forked from OctaForge/libostd
implement a stack pool (allocates a chunk of stacks, gives out as requested)
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@ -108,6 +108,154 @@ private:
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using fixedsize_stack = basic_fixedsize_stack<stack_traits, false>;
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using fixedsize_stack = basic_fixedsize_stack<stack_traits, false>;
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using protected_fixedsize_stack = basic_fixedsize_stack<stack_traits, true>;
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using protected_fixedsize_stack = basic_fixedsize_stack<stack_traits, true>;
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template<typename TR, bool Protected>
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struct basic_stack_pool {
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private:
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struct allocator {
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allocator() = delete;
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allocator(basic_stack_pool &p) noexcept: p_pool(&p) {}
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stack_context allocate() {
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return p_pool->allocate();
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}
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void deallocate(stack_context &st) noexcept {
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p_pool->deallocate(st);
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}
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private:
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basic_stack_pool *p_pool;
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};
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public:
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static constexpr size_t DEFAULT_CHUNK_SIZE = 32;
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using allocator_type = allocator;
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basic_stack_pool(
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size_t ss = TR::default_size(), size_t cs = DEFAULT_CHUNK_SIZE
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) {
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/* precalculate the sizes */
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size_t pgs = TR::page_size();
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size_t npg = std::max(ss / pgs, size_t(size_t(Protected) + 1));
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size_t asize = npg * pgs;
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p_stacksize = asize;
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p_chunksize = cs * asize;
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}
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basic_stack_pool(basic_stack_pool const &) = delete;
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basic_stack_pool(basic_stack_pool &&p) noexcept {
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swap(p);
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}
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basic_stack_pool &operator=(basic_stack_pool const &) = delete;
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basic_stack_pool &operator=(basic_stack_pool &&p) noexcept {
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swap(p);
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return *this;
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}
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~basic_stack_pool() {
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size_t ss = p_stacksize;
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size_t cs = p_chunksize;
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void *pc = p_chunk;
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while (pc) {
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void *p = pc;
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pc = get_node(p, ss, 1)->next_chunk;
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detail::stack_free(p, cs);
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}
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}
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stack_context allocate() {
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stack_node *nd = request();
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size_t ss = p_stacksize - sizeof(stack_node);
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auto *p = reinterpret_cast<unsigned char *>(nd) - ss;
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if constexpr(Protected) {
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detail::stack_protect(p, TR::page_size());
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}
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stack_context ret{nd, ss};
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#ifdef OSTD_USE_VALGRIND
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ret.valgrind_id = VALGRIND_STACK_REGISTER(ret.ptr, p);
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#endif
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return ret;
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}
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void deallocate(stack_context &st) noexcept {
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if (!st.ptr) {
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return;
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}
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#ifdef OSTD_USE_VALGRIND
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VALGRIND_STACK_DEREGISTER(st.valgrind_id);
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#endif
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stack_node *nd = static_cast<stack_node *>(st.ptr);
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stack_node *unused = p_unused;
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nd->next = unused;
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p_unused = nd;
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}
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void swap(basic_stack_pool &p) noexcept {
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using std::swap;
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swap(p_chunk, p.p_chunk);
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swap(p_unused, p.p_unused);
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swap(p_chunksize, p.p_chunksize);
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swap(p_stacksize, p.p_stacksize);
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}
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allocator_type get_allocator() noexcept {
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return allocator{*this};
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}
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private:
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struct stack_node {
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void *next_chunk;
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void *next;
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};
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stack_node *request() {
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if (!p_unused) {
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size_t ss = p_stacksize;
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size_t cs = p_chunksize;
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size_t cnum = cs / ss;
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void *chunk = detail::stack_alloc(cs);
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void *prevn = nullptr;
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for (size_t i = cnum; i >= 2; --i) {
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auto *nd = get_node(chunk, ss, i);
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nd->next_chunk = nullptr;
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nd->next = prevn;
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prevn = nd;
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}
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auto *fnd = get_node(chunk, ss, 1);
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fnd->next_chunk = p_chunk;
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p_chunk = chunk;
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fnd->next = prevn;
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p_unused = fnd;
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}
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stack_node *r = p_unused;
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p_unused = static_cast<stack_node *>(r->next);
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return r;
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}
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stack_node *get_node(void *chunk, size_t ssize, size_t n) {
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return reinterpret_cast<stack_node *>(
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static_cast<unsigned char *>(chunk) + (ssize * n) - sizeof(stack_node)
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);
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}
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void *p_chunk = nullptr;
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stack_node *p_unused = nullptr;
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size_t p_chunksize;
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size_t p_stacksize;
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};
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template<typename TR, bool P>
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inline void swap(basic_stack_pool<TR, P> &a, basic_stack_pool<TR, P> &b) noexcept {
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a.swap(b);
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}
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using stack_pool = basic_stack_pool<stack_traits, false>;
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using protected_stack_pool = basic_stack_pool<stack_traits, true>;
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#ifdef OSTD_USE_SEGMENTED_STACKS
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#ifdef OSTD_USE_SEGMENTED_STACKS
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namespace detail {
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namespace detail {
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extern "C" {
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extern "C" {
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