80 lines
2.4 KiB
Go
80 lines
2.4 KiB
Go
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package lnpeer
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import (
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"time"
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"github.com/lightningnetwork/lnd/lnwire"
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"github.com/lightningnetwork/lnd/queue"
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)
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const (
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// DefaultGCInterval is the default interval that the WriteBufferPool
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// will perform a sweep to see which expired buffers can be released to
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// the runtime.
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DefaultGCInterval = 15 * time.Second
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// DefaultExpiryInterval is the default, minimum interval that must
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// elapse before a WriteBuffer will be released. The maximum time before
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// the buffer can be released is equal to the expiry interval plus the
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// gc interval.
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DefaultExpiryInterval = 30 * time.Second
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)
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// WriteBuffer is static byte array occupying to maximum-allowed
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// plaintext-message size.
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type WriteBuffer [lnwire.MaxMessagePayload]byte
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// Recycle zeroes the WriteBuffer, making it fresh for another use.
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// Zeroing the buffer using a logarithmic number of calls to the optimized copy
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// method. Benchmarking shows this to be ~30 times faster than a for loop that
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// sets each index to 0 for this buffer size. Inspired by:
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// https://stackoverflow.com/questions/30614165/is-there-analog-of-memset-in-go
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//
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// This is part of the queue.Recycler interface.
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func (b *WriteBuffer) Recycle() {
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b[0] = 0
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for i := 1; i < lnwire.MaxMessagePayload; i *= 2 {
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copy(b[i:], b[:i])
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}
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}
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// newRecyclableWriteBuffer is a constructor that returns a WriteBuffer typed as
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// a queue.Recycler.
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func newRecyclableWriteBuffer() queue.Recycler {
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return new(WriteBuffer)
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}
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// A compile-time constraint to ensure that *WriteBuffer implements the
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// queue.Recycler interface.
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var _ queue.Recycler = (*WriteBuffer)(nil)
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// WriteBufferPool acts a global pool of WriteBuffers, that dynamically
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// allocates and reclaims buffers in response to load.
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type WriteBufferPool struct {
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pool *queue.GCQueue
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}
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// NewWriteBufferPool returns a freshly instantiated WriteBufferPool, using the
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// given gcInterval and expiryIntervals.
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func NewWriteBufferPool(
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gcInterval, expiryInterval time.Duration) *WriteBufferPool {
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return &WriteBufferPool{
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pool: queue.NewGCQueue(
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newRecyclableWriteBuffer, 100,
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gcInterval, expiryInterval,
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),
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}
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}
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// Take returns a fresh WriteBuffer to the caller.
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func (p *WriteBufferPool) Take() *WriteBuffer {
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return p.pool.Take().(*WriteBuffer)
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}
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// Return returns the WriteBuffer to the pool, so that it can be recycled or
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// released.
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func (p *WriteBufferPool) Return(buf *WriteBuffer) {
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p.pool.Return(buf)
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}
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