add limit to number of iternations

Summary:
We identifly cases that this while can be infinite
This cahnge both stops early and add inticative message

Differential Revision: D64535095

fbshipit-source-id: ffd1139991a1a1c92e80faf9180d79555765d223

Author: Boaz Cahlon

litho-flexlayout/src/main/cpp/flexlayout/FlexLine.cpp

@@ -5,6 +5,7 @@
 #include <algorithm>
 #include <functional>
 #include <numeric>
+#include <stdexcept>
 
 namespace facebook {
 namespace flexlayout {
@@ -38,6 +39,8 @@ struct Item {
 };
 } // namespace
 
+static constexpr auto kMaxIterations = 10000;
+
 static auto calculateRemainingFreeSpace(
     const std::vector<Item>& items,
     const FlexDirection mainAxis,
@@ -151,7 +154,12 @@ auto FlexLine::resolveFlexibleLengths(
   // 4. Loop:
   // a. Check for flexible items. If all the flex items on the line are
   // frozen, free space has been distributed; exit this loop.
+  auto numIterations = 0;
   while (any_of(items, [](const Item& item) { return !item.isFrozen; })) {
+    ++numIterations;
+    if (numIterations > kMaxIterations) {
+      throw std::logic_error("Too many iterations: exceeded 10000 iterations");
+    }
     // Calculate the remaining free space as for initial free space, above.
     auto remainingFreeSpace = calculateRemainingFreeSpace(
         items,