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Fix race condition on propertyUsageMap via AtomicReference #699

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merged 3 commits into from
Jan 19, 2024
Merged

Fix race condition on propertyUsageMap via AtomicReference #699

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ed35d1f
Fix race condition on propertyUsageMap via AtomicReference
akang31 Jan 19, 2024
8f8bad6
Change to getAndSet
akang31 Jan 19, 2024
762634b
Some fixes to the usage of the usageMapRef
akang31 Jan 19, 2024
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27 changes: 13 additions & 14 deletions archaius2-core/src/main/java/com/netflix/archaius/instrumentation/AccessMonitorUtil.java
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Original file line number Diff line number Diff line change
Expand Up @@ -16,14 +16,15 @@
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Consumer;

/** Tracks property usage data and flushes the data periodically to a sink. */
public class AccessMonitorUtil implements AutoCloseable {
private static final Logger LOG = LoggerFactory.getLogger(AccessMonitorUtil.class);

// Map from property id to property usage data
private final ConcurrentHashMap<String, PropertyUsageData> propertyUsageMap;
private final AtomicReference<ConcurrentHashMap<String, PropertyUsageData>> propertyUsageMapRef;

// Map from stack trace to how many times that stack trace appeared
private final ConcurrentHashMap<String, Integer> stackTrace;
Expand Down Expand Up @@ -75,7 +76,7 @@ public static Builder builder() {
private AccessMonitorUtil(
Consumer<PropertiesInstrumentationData> dataFlushConsumer,
boolean recordStackTrace) {
this.propertyUsageMap = new ConcurrentHashMap<>();
this.propertyUsageMapRef = new AtomicReference(new ConcurrentHashMap<>());
this.stackTrace = new ConcurrentHashMap<>();
this.dataFlushConsumer = dataFlushConsumer;
this.recordStackTrace = recordStackTrace;
Expand All @@ -89,9 +90,9 @@ private AccessMonitorUtil(
}

private void startFlushing(int initialDelay, int period) {
if (!flushingEnabled()) {
LOG.info("Property usage data is being captured, but not flushed as there is no consumer specified.");
} else {
if (flushingEnabled()) {
LOG.info("Starting flushing property usage data in {} seconds and then every {} seconds after.",
initialDelay, period);
executor.scheduleWithFixedDelay(this::flushUsageData, initialDelay, period, TimeUnit.SECONDS);
}
}
Expand All @@ -108,8 +109,9 @@ private void flushUsageData() {

/** Merge the results of given accessMonitorUtil into this one. */
public void merge(AccessMonitorUtil accessMonitorUtil) {
for (Map.Entry<String, PropertyUsageData> entry : accessMonitorUtil.propertyUsageMap.entrySet()) {
propertyUsageMap.putIfAbsent(entry.getKey(), entry.getValue());
Map<String, PropertyUsageData> myMap = propertyUsageMapRef.get();
for (Map.Entry<String, PropertyUsageData> entry : accessMonitorUtil.propertyUsageMapRef.get().entrySet()) {
myMap.putIfAbsent(entry.getKey(), entry.getValue());
}
for (Map.Entry<String, Integer> entry : accessMonitorUtil.stackTrace.entrySet()) {
stackTrace.merge(entry.getKey(), entry.getValue(), Integer::sum);
Expand All @@ -118,7 +120,7 @@ public void merge(AccessMonitorUtil accessMonitorUtil) {

public void registerUsage(PropertyDetails propertyDetails) {
// Initially, we limit the number of events we keep to one event per property id per flush.
propertyUsageMap.putIfAbsent(
propertyUsageMapRef.get().putIfAbsent(
propertyDetails.getId(),
new PropertyUsageData(createEventList(new PropertyUsageEvent(System.currentTimeMillis()))));

Expand All @@ -138,15 +140,12 @@ private List<PropertyUsageEvent> createEventList(PropertyUsageEvent event) {
}

private Map<String, PropertyUsageData> getAndClearUsageMap() {
synchronized (propertyUsageMap) {
Map<String, PropertyUsageData> ret = getUsageMapImmutable();
propertyUsageMap.clear();
return ret;
}
Map<String, PropertyUsageData> map = propertyUsageMapRef.getAndSet(new ConcurrentHashMap<>());
return Collections.unmodifiableMap(map);
}

public Map<String, PropertyUsageData> getUsageMapImmutable() {
return Collections.unmodifiableMap(new HashMap<>(propertyUsageMap));
return Collections.unmodifiableMap(new HashMap<>(propertyUsageMapRef.get()));
}

public Map<String, Integer> getStackTracesImmutable() {
Expand Down