Adds Cache Groups concepts to Cripts

doc/developer-guide/cripts/cripts-misc.en.rst

@@ -414,3 +414,63 @@ Debug logging uses the same format string syntax as ``fmt::format()`` in ``libfm
     debug tags in your ATS configuration to enable debug output for your Cripts.
     The default debug tag for Cripts is the name of the Cript itself, either
     the Cript source file, or the compiled plugin name.
+
+Cache Groups
+============
+
+As a way to manage association between cache entries, Cripts provides an infrastructure
+for cache groups. A cache group is a set of cache entries that are logically
+associated with each other via custom identifiers.
+
+Example implementation of the Cache Groups RFC
+
+.. code-block:: cpp
+
+   do_create_instance()
+   {
+     // Create a cache-group for this site / remap rule(s). They can be shared.
+     instance.data[0] = cripts::Cache::Group::Manager::Factory("example_site");
+   }
+
+   do_delete_instance()
+   {
+     void *ptr = AsPointer(instance.data[0]);
+
+     if (ptr) {
+       delete static_cast<std::shared_ptr<cripts::Cache::Group> *>(ptr);
+       instance.data[0] = nullptr;
+     }
+   }
+
+   do_cache_lookup()
+   {
+     if (cached.response.lookupstatus != cripts::LookupStatus::MISS) {
+       void *ptr = AsPointer(instance.data[0]);
+
+       if (ptr) {
+         auto date = cached.response.AsDate("Date");
+         if (date != 0) {
+           auto cache_groups = cached.response["Cache-Groups"];
+           if (!cache_groups.empty()) {
+             borrow cg = *static_cast<std::shared_ptr<cripts::Cache::Group> *>(ptr);
+             if (cg->Lookup(cache_groups.split(','), date)) {
+               cached.response.lookupstatus = cripts::LookupStatus::HIT_STALE;
+             }
+           }
+         }
+       }
+     }
+   }
+
+   do_read_response()
+   {
+     void *ptr = AsPointer(instance.data[0]);
+
+     if (ptr) {
+       auto invalidation = client.request["Cache-Group-Invalidation"];
+       if (!invalidation.empty()) {
+         borrow cg = *static_cast<std::shared_ptr<cripts::Cache::Group> *>(ptr);
+         cg->Insert(invalidation.split(','));
+       }
+     }
+   }

example/cripts/cache_groups.cc

@@ -0,0 +1,106 @@
+/*
+  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.
+*/
+
+#define CRIPTS_CONVENIENCE_APIS 1
+
+#include <cripts/CacheGroup.hpp>
+#include <cripts/Preamble.hpp>
+
+do_create_instance()
+{
+  // Create a cache-group for this site / remap rule(s). They can be shared.
+  instance.data[0] = cripts::Cache::Group::Manager::Factory("example");
+}
+
+do_delete_instance()
+{
+  void *ptr = AsPointer(instance.data[0]);
+
+  if (ptr) {
+    delete static_cast<std::shared_ptr<cripts::Cache::Group> *>(ptr);
+    instance.data[0] = nullptr;
+  }
+}
+
+do_cache_lookup()
+{
+  if (cached.response.lookupstatus != cripts::LookupStatus::MISS) {
+    void *ptr = AsPointer(instance.data[0]);
+
+    if (ptr) {
+      auto date = cached.response.AsDate("Date");
+
+      if (date != 0) {
+        auto cache_groups = cached.response["Cache-Groups"];
+
+        CDebug("Looking up {}", cache_groups);
+        if (!cache_groups.empty()) {
+          borrow cg = *static_cast<std::shared_ptr<cripts::Cache::Group> *>(ptr);
+
+          if (cg->Lookup(cache_groups.split(','), date)) {
+            CDebug("Cache Group hit, forcing revalidation for request");
+            cached.response.lookupstatus = cripts::LookupStatus::HIT_STALE;
+          }
+        }
+      }
+    }
+  }
+}
+
+do_read_response()
+{
+  void *ptr = AsPointer(instance.data[0]);
+
+  if (ptr) {
+    auto invalidation = client.request["Cache-Group-Invalidation"];
+
+    if (!invalidation.empty()) {
+      borrow cg = *static_cast<std::shared_ptr<cripts::Cache::Group> *>(ptr);
+
+      cg->Insert(invalidation.split(','));
+    }
+  }
+
+// This is just for simulating origin responses that would include cache-groups.
+#if 0
+  server.response["Cache-Groups"] = "\"foo\", \"bar\"";
+#endif
+}
+
+// The RFC draft does not support / provide definitions for this. It is useful,
+// but should be protected with appropriate ACLs / authentication.
+#if 0
+do_remap()
+{
+  void *ptr = AsPointer(instance.data[0]);
+
+  if (ptr && urls.pristine.path == ".well-known/Cache-Groups") {
+    auto invalidation = client.request["Cache-Group-Invalidation"];
+
+    if (!invalidation.empty()) {
+      borrow cg = *static_cast<std::shared_ptr<cripts::Cache::Group> *>(ptr);
+
+      cg->Insert(invalidation.split(','));
+      CDebug("Forcing a cache miss for cache-groups: {}", invalidation);
+      StatusCode(202);
+    }
+  }
+}
+#endif
+
+#include <cripts/Epilogue.hpp>

