Move payload generator files to payload_generator/ directory.
This creates a new subdirectory payload_generator/ with all the
payload generator specific files.
The SConstruct file is updated to continue building all the files
together, including those in the subdirectories, since some parts
of the update_engine are using parts of the payload generation code.
To reduce this code coupling, a new payload_constants.h file is
introduced, with few constants used on the payload definition by both
the payload generation and the payload performer.
Finally, includes are updated and in some cases removed when they
weren't used. Order of includes is also fixed to comply with the
style guide.
BUG=chromium:374377
TEST=Build and unittests still pass. delta_generator still present on base directory.
Change-Id: I454bbc7a66c70ebb19fd596c352c7be40a081f3d
Reviewed-on: https://chromium-review.googlesource.com/200325
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>
diff --git a/payload_generator/cycle_breaker.cc b/payload_generator/cycle_breaker.cc
new file mode 100644
index 0000000..10ef6fb
--- /dev/null
+++ b/payload_generator/cycle_breaker.cc
@@ -0,0 +1,199 @@
+// Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "update_engine/payload_generator/cycle_breaker.h"
+
+#include <inttypes.h>
+
+#include <set>
+#include <utility>
+
+#include <base/strings/string_util.h>
+#include <base/strings/stringprintf.h>
+
+#include "update_engine/payload_generator/graph_utils.h"
+#include "update_engine/payload_generator/tarjan.h"
+#include "update_engine/utils.h"
+
+using std::make_pair;
+using std::set;
+using std::vector;
+
+namespace chromeos_update_engine {
+
+// This is the outer function from the original paper.
+void CycleBreaker::BreakCycles(const Graph& graph, set<Edge>* out_cut_edges) {
+ cut_edges_.clear();
+
+ // Make a copy, which we will modify by removing edges. Thus, in each
+ // iteration subgraph_ is the current subgraph or the original with
+ // vertices we desire. This variable was "A_K" in the original paper.
+ subgraph_ = graph;
+
+ // The paper calls for the "adjacency structure (i.e., graph) of
+ // strong (-ly connected) component K with least vertex in subgraph
+ // induced by {s, s + 1, ..., n}".
+ // We arbitrarily order each vertex by its index in the graph. Thus,
+ // each iteration, we are looking at the subgraph {s, s + 1, ..., n}
+ // and looking for the strongly connected component with vertex s.
+
+ TarjanAlgorithm tarjan;
+ skipped_ops_ = 0;
+
+ for (Graph::size_type i = 0; i < subgraph_.size(); i++) {
+ DeltaArchiveManifest_InstallOperation_Type op_type = graph[i].op.type();
+ if (op_type == DeltaArchiveManifest_InstallOperation_Type_REPLACE ||
+ op_type == DeltaArchiveManifest_InstallOperation_Type_REPLACE_BZ) {
+ skipped_ops_++;
+ continue;
+ }
+
+ if (i > 0) {
+ // Erase node (i - 1) from subgraph_. First, erase what it points to
+ subgraph_[i - 1].out_edges.clear();
+ // Now, erase any pointers to node (i - 1)
+ for (Graph::size_type j = i; j < subgraph_.size(); j++) {
+ subgraph_[j].out_edges.erase(i - 1);
+ }
+ }
+
+ // Calculate SCC (strongly connected component) with vertex i.
+ vector<Vertex::Index> component_indexes;
+ tarjan.Execute(i, &subgraph_, &component_indexes);
+
+ // Set subgraph edges for the components in the SCC.
+ for (vector<Vertex::Index>::iterator it = component_indexes.begin();
+ it != component_indexes.end(); ++it) {
+ subgraph_[*it].subgraph_edges.clear();
+ for (vector<Vertex::Index>::iterator jt = component_indexes.begin();
+ jt != component_indexes.end(); ++jt) {
+ // If there's a link from *it -> *jt in the graph,
+ // add a subgraph_ edge
+ if (utils::MapContainsKey(subgraph_[*it].out_edges, *jt))
+ subgraph_[*it].subgraph_edges.insert(*jt);
+ }
+ }
+
+ current_vertex_ = i;
+ blocked_.clear();
+ blocked_.resize(subgraph_.size());
+ blocked_graph_.clear();
+ blocked_graph_.resize(subgraph_.size());
+ Circuit(current_vertex_, 0);
+ }
+
+ out_cut_edges->swap(cut_edges_);
+ LOG(INFO) << "Cycle breaker skipped " << skipped_ops_ << " ops.";
+ DCHECK(stack_.empty());
+}
+
+static const size_t kMaxEdgesToConsider = 2;
+
+void CycleBreaker::HandleCircuit() {
+ stack_.push_back(current_vertex_);
+ CHECK_GE(stack_.size(),
+ static_cast<std::vector<Vertex::Index>::size_type>(2));
+ Edge min_edge = make_pair(stack_[0], stack_[1]);
+ uint64_t min_edge_weight = kuint64max;
+ size_t edges_considered = 0;
+ for (vector<Vertex::Index>::const_iterator it = stack_.begin();
+ it != (stack_.end() - 1); ++it) {
+ Edge edge = make_pair(*it, *(it + 1));
+ if (cut_edges_.find(edge) != cut_edges_.end()) {
+ stack_.pop_back();
+ return;
+ }
+ uint64_t edge_weight = graph_utils::EdgeWeight(subgraph_, edge);
+ if (edge_weight < min_edge_weight) {
+ min_edge_weight = edge_weight;
+ min_edge = edge;
+ }
+ edges_considered++;
+ if (edges_considered == kMaxEdgesToConsider)
+ break;
+ }
+ cut_edges_.insert(min_edge);
+ stack_.pop_back();
+}
+
+void CycleBreaker::Unblock(Vertex::Index u) {
+ blocked_[u] = false;
+
+ for (Vertex::EdgeMap::iterator it = blocked_graph_[u].out_edges.begin();
+ it != blocked_graph_[u].out_edges.end(); ) {
+ Vertex::Index w = it->first;
+ blocked_graph_[u].out_edges.erase(it++);
+ if (blocked_[w])
+ Unblock(w);
+ }
+}
+
+bool CycleBreaker::StackContainsCutEdge() const {
+ for (std::vector<Vertex::Index>::const_iterator it = ++stack_.begin(),
+ e = stack_.end(); it != e; ++it) {
+ Edge edge = make_pair(*(it - 1), *it);
+ if (utils::SetContainsKey(cut_edges_, edge)) {
+ return true;
+ }
+ }
+ return false;
+}
+
+bool CycleBreaker::Circuit(Vertex::Index vertex, Vertex::Index depth) {
+ // "vertex" was "v" in the original paper.
+ bool found = false; // Was "f" in the original paper.
+ stack_.push_back(vertex);
+ blocked_[vertex] = true;
+ {
+ static int counter = 0;
+ counter++;
+ if (counter == 10000) {
+ counter = 0;
+ std::string stack_str;
+ for (vector<Vertex::Index>::const_iterator it = stack_.begin();
+ it != stack_.end(); ++it) {
+ stack_str += base::StringPrintf("%lu -> ",
+ static_cast<long unsigned int>(*it));
+ }
+ LOG(INFO) << "stack: " << stack_str;
+ }
+ }
+
+ for (Vertex::SubgraphEdgeMap::iterator w =
+ subgraph_[vertex].subgraph_edges.begin();
+ w != subgraph_[vertex].subgraph_edges.end(); ++w) {
+ if (*w == current_vertex_) {
+ // The original paper called for printing stack_ followed by
+ // current_vertex_ here, which is a cycle. Instead, we call
+ // HandleCircuit() to break it.
+ HandleCircuit();
+ found = true;
+ } else if (!blocked_[*w]) {
+ if (Circuit(*w, depth + 1)) {
+ found = true;
+ if ((depth > kMaxEdgesToConsider) || StackContainsCutEdge())
+ break;
+ }
+ }
+ }
+
+ if (found) {
+ Unblock(vertex);
+ } else {
+ for (Vertex::SubgraphEdgeMap::iterator w =
+ subgraph_[vertex].subgraph_edges.begin();
+ w != subgraph_[vertex].subgraph_edges.end(); ++w) {
+ if (blocked_graph_[*w].out_edges.find(vertex) ==
+ blocked_graph_[*w].out_edges.end()) {
+ blocked_graph_[*w].out_edges.insert(make_pair(vertex,
+ EdgeProperties()));
+ }
+ }
+ }
+ CHECK_EQ(vertex, stack_.back());
+ stack_.pop_back();
+ return found;
+}
+
+} // namespace chromeos_update_engine