In the previous article: EurekaClient automatic assembly and startup process analysis , we mentioned DiscoveryClientthat there is a refresh thread in the class constructor and the operation of pulling registration information from the server
These two are the two cases where eureka gets the service list:
- Full acquisition: Pull all services when Eureka starts
- Incremental acquisition: timed acquisition of a scheduled task
Get the full amount
if (clientConfig.shouldFetchRegistry() && !fetchRegistry(false)) {
fetchRegistryFromBackup();
}
The method used to obtain the full amount fetchRegistry. If this method is not successfully obtained, the method will be executed fetchRegistryFromBackupusing the backup method to pull. The backup pull uses BackupRegistrythe implementation class of the interface, but eureka does not implement it by default.
Continue to see the pull process
private boolean fetchRegistry(boolean forceFullRegistryFetch) {
Stopwatch tracer = FETCH_REGISTRY_TIMER.start();
try {
Applications applications = getApplications();
if (clientConfig.shouldDisableDelta()//禁用部分获取
|| (!Strings.isNullOrEmpty(clientConfig.getRegistryRefreshSingleVipAddress()))
|| forceFullRegistryFetch//全部获取
|| (applications == null)//本地没有任何实例
|| (applications.getRegisteredApplications().size() == 0)
|| (applications.getVersion() == -1)) //Client application does not have latest library supporting delta
{
logger.info("Disable delta property : {}", clientConfig.shouldDisableDelta());
logger.info("Single vip registry refresh property : {}", clientConfig.getRegistryRefreshSingleVipAddress());
logger.info("Force full registry fetch : {}", forceFullRegistryFetch);
logger.info("Application is null : {}", (applications == null));
logger.info("Registered Applications size is zero : {}",
(applications.getRegisteredApplications().size() == 0));
logger.info("Application version is -1: {}", (applications.getVersion() == -1));
getAndStoreFullRegistry();
} else {
getAndUpdateDelta(applications);
}
applications.setAppsHashCode(applications.getReconcileHashCode());
logTotalInstances();
} catch (Throwable e) {
logger.error(PREFIX + "{} - was unable to refresh its cache! status = {}", appPathIdentifier, e.getMessage(), e);
return false;
} finally {
if (tracer != null) {
tracer.stop();
}
}
- The first entry
forceFullRegistryFetchrepresents full acquisition or incremental acquisition - Get these instances of the local cache
private final AtomicReference<Applications> localRegionApps = new AtomicReference<Applications>();
public Applications getApplications() {
return localRegionApps.get();
}
It can be seen that all instances should be cached in the localRegionAppsobject 3. Then according to some conditions, it is judged whether full acquisition should be performed, that is, even if the input parameters specify incremental acquisition, but these conditions are not met, the full acquisition will still be performed 4. Then print the current Number of instances 5. Finally, update the status of the pulled instance
Full pull processing
private void getAndStoreFullRegistry() throws Throwable {
long currentUpdateGeneration = fetchRegistryGeneration.get();
logger.info("Getting all instance registry info from the eureka server");
Applications apps = null;
//发起获取
EurekaHttpResponse<Applications> httpResponse = clientConfig.getRegistryRefreshSingleVipAddress() == null
? eurekaTransport.queryClient.getApplications(remoteRegionsRef.get())
: eurekaTransport.queryClient.getVip(clientConfig.getRegistryRefreshSingleVipAddress(), remoteRegionsRef.get());
if (httpResponse.getStatusCode() == Status.OK.getStatusCode()) {
apps = httpResponse.getEntity();
}
logger.info("The response status is {}", httpResponse.getStatusCode());
if (apps == null) {
logger.error("The application is null for some reason. Not storing this information");
} else if (fetchRegistryGeneration.compareAndSet(currentUpdateGeneration, currentUpdateGeneration + 1)) {
//缓存结果
localRegionApps.set(this.filterAndShuffle(apps));
logger.debug("Got full registry with apps hashcode {}", apps.getAppsHashCode());
} else {
logger.warn("Not updating applications as another thread is updating it already");
}
}
The logic of the call is relatively simple:
public EurekaHttpResponse<Applications> getApplications(String... regions) {
return getApplicationsInternal("apps/", regions);
}
private EurekaHttpResponse<Applications> getApplicationsInternal(String urlPath, String[] regions) {
