Add CacheInsertPolicyInterface and AlwaysInsertNeverPrunePolicy

Signed-off-by: methylDragon <[email protected]>

Author: methylDragon

moveit_ros/trajectory_cache/CMakeLists.txt

@@ -34,6 +34,7 @@ set(TRAJECTORY_CACHE_DEPENDENCIES
 
 set(TRAJECTORY_CACHE_LIBRARIES moveit_ros_trajectory_cache_utils_lib
                                moveit_ros_trajectory_cache_features_lib
+                               moveit_ros_trajectory_cache_cache_insert_policies_lib
                                moveit_ros_trajectory_cache_lib)
 
 # Utils library
@@ -60,6 +61,19 @@ target_include_directories(
 ament_target_dependencies(moveit_ros_trajectory_cache_features_lib
                           ${TRAJECTORY_CACHE_DEPENDENCIES})
 
+# Cache insert policies library
+add_library(moveit_ros_trajectory_cache_cache_insert_policies_lib
+            src/cache_insert_policies/always_insert_never_prune_policy.cpp)
+generate_export_header(moveit_ros_trajectory_cache_cache_insert_policies_lib)
+target_link_libraries(moveit_ros_trajectory_cache_cache_insert_policies_lib
+                      moveit_ros_trajectory_cache_utils_lib)
+target_include_directories(
+  moveit_ros_trajectory_cache_cache_insert_policies_lib
+  PUBLIC $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
+         $<INSTALL_INTERFACE:include/moveit_ros_trajectory_cache>)
+ament_target_dependencies(moveit_ros_trajectory_cache_cache_insert_policies_lib
+                          ${TRAJECTORY_CACHE_DEPENDENCIES})
+
 # Trajectory cache library
 add_library(moveit_ros_trajectory_cache_lib src/trajectory_cache.cpp)
 generate_export_header(moveit_ros_trajectory_cache_lib)

moveit_ros/trajectory_cache/include/moveit/trajectory_cache/cache_insert_policies/always_insert_never_prune_policy.hpp

