1 files changed, 143 insertions, 0 deletions
diff --git a/libmemunreachable/LeakFolding.cpp b/libmemunreachable/LeakFolding.cpp
new file mode 100644
index 000000000..0b4e7ddc6
--- /dev/null
+++ b/libmemunreachable/LeakFolding.cpp
@@ -0,0 +1,143 @@
+/*
+ * 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.
+ */
+
+#include <inttypes.h>
+
+#include "Allocator.h"
+#include "HeapWalker.h"
+#include "LeakFolding.h"
+#include "Tarjan.h"
+#include "log.h"
+
+// Converts possibly cyclic graph of leaks to a DAG by combining
+// strongly-connected components into a object, stored in the scc pointer
+// of each node in the component.
+void LeakFolding::ComputeDAG() {
+  SCCList<LeakInfo> scc_list{allocator_};
+  Tarjan(leak_graph_, scc_list);
+
+  Allocator<SCCInfo> scc_allocator = allocator_;
+
+  for (auto& scc_nodes: scc_list) {
+    Allocator<SCCInfo>::unique_ptr leak_scc;
+    leak_scc = scc_allocator.make_unique(scc_allocator);
+
+    for (auto& node: scc_nodes) {
+      node->ptr->scc = leak_scc.get();
+      leak_scc->count++;
+      leak_scc->size += node->ptr->range.size();
+    }
+
+    leak_scc_.emplace_back(std::move(leak_scc));
+  }
+
+  for (auto& it : leak_map_) {
+    LeakInfo& leak = it.second;
+    for (auto& ref: leak.node.references_out) {
+      if (leak.scc != ref->ptr->scc) {
+        leak.scc->node.Edge(&ref->ptr->scc->node);
+      }
+    }
+  }
+}
+
+void LeakFolding::AccumulateLeaks(SCCInfo* dominator) {
+  std::function<void(SCCInfo*)> walk(std::allocator_arg, allocator_,
+      [&](SCCInfo* scc) {
+        if (scc->accumulator != dominator) {
+          scc->accumulator = dominator;
+          dominator->cuumulative_size += scc->size;
+          dominator->cuumulative_count += scc->count;
+          scc->node.Foreach([&](SCCInfo* ref) {
+            walk(ref);
+          });
+        }
+      });
+  walk(dominator);
+}
+
+bool LeakFolding::FoldLeaks() {
+  Allocator<LeakInfo> leak_allocator = allocator_;
+
+  // Find all leaked allocations insert them into leak_map_ and leak_graph_
+  heap_walker_.ForEachAllocation(
+      [&](const Range& range, HeapWalker::AllocationInfo& allocation) {
+        if (!allocation.referenced_from_root) {
+          auto it = leak_map_.emplace(std::piecewise_construct,
+              std::forward_as_tuple(range),
+              std::forward_as_tuple(range, allocator_));
+          LeakInfo& leak = it.first->second;
+          leak_graph_.push_back(&leak.node);
+        }
+      });
+
+  // Find references between leaked allocations and connect them in leak_graph_
+  for (auto& it : leak_map_) {
+    LeakInfo& leak = it.second;
+    heap_walker_.ForEachPtrInRange(leak.range,
+        [&](Range& ptr_range, HeapWalker::AllocationInfo* ptr_info) {
+          if (!ptr_info->referenced_from_root) {
+            LeakInfo* ptr_leak = &leak_map_.at(ptr_range);
+            leak.node.Edge(&ptr_leak->node);
+          }
+        });
+  }
+
+  // Convert the cyclic graph to a DAG by grouping strongly connected components
+  ComputeDAG();
+
+  // Compute dominators and cuumulative sizes
+  for (auto& scc : leak_scc_) {
+    if (scc->node.references_in.size() == 0) {
+      scc->dominator = true;
+      AccumulateLeaks(scc.get());
+    }
+  }
+
+  return true;
+}
+
+bool LeakFolding::Leaked(allocator::vector<LeakFolding::Leak>& leaked,
+    size_t limit, size_t* num_leaks_out, size_t* leak_bytes_out) {
+  size_t num_leaks = 0;
+  size_t leak_bytes = 0;
+  for (auto& it : leak_map_) {
+    const LeakInfo& leak = it.second;
+    num_leaks++;
+    leak_bytes += leak.range.size();
+  }
+
+  size_t n = 0;
+  for (auto& it : leak_map_) {
+    const LeakInfo& leak = it.second;
+    if (leak.scc->dominator) {
+      if (n++ < limit) {
+        leaked.emplace_back(Leak{leak.range,
+          leak.scc->cuumulative_count - 1,
+          leak.scc->cuumulative_size - leak.range.size()});
+      }
+    }
+  }
+
+  if (num_leaks_out) {
+    *num_leaks_out = num_leaks;
+  }
+  if (leak_bytes_out) {
+    *leak_bytes_out = leak_bytes;
+  }
+
+  return true;
+}