initial commit

crypto/vm/atom.cpp

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+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#include "atom.h"
+
+namespace vm {
+using td::Ref;
+
+std::atomic<Atom*> Atom::hashtable[hashtable_size] = {};
+std::atomic<int> Atom::atoms_defined{0};
+std::atomic<int> Atom::anon_atoms{0};
+
+void Atom::print_to(std::ostream& os) const {
+  if (name_.empty()) {
+    os << "atom#" << index_;
+  } else {
+    os << name_;
+  }
+}
+
+std::string Atom::make_name() const {
+  char buffer[16];
+  sprintf(buffer, "atom#%d", index_);
+  return buffer;
+}
+
+std::ostream& operator<<(std::ostream& os, const Atom& atom) {
+  atom.print_to(os);
+  return os;
+}
+
+std::ostream& operator<<(std::ostream& os, Ref<Atom> atom_ref) {
+  atom_ref->print_to(os);
+  return os;
+}
+
+std::pair<unsigned, unsigned> Atom::compute_hash(td::Slice name) {
+  unsigned h1 = 1, h2 = 1;
+  for (std::size_t i = 0; i < name.size(); i++) {
+    h1 = (239 * h1 + (unsigned char)name[i]) % hashtable_size;
+    h2 = (17 * h2 + (unsigned char)name[i]) % (hashtable_size - 1);
+  }
+  return std::make_pair(h1, h2 + 1);
+}
+
+Ref<Atom> Atom::find(td::Slice name, bool create) {
+  auto hash = compute_hash(name);
+  while (true) {
+    auto& pos = hashtable[hash.first];
+    Atom* ptr = pos.load(std::memory_order_acquire);
+    if (ptr) {
+      if (ptr->name_as_slice() == name) {
+        return Ref<Atom>(ptr);
+      }
+    } else if (!create) {
+      return {};
+    } else {
+      Atom* p2 = new Atom(name.str(), hash.first);
+      Atom* p1 = nullptr;
+      if (pos.compare_exchange_strong(p1, p2)) {
+        atoms_defined.fetch_add(1, std::memory_order_relaxed);
+        return Ref<Atom>(p2);
+      }
+      delete p2;
+      CHECK(p1);
+      if (p1->name_as_slice() == name) {
+        return Ref<Atom>(p1);
+      }
+    }
+    hash.first += hash.second;
+    if (hash.first >= hashtable_size) {
+      hash.first -= hashtable_size;
+    }
+  }
+}
+
+Ref<Atom> Atom::anon() {
+  int c = anon_atoms.fetch_add(1, std::memory_order_relaxed);
+  return Ref<Atom>{true, "", ~c};
+}
+
+}  // namespace vm