63 lines
1.9 KiB
Go
63 lines
1.9 KiB
Go
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package render
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import (
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"bytes"
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)
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// Pulled from the github.com/oxtoacart/bpool package (Apache licensed).
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// SizedBufferPool implements a pool of bytes.Buffers in the form of a bounded
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// channel. Buffers are pre-allocated to the requested size.
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type SizedBufferPool struct {
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c chan *bytes.Buffer
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a int
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}
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// NewSizedBufferPool creates a new BufferPool bounded to the given size.
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// size defines the number of buffers to be retained in the pool and alloc sets
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// the initial capacity of new buffers to minimize calls to make().
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//
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// The value of alloc should seek to provide a buffer that is representative of
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// most data written to the the buffer (i.e. 95th percentile) without being
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// overly large (which will increase static memory consumption). You may wish to
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// track the capacity of your last N buffers (i.e. using an []int) prior to
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// returning them to the pool as input into calculating a suitable alloc value.
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func NewSizedBufferPool(size int, alloc int) (bp *SizedBufferPool) {
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return &SizedBufferPool{
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c: make(chan *bytes.Buffer, size),
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a: alloc,
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}
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}
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// Get gets a Buffer from the SizedBufferPool, or creates a new one if none are
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// available in the pool. Buffers have a pre-allocated capacity.
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func (bp *SizedBufferPool) Get() (b *bytes.Buffer) {
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select {
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case b = <-bp.c:
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// reuse existing buffer
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default:
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// create new buffer
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b = bytes.NewBuffer(make([]byte, 0, bp.a))
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}
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return
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}
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// Put returns the given Buffer to the SizedBufferPool.
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func (bp *SizedBufferPool) Put(b *bytes.Buffer) {
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b.Reset()
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// Release buffers over our maximum capacity and re-create a pre-sized
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// buffer to replace it.
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// Note that the cap(b.Bytes()) provides the capacity from the read off-set
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// only, but as we've called b.Reset() the full capacity of the underlying
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// byte slice is returned.
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if cap(b.Bytes()) > bp.a {
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b = bytes.NewBuffer(make([]byte, 0, bp.a))
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}
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select {
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case bp.c <- b:
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default: // Discard the buffer if the pool is full.
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}
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}
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