Draft: Feature/mongo db

MongoDB implementation of the long-term memory as part of the bachelor thesis of Robin Müller (utwee_mueller).

Tasks:

• implement a Mixin for the MongoDB version of the LTM
  • set-up and connection to database
  • writing into the database
  • reading from the database
  • adjusting keys
• test MongoDBMixin for different memory servers
  • VisionMemory
  • ObjectMemory
  • RobotStateMemory
  • GraspMemory
  • ...
• Implement an autonomous key selection algorithm

source/RobotAPI/libraries/armem/server/ltm/detail/mixins/util/mongodb.cpp

@@ -39,13 +39,56 @@ namespace armarx::armem::server::ltm::util::mongodb
             return ret;
         }
 
+        //Only for MongoCXX Version < 3.5.0 required.
+        std::vector<std::string>
+        list_database_names(mongocxx::client& client)
+        {
+            std::vector<std::string> database_names;
+
+            auto dbs = client.list_databases();
+
+            for (auto&& view : dbs)
+            {
+                std::string name = std::string(view["name"].get_utf8().value);
+                database_names.push_back(name);
+            }
+            return database_names;
+        }
+
+        //Only for MongoCXX Version < 3.4.0 required.
+        std::vector<std::string>
+        list_collection_names(mongocxx::database& db)
+        {
+            std::vector<std::string> collection_names;
+
+            auto dbs = db.list_collections();
+            ;
+
+            for (auto&& view : dbs)
+            {
+                std::string name = std::string(view["name"].get_utf8().value);
+                collection_names.push_back(name);
+            }
+            return collection_names;
+        }
+
         bool
         insert(mongocxx::collection& coll, const nlohmann::json& value)
         {
+            nlohmann::json json = value;
             std::string v = value.dump();
             auto q = bsoncxx::from_json(v);
-            auto res = coll.insert_one(q.view());
 
+            size_t document_size = q.view().length();
+            if (document_size > 16 * 1024 * 1024)
+            { // 16 MB Document
+                ARMARX_INFO << deactivateSpam()
+                            << "Document size exceeds the 16MB limit: " << document_size
+                            << " bytes. Delete image in VisonMemory.";
+                for (auto& instance : json["_data"]["_entity_instances"]) instance["_data"] = nullptr;
+                q = bsoncxx::from_json(json.dump());
+            }
+            auto res = coll.insert_one(q.view());
             return (bool)res;
         }
 
@@ -77,17 +120,57 @@ namespace armarx::armem::server::ltm::util::mongodb
 
             return (bool)res;
         }
+
+        std::string
+        extractLastElementFromCollectionName(const std::string& collectionName)
+        {
+            size_t pos = collectionName.rfind('.');
+
+            if (pos != std::string::npos)
+            {
+                return collectionName.substr(pos + 1);
+            }
+            else
+            {
+                return collectionName;
+            }
+        }
+
+        std::string 
+        removeLastElementFromCollectionName(const std::string& collectionName) 
+        {
+            size_t pos = collectionName.find_last_of('.');
+            if (pos != std::string::npos) {
+                return collectionName.substr(0, pos);
+            }
+            return collectionName;
+        }    
     } // namespace detail
 
     std::optional<mongocxx::database>
     databaseExists(mongocxx::client& client, const std::string& databaseName)
     {
-        //auto names = client.list_databases();
-        //if (auto it = std::find(names.begin(), names.end(), databaseName); it != names.end())
-        //{
-        //    return client[databaseName];
-        //}
-        return std::nullopt;
+        // MongoCXX Version > 3.5.0 required
+        //auto names = client.list_database_names();
+        //return client[databaseName];
+        try
+        {
+            mongocxx::cursor dbs = client.list_databases();
+            bsoncxx::stdx::string_view databaseNameView{databaseName};
+            for (auto& view : dbs)
+            {
+                if (view["name"].get_utf8().value == databaseNameView)
+                {
+                    return client[databaseName];
+                }
+            }
+            return std::nullopt;
+        }
+        catch (...)
+        {
+            ARMARX_ERROR << "Exception while checking database existence";
+            return std::nullopt;
+        }
     }
 
     mongocxx::database
@@ -104,12 +187,17 @@ namespace armarx::armem::server::ltm::util::mongodb
                                              databaseName);
             }
         }
+        //Workaround to create an empty Database client[databaseName] does not create a database if nothing is added
+        //db = client[databaseName];
+        //db.create_collection("empty");
         return client[databaseName];
     }
 
     std::optional<mongocxx::collection>
     collectionExists(mongocxx::database& db, const std::string& collectionName)
     {
+        //ARMARX_INFO << "CollectionName: " << collectionName;
+        //return db[collectionName];
         if (db.has_collection(collectionName))
         {
             return db[collectionName];
@@ -131,6 +219,7 @@ namespace armarx::armem::server::ltm::util::mongodb
                                              collectionName);
             }
         }
+        //Workaround to create an empty Collection db[collectionName] does not create a Collection if no document is added
         return db[collectionName];
     }
 
