Externalize config to increment or not VM metrics in memory (#5351)

Co-authored-by: SadiJr <[email protected]>

Author: SadiJr

server/src/main/java/com/cloud/server/StatsCollector.java

@@ -51,6 +51,7 @@
 import org.apache.commons.collections.CollectionUtils;
 import org.apache.commons.collections.MapUtils;
 import org.apache.commons.lang.StringUtils;
+import org.apache.commons.lang3.BooleanUtils;
 import org.apache.log4j.Logger;
 import org.influxdb.BatchOptions;
 import org.influxdb.InfluxDB;
@@ -221,6 +222,9 @@ public String toString() {
     private static final ConfigKey<String> statsOutputUri = new ConfigKey<String>("Advanced", String.class, "stats.output.uri", "",
             "URI to send StatsCollector statistics to. The collector is defined on the URI scheme. Example: graphite://graphite-hostaddress:port or influxdb://influxdb-hostaddress/dbname. Note that the port is optional, if not added the default port for the respective collector (graphite or influxdb) will be used. Additionally, the database name '/dbname' is  also optional; default db name is 'cloudstack'. You must create and configure the database if using influxdb.",
             true);
+    private static final ConfigKey<Boolean> VM_STATS_INCREMENT_METRICS_IN_MEMORY = new ConfigKey<Boolean>("Advanced", Boolean.class, "vm.stats.increment.metrics.in.memory", "true",
+            "When set to 'true', VM metrics(NetworkReadKBs, NetworkWriteKBs, DiskWriteKBs, DiskReadKBs, DiskReadIOs and DiskWriteIOs) that are collected from the hypervisor are summed and stored in memory. "
+            + "On the other hand, when set to 'false', the VM metrics API will just display the latest metrics collected.", true);
 
     private static StatsCollector s_instance = null;
 
@@ -1460,11 +1464,12 @@ private void prepareVmMetricsForGraphite(Map<Object, Object> metrics, VmStatsEnt
     private void storeVirtualMachineStatsInMemory(VmStatsEntry statsForCurrentIteration) {
         VmStatsEntry statsInMemory = (VmStatsEntry)_VmStats.get(statsForCurrentIteration.getVmId());
 
-        if (statsInMemory == null) {
-            //no stats exist for this vm, directly persist
+        boolean vmStatsIncrementMetrics = BooleanUtils.toBoolean(VM_STATS_INCREMENT_METRICS_IN_MEMORY.value());
+        if (statsInMemory == null || !vmStatsIncrementMetrics) {
             _VmStats.put(statsForCurrentIteration.getVmId(), statsForCurrentIteration);
         } else {
-            //update each field
+            s_logger.debug(String.format("Increment saved values of NetworkReadKBs, NetworkWriteKBs, DiskWriteKBs, DiskReadKBs, DiskReadIOs, DiskWriteIOs, with current metrics for VM with ID [%s]. "
+                    + "To change this process, check value of 'vm.stats.increment.metrics.in.memory' configuration.", statsForCurrentIteration.getVmId()));
             statsInMemory.setCPUUtilization(statsForCurrentIteration.getCPUUtilization());
             statsInMemory.setNumCPUs(statsForCurrentIteration.getNumCPUs());
             statsInMemory.setNetworkReadKBs(statsInMemory.getNetworkReadKBs() + statsForCurrentIteration.getNetworkReadKBs());
@@ -1625,7 +1630,7 @@ public String getConfigComponentName() {
 
     @Override
     public ConfigKey<?>[] getConfigKeys() {
-        return new ConfigKey<?>[] {vmDiskStatsInterval, vmDiskStatsIntervalMin, vmNetworkStatsInterval, vmNetworkStatsIntervalMin, StatsTimeout, statsOutputUri};
+        return new ConfigKey<?>[] {vmDiskStatsInterval, vmDiskStatsIntervalMin, vmNetworkStatsInterval, vmNetworkStatsIntervalMin, StatsTimeout, statsOutputUri, VM_STATS_INCREMENT_METRICS_IN_MEMORY};
     }
 
     public double getImageStoreCapacityThreshold() {