[REVIEW] Circular buffer implementation for historydata plugin (open6…

…2541#4740)

examples/CMakeLists.txt

@@ -165,6 +165,7 @@ add_example(server_loglevel server_loglevel.c)
 
 if(UA_ENABLE_HISTORIZING)
     add_example(tutorial_server_historicaldata tutorial_server_historicaldata.c)
+    add_example(tutorial_server_historicaldata_circular tutorial_server_historicaldata_circular.c)
 endif()
 
 if(UA_ENABLE_ENCRYPTION OR UA_ENABLE_ENCRYPTION STREQUAL "MBEDTLS" OR UA_ENABLE_ENCRYPTION STREQUAL "OPENSSL")

examples/tutorial_server_historicaldata_circular.c

@@ -0,0 +1,133 @@
+/* This work is licensed under a Creative Commons CCZero 1.0 Universal License.
+ * See http://creativecommons.org/publicdomain/zero/1.0/ for more information.
+ *
+ * Copyright 2019 (c) basysKom GmbH <[email protected]> (Author: Peter Rustler)
+ * Copyright 2021 (c) luibass92 <[email protected]> (Author: Luigi Bassetta)
+ */
+
+#include <open62541/plugin/historydata/history_data_backend_memory.h>
+#include <open62541/plugin/historydata/history_data_gathering_default.h>
+#include <open62541/plugin/historydata/history_database_default.h>
+#include <open62541/plugin/historydatabase.h>
+#include <open62541/plugin/log_stdout.h>
+#include <open62541/server.h>
+#include <open62541/server_config_default.h>
+
+#include <signal.h>
+#include <stdlib.h>
+
+static volatile UA_Boolean running = true;
+static void stopHandler(int sign) {
+    (void)sign;
+    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "received ctrl-c");
+    running = false;
+}
+
+int main(void) {
+    signal(SIGINT, stopHandler);
+    signal(SIGTERM, stopHandler);
+
+    UA_Server *server = UA_Server_new();
+    UA_ServerConfig *config = UA_Server_getConfig(server);
+    UA_ServerConfig_setDefault(config);
+
+    /* We need a gathering for the plugin to constuct.
+     * The UA_HistoryDataGathering is responsible to collect data and store it to the database.
+     * We will use this gathering for one node, only. initialNodeIdStoreSize = 1
+     * The store will NOT automatically grow if you register more than one node will return a UA_STATUS_BADOUTOFMEMORY. */
+    UA_HistoryDataGathering gathering = UA_HistoryDataGathering_Circular(1);
+
+    /* We set the responsible plugin in the configuration. UA_HistoryDatabase is
+     * the main plugin which handles the historical data service. */
+    config->historyDatabase = UA_HistoryDatabase_default(gathering);
+
+    /* Define the attribute of the uint32 variable node */
+    UA_VariableAttributes attr = UA_VariableAttributes_default;
+    UA_UInt32 myUint32 = 40;
+    UA_Variant_setScalar(&attr.value, &myUint32, &UA_TYPES[UA_TYPES_UINT32]);
+    attr.description = UA_LOCALIZEDTEXT("en-US","myUintValue");
+    attr.displayName = UA_LOCALIZEDTEXT("en-US","myUintValue");
+    attr.dataType = UA_TYPES[UA_TYPES_UINT32].typeId;
+    /* We set the access level to also support history read
+     * This is what will be reported to clients */
+    attr.accessLevel = UA_ACCESSLEVELMASK_READ | UA_ACCESSLEVELMASK_WRITE | UA_ACCESSLEVELMASK_HISTORYREAD;
+    /* We also set this node to historizing, so the server internals also know from it. */
+    attr.historizing = true;
+
+    /* Add the variable node to the information model */
+    UA_NodeId uint32NodeId = UA_NODEID_STRING(1, "myUintValue");
+    UA_QualifiedName uint32Name = UA_QUALIFIEDNAME(1, "myUintValue");
+    UA_NodeId parentNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER);
+    UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_ORGANIZES);
+    UA_NodeId outNodeId;
+    UA_NodeId_init(&outNodeId);
+    UA_StatusCode retval = UA_Server_addVariableNode(server,
+                                                     uint32NodeId,
+                                                     parentNodeId,
+                                                     parentReferenceNodeId,
+                                                     uint32Name,
+                                                     UA_NODEID_NUMERIC(0, UA_NS0ID_BASEDATAVARIABLETYPE),
+                                                     attr,
+                                                     NULL,
+                                                     &outNodeId);
+
+    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
+                "UA_Server_addVariableNode %s", UA_StatusCode_name(retval));
+
+    /* Now we define the settings for our node */
+    UA_HistorizingNodeIdSettings setting;
+
+    /* There is a memory based database plugin. We will use that. We just
+     * reserve space for 3 nodes with 10 values each. This will NOT automatically grow
+     * but will store data as a circular buffer of size 10. The 11th value will be
+     * stored replacing the oldest one and the process will continue like that. */
+    setting.historizingBackend = UA_HistoryDataBackend_Memory_Circular(3, 10);
+
+    /* We want the server to serve a maximum of 100 values per request. This
+     * value depend on the plattform you are running the server. A big server
+     * can serve more values, smaller ones less. */
+    setting.maxHistoryDataResponseSize = 100;
+
+    /* If we have a sensor which do not report updates
+     * and need to be polled we change the setting like that.
+     * The polling interval in ms.
+     *
+    setting.pollingInterval = 100;
+     *
+     * Set the update strategie to polling.
+     *
+    setting.historizingUpdateStrategy = UA_HISTORIZINGUPDATESTRATEGY_POLL;
+     */
+
+    /* If you want to insert the values to the database yourself, we can set the user strategy here.
+     * This is useful if you for example want a value stored, if a defined delta is reached.
+     * Then you should use a local monitored item with a fuzziness and store the value in the callback.
+     *
+    setting.historizingUpdateStrategy = UA_HISTORIZINGUPDATESTRATEGY_USER;
+     */
+
+    /* We want the values stored in the database, when the nodes value is
+     * set. */
+    setting.historizingUpdateStrategy = UA_HISTORIZINGUPDATESTRATEGY_VALUESET;
+
+    /* At the end we register the node for gathering data in the database. */
+    retval = gathering.registerNodeId(server, gathering.context, &outNodeId, setting);
+    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "registerNodeId %s", UA_StatusCode_name(retval));
+
+    /* If you use UA_HISTORIZINGUPDATESTRATEGY_POLL, then start the polling.
+     *
+    retval = gathering.startPoll(server, gathering.context, &outNodeId);
+    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "startPoll %s", UA_StatusCode_name(retval));
+    */
+    retval = UA_Server_run(server, &running);
+    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "UA_Server_run %s", UA_StatusCode_name(retval));
+    /*
+     * If you use UA_HISTORIZINGUPDATESTRATEGY_POLL, then stop the polling.
+     *
+    retval = gathering.stopPoll(server, gathering.context, &outNodeId);
+    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "stopPoll %s", UA_StatusCode_name(retval));
+    */
+
+    UA_Server_delete(server);
+    return retval == UA_STATUSCODE_GOOD ? EXIT_SUCCESS : EXIT_FAILURE;
+}