@@ -141,7 +230,6 @@ namespace armarx::armem::server::ltm::util::mongodb
         {
             return id.timestampStr();
         }
-
         // fallback
         throw armarx::LocalException("Called toDocumentName() on non-snapshot id: " + id.str());
     }
@@ -153,7 +241,7 @@ namespace armarx::armem::server::ltm::util::mongodb
         std::stringstream ss;
         if (id.hasMemoryName())
         {
-            ss << detail::escapeName(id.memoryName);
+            ss << (detail::escapeName(id.memoryName));
         }
         if (id.hasCoreSegmentName())
         {
@@ -168,9 +256,75 @@ namespace armarx::armem::server::ltm::util::mongodb
             ss << "." << detail::escapeName(id.entityName);
         }
 
+        //ARMARX_INFO << deactivateSpam() << ss.str();
+        return ss.str();
+    }
+
+    std::string
+    toGridFSFileName(const armem::MemoryID& id)
+    {
+        ARMARX_CHECK(id.isWellDefined());
+        std::stringstream ss;
+        if (id.hasMemoryName())
+        {
+            ss << id.memoryName;
+        }
+        if (id.hasCoreSegmentName())
+        {
+            ss << "." << id.coreSegmentName;
+        }
+        if (id.hasProviderSegmentName())
+        {
+            ss << "." << id.providerSegmentName;
+        }
+        if (id.hasEntityName())
+        {
+            ss << "." << id.entityName;
+        }
+        if (id.hasTimestamp())
+        {
+            ss << "." << id.timestampStr();
+        }
+        if (id.hasInstanceIndex())
+        {
+            ss << "." << id.instanceIndexStr();
+        }
+
+        //ARMARX_INFO << deactivateSpam() << ss.str();
         return ss.str();
     }
 
+    /*unused
+    std::vector<std::string>
+    getDirectSuccessors(const std::vector<std::string>& collection_names, const std::string& prefix) {
+        std::vector<std::string> direct_successors;
+        for (const auto& coll_name : collection_names) {
+            auto segments = split(coll_name, ".");
+            if (segments.size() > collectionNameDepth) {
+                std::string current_prefix;
+                for (size_t i = 0; i < collectionNameDepth; ++i) {
+                    if (i > 0) {
+                        current_prefix += ".";
+                    }
+                    current_prefix += segments[i];
+                }
+                if (current_prefix == prefix) {
+                    direct_successors.push_back(segments[collectionNameDepth]);
+                }
+            }
+        }
+        // Removing duplicates
+        std::set<std::string> unique_successors(direct_successors.begin(), direct_successors.end());
+        direct_successors.assign(unique_successors.begin(), unique_successors.end());
+        return direct_successors;
+    }
+
+    std::vector<std::string>
+    getSubCollections(mongocxx::database& db, const armem::MemoryID& id) {
+        return getDirectSuccessors(detail::list_collection_names(db), toCollectionName(id));
+    }
+    */
+
     std::optional<nlohmann::json>
     documentExists(mongocxx::collection& collection, const nlohmann::json& json)
     {
@@ -217,6 +371,33 @@ namespace armarx::armem::server::ltm::util::mongodb
         return *doc;
     }
 
+    std::string
+    readSpecialDataFromGridFS(mongocxx::gridfs::bucket &bucket, const std::string &oidStr)
+    {
+        // Newer MongoCXX Versions tested on 3.10.2
+        //auto downloader = bucket.open_download_stream(bsoncxx::types::bson_value::value((bsoncxx::oid(oidStr))).view());
+        // OR
+        //bsoncxx::oid oid(oidStr);
+        //bsoncxx::types::bson_value::value oid_value(oid);
+        //auto downloader = bucket.open_download_stream(oid_value.view());
+
+        bsoncxx::oid oid(oidStr);
+        
+        bsoncxx::document::value filter = bsoncxx::builder::stream::document{}
+            << "oid" << oid << bsoncxx::builder::stream::finalize;
+            
+        auto downloader = bucket.open_download_stream(filter.view()["oid"].get_value());
+
+        std::int64_t file_length = downloader.file_length();
+        std::vector<std::uint8_t> download_buffer(file_length);
+
+        downloader.read(download_buffer.data(), file_length);
+
+        downloader.close();
+
+        return std::string(download_buffer.begin(), download_buffer.end());
+    }
+
     void
     writeDataToDocument(mongocxx::collection& collection,
                         const nlohmann::json& query,
@@ -235,6 +416,20 @@ namespace armarx::armem::server::ltm::util::mongodb
         }
     }
 
+    std::string
+    writeSpecialDataToGridFS(mongocxx::gridfs::bucket &bucket,
+                             const bsoncxx::stdx::string_view& filename,
+                             const std::string& data)
+    {
+        auto uploader = bucket.open_upload_stream(filename);
+
+        uploader.write(reinterpret_cast<const std::uint8_t*>(data.c_str()), data.size());
+
+        auto result = uploader.close();
+        
+        return result.id().get_oid().value.to_string();
+    }
+
     std::vector<nlohmann::json>
     getAllDocuments(mongocxx::collection& collection)
     {
@@ -247,5 +442,4 @@ namespace armarx::armem::server::ltm::util::mongodb
         }
         return ret;
     }
-
 } // namespace armarx::armem::server::ltm::util::mongodb