ClientResponse response = null;
String regionsParamValue = null;
try {
WebResource webResource = jerseyClient.resource(serviceUrl).path(urlPath);
if (regions != null && regions.length > 0) {
regionsParamValue = StringUtil.join(regions);
webResource = webResource.queryParam("regions", regionsParamValue);
}
Builder requestBuilder = webResource.getRequestBuilder();
addExtraHeaders(requestBuilder);
response = requestBuilder.accept(MediaType.APPLICATION_JSON_TYPE).get(ClientResponse.class); // JSON
Applications applications = null;
if (response.getStatus() == Status.OK.getStatusCode() && response.hasEntity()) {
applications = response.getEntity(Applications.class);
}
return anEurekaHttpResponse(response.getStatus(), Applications.class)
.headers(headersOf(response))
.entity(applications)
.build();
} finally {
if (logger.isDebugEnabled()) {
logger.debug("Jersey HTTP GET {}/{}?{}; statusCode={}",
serviceUrl, urlPath,
regionsParamValue == null ? "" : "regions=" + regionsParamValue,
response == null ? "N/A" : response.getStatus()
);
}
if (response != null) {
response.close();
}
}
}
Full pull server processing
The fully obtained server-side Controller is in the ApplicationsResourceclass
@GET
public Response getContainers(@PathParam("version") String version,
@HeaderParam(HEADER_ACCEPT) String acceptHeader,@HeaderParam(HEADER_ACCEPT_ENCODING) String acceptEncoding,@HeaderParam(EurekaAccept.HTTP_X_EUREKA_ACCEPT) String eurekaAccept,@Context UriInfo uriInfo,@Nullable @QueryParam("regions") String regionsStr) {
boolean isRemoteRegionRequested = null != regionsStr && !regionsStr.isEmpty();
String[] regions = null;
if (!isRemoteRegionRequested) {
EurekaMonitors.GET_ALL.increment();
} else {
regions = regionsStr.toLowerCase().split(",");
Arrays.sort(regions); // So we don't have different caches for same regions queried in different order.
EurekaMonitors.GET_ALL_WITH_REMOTE_REGIONS.increment();
}
// Check if the server allows the access to the registry. The server can
// restrict access if it is not
// ready to serve traffic depending on various reasons.
if (!registry.shouldAllowAccess(isRemoteRegionRequested)) {
return Response.status(Status.FORBIDDEN).build();
}
CurrentRequestVersion.set(Version.toEnum(version));
KeyType keyType = Key.KeyType.JSON;
String returnMediaType = MediaType.APPLICATION_JSON;
if (acceptHeader == null || !acceptHeader.contains(HEADER_JSON_VALUE)) {
keyType = Key.KeyType.XML;
returnMediaType = MediaType.APPLICATION_XML;
}
Key cacheKey = new Key(Key.EntityType.Application,
ResponseCacheImpl.ALL_APPS,
keyType, CurrentRequestVersion.get(), EurekaAccept.fromString(eurekaAccept), regions
);
Response response;
if (acceptEncoding != null && acceptEncoding.contains(HEADER_GZIP_VALUE)) {
response = Response.ok(responseCache.getGZIP(cacheKey))
.header(HEADER_CONTENT_ENCODING, HEADER_GZIP_VALUE)
.header(HEADER_CONTENT_TYPE, returnMediaType)
.build();
} else {
response = Response.ok(responseCache.get(cacheKey))
.build();
}
return response;
}
Although this Controller is very long, there are only a few lines related to the returned result
Key cacheKey = new Key(Key.EntityType.Application,
ResponseCacheImpl.ALL_APPS,
keyType, CurrentRequestVersion.get(), EurekaAccept.fromString(eurekaAccept), regions
);
Response response;
if (acceptEncoding != null && acceptEncoding.contains(HEADER_GZIP_VALUE)) {
response = Response.ok(responseCache.getGZIP(cacheKey))
.header(HEADER_CONTENT_ENCODING, HEADER_GZIP_VALUE)
.header(HEADER_CONTENT_TYPE, returnMediaType)
.build();
} else {
response = Response.ok(responseCache.get(cacheKey))
.build();
}
There are two points here, KeyandResponseCacheImpl
Key
This object contains the cache key
public Key(EntityType entityType, String entityName, KeyType type, Version v, EurekaAccept eurekaAccept, @Nullable String[] regions) {
this.regions = regions;
this.entityType = entityType;
this.entityName = entityName;
this.requestType = type;
this.requestVersion = v;
this.eurekaAccept = eurekaAccept;
hashKey = this.entityType + this.entityName + (null != this.regions ? Arrays.toString(this.regions) : "")
+ requestType.name() + requestVersion.name() + this.eurekaAccept.name();
}
The final result of this hashKey is similar to this: ApplicationALL_APPSJSONV2full
ResponseCacheImpl
This object is the implementation of the response cache. When the hashKey is created, responseCache.getGZIP(cacheKey)it is the method to read the cache and compress it.
