perf: introduce ToBytes in bls.h and use it in all spots trivially po…

…ssible, convert vecBytes to std::array

this results in an improved reindex speed as previously roughly 2% of total cycles were just in allocating the vector.

src/bls/bls.h

@@ -136,6 +136,15 @@ class CBLSWrapper
         return ToByteVector(bls::bls_legacy_scheme.load());
     }
 
+    std::array<uint8_t, SerSize> ToBytes(const bool specificLegacyScheme) const
+    {
+        return impl.SerializeToArray(specificLegacyScheme);
+    }
+    std::array<uint8_t, SerSize> ToBytes() const
+    {
+        return ToBytes(bls::bls_legacy_scheme.load());
+    }
+
     const uint256& GetHash() const
     {
         if (cachedHash.IsNull()) {
@@ -167,7 +176,7 @@ class CBLSWrapper
     template <typename Stream>
     inline void Serialize(Stream& s, const bool specificLegacyScheme) const
     {
-        s.write(AsBytes(Span{ToByteVector(specificLegacyScheme).data(), SerSize}));
+        s.write(AsBytes(Span{ToBytes(specificLegacyScheme).data(), SerSize}));
     }
 
     template <typename Stream>
@@ -206,7 +215,7 @@ class CBLSWrapper
 
     inline bool CheckMalleable(Span<uint8_t> vecBytes, const bool specificLegacyScheme) const
     {
-        if (memcmp(vecBytes.data(), ToByteVector(specificLegacyScheme).data(), SerSize)) {
+        if (memcmp(vecBytes.data(), ToBytes(specificLegacyScheme).data(), SerSize)) {
             // TODO not sure if this is actually possible with the BLS libs. I'm assuming here that somewhere deep inside
             // these libs masking might happen, so that 2 different binary representations could result in the same object
             // representation
@@ -222,7 +231,7 @@ class CBLSWrapper
 
     inline std::string ToString(const bool specificLegacyScheme) const
     {
-        std::vector<uint8_t> buf = ToByteVector(specificLegacyScheme);
+        auto buf = ToBytes(specificLegacyScheme);
         return HexStr(buf);
     }
 
@@ -249,6 +258,10 @@ struct CBLSIdImplicit : public uint256
     {
         return {begin(), end()};
     }
+    [[nodiscard]] std::array<uint8_t, 32> SerializeToArray(const bool fLegacy) const
+    {
+        return m_data;
+    }
 };
 
 class CBLSId : public CBLSWrapper<CBLSIdImplicit, BLS_CURVE_ID_SIZE, CBLSId>
@@ -381,7 +394,7 @@ class CBLSLazyWrapper
 private:
     mutable std::mutex mutex;
 
-    mutable std::vector<uint8_t> vecBytes;
+    mutable std::array<uint8_t, BLSObject::SerSize> vecBytes;
     mutable bool bufValid{false};
     mutable bool bufLegacyScheme{true};
 
@@ -392,7 +405,7 @@ class CBLSLazyWrapper
 
 public:
     CBLSLazyWrapper() :
-            vecBytes(BLSObject::SerSize, 0),
+            vecBytes{0},
             bufLegacyScheme(bls::bls_legacy_scheme.load())
     {}
 
@@ -410,7 +423,6 @@ class CBLSLazyWrapper
         if (r.bufValid) {
             vecBytes = r.vecBytes;
         } else {
-            vecBytes.resize(BLSObject::SerSize);
             std::fill(vecBytes.begin(), vecBytes.end(), 0);
         }
         objInitialized = r.objInitialized;
@@ -433,10 +445,9 @@ class CBLSLazyWrapper
     {
         std::unique_lock<std::mutex> l(mutex);
         if (!objInitialized && !bufValid) {
-            vecBytes.resize(BLSObject::SerSize);
             std::fill(vecBytes.begin(), vecBytes.end(), 0);
         } else if (!bufValid || (bufLegacyScheme != specificLegacyScheme)) {
-            vecBytes = obj.ToByteVector(specificLegacyScheme);
+            vecBytes = obj.ToBytes(specificLegacyScheme);
             bufValid = true;
             bufLegacyScheme = specificLegacyScheme;
             hash.SetNull();
@@ -518,11 +529,10 @@ class CBLSLazyWrapper
     {
         std::unique_lock<std::mutex> l(mutex);
         if (!objInitialized && !bufValid) {
-            vecBytes.resize(BLSObject::SerSize);
             std::fill(vecBytes.begin(), vecBytes.end(), 0);
             hash.SetNull();
         } else if (!bufValid) {
-            vecBytes = obj.ToByteVector(bufLegacyScheme);
+            vecBytes = obj.ToBytes(bufLegacyScheme);
             bufValid = true;
             hash.SetNull();
         }

src/llmq/dkgsession.cpp

@@ -1016,12 +1016,12 @@ void CDKGSession::SendCommitment(CDKGPendingMessages& pendingMessages, PeerManag
 
     if (lieType == 3) {
         const bool is_bls_legacy = bls::bls_legacy_scheme.load();
-        std::vector<uint8_t> buf = qc.sig.ToByteVector(is_bls_legacy);
+        auto buf = qc.sig.ToBytes(is_bls_legacy);
         buf[5]++;
         qc.sig.SetBytes(buf, is_bls_legacy);
     } else if (lieType == 4) {
         const bool is_bls_legacy = bls::bls_legacy_scheme.load();
-        std::vector<uint8_t> buf = qc.quorumSig.ToByteVector(is_bls_legacy);
+        auto buf = qc.quorumSig.ToBytes(is_bls_legacy);
         buf[5]++;
         qc.quorumSig.SetBytes(buf, is_bls_legacy);
     }