multi: add buffer.Write and pool.WriteBuffer, make GCQueue generic

lnpeer/write_buffer_pool.go

@@ -1,79 +0,0 @@
-package lnpeer
-
-import (
-	"time"
-
-	"github.com/lightningnetwork/lnd/lnwire"
-	"github.com/lightningnetwork/lnd/queue"
-)
-
-const (
-	// DefaultGCInterval is the default interval that the WriteBufferPool
-	// will perform a sweep to see which expired buffers can be released to
-	// the runtime.
-	DefaultGCInterval = 15 * time.Second
-
-	// DefaultExpiryInterval is the default, minimum interval that must
-	// elapse before a WriteBuffer will be released. The maximum time before
-	// the buffer can be released is equal to the expiry interval plus the
-	// gc interval.
-	DefaultExpiryInterval = 30 * time.Second
-)
-
-// WriteBuffer is static byte array occupying to maximum-allowed
-// plaintext-message size.
-type WriteBuffer [lnwire.MaxMessagePayload]byte
-
-// Recycle zeroes the WriteBuffer, making it fresh for another use.
-// Zeroing the buffer using a logarithmic number of calls to the optimized copy
-// method. Benchmarking shows this to be ~30 times faster than a for loop that
-// sets each index to 0 for this buffer size. Inspired by:
-// https://stackoverflow.com/questions/30614165/is-there-analog-of-memset-in-go
-//
-// This is part of the queue.Recycler interface.
-func (b *WriteBuffer) Recycle() {
-	b[0] = 0
-	for i := 1; i < lnwire.MaxMessagePayload; i *= 2 {
-		copy(b[i:], b[:i])
-	}
-}
-
-// newRecyclableWriteBuffer is a constructor that returns a WriteBuffer typed as
-// a queue.Recycler.
-func newRecyclableWriteBuffer() queue.Recycler {
-	return new(WriteBuffer)
-}
-
-// A compile-time constraint to ensure that *WriteBuffer implements the
-// queue.Recycler interface.
-var _ queue.Recycler = (*WriteBuffer)(nil)
-
-// WriteBufferPool acts a global pool of WriteBuffers, that dynamically
-// allocates and reclaims buffers in response to load.
-type WriteBufferPool struct {
-	pool *queue.GCQueue
-}
-
-// NewWriteBufferPool returns a freshly instantiated WriteBufferPool, using the
-// given gcInterval and expiryIntervals.
-func NewWriteBufferPool(
-	gcInterval, expiryInterval time.Duration) *WriteBufferPool {
-
-	return &WriteBufferPool{
-		pool: queue.NewGCQueue(
-			newRecyclableWriteBuffer, 100,
-			gcInterval, expiryInterval,
-		),
-	}
-}
-
-// Take returns a fresh WriteBuffer to the caller.
-func (p *WriteBufferPool) Take() *WriteBuffer {
-	return p.pool.Take().(*WriteBuffer)
-}
-
-// Return returns the WriteBuffer to the pool, so that it can be recycled or
-// released.
-func (p *WriteBufferPool) Return(buf *WriteBuffer) {
-	p.pool.Return(buf)
-}

lnpeer/write_buffer_pool_test.go

@@ -1,67 +0,0 @@
-package lnpeer_test
-
-import (
-	"testing"
-	"time"
-
-	"github.com/lightningnetwork/lnd/lnpeer"
-)
-
-// TestWriteBufferPool verifies that buffer pool properly resets used write
-// buffers.
-func TestWriteBufferPool(t *testing.T) {
-	const (
-		gcInterval     = time.Second
-		expiryInterval = 250 * time.Millisecond
-	)
-
-	bp := lnpeer.NewWriteBufferPool(gcInterval, expiryInterval)
-
-	// Take a fresh write buffer from the pool.
-	writeBuf := bp.Take()
-
-	// Dirty the write buffer.
-	for i := range writeBuf[:] {
-		writeBuf[i] = 0xff
-	}
-
-	// Return the buffer to the pool.
-	bp.Return(writeBuf)
-
-	// Take buffers from the pool until we find the original. We expect at
-	// most two, in the even that a fresh buffer is populated after the
-	// first is taken.
-	for i := 0; i < 2; i++ {
-		// Wait a small duration to ensure the tests behave reliable,
-		// and don't activate the non-blocking case unintentionally.
-		<-time.After(time.Millisecond)
-
-		// Take a buffer, skipping those whose pointer does not match
-		// the one we dirtied.
-		writeBuf2 := bp.Take()
-		if writeBuf2 != writeBuf {
-			continue
-		}
-
-		// Finally, verify that the buffer has been properly cleaned.
-		for i := range writeBuf2[:] {
-			if writeBuf2[i] != 0 {
-				t.Fatalf("buffer was not recycled")
-			}
-		}
-
-		return
-	}
-
-	t.Fatalf("original buffer not found")
-}
-
-// BenchmarkWriteBufferRecycle tests how quickly a WriteBuffer can be zeroed.
-func BenchmarkWriteBufferRecycle(b *testing.B) {
-	b.ReportAllocs()
-
-	buffer := new(lnpeer.WriteBuffer)
-	for i := 0; i < b.N; i++ {
-		buffer.Recycle()
-	}
-}