bytespool

A collection of pools for variable-sized objects: []byte, *bufio.Reader, *bufio.Writer and *bytes.Buffer.

High-level APIs

Once you import github.com/CAFxX/bytespool you have access to these high-level APIs:

• GetBufferPool(size int) httputil.BufferPool
• GetBufioReader(pr io.Reader, size int) *bufio.Reader and PutBufioReader(r *bufio.Reader) bool
• GetBufioWriter(pw io.Writer, size int) *bufio.Writer and PutBufioWriter(w *bufio.Writer) bool
• GetBytesBuffer(size int) *bytes.Buffer and PutBytesBuffer(b *bytes.Buffer) bool
• GetBytesSlice(size int) []byte and PutBytesSlice(b []byte) bool
• GetBytesSlicePtr(size int) *[]byte and PutBytesSlicePtr(b *[]byte) bool

In addition, the following utility APIs are available:

• Append is a replacement for append that uses the backing pools to avoid allocations when appending to byte slices.

bytespool relies on code generation to allow to control the granularity of the backing pools.

The generated code contains specialized versions of all functions for each of the backing pools. These functions can be used to provide a small speed-up if you statically know the desired sizes at compile-time.

Note that it is allowed to pass to the PutXxx functions objects that have been obtained not from GetXxx or that have undergone resizing. If the PutXxx functions detect that the object can not be recycled they will return false without modifying the object.

Examples

Minimizing allocations in ReverseProxy

httputil.ReverseProxy can use an httputil.BufferPool to minimize allocations. You can provide one as follows:

rp := httputil.NewSingleHostReverseProxy(target)
rp.BufferPool = bytespool.GetBufferPool(32*1024)

Benchmarks

There is a small set of benchmarks you can run with make bench (you need to have benchstat on your PATH), from which you can validate that in steady state no allocations are performed even for []byte:

name                           time/op
GetBytesSlice-12               8.56ns ±14%
GetBytesSliceSemiStatic-12     8.26ns ±14%
GetBytesSliceStatic-12         8.19ns ±16%
GetBytesSlicePtr-12            5.18ns ±23%
GetBytesSlicePtrSemiStatic-12  4.74ns ±22%
GetBytesSlicePtrStatic-12      4.74ns ±22%
GetBytesBuffer-12              3.64ns ± 8%
GetBytesBufferSemiStatic-12    3.18ns ± 5%
GetBytesBufferStatic-12        3.12ns ± 5%
GetBufioReader-12              5.82ns ± 7%
GetBufioReaderSemiStatic-12    5.45ns ±10%
GetBufioReaderStatic-12        5.39ns ± 6%
GetBufioWriter-12              4.02ns ± 2%
GetBufioWriterSemiStatic-12    3.73ns ± 4%
GetBufioWriterStatic-12        3.56ns ± 3%

name                           alloc/op
GetBytesSlice-12                0.00B
GetBytesSliceSemiStatic-12      0.00B
GetBytesSliceStatic-12          0.00B
GetBytesSlicePtr-12             0.00B
GetBytesSlicePtrSemiStatic-12   0.00B
GetBytesSlicePtrStatic-12       0.00B
GetBytesBuffer-12               0.00B
GetBytesBufferSemiStatic-12     0.00B
GetBytesBufferStatic-12         0.00B
GetBufioReader-12               0.00B
GetBufioReaderSemiStatic-12     0.00B
GetBufioReaderStatic-12         0.00B
GetBufioWriter-12               0.00B
GetBufioWriterSemiStatic-12     0.00B
GetBufioWriterStatic-12         0.00B

name                           allocs/op
GetBytesSlice-12                 0.00
GetBytesSliceSemiStatic-12       0.00
GetBytesSliceStatic-12           0.00
GetBytesSlicePtr-12              0.00
GetBytesSlicePtrSemiStatic-12    0.00
GetBytesSlicePtrStatic-12        0.00
GetBytesBuffer-12                0.00
GetBytesBufferSemiStatic-12      0.00
GetBytesBufferStatic-12          0.00
GetBufioReader-12                0.00
GetBufioReaderSemiStatic-12      0.00
GetBufioReaderStatic-12          0.00
GetBufioWriter-12                0.00
GetBufioWriterSemiStatic-12      0.00
GetBufioWriterStatic-12          0.00

Developing

Most of the code is in gen/main.go. You can run make generate to generate bytespool.go.

TODO

• Split low-level APIs in a separate package
• Ensure that users of the low-level API are not forced to compile also the high-level APIs
• Define BufferPool-like interfaces for all objects (e.g. BytesBufferPool)
• Provide non-singleton pools