public byte[] getGZIP(Key key) {
Value payload = getValue(key, shouldUseReadOnlyResponseCache);
if (payload == null) {
return null;
}
return payload.getGzipped();
}
payload.getGzipped()It's a compression method, so don't look at it, look at itgetValue
Value getValue(final Key key, boolean useReadOnlyCache) {
Value payload = null;
try {
if (useReadOnlyCache) {
final Value currentPayload = readOnlyCacheMap.get(key);
if (currentPayload != null) {
payload = currentPayload;
} else {
payload = readWriteCacheMap.get(key);
readOnlyCacheMap.put(key, payload);
}
} else {
payload = readWriteCacheMap.get(key);
}
} catch (Throwable t) {
logger.error("Cannot get value for key : {}", key, t);
}
return payload;
}
Roughly, it is readOnlyCacheMapobtained from the read-only cache first, and if it does not exist, it readWriteCacheMapis obtained from the read-write cache
cache generation
The above server reads the request directly from the cache, so when is the cache generated?
read and write cache
The cache is generated in ResponseCacheImplthe constructor of
this.readWriteCacheMap =
CacheBuilder.newBuilder().initialCapacity(1000)
.expireAfterWrite(serverConfig.getResponseCacheAutoExpirationInSeconds(), TimeUnit.SECONDS)
.removalListener(new RemovalListener<Key, Value>() {
@Override
public void onRemoval(RemovalNotification<Key, Value> notification) {
Key removedKey = notification.getKey();
if (removedKey.hasRegions()) {
Key cloneWithNoRegions = removedKey.cloneWithoutRegions();
regionSpecificKeys.remove(cloneWithNoRegions, removedKey);
}
}
})
.build(new CacheLoader<Key, Value>() {
@Override
public Value load(Key key) throws Exception {
if (key.hasRegions()) {
Key cloneWithNoRegions = key.cloneWithoutRegions();
regionSpecificKeys.put(cloneWithNoRegions, key);
}
Value value = generatePayload(key);
return value;
}
});
It can be seen that the capacity of the read and write cache is 1000, and the generation method of the cache is in the generatePayloadmethod
private Value generatePayload(Key key) {
Stopwatch tracer = null;
try {
String payload;
switch (key.getEntityType()) {
case Application:
boolean isRemoteRegionRequested = key.hasRegions();
if (ALL_APPS.equals(key.getName())) {
if (isRemoteRegionRequested) {
tracer = serializeAllAppsWithRemoteRegionTimer.start();
payload = getPayLoad(key, registry.getApplicationsFromMultipleRegions(key.getRegions()));
} else {
tracer = serializeAllAppsTimer.start();
payload = getPayLoad(key, registry.getApplications());
}
} else if (ALL_APPS_DELTA.equals(key.getName())) {
if (isRemoteRegionRequested) {
tracer = serializeDeltaAppsWithRemoteRegionTimer.start();
versionDeltaWithRegions.incrementAndGet();
versionDeltaWithRegionsLegacy.incrementAndGet();
payload = getPayLoad(key,
registry.getApplicationDeltasFromMultipleRegions(key.getRegions()));
} else {
tracer = serializeDeltaAppsTimer.start();
versionDelta.incrementAndGet();
versionDeltaLegacy.incrementAndGet();
payload = getPayLoad(key, registry.getApplicationDeltas());
}
} else {
tracer = serializeOneApptimer.start();
payload = getPayLoad(key, registry.getApplication(key.getName()));
}
break;
case VIP:
case SVIP:
tracer = serializeViptimer.start();
payload = getPayLoad(key, getApplicationsForVip(key, registry));
break;
default:
logger.error("Unidentified entity type: {} found in the cache key.", key.getEntityType());
payload = "";
break;
}
return new Value(payload);
} finally {
if (tracer != null) {
tracer.stop();
}
}
}
The focus of this method is on this sentencepayload = getPayLoad(key, registry.getApplications());
getApplications
public Applications getApplications() {
boolean disableTransparentFallback = serverConfig.disableTransparentFallbackToOtherRegion();
if (disableTransparentFallback) {
return getApplicationsFromLocalRegionOnly();
} else {
return getApplicationsFromAllRemoteRegions(); // Behavior of falling back to remote region can be disabled.
