Function foreachpair

src/slave/containerizer/fetcher.cpp:496–515

      hashmap<CommandInfo::URI, Option<shared_ptr<Cache::Entry>>> result;

      foreachpair (const CommandInfo::URI& uri,
                   const Option<Future<shared_ptr<Cache::Entry>>>& entry,
                   entries) {
        if (entry.isSome()) {
          if (entry->isReady()) {
            result[uri] = entry->get();
          } else {
            LOG(WARNING)
              << "Reverting to fetching directly into the sandbox for '"
              << uri.value()
              << "', due to failure to fetch through the cache, "
              << "with error: " << entry->failure();

            result[uri] = None();
          }
        } else {
          // No entry means bypassing the cache.
          result[uri] = None();
        }
      }

      // NOTE: While we could inline '__fetch' we've explicitly kept
      // it as a separate function to minimize complexity. Like with