From 7f86c75360072879bbdfdc61c5ea777a0eed8885 Mon Sep 17 00:00:00 2001
From: c9s <yoan@maicoin.com>
Date: Wed, 19 May 2021 00:15:11 +0800
Subject: [PATCH] add CopyDepth for avoid copying the whole book

---
 pkg/types/orderbook.go | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/pkg/types/orderbook.go b/pkg/types/orderbook.go
index e8b93fd4a..6df288aa5 100644
--- a/pkg/types/orderbook.go
+++ b/pkg/types/orderbook.go
@@ -38,6 +38,16 @@ func (slice PriceVolumeSlice) Trim() (pvs PriceVolumeSlice) {
 	return pvs
 }
 
+func (slice PriceVolumeSlice) CopyDepth(depth int) PriceVolumeSlice {
+	if depth > len(slice) {
+		return slice.Copy()
+	}
+
+	var s = make(PriceVolumeSlice, depth, depth)
+	copy(s, slice[:depth])
+	return s
+}
+
 func (slice PriceVolumeSlice) Copy() PriceVolumeSlice {
 	var s = make(PriceVolumeSlice, len(slice), len(slice))
 	copy(s, slice)
@@ -196,6 +206,13 @@ func (b *OrderBook) PriceVolumesBySide(side SideType) PriceVolumeSlice {
 	return nil
 }
 
+func (b *OrderBook) CopyDepth(depth int) (book OrderBook) {
+	book = *b
+	book.Bids = book.Bids.CopyDepth(depth)
+	book.Asks = book.Asks.CopyDepth(depth)
+	return book
+}
+
 func (b *OrderBook) Copy() (book OrderBook) {
 	book = *b
 	book.Bids = book.Bids.Copy()
@@ -307,6 +324,12 @@ func (b *MutexOrderBook) Reset() {
 	b.Unlock()
 }
 
+func (b *MutexOrderBook) CopyDepth(depth int) OrderBook {
+	b.Lock()
+	defer b.Unlock()
+	return b.OrderBook.CopyDepth(depth)
+}
+
 func (b *MutexOrderBook) Get() OrderBook {
 	b.Lock()
 	defer b.Unlock()