From 92e8064d9f43ca3e28ce9832cfe475034ab98704 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 10 Dec 2022 01:47:45 +0200
Subject: [PATCH] Rework protocol hash calculation

Instead of creating a string and hashing it, just build the hash
directly.
---
 source/net/protocol.cpp | 10 ++++----
 source/net/protocol.h   | 53 +++++++++++++++++------------------------
 2 files changed, 28 insertions(+), 35 deletions(-)

diff --git a/source/net/protocol.cpp b/source/net/protocol.cpp
index 9cba638..81e9d14 100644
--- a/source/net/protocol.cpp
+++ b/source/net/protocol.cpp
@@ -1,6 +1,5 @@
 #include <cstring>
 #include <string>
-#include <msp/core/hash.h>
 #include <msp/core/maputils.h>
 #include <msp/strings/format.h>
 #include <msp/strings/lexicalcast.h>
@@ -76,10 +75,13 @@ size_t Protocol::get_packet_size(const char *buf, size_t size) const
 
 uint64_t Protocol::get_hash() const
 {
-	string description;
+	uint64_t result = hash<64>(packet_id_defs.size());
 	for(auto &kvp: packet_id_defs)
-		description += format("%d:%s\n", kvp.first, kvp.second->describe());
-	return hash<64>(description);
+	{
+		hash_update<64>(result, kvp.first);
+		hash_update<64>(result, kvp.second->get_hash());
+	}
+	return result;
 }
 
 
diff --git a/source/net/protocol.h b/source/net/protocol.h
index 9f09fe5..e867c0a 100644
--- a/source/net/protocol.h
+++ b/source/net/protocol.h
@@ -5,6 +5,7 @@
 #include <map>
 #include <stdexcept>
 #include <vector>
+#include <msp/core/hash.h>
 #include "receiver.h"
 
 namespace Msp {
@@ -38,7 +39,7 @@ private:
 	{
 		virtual ~CompoundTypeDef() = default;
 
-		virtual std::string describe() const = 0;
+		virtual std::uint64_t get_hash() const = 0;
 		virtual char *serialize(const C &, char *, char *) const = 0;
 		virtual const char *deserialize(C &, const char *, const char *) const = 0;
 	};
@@ -50,7 +51,7 @@ private:
 
 		CompoundDef(const S &);
 
-		std::string describe() const override;
+		std::uint64_t get_hash() const override;
 		char *serialize(const C &, char *, char *) const override;
 		const char *deserialize(C &, const char *, const char *) const override;
 	};
@@ -63,7 +64,7 @@ private:
 
 		BasicSerializer(const Protocol &) { }
 
-		std::string describe() const { return get_type_signature<T>(); }
+		std::uint64_t get_hash() const { return Traits<T>::signature; }
 		char *serialize(const T &, char *, char *) const;
 		const char *deserialize(T &, const char *, const char *) const;
 	};
@@ -79,7 +80,7 @@ private:
 	public:
 		StringSerializer(const Protocol &);
 
-		std::string describe() const { return get_type_signature<std::string>(); }
+		std::uint64_t get_hash() const;
 		char *serialize(const std::string &, char *, char *) const;
 		const char *deserialize(std::string &, const char *, const char *) const;
 	};
@@ -97,7 +98,7 @@ private:
 	public:
 		ArraySerializer(const Protocol &);
 
-		std::string describe() const;
+		std::uint64_t get_hash() const;
 		char *serialize(const A &, char *, char *) const;
 		const char *deserialize(A &, const char *, const char *) const;
 	};
@@ -114,7 +115,6 @@ private:
 	public:
 		CompoundSerializer(const Protocol &);
 
-		std::string describe() const { return def.describe(); }
 		char *serialize(const C &, char *, char *) const;
 		const char *deserialize(C &, const char *, const char *) const;
 	};
@@ -138,7 +138,7 @@ private:
 	public:
 		Serializer(const Head &, Pointer, const Protocol &);
 