@@ -0,0 +1,119 @@
+// Copyright 2024 Intrinsic Innovation LLC.
+//
+// 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.
+
+/** @file
+ * @brief A cache insertion policy that always decides to insert and never decides to prune for motion plan requests.
+
+ * This is mainly for explanatory purposes.
+ * @see CacheInsertPolicyInterface<KeyT, ValueT, CacheEntryT>
+ *
+ * @author methylDragon
+ */
+
+#pragma once
+
+#include <memory>
+
+#include <warehouse_ros/message_collection.h>
+#include <moveit/move_group_interface/move_group_interface.h>
+#include <moveit_msgs/msg/motion_plan_request.hpp>
+
+#include <moveit/trajectory_cache/cache_insert_policies/cache_insert_policy_interface.hpp>
+#include <moveit/trajectory_cache/features/features_interface.hpp>
+
+namespace moveit_ros
+{
+namespace trajectory_cache
+{
+
+// moveit_msgs::msg::MotionPlanRequest <=> moveit::planning_interface::MoveGroupInterface::Plan ====
+
+/** @class AlwaysInsertNeverPrunePolicy
+ *
+ * @brief A cache insertion policy that always decides to insert and never decides to prune for motion plan requests.
+ *
+ * Supported Metadata and Features
+ * ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ * Appends the following additional metadata, which can be used for querying and sorting:
+ *   - execution_time_s
+ *   - planning_time_s
+ *
+ * Usable with the motion plan request features:
+ *   - WorkspaceFeatures
+ *   - StartStateJointStateFeatures
+ *   - MaxSpeedAndAccelerationFeatures
+ *   - GoalConstraintsFeatures
+ *   - PathConstraintsFeatures
+ *   - TrajectoryConstraintsFeatures
+ *
+ * @see motion_plan_request_features.hpp
+ * @see FeaturesInterface<FeatureSourceT>
+ *
+ * Matches, Pruning, and Insertion
+ * ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ * A matching cache entry is one that exactly matches on every one of the features above.
+ *
+ * The sort order is ordered on execution_time_s in ascending order (so loweest execution time first).
+ * This policy never indicates that pruning should happen, and always indicates that insertion should happen.
+ */
+class AlwaysInsertNeverPrunePolicy final
+  : public CacheInsertPolicyInterface<moveit_msgs::msg::MotionPlanRequest,
+                                      moveit::planning_interface::MoveGroupInterface::Plan,
+                                      moveit_msgs::msg::RobotTrajectory>
+{
+public:
+  /** @brief Configures and returns a vector of feature extractors that can be used with this policy. */
+  static std::vector<std::unique_ptr<FeaturesInterface<moveit_msgs::msg::MotionPlanRequest>>>
+  getSupportedFeatures(double start_tolerance, double goal_tolerance);
+
+  AlwaysInsertNeverPrunePolicy();
+
+  std::string getName() const override;
+
+  moveit::core::MoveItErrorCode
+  checkCacheInsertInputs(const moveit::planning_interface::MoveGroupInterface& move_group,
+                         const warehouse_ros::MessageCollection<moveit_msgs::msg::RobotTrajectory>& coll,
+                         const moveit_msgs::msg::MotionPlanRequest& key,
+                         const moveit::planning_interface::MoveGroupInterface::Plan& value) override;
+
+  std::vector<warehouse_ros::MessageWithMetadata<moveit_msgs::msg::RobotTrajectory>::ConstPtr>
+  fetchMatchingEntries(const moveit::planning_interface::MoveGroupInterface& move_group,
+                       const warehouse_ros::MessageCollection<moveit_msgs::msg::RobotTrajectory>& coll,
+                       const moveit_msgs::msg::MotionPlanRequest& key,
+                       const moveit::planning_interface::MoveGroupInterface::Plan& value,
+                       double exact_match_precision) override;
+
+  bool prunePredicate(
+      const moveit::planning_interface::MoveGroupInterface& move_group, const moveit_msgs::msg::MotionPlanRequest& key,
+      const moveit::planning_interface::MoveGroupInterface::Plan& value,
+      const warehouse_ros::MessageWithMetadata<moveit_msgs::msg::RobotTrajectory>::ConstPtr& matched_entry) override;
+
+  bool insertPredicate(const moveit::planning_interface::MoveGroupInterface& move_group,
+                       const moveit_msgs::msg::MotionPlanRequest& key,
+                       const moveit::planning_interface::MoveGroupInterface::Plan& value) override;
+
+  moveit::core::MoveItErrorCode
+  appendInsertMetadata(warehouse_ros::Metadata& metadata,
+                       const moveit::planning_interface::MoveGroupInterface& move_group,
+                       const moveit_msgs::msg::MotionPlanRequest& key,
+                       const moveit::planning_interface::MoveGroupInterface::Plan& value) override;
+
+  void reset() override;
+
+private:
+  const std::string name_;
+};
+
+}  // namespace trajectory_cache
+}  // namespace moveit_ros

moveit_ros/trajectory_cache/include/moveit/trajectory_cache/cache_insert_policies/cache_insert_policy_interface.hpp

