[GitHub] [arrow] ggershinsky commented on a change in pull request #8023: ARROW-9318: [C++] Parquet encryption key management

[GitBox <gi...@apache.org>]

ggershinsky commented on a change in pull request #8023:
URL: https://github.com/apache/arrow/pull/8023#discussion_r497990092



##########
File path: cpp/src/parquet/encryption/two_level_cache_with_expiration.h
##########
@@ -0,0 +1,167 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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.
+
+#pragma once
+
+#include <unordered_map>
+
+#include "arrow/util/concurrent_map.h"
+#include "arrow/util/mutex.h"
+
+#include "parquet/encryption/key_toolkit_internal.h"
+
+using arrow::util::ConcurrentMap;
+
+namespace parquet {
+namespace encryption {
+
+namespace internal {
+
+// in miliseconds
+using TimePoint = std::chrono::system_clock::time_point;
+
+static inline TimePoint CurrentTimePoint() { return std::chrono::system_clock::now(); }
+
+template <typename E>
+class ExpiringCacheEntry {
+ public:
+  ExpiringCacheEntry() = default;
+
+  ExpiringCacheEntry(const E& cached_item, uint64_t expiration_interval_millis)
+      : cached_item_(cached_item) {
+    expiration_timestamp_ =
+        CurrentTimePoint() + std::chrono::milliseconds(expiration_interval_millis);
+  }
+
+  bool IsExpired() {
+    auto now = CurrentTimePoint();
+    return (now > expiration_timestamp_);
+  }
+
+  E cached_item() { return cached_item_; }
+
+ private:
+  TimePoint expiration_timestamp_;
+  E cached_item_;
+};
+
+// This class is to avoid the below warning when compiling KeyToolkit class with VS2015
+// warning C4503: decorated name length exceeded, name was truncated
+template <typename V>
+class ExpiringCacheMapEntry {
+ public:
+  ExpiringCacheMapEntry() = default;
+
+  explicit ExpiringCacheMapEntry(std::shared_ptr<ConcurrentMap<V>> cached_item,
+                                 uint64_t expiration_interval_millis)
+      : map_cache_(cached_item, expiration_interval_millis) {}
+
+  bool IsExpired() { return map_cache_.IsExpired(); }
+
+  std::shared_ptr<ConcurrentMap<V>> cached_item() { return map_cache_.cached_item(); }
+
+ private:
+  ExpiringCacheEntry<std::shared_ptr<ConcurrentMap<V>>> map_cache_;
+};
+
+}  // namespace internal
+
+// Two-level cache with expiration of internal caches according to token lifetime.
+// External cache is per token, internal is per string key.
+// Wrapper class around:
+//    std::unordered_map<std::string,
+//    internal::ExpiringCacheEntry<std::unordered_map<std::string, V>>>
+// This cache is safe to be shared between threads.
+template <typename V>
+class TwoLevelCacheWithExpiration {
+ public:
+  TwoLevelCacheWithExpiration() {
+    last_cache_cleanup_timestamp_ = internal::CurrentTimePoint();
+  }
+
+  std::shared_ptr<ConcurrentMap<V>> GetOrCreateInternalCache(
+      const std::string& access_token, uint64_t cache_entry_lifetime_ms) {

Review comment:
       The public API uses seconds, so it should be ok to use seconds in the internal functions.




----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

For queries about this service, please contact Infrastructure at:
users@infra.apache.org