unit_tests/ex_MemArena.cc

/** @file MemArena example code. Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. */ #include <string_view> #include <memory> #include <random> #include "swoc/BufferWriter.h" #include "swoc/MemArena.h" #include "swoc/TextView.h" #include "swoc/IntrusiveHashMap.h" #include "swoc/bwf_base.h" #include "swoc/ext/HashFNV.h" #include "catch.hpp" using swoc::MemSpan; using swoc::MemArena; using swoc::TextView; using std::string_view; using swoc::FixedBufferWriter; using namespace std::literals; TextView localize(MemArena &arena, TextView view) { auto span = arena.alloc(view.size()).rebind<char>(); memcpy(span, view); return span; } template <typename T> struct Destructor { void operator()(T *t) { t->~T(); } }; void Destroy(MemArena *arena) { arena->~MemArena(); } TEST_CASE("MemArena inversion", "[libswoc][MemArena][example][inversion]") { TextView tv{"You done messed up A-A-Ron"}; TextView text{"SolidWallOfCode"}; { MemArena tmp; MemArena *arena = tmp.make<MemArena>(std::move(tmp)); arena->~MemArena(); } { std::unique_ptr<MemArena> arena{new MemArena}; TextView local_tv = localize(*arena, tv); REQUIRE(local_tv == tv); REQUIRE(arena->contains(local_tv.data())); } { auto destroyer = [](MemArena *arena) -> void { arena->~MemArena(); }; MemArena ta; TextView local_tv = localize(ta, tv); REQUIRE(local_tv == tv); REQUIRE(ta.contains(local_tv.data())); // 16 bytes. std::unique_ptr<MemArena, void (*)(MemArena *)> arena(ta.make<MemArena>(std::move(ta)), destroyer); REQUIRE(ta.size() == 0); REQUIRE(ta.contains(local_tv.data()) == false); REQUIRE(arena->size() >= local_tv.size()); REQUIRE(local_tv == tv); REQUIRE(arena->contains(local_tv.data())); TextView local_text = localize(*arena, text); REQUIRE(local_text == text); REQUIRE(local_tv != local_text); REQUIRE(local_tv.data() != local_text.data()); REQUIRE(arena->contains(local_text.data())); REQUIRE(arena->size() >= local_tv.size() + local_text.size()); } { MemArena ta; // 8 bytes. std::unique_ptr<MemArena, Destructor<MemArena>> arena(ta.make<MemArena>(std::move(ta))); } { MemArena ta; // 16 bytes std::unique_ptr<MemArena, void (*)(MemArena *)> arena(ta.make<MemArena>(std::move(ta)), &Destroy); } { MemArena ta; // 16 bytes std::unique_ptr<MemArena, void (*)(MemArena *)> arena(ta.make<MemArena>(std::move(ta)), [](MemArena *arena) -> void { arena->~MemArena(); }); } { auto destroyer = [](MemArena *arena) -> void { arena->~MemArena(); }; MemArena ta; // 8 bytes std::unique_ptr<MemArena, decltype(destroyer)> arena(ta.make<MemArena>(std::move(ta)), destroyer); } }; template <typename... Args> TextView bw_localize(MemArena &arena, TextView const &fmt, Args &&...args) { FixedBufferWriter w(arena.remnant()); auto arg_tuple{std::forward_as_tuple(args...)}; w.print_v(fmt, arg_tuple); if (w.error()) { FixedBufferWriter(arena.require(w.extent()).remnant()).print_v(fmt, arg_tuple); } return arena.alloc(w.extent()).rebind<char>(); } TEST_CASE("MemArena example", "[libswoc][MemArena][example]") { struct Thing { using self_type = Thing; int n{10}; std::string_view name{"name"}; self_type *_next{nullptr}; self_type *_prev{nullptr}; Thing() {} Thing(int x) : n(x) {} Thing(std::string_view const &s) : name(s) {} Thing(int x, std::string_view s) : n(x), name(s) {} Thing(std::string_view const &s, int x) : n(x), name(s) {} struct Linkage : swoc::IntrusiveLinkage<self_type> { static std::string_view key_of(self_type *thing) { return thing->name; } static uint32_t hash_of(std::string_view const &s) { return swoc::Hash32FNV1a().hash_immediate(swoc::transform_view_of(&toupper, s)); } static bool equal(std::string_view const &lhs, std::string_view const &rhs) { return lhs == rhs; } }; }; MemArena arena; TextView text = localize(arena, "Goofy Goober"); Thing *thing = arena.make<Thing>(); REQUIRE(thing->name == "name"); REQUIRE(thing->n == 10); thing = arena.make<Thing>(text, 956); REQUIRE(thing->name.data() == text.data()); REQUIRE(thing->n == 956); // Consume most of the space left. arena.alloc(arena.remaining() - 16); FixedBufferWriter w(arena.remnant()); w.print("Much ado about not much text"); if (w.error()) { FixedBufferWriter lw(arena.require(w.extent()).remnant()); lw.print("Much ado about not much text"); } auto span = arena.alloc(w.extent()).rebind<char>(); // commit the memory. REQUIRE(TextView(span) == "Much ado about not much text"); auto tv1 = bw_localize(arena, "Text: {} - '{}'", 956, "Additional"); REQUIRE(tv1 == "Text: 956 - 'Additional'"); REQUIRE(arena.contains(tv1.data())); arena.clear(); using Map = swoc::IntrusiveHashMap<Thing::Linkage>; Map *ihm = arena.make<Map>(); { std::string key_1{"Key One"}; std::string key_2{"Key Two"}; ihm->insert(arena.make<Thing>(localize(arena, key_1), 1)); ihm->insert(arena.make<Thing>(localize(arena, key_2), 2)); } thing = ihm->find("Key One"); REQUIRE(thing->name == "Key One"); REQUIRE(thing->n == 1); REQUIRE(arena.contains(ihm)); REQUIRE(arena.contains(thing)); REQUIRE(arena.contains(thing->name.data())); // Call the destructor for the IntrusiveHashMap to free anything it allocated. ihm->~Map(); };

unit_tests/ex_MemArena.cc (159 lines of code) (raw):