async maps: Create utility library to handle cycle detection

1 files changed, 81 insertions, 0 deletions

diff --git a/src/buildtool/multithreading/async_map_utils.hpp b/src/buildtool/multithreading/async_map_utils.hpp
new file mode 100644
index 00000000..03469b02
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+++ b/src/buildtool/multithreading/async_map_utils.hpp
@@ -0,0 +1,81 @@
+// Copyright 2024 Huawei Cloud Computing Technology Co., Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef INCLUDED_SRC_BUILDTOOL_MULTITHREADING_ASYNC_MAP_UTILS_HPP
+#define INCLUDED_SRC_BUILDTOOL_MULTITHREADING_ASYNC_MAP_UTILS_HPP
+
+#include <functional>
+#include <optional>
+#include <sstream>
+#include <string>
+
+#include "fmt/core.h"
+#include "src/buildtool/logging/log_level.hpp"
+#include "src/buildtool/logging/logger.hpp"
+#include "src/buildtool/multithreading/async_map_consumer.hpp"
+#include "src/utils/cpp/concepts.hpp"
+
+/// \brief Utility to detect and report cycles for an AsyncMap instance.
+/// \param name Human-readable string identifier related to the map or its use.
+/// \param map The AsyncMap instance.
+/// \param key_printer Callable returning key-specific identifier in string
+/// format.
+/// \returns The resulting cycle message as a string, or nullopt if no cycle
+/// detected.
+template <typename K, typename V>
+[[nodiscard]] auto DetectAndReportCycle(
+    std::string const& name,
+    AsyncMapConsumer<K, V> const& map,
+    std::function<std::string(K const&)> key_printer)
+    -> std::optional<std::string> {
+    using namespace std::string_literals;
+    auto cycle = map.DetectCycle();
+    if (cycle) {
+        bool found{false};
+        std::ostringstream oss{};
+        oss << fmt::format("Cycle detected in {}:", name) << std::endl;
+        for (auto const& k : *cycle) {
+            auto match = (k == cycle->back());
+            auto prefix{match   ? found ? "`-- "s : ".-> "s
+                        : found ? "|   "s
+                                : "    "s};
+            oss << prefix << key_printer(k) << std::endl;
+            found = found or match;
+        }
+        return oss.str();
+    }
+    return std::nullopt;
+}
+
+/// \brief Utility to detect and report pending tasks for an AsyncMap instance.
+/// \param name Human-readable string identifier related to the map or its use.
+/// \param map The AsyncMap instance.
+template <HasToString K, typename V>
+void DetectAndReportPending(std::string const& name,
+                            AsyncMapConsumer<K, V> const& map) {
+    using namespace std::string_literals;
+    auto keys = map.GetPendingKeys();
+    if (not keys.empty()) {
+        std::ostringstream oss{};
+        oss << fmt::format("Internal error, failed to evaluate pending {}:",
+                           name)
+            << std::endl;
+        for (auto const& k : keys) {
+            oss << "  " << k.ToString() << std::endl;
+        }
+        Logger::Log(LogLevel::Error, "{}", oss.str());
+    }
+}
+
+#endif  // INCLUDED_SRC_BUILDTOOL_MULTITHREADING_ASYNC_MAP_UTILS_HPP