// parse the heap to find valid objects and initialize metadata, then
// add edges for every known root pointer and every known obj->obj ptr.
HeapGraph makeHeapGraph(bool include_free) {
HeapGraph g;
PtrMap blocks;
// parse the heap once to create a PtrMap for pointer filtering. Create
// one node for every parsed block, including NativeData and AsyncFuncFrame
// blocks. Only include free blocks if requested.
MM().forEachHeader([&](Header* h, size_t alloc_size) {
if (h->kind() != HeaderKind::Free || include_free) {
blocks.insert(h, alloc_size); // adds interval [h, h+alloc_size[
}
});
blocks.prepare();
// initialize nodes by iterating over PtrMap's regions
g.nodes.reserve(blocks.size());
blocks.iterate([&](const Header* h, size_t size) {
type_scan::Index ty;
switch (h->kind()) {
case HeaderKind::NativeData:
ty = h->native_.typeIndex();
break;
case HeaderKind::Resource:
ty = h->res_.typeIndex();
break;
case HeaderKind::SmallMalloc:
case HeaderKind::BigMalloc:
ty = h->malloc_.typeIndex();
break;
default:
ty = type_scan::kIndexUnknown;
break;
}
g.nodes.push_back(
HeapGraph::Node{h, size, false, ty, -1, -1}
);
});
// find root nodes
type_scan::Scanner scanner;
iterateRoots([&](const void* h, size_t size, type_scan::Index tyindex) {
// it's important that we actually scan each root node before
// returning, since at least one will be the C++ stack, and some
// nodes will only exist for the duration of the call to this lambda,
// for example EphemeralPtrWrapper<T>.
addRootNode(g, blocks, scanner, h, size, tyindex);
});
// find heap->heap pointers
for (size_t i = 0, n = g.nodes.size(); i < n; i++) {
if (g.nodes[i].is_root) continue;
auto h = g.nodes[i].h;
scanHeader(h, scanner);
auto from = blocks.index(h);
assert(from == i);
scanner.finish(
[&](const void* p) {
// definitely a ptr, but maybe interior, and maybe not counted
if (auto r = blocks.region(p)) {
addPtr(g, from, blocks.index(r), HeapGraph::Implicit, UnknownOffset);
}
},
[&](const void* p, std::size_t size) {
conservativeScan(p, size, [&](const void** addr, const void* ptr) {
if (auto r = blocks.region(ptr)) {
auto to = blocks.index(r);
auto offset = uintptr_t(addr) - uintptr_t(h);
addPtr(g, from, to, HeapGraph::Ambiguous, offset);
}
});
},
[&](const void** addr) {
if (auto r = blocks.region(*addr)) {
auto to = blocks.index(r);
auto offset = uintptr_t(addr) - uintptr_t(h);
addPtr(g, from, to, HeapGraph::Counted, offset);
}
}
);
}
g.nodes.shrink_to_fit();
g.ptrs.shrink_to_fit();
g.root_ptrs.shrink_to_fit();
g.root_nodes.shrink_to_fit();
return g;
}