}
}
here will enter the getApplicationsFromLocalRegionOnlymethod
public Applications getApplicationsFromLocalRegionOnly() {
return getApplicationsFromMultipleRegions(EMPTY_STR_ARRAY);
}
public Applications getApplicationsFromMultipleRegions(String[] remoteRegions) {
boolean includeRemoteRegion = null != remoteRegions && remoteRegions.length != 0;
logger.debug("Fetching applications registry with remote regions: {}, Regions argument {}",
includeRemoteRegion, remoteRegions);
if (includeRemoteRegion) {
GET_ALL_WITH_REMOTE_REGIONS_CACHE_MISS.increment();
} else {
GET_ALL_CACHE_MISS.increment();
}
Applications apps = new Applications();
apps.setVersion(1L);
for (Entry<String, Map<String, Lease<InstanceInfo>>> entry : registry.entrySet()) {
Application app = null;
if (entry.getValue() != null) {
for (Entry<String, Lease<InstanceInfo>> stringLeaseEntry : entry.getValue().entrySet()) {
Lease<InstanceInfo> lease = stringLeaseEntry.getValue();
if (app == null) {
app = new Application(lease.getHolder().getAppName());
}
app.addInstance(decorateInstanceInfo(lease));
}
}
if (app != null) {
apps.addApplication(app);
}
}
if (includeRemoteRegion) {
for (String remoteRegion : remoteRegions) {
RemoteRegionRegistry remoteRegistry = regionNameVSRemoteRegistry.get(remoteRegion);
if (null != remoteRegistry) {
Applications remoteApps = remoteRegistry.getApplications();
for (Application application : remoteApps.getRegisteredApplications()) {
if (shouldFetchFromRemoteRegistry(application.getName(), remoteRegion)) {
logger.info("Application {} fetched from the remote region {}",
application.getName(), remoteRegion);
Application appInstanceTillNow = apps.getRegisteredApplications(application.getName());
if (appInstanceTillNow == null) {
appInstanceTillNow = new Application(application.getName());
apps.addApplication(appInstanceTillNow);
}
for (InstanceInfo instanceInfo : application.getInstances()) {
appInstanceTillNow.addInstance(instanceInfo);
}
} else {
logger.debug("Application {} not fetched from the remote region {} as there exists a "
+ "whitelist and this app is not in the whitelist.",
application.getName(), remoteRegion);
}
}
} else {
logger.warn("No remote registry available for the remote region {}", remoteRegion);
}
}
}
apps.setAppsHashCode(apps.getReconcileHashCode());
return apps;
}
The acquisition here is divided into 3 parts:
- In the first for loop, all instance information is obtained according to the lease information of the current server. Each instance information
Applicationis encapsulated by objects, and multiple instances are encapsulatedApplicationbyApplicationsobjects . - The second for loop is to handle the case if a partition is to be obtained in the request
- Set the hashCode of all instances. This hashCode is used to distinguish the returned results during incremental acquisition.
getPayLoadHere is just a code
private String getPayLoad(Key key, Applications apps) {
// 获得编码器
EncoderWrapper encoderWrapper = serverCodecs.getEncoder(key.getType(), key.getEurekaAccept());
String result;
try {
// 编码
result = encoderWrapper.encode(apps);
} catch (Exception e) {
logger.error("Failed to encode the payload for all apps", e);
return "";
}
if(logger.isDebugEnabled()) {
logger.debug("New application cache entry {} with apps hashcode {}", key.toStringCompact(), apps.getