Fold leaks that are referenced by other leaks
Find leaks that have no references at all, or are only referenced by
other leaks in the same strongly connected component, and hide all
referenced leaks.
Bug: 27208635
Change-Id: Ifbfd14e24e2ba0f8af7c1b887e57f34362720f2d
(cherry picked from commit 8e8f34c5580d3b0b466d35f98bb12175e5dcf30a)
diff --git a/libmemunreachable/Tarjan.h b/libmemunreachable/Tarjan.h
new file mode 100644
index 0000000..d7ecdb9
--- /dev/null
+++ b/libmemunreachable/Tarjan.h
@@ -0,0 +1,131 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed 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.
+ */
+
+// Based on system/update_engine/payload_generator/tarjan.cc
+
+#ifndef LIBMEMUNREACHABLE_TARJAN_H_
+#define LIBMEMUNREACHABLE_TARJAN_H_
+
+#include <algorithm>
+
+#include "Allocator.h"
+
+template<class T>
+class Node {
+ public:
+ allocator::set<Node<T>*> references_in;
+ allocator::set<Node<T>*> references_out;
+ size_t index;
+ size_t lowlink;
+
+ T* ptr;
+
+ Node(T* ptr, Allocator<Node> allocator) : references_in(allocator), references_out(allocator),
+ ptr(ptr) {};
+ Node(Node&& rhs) = default;
+ void Edge(Node<T>* ref) {
+ references_out.emplace(ref);
+ ref->references_in.emplace(this);
+ }
+ template<class F>
+ void Foreach(F&& f) {
+ for (auto& node: references_out) {
+ f(node->ptr);
+ }
+ }
+ private:
+ DISALLOW_COPY_AND_ASSIGN(Node<T>);
+};
+
+template<class T>
+using Graph = allocator::vector<Node<T>*>;
+
+template<class T>
+using SCC = allocator::vector<Node<T>*>;
+
+template<class T>
+using SCCList = allocator::vector<SCC<T>>;
+
+template<class T>
+class TarjanAlgorithm {
+ public:
+ TarjanAlgorithm(Allocator<void> allocator) : index_(0),
+ stack_(allocator), components_(allocator) {}
+
+ void Execute(Graph<T>& graph, SCCList<T>& out);
+ private:
+ static constexpr size_t UNDEFINED_INDEX = static_cast<size_t>(-1);
+ void Tarjan(Node<T>* vertex, Graph<T>& graph);
+
+ size_t index_;
+ allocator::vector<Node<T>*> stack_;
+ SCCList<T> components_;
+};
+
+template<class T>
+void TarjanAlgorithm<T>::Execute(Graph<T>& graph, SCCList<T>& out) {
+ stack_.clear();
+ components_.clear();
+ index_ = 0;
+ for (auto& it: graph) {
+ it->index = UNDEFINED_INDEX;
+ it->lowlink = UNDEFINED_INDEX;
+ }
+
+ for (auto& it: graph) {
+ if (it->index == UNDEFINED_INDEX) {
+ Tarjan(it, graph);
+ }
+ }
+ out.swap(components_);
+}
+
+template<class T>
+void TarjanAlgorithm<T>::Tarjan(Node<T>* vertex, Graph<T>& graph) {
+ assert(vertex->index == UNDEFINED_INDEX);
+ vertex->index = index_;
+ vertex->lowlink = index_;
+ index_++;
+ stack_.push_back(vertex);
+ for (auto& it: vertex->references_out) {
+ Node<T>* vertex_next = it;
+ if (vertex_next->index == UNDEFINED_INDEX) {
+ Tarjan(vertex_next, graph);
+ vertex->lowlink = std::min(vertex->lowlink, vertex_next->lowlink);
+ } else if (std::find(stack_.begin(), stack_.end(), vertex_next) != stack_.end()) {
+ vertex->lowlink = std::min(vertex->lowlink, vertex_next->index);
+ }
+ }
+ if (vertex->lowlink == vertex->index) {
+ SCC<T> component{components_.get_allocator()};
+ Node<T>* other_vertex;
+ do {
+ other_vertex = stack_.back();
+ stack_.pop_back();
+ component.push_back(other_vertex);
+ } while (other_vertex != vertex && !stack_.empty());
+
+ components_.emplace_back(component);
+ }
+}
+
+template<class T>
+void Tarjan(Graph<T>& graph, SCCList<T>& out) {
+ TarjanAlgorithm<T> tarjan{graph.get_allocator()};
+ tarjan.Execute(graph, out);
+}
+
+#endif // LIBMEMUNREACHABLE_TARJAN_H_