@@ -0,0 +1,205 @@
+// Copyright 2024 Intrinsic Innovation LLC.
+//
+// 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.
+
+/* Author: methylDragon */
+
+#pragma once
+
+#include <warehouse_ros/message_collection.h>
+#include <moveit/move_group_interface/move_group_interface.h>
+
+namespace moveit_ros
+{
+namespace trajectory_cache
+{
+
+/** @class CacheInsertPolicyInterface<KeyT, ValueT, CacheEntryT>
+ * @headerfile cache_insert_policy_interface.hpp
+ * "moveit/trajectory_cache/cache_insert_policies/cache_insert_policy_interface.hpp"
+ *
+ * @brief Abstract class for injecting logic for determining when to prune and insert a cache entry, and what metadata
+ * to attach to the cache entry.
+ *
+ * @tparam KeyT. The object to extract features from which to key the cache. Typically the plan request.
+ * @tparam ValueT. The object that the TrajectoryCache was passed to insert. Typically the plan response.
+ * @tparam CacheEntryT. The actual type of the cache entry.
+ *
+ * Notably, implementations of this interface are used to determine all the logic leading up to, but not including, the
+ * insert call itself.
+ *
+ * Additionally, the choice of which implementation to use will constraint the set of FeaturesInterface<FeatureSourceT>
+ * implementations that can be used to fetch cache entries with, with a caveat mentioned later.
+ *
+ * Users may implement this interface to add additional cache insertion functionality beyond the ones provided by this
+ * package (e.g., prioritizing minimum jerk, or minimal path length), and the set of metadata considered when inserting
+ * the cache entry.
+ *
+ * @see TrajectoryCache
+ * @see FeaturesInterface<FeatureSourceT>
+ *
+ * Usage
+ * ^^^^^
+ * Each policy makes certain decisions about what pieces of metadata to attach to the cache
+ * entry for later fetching.
+ *
+ * As such, an implementation will necessarily constrain the set of FeaturesInterface<FeatureSourceT> implementations
+ * that can be used to fetch entries from the cache that were tagged by a policy.
+ *
+ * There is no way to meaningfully express this coupling at compile time, so users must ensure that they read the
+ * documentation of each implementation of the interface to determine what FeaturesInterface<FeatureSourceT>
+ * implementations can be used with cache entries processed by the implementation.
+ *
+ * Two mitigations may be applied to alleviate this:
+ *   1. Implementations of this interface may expose helper methods that can be called at runtime that take in arbitrary
+ *      configuration parameters to them initialize the features that are used to fetch cache entries at point of use.
+ *
+ *   2. The TrajectoryCache class' insertion methods allow the bubbling down of additional user-specified features to
+ *      be appended by the TrajectoryCache independent of a policy, which can be used to
+ *      support features that are not explicitly supported by the policy.
+ *
+ *      Care must be taken to ensure that there are no overlaps when doing so, though, because it could potentially
+ *      result in duplicate metadata entries otherwise.
+ *
+ * Consequently, a set of FeaturesInterface<FeatureSourceT> implementations can be used to fetch a cache entry if that
+ * set is a subset of the union of:
+ *   - The `additional_features` passed to `TrajectoryCache`
+ *   - The features used by a policy to append metadata to the cache entry
+ *
+ * Pruning and Insertion
+ * ^^^^^^^^^^^^^^^^^^^^^
+ * Pruning is a two step process:
+ *   1. Fetch all "matching" cache entries, as defined by the policy
+ *   2. From the fetched "matching" entries, subject each to the `prunePredicate` method, again defined by the
+ *      policy.
+ *
+ * This allows a user to define a policy to match and prune on any arbitrary properties of
+ * the cache entries and insertion candidate.
+ *
+ * Similarly, logic can be injected to determine when the insertion candidate should be inserted.
+ *
+ * NOTE: The TrajectoryCache class also has some top-level logic to preserve cache entries that would have been pruned.
+ *
+ * Stateful Policies
+ * ^^^^^^^^^^^^^^^^^
+ * Finally, as there can be information that must be preserved across the multiple steps of the match-prune-insert
+ * process, this interface assumes stateful operation within a single insert call.
+ *
+ * For example, preserving information in state will be required to propagate aggregated or rollup information about the
+ * entire set of matched cache entries to future calls.
+ *
+ * The TrajectoryCache will call `reset()` on the policy at the end of the insert call.
+ *
+ * Call Flow
+ * ^^^^^^^^^
+ * The TrajectoryCache will call the following interface methods in the following order:
+ *   1. sanitize, once
+ *   2. fetchMatchingEntries, once
+ *   3. prunePredicate, once per fetched entry from fetchMatchingEntries
+ *   4. insertPredicate, once
+ *   5. appendInsertMetadata, once, if insertPredicate returns true
+ *   6. reset, once, at the end.
+ */
+template <typename KeyT, typename ValueT, typename CacheEntryT>
