import com.google.common.annotations.VisibleForTesting;

import com.google.common.collect.ImmutableList;

import io.grpc.MetricRecorder;

import io.grpc.internal.ExponentialBackoffPolicy;

import io.grpc.internal.GrpcUtil;

import io.grpc.internal.ObjectPool;

private static final boolean LOG_XDS_NODE_ID = Boolean.parseBoolean(

System.getenv("GRPC_LOG_XDS_NODE_ID"));

private static final Logger log = Logger.getLogger(XdsClientImpl.class.getName());

private static final ExponentialBackoffPolicy.Provider BACKOFF_POLICY_PROVIDER =

new ExponentialBackoffPolicy.Provider();

private final Bootstrapper bootstrapper;

private final Object lock = new Object();

}

@Override

public ObjectPool<XdsClient> getOrCreate(String target) throws XdsInitializationException {

public ObjectPool<XdsClient> getOrCreate(String target, MetricRecorder metricRecorder)

throws XdsInitializationException {

ObjectPool<XdsClient> ref = targetToXdsClientMap.get(target);

if (ref == null) {

synchronized (lock) {

if (bootstrapInfo.servers().isEmpty()) {

throw new XdsInitializationException("No xDS server provided");

}

ref = new RefCountedXdsClientObjectPool(bootstrapInfo, target);

ref = new RefCountedXdsClientObjectPool(bootstrapInfo, target, metricRecorder);

targetToXdsClientMap.put(target, ref);

}

}

return ImmutableList.copyOf(targetToXdsClientMap.keySet());

}

private static class SharedXdsClientPoolProviderHolder {

private static final SharedXdsClientPoolProvider instance = new SharedXdsClientPoolProvider();

}

@ThreadSafe

@VisibleForTesting

static class RefCountedXdsClientObjectPool implements ObjectPool<XdsClient> {

class RefCountedXdsClientObjectPool implements ObjectPool<XdsClient> {

private static final ExponentialBackoffPolicy.Provider BACKOFF_POLICY_PROVIDER =

new ExponentialBackoffPolicy.Provider();

private final BootstrapInfo bootstrapInfo;

private final String target; // The target associated with the xDS client.

private final MetricRecorder metricRecorder;

private final Object lock = new Object();

@GuardedBy("lock")

private ScheduledExecutorService scheduler;

@GuardedBy("lock")

private XdsClient xdsClient;

@GuardedBy("lock")

private int refCount;

@GuardedBy("lock")

private XdsClientMetricReporterImpl metricReporter;

@VisibleForTesting

RefCountedXdsClientObjectPool(BootstrapInfo bootstrapInfo, String target) {

RefCountedXdsClientObjectPool(BootstrapInfo bootstrapInfo, String target,

MetricRecorder metricRecorder) {

this.bootstrapInfo = checkNotNull(bootstrapInfo);

this.target = target;

this.metricRecorder = metricRecorder;

}

@Override

log.log(Level.INFO, "xDS node ID: {0}", bootstrapInfo.node().getId());

}

scheduler = SharedResourceHolder.get(GrpcUtil.TIMER_SERVICE);

metricReporter = new XdsClientMetricReporterImpl(metricRecorder, target);

xdsClient = new XdsClientImpl(

DEFAULT_XDS_TRANSPORT_FACTORY,

bootstrapInfo,

GrpcUtil.STOPWATCH_SUPPLIER,

TimeProvider.SYSTEM_TIME_PROVIDER,

MessagePrinter.INSTANCE,

new TlsContextManagerImpl(bootstrapInfo));

new TlsContextManagerImpl(bootstrapInfo),

metricReporter);

metricReporter.setXdsClient(xdsClient);

}

refCount++;

return xdsClient;

if (refCount == 0) {

xdsClient.shutdown();

xdsClient = null;

metricReporter.close();

metricReporter = null;

targetToXdsClientMap.remove(target);

scheduler = SharedResourceHolder.release(GrpcUtil.TIMER_SERVICE, scheduler);

}

return null;