buffer+pool: add buffer.Read and pool.ReadBuffer

pool/read_buffer.go

@@ -0,0 +1,48 @@
+package pool
+
+import (
+	"time"
+
+	"github.com/lightningnetwork/lnd/buffer"
+)
+
+const (
+	// DefaultReadBufferGCInterval is the default interval that a Read will
+	// perform a sweep to see which expired buffer.Reads can be released to
+	// the runtime.
+	DefaultReadBufferGCInterval = 15 * time.Second
+
+	// DefaultReadBufferExpiryInterval is the default, minimum interval that
+	// must elapse before a Read will release a buffer.Read. The maximum
+	// time before the buffer can be released is equal to the expiry
+	// interval plus the gc interval.
+	DefaultReadBufferExpiryInterval = 30 * time.Second
+)
+
+// ReadBuffer is a pool of buffer.Read items, that dynamically allocates and
+// reclaims buffers in response to load.
+type ReadBuffer struct {
+	pool *Recycle
+}
+
+// NewReadBuffer returns a freshly instantiated ReadBuffer, using the given
+// gcInterval and expieryInterval.
+func NewReadBuffer(gcInterval, expiryInterval time.Duration) *ReadBuffer {
+	return &ReadBuffer{
+		pool: NewRecycle(
+			func() interface{} { return new(buffer.Read) },
+			100, gcInterval, expiryInterval,
+		),
+	}
+}
+
+// Take returns a fresh buffer.Read to the caller.
+func (p *ReadBuffer) Take() *buffer.Read {
+	return p.pool.Take().(*buffer.Read)
+}
+
+// Return returns the buffer.Read to the pool, so that it can be cycled or
+// released.
+func (p *ReadBuffer) Return(buf *buffer.Read) {
+	p.pool.Return(buf)
+}