include/cripts/CacheGroup.hpp

@@ -0,0 +1,215 @@
+/*
+  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 <string>
+#include <vector>
+#include <chrono>
+#include <mutex>
+#include <shared_mutex>
+#include <fstream>
+#include <memory>
+#include <cstdint>
+
+#include "cripts/Context.hpp"
+#include "cripts/Time.hpp"
+
+// Implemented in the .cc file
+int _cripts_cache_group_sync(TSCont cont, TSEvent event, void *edata);
+
+namespace cripts::Cache
+{
+
+class Group
+{
+private:
+  using self_type = Group;
+
+  struct _Entry {
+    cripts::Time::Point timestamp; // Timestamp of when the entry was created
+    size_t              length;    // Length of the group ID
+    uint32_t            prefix;    // First 4 characters of the group ID
+    uint64_t            hash;      // Hash value of the group ID, needed when writing to disk
+  };
+
+  // Header structure for on-disk map files (after VERSION field)
+  struct _MapHeader {
+    time_t created_ts;
+    time_t last_write_ts;
+    time_t last_sync_ts;
+    size_t count;
+  };
+
+  using _MapType = std::unordered_map<uint64_t, _Entry>;
+
+  struct _MapSlot {
+    std::unique_ptr<_MapType> map;
+    std::string               path;
+    cripts::Time::Point       created;
+    cripts::Time::Point       last_write;
+    cripts::Time::Point       last_sync;
+  };
+
+public:
+  static constexpr uint64_t VERSION = (static_cast<uint64_t>('C') << 56) | (static_cast<uint64_t>('G') << 48) |
+                                      (static_cast<uint64_t>('M') << 40) | (static_cast<uint64_t>('A') << 32) |
+                                      (static_cast<uint64_t>('P') << 24) | (static_cast<uint64_t>('S') << 16) |
+                                      (static_cast<uint64_t>('0') << 8) | 0x00; // Change this on version bump
+
+  static constexpr std::chrono::seconds DEFAULT_MAX_AGE{63072000}; // 2 Years, max cache lifetime in ATS as well
+
+  Group(const std::string &name, const std::string &base_dir, size_t max_entries = 1024, size_t num_maps = 3)
+  {
+    Initialize(name, base_dir, num_maps, max_entries, DEFAULT_MAX_AGE);
+  }
+
+  // Not used at the moment.
+  Group() = default;
+
+  ~Group() { WriteToDisk(); }
+
+  Group(const self_type &)                = delete;
+  self_type &operator=(const self_type &) = delete;
+
+  void Initialize(const std::string &name, const std::string &base_dir, size_t num_maps = 3, size_t max_entries = 1024,
+                  std::chrono::seconds max_age = DEFAULT_MAX_AGE);
+
+  void
+  SetMaxEntries(size_t max_entries)
+  {
+    std::unique_lock lock(_mutex);
+    _max_entries = max_entries;
+  }
+
+  void
+  SetMaxAge(std::chrono::seconds max_age)
+  {
+    std::unique_lock lock(_mutex);
+    _max_age = max_age;
+  }
+
+  void Insert(cripts::string_view key);
+  void Insert(const std::vector<cripts::string_view> &keys);
+  bool Lookup(cripts::string_view key, cripts::Time::Point age) const;
+  bool Lookup(const std::vector<cripts::string_view> &keys, cripts::Time::Point age) const;
+
+  bool
+  Lookup(cripts::string_view key, time_t age) const
+  {
+    return Lookup(key, cripts::Time::Clock::from_time_t(age));
+  }
+
+  bool
