From 305453b52d03d83fc1973c04de928b2fd023051e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20Rydg=C3=A5rd?= <hrydgard@gmail.com>
Date: Fri, 22 Nov 2024 10:13:41 +0100
Subject: [PATCH] Buffer: Optimize scanning for the next crlf

---
 Common/Buffer.cpp                   | 10 +++++-----
 Common/Data/Collections/CharQueue.h | 21 +++++++++++++++++++++
 Common/Net/NetBuffer.cpp            |  4 ++++
 unittest/UnitTest.cpp               |  4 ++++
 4 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/Common/Buffer.cpp b/Common/Buffer.cpp
index eb56a490a6..e667020579 100644
--- a/Common/Buffer.cpp
+++ b/Common/Buffer.cpp
@@ -95,12 +95,12 @@ int Buffer::SkipLineCRLF() {
 
 // This relies on having buffered data!
 int Buffer::OffsetToAfterNextCRLF() {
-	for (int i = 0; i < (int)data_.size() - 1; i++) {
-		if (data_.peek(i) == '\r' && data_.peek(i + 1) == '\n') {
-			return i + 2;
-		}
+	int offset = data_.next_crlf_offset();
+	if (offset >= 0) {
+		return offset + 2;
+	} else {
+		return -1;
 	}
-	return -1;
 }
 
 void Buffer::Printf(const char *fmt, ...) {
diff --git a/Common/Data/Collections/CharQueue.h b/Common/Data/Collections/CharQueue.h
index 2be72d35b1..9d570b99e8 100644
--- a/Common/Data/Collections/CharQueue.h
+++ b/Common/Data/Collections/CharQueue.h
@@ -186,6 +186,27 @@ public:
 		head_ = b;
 	}
 
+	// If return value is negative, one wasn't found.
+	int next_crlf_offset() {
+		int offset = 0;
+		Block *b = head_;
+		do {
+			int remain = b->tail - b->head;
+			for (int i = 0; i < remain; i++) {
+				if (b->data[b->head + i] == '\r') {
+					// Use peek to avoid handling edge cases.
+					if (peek(offset + i + 1) == '\n') {
+						return offset + i;
+					}
+				}
+			}
+			offset += remain;
+			b = b->next;
+		} while (b);
+		// Ran out of data.
+		return -1;
+	}
+
 private:
 	struct Block {
 		~Block() {
diff --git a/Common/Net/NetBuffer.cpp b/Common/Net/NetBuffer.cpp
index eccc12a3fa..00886bd95d 100644
--- a/Common/Net/NetBuffer.cpp
+++ b/Common/Net/NetBuffer.cpp
@@ -15,6 +15,10 @@
 #define MSG_NOSIGNAL 0x00
 #endif
 
+#if _MSC_VER
+#pragma warning(disable:4267)
+#endif
+
 #include "Common/File/FileDescriptor.h"
 #include "Common/Log.h"
 #include "Common/Net/NetBuffer.h"
diff --git a/unittest/UnitTest.cpp b/unittest/UnitTest.cpp
index f800437934..3aed4a6991 100644
--- a/unittest/UnitTest.cpp
+++ b/unittest/UnitTest.cpp
@@ -1076,6 +1076,10 @@ bool TestCharQueue() {
 	queue.pop_front_bulk(dest, 4);
 	EXPECT_EQ_MEM(dest, "opqr", 4);
 	EXPECT_TRUE(queue.empty());
+	queue.push_back("asdf");
+	EXPECT_EQ_INT(queue.next_crlf_offset(), -1);
+	queue.push_back("\r\r\n");
+	EXPECT_EQ_INT(queue.next_crlf_offset(), 5);
 	return true;
 }