From 9d75ed14b4da0841cbf9a2a93107403ad6a4b5b8 Mon Sep 17 00:00:00 2001
From: Adrien Beraud <adrien.beraud@savoirfairelinux.com>
Date: Mon, 10 Apr 2017 15:44:06 +0200
Subject: [PATCH] infohash: add to_c_str(), improve toString() performance
---
include/opendht/infohash.h | 2 ++
src/infohash.cpp | 34 +++++++++++++++++++++++++++-------
2 files changed, 29 insertions(+), 7 deletions(-)
diff --git a/include/opendht/infohash.h b/include/opendht/infohash.h
index 5e07ba1c..74186ed2 100644
--- a/include/opendht/infohash.h
+++ b/include/opendht/infohash.h
@@ -278,6 +278,8 @@ public:
OPENDHT_PUBLIC friend std::ostream& operator<< (std::ostream& s, const InfoHash& h);
OPENDHT_PUBLIC friend std::istream& operator>> (std::istream& s, InfoHash& h);
+ const char* to_c_str() const;
+
std::string toString() const;
template <typename Packer>
diff --git a/src/infohash.cpp b/src/infohash.cpp
index 5070abe4..7530ca1d 100644
--- a/src/infohash.cpp
+++ b/src/infohash.cpp
@@ -71,20 +71,40 @@ InfoHash::getRandom()
return h;
}
+struct HexMap : public std::array<std::array<char, 2>, 256> {
+ HexMap() {
+ for (size_t i=0; i<size(); i++) {
+ auto& e = (*this)[i];
+ e[0] = hex_digits[(i >> 4) & 0x0F];
+ e[1] = hex_digits[i & 0x0F];
+ }
+ }
+private:
+ static constexpr const char* hex_digits = "0123456789abcdef";
+};
+
+const char*
+InfoHash::to_c_str() const
+{
+ static const HexMap map;
+ thread_local std::array<char, HASH_LEN*2+1> buf;
+ for (size_t i=0; i<HASH_LEN; i++) {
+ auto b = buf.data()+i*2;
+ const auto& m = map[(*this)[i]];
+ *((uint16_t*)b) = *((uint16_t*)&m);
+ }
+ return buf.data();
+}
+
std::string
InfoHash::toString() const
{
- std::stringstream ss;
- ss << *this;
- return ss.str();
+ return std::string(to_c_str(), HASH_LEN*2);
}
std::ostream& operator<< (std::ostream& s, const InfoHash& h)
{
- s << std::hex;
- for (unsigned i=0; i<HASH_LEN; i++)
- s << std::setfill('0') << std::setw(2) << (unsigned)h[i];
- s << std::dec;
+ s.write(h.to_c_str(), HASH_LEN*2);
return s;
}
--
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