+class CacheInsertPolicyInterface
+{
+public:
+  virtual ~CacheInsertPolicyInterface() = default;
+
+  /** @brief Gets the name of the cache insert policy. */
+  virtual std::string getName() const = 0;
+
+  /** @brief Checks inputs to the cache insert call to see if we should abort instead.
+
+   * @param[in] move_group. The manipulator move group, used to get its state.
+   * @param[in] coll. The cache database to fetch messages from.
+   * @param[in] key. The object used to key the insertion candidate with.
+   * @param[in] value. The object that the TrajectoryCache was passed to insert.
+   * @returns moveit::core::MoveItErrorCode::SUCCESS if the cache insert should proceed. Otherwise, will return a
+   different error code with the reason why it should not.
+   */
+  virtual moveit::core::MoveItErrorCode
+  checkCacheInsertInputs(const moveit::planning_interface::MoveGroupInterface& move_group,
+                         const warehouse_ros::MessageCollection<CacheEntryT>& coll, const KeyT& key,
+                         const ValueT& value) = 0;
+
+  /** @brief Fetches all "matching" cache entries for comparison for pruning.
+   *
+   * The policy should also make the decision about how to sort them.
+   * The order in which cache entries are presented to the prunePredicate will be the order of cache entries returned by
+   * this function.
+   *
+   * @see CacheInsertPolicyInterface<KeyT, ValueT, CacheEntryT>#prunePredicate
+   *
+   * @param[in] move_group. The manipulator move group, used to get its state.
+   * @param[in] coll. The cache database to fetch messages from.
+   * @param[in] key. The object used to key the insertion candidate with.
+   * @param[in] value. The object that the TrajectoryCache was passed to insert.
+   * @param[in] exact_match_precision. Tolerance for float precision comparison for what counts as an exact match.
+   * @returns A vector of matching cache entries for use by the other methods.
+   */
+  virtual std::vector<typename warehouse_ros::MessageWithMetadata<CacheEntryT>::ConstPtr>
+  fetchMatchingEntries(const moveit::planning_interface::MoveGroupInterface& move_group,
+                       const warehouse_ros::MessageCollection<CacheEntryT>& coll, const KeyT& key, const ValueT& value,
+                       double exact_match_precision) = 0;
+
+  /** @brief Returns whether a matched cache entry should be pruned.
+   *
+   * NOTE: The TrajectoryCache class also has some top-level logic to preserve cache entries that would have been
+   * pruned.
+   *
+   * @param[in] move_group. The manipulator move group, used to get its state.
+   * @param[in] key. The object used to key the insertion candidate with.
+   * @param[in] value. The object that the TrajectoryCache was passed to insert.
+   * @param[in] matched_entry. The matched cache entry to be possibly pruned.
+   * @returns True if the cache entry should be pruned.
+   */
+  virtual bool
+  prunePredicate(const moveit::planning_interface::MoveGroupInterface& move_group, const KeyT& key, const ValueT& value,
+                 const typename warehouse_ros::MessageWithMetadata<CacheEntryT>::ConstPtr& matched_entry) = 0;
+
+  /** @brief Returns whether the insertion candidate should be inserted into the cache.
+   *
+   * NOTE: The TrajectoryCache class executes the insert, but this class informs it on whether the insert should happen
+   * or not.
+   *
+   * @param[in] move_group. The manipulator move group, used to get its state.
+   * @param[in] key. The object used to key the insertion candidate with.
+   * @param[in] value. The object that the TrajectoryCache was passed to insert.
+   * @returns True if the insertion candidate should be inserted into the cache.
+   */
+  virtual bool insertPredicate(const moveit::planning_interface::MoveGroupInterface& move_group, const KeyT& key,
+                               const ValueT& value) = 0;
+
+  /** @brief Appends the insert metadata with the features supported by the policy.
+   *
+   * See notes in docstrings regarding the feature contract.
+   *
+   * @param[in,out] metadata. The metadata to add features to.
+   * @param[in] move_group. The manipulator move group, used to get its state.
+   * @param[in] key. The object used to key the insertion candidate with.
+   * @param[in] value. The object that the TrajectoryCache was passed to insert.
+   * @returns moveit::core::MoveItErrorCode::SUCCESS if successfully appended. Otherwise, will return a different error
+   * code, in which case the metadata should not be reused, and the TrajectoryCache will abort the insert.
+   */
+  virtual moveit::core::MoveItErrorCode
+  appendInsertMetadata(warehouse_ros::Metadata& metadata,
+                       const moveit::planning_interface::MoveGroupInterface& move_group, const KeyT& key,
+                       const ValueT& value) = 0;
+
+  /** @brief Resets the state of the policy. */
+  virtual void reset() = 0;
+};
+
+}  // namespace trajectory_cache
+}  // namespace moveit_ros