 -55.55%
DecodeInv 150005 50003 -66.67%
DecodeNotFound 150004 50002 -66.67%
DecodeMerkleBlock 222 108 -51.35%
TxSha 10 2 -80.00%
This commit contains the entire btcwire repository along with several
changes needed to move all of the files into the wire directory in
order to prepare it for merging. This does NOT update btcd or any of the
other packages to use the new location as that will be done separately.
- All import paths in the old btcwire test files have been changed to the
new location
- All references to btcwire as the package name have been chagned to
wire
- The coveralls badge has been removed since it unfortunately doesn't
support coverage of sub-packages
This is ongoing work toward #214.