-		std::string describe() const;
+		std::uint64_t get_hash() const;
 		char *serialize(const P &, char *, char *) const;
 		const char *deserialize(P &, const char *, const char *) const;
 	};
@@ -153,7 +153,7 @@ private:
 			typedef Serializer<P, NullSerializer, typename Traits<N>::Serializer> Type;
 		};
 
-		std::string describe() const { return std::string(); }
+		std::uint64_t get_hash() const { return 0; }
 		char *serialize(const P &, char *b, char *) const { return b; }
 		const char *deserialize(P &, const char *b, const char *) const { return b; }
 	};
@@ -169,7 +169,7 @@ private:
 
 		virtual unsigned get_class_id() const = 0;
 		unsigned get_id() const { return id; }
-		virtual std::string describe() const = 0;
+		virtual std::uint64_t get_hash() const = 0;
 		virtual const char *dispatch(ReceiverBase &, const char *, const char *) const = 0;
 	};
 
@@ -190,7 +190,7 @@ private:
 
 		const CompoundTypeDef<P> &get_compound() const { return *compound; }
 
-		std::string describe() const override { return compound->describe(); }
+		std::uint64_t get_hash() const override { return compound->get_hash(); }
 		char *serialize(const P &, char *, char *) const;
 		const char *deserialize(P &, const char *, const char *) const;
 		const char *dispatch(ReceiverBase &, const char *, const char *) const override;
@@ -261,10 +261,6 @@ public:
 	std::size_t dispatch(ReceiverBase &, const char *, std::size_t) const;
 
 	std::uint64_t get_hash() const;
-
-private:
-	template<typename T>
-	static std::string get_type_signature();
 };
 
 
@@ -308,17 +304,6 @@ std::size_t Protocol::serialize(const P &pkt, char *buf, std::size_t size) const
 	return size;
 }
 
-template<typename T>
-std::string Protocol::get_type_signature()
-{
-	const std::uint16_t sig = Traits<T>::signature;
-	std::string result;
-	result += sig&0xFF;
-	if(sig>=0x100)
-		result += '0'+(sig>>8);
-	return result;
-}
-
 
 template<typename T, std::uint8_t K>
 struct Protocol::BasicTraits
@@ -367,9 +352,9 @@ Protocol::CompoundDef<C, S>::CompoundDef(const S &s):
 { }
 
 template<typename C, typename S>
-std::string Protocol::CompoundDef<C, S>::describe() const
+std::uint64_t Protocol::CompoundDef<C, S>::get_hash() const
 {
-	return "{"+serializer.describe()+"}";
+	return hash_round<64>(serializer.get_hash(), 'C');
 }
 
 template<typename C, typename S>
@@ -385,6 +370,12 @@ const char *Protocol::CompoundDef<C, S>::deserialize(C &com, const char *buf, co
 }
 
 
+inline std::uint64_t Protocol::StringSerializer::get_hash() const
+{
+	return Traits<std::string>::signature;
+}
+
+
 template<typename A>
 Protocol::ArraySerializer<A>::ArraySerializer(const Protocol &proto):
 	length_serializer(proto),
@@ -392,9 +383,9 @@ Protocol::ArraySerializer<A>::ArraySerializer(const Protocol &proto):
 { }
 
 template<typename A>
-std::string Protocol::ArraySerializer<A>::describe() const
+std::uint64_t Protocol::ArraySerializer<A>::get_hash() const
 {
-	return "["+element_serializer.describe()+"]";
+	return hash_round<64>(element_serializer.get_hash(), 'A');
 }
 
 template<typename A>
@@ -444,9 +435,9 @@ Protocol::Serializer<P, Head, S>::Serializer(const Head &h, Pointer p, const Pro
 { }
 
 template<typename P, typename Head, typename S>
-std::string Protocol::Serializer<P, Head, S>::describe() const
+std::uint64_t Protocol::Serializer<P, Head, S>::get_hash() const
 {
-	return Head::describe()+ser.describe();
+	return hash_update<64>(Head::get_hash(), ser.get_hash());
 }
 
 template<typename P, typename Head, typename S>
-- 
2.43.0