+  Lookup(const std::vector<cripts::string_view> &keys, time_t age) const
+  {
+    return Lookup(keys, cripts::Time::Clock::from_time_t(age));
+  }
+
+  cripts::Time::Point
+  LastSync() const
+  {
+    std::shared_lock lock(_mutex);
+    return _last_sync;
+  }
+
+  void WriteToDisk();
+  void LoadFromDisk();
+
+private:
+  mutable std::shared_mutex _mutex;
+  std::string               _name        = "CacheGroup";
+  size_t                    _num_maps    = 3;
+  size_t                    _max_entries = 1024;
+  std::chrono::seconds      _max_age     = DEFAULT_MAX_AGE;
+  size_t                    _map_index   = 0;
+  cripts::Time::Point       _last_sync   = cripts::Time::Point{};
+
+  std::vector<_MapSlot> _slots;
+  std::ofstream         _txn_log;
+  std::string           _log_path;
+  std::string           _base_dir;
+
+  void appendLog(const _Entry &entry);
+  void clearLog();
+  void syncMap(size_t index);
+
+public:
+  class Manager
+  {
+    friend int ::_cripts_cache_group_sync(TSCont cont, TSEvent event, void *edata);
+    using self_type = Manager;
+
+  public:
+    static void *Factory(const std::string &name, size_t max_entries = 1024, size_t num_maps = 3);
+
+    Manager(const self_type &)              = delete;
+    self_type &operator=(const self_type &) = delete;
+
+  protected:
+    void _scheduleCont();
+
+    std::unordered_map<std::string, std::weak_ptr<Group>> _groups;
+    std::mutex                                            _mutex;
+
+  private:
+    Manager()
+    {
+      _base_dir = TSRuntimeDirGet();
+
+      if (std::filesystem::exists(_base_dir)) {
+        _base_dir += "/cache_groups";
+        if (!std::filesystem::exists(_base_dir)) {
+          std::error_code ec;
+
+          std::filesystem::create_directories(_base_dir, ec);
+          if (ec) {
+            TSError("cripts::Cache::Group::Manager: Failed to create directory `%s': %s", _base_dir.c_str(), ec.message().c_str());
+          } else {
+            std::filesystem::permissions(_base_dir, std::filesystem::perms::group_write, std::filesystem::perm_options::add, ec);
+
+            if (ec) {
+              TSWarning("cripts::Cache::Group::Manager: Failed to set permissions on `%s': %s", _base_dir.c_str(),
+                        ec.message().c_str());
+            }
+          }
+        }
+      }
+      _scheduleCont(); // Kick it off
+    }
+
+    ~Manager()
+    {
+      if (_action) {
+        TSActionCancel(_action);
+        _action = nullptr;
+      }
+      if (_cont) {
+        TSContDestroy(_cont);
+        _cont = nullptr;
+      }
+    }
+
+    static self_type &_instance();
+
+    TSCont      _cont   = nullptr;
+    TSAction    _action = nullptr;
+    std::string _base_dir;
+  };
+};
+} // namespace cripts::Cache

src/cripts/CMakeLists.txt

@@ -28,6 +28,7 @@ list(REMOVE_ITEM CPP_FILES ${TEST_CPP_FILES})
 
 set(CRIPTS_PUBLIC_HEADERS
     ${PROJECT_SOURCE_DIR}/include/cripts/Bundle.hpp
+    ${PROJECT_SOURCE_DIR}/include/cripts/CacheGroup.hpp
     ${PROJECT_SOURCE_DIR}/include/cripts/Certs.hpp
     ${PROJECT_SOURCE_DIR}/include/cripts/Configs.hpp
     ${PROJECT_SOURCE_DIR}/include/cripts/ConfigsBase.hpp