1 files changed, 129 insertions, 0 deletions
diff --git a/perfprofd/map_utils.h b/perfprofd/map_utils.h
new file mode 100644
index 00000000..2e3d97d9
--- /dev/null
+++ b/perfprofd/map_utils.h
@@ -0,0 +1,129 @@
+#ifndef SYSTEM_EXTRAS_PERFPROFD_MAP_UTILS_H_
+#define SYSTEM_EXTRAS_PERFPROFD_MAP_UTILS_H_
+
+#include <map>
+#include <set>
+
+#include <android-base/logging.h>
+
+namespace android {
+namespace perfprofd {
+
+template <typename T, typename U>
+decltype(static_cast<T*>(nullptr)->begin()) GetLeqIterator(T& map, U key) {
+  if (map.empty()) {
+    return map.end();
+  }
+  auto it = map.upper_bound(key);
+  if (it == map.begin()) {
+    return map.end();
+  }
+  --it;
+  return it;
+}
+
+template <typename SymType, typename ValType>
+class RangeMap {
+ public:
+  struct AggregatedSymbol {
+    SymType symbol;
+    std::set<ValType> offsets;
+    AggregatedSymbol(const SymType& sym, const ValType& offset) : symbol(sym) {
+      offsets.insert(offset);
+    }
+  };
+
+ public:
+  void Insert(const SymType& sym, const ValType& val) {
+    auto aggr_it = GetLeqIterator(map_, val);
+    if (aggr_it == map_.end()) {
+      // Maybe we need to extend the first one.
+      if (!map_.empty()) {
+        AggregatedSymbol& first = map_.begin()->second;
+        CHECK_LT(val, map_.begin()->first);
+        if (first.symbol == sym) {
+          ExtendLeft(map_.begin(), val);
+          return;
+        }
+      }
+      // Nope, new entry needed.
+      map_.emplace(val, AggregatedSymbol(sym, val));
+      return;
+    }
+
+    AggregatedSymbol& maybe_match = aggr_it->second;
+
+    if (maybe_match.symbol == sym) {
+      // Same symbol, just insert. This is true for overlap as well as extension.
+      maybe_match.offsets.insert(val);
+      return;
+    }
+
+    // Is there overlap?
+    if (*maybe_match.offsets.rbegin() < val) {
+      // No. See if it can be merged with the next one.
+      ++aggr_it;
+      if (aggr_it != map_.end() && aggr_it->second.symbol == sym) {
+        ExtendLeft(aggr_it, val);
+        return;
+      }
+
+      // Just add a new symbol entry.
+      map_.emplace(val, AggregatedSymbol(sym, val));
+      return;
+    }
+
+    // OK, we have an overlapping non-symbol-equal AggregatedSymbol. Need to break
+    // things up.
+    AggregatedSymbol left(maybe_match.symbol, *maybe_match.offsets.begin());
+    auto offset_it = maybe_match.offsets.begin();
+    for (; *offset_it < val; ++offset_it) {
+      left.offsets.insert(*offset_it);
+    }
+
+    if (*offset_it == val) {
+      // This should not happen.
+      LOG(ERROR) << "Unexpected overlap!";
+      return;
+    }
+
+    AggregatedSymbol right(maybe_match.symbol, *offset_it);
+    for (; offset_it != maybe_match.offsets.end(); ++offset_it) {
+      right.offsets.insert(*offset_it);
+    }
+
+    map_.erase(aggr_it);
+    map_.emplace(*left.offsets.begin(), std::move(left));
+    map_.emplace(val, AggregatedSymbol(sym, val));
+    map_.emplace(*right.offsets.begin(), std::move(right));
+  }
+
+  using RangeMapType = std::map<ValType, AggregatedSymbol>;
+
+  typename RangeMapType::const_iterator begin() const {
+    return map_.begin();
+  }
+  typename RangeMapType::const_iterator end() const {
+    return map_.end();
+  }
+
+  bool empty() const {
+    return map_.empty();
+  }
+
+ private:
+  void ExtendLeft(typename RangeMapType::iterator it, const ValType& val) {
+    CHECK(val < *it->second.offsets.begin());
+    AggregatedSymbol copy = std::move(it->second);
+    map_.erase(it);
+    copy.offsets.insert(val);
+    map_.emplace(val, std::move(copy));
+  }
+
+  RangeMapType map_;
+};
+
+}  // namespace perfprofd
+}  // namespace android
+
+#endif  // SYSTEM_EXTRAS_PERFPROFD_MAP_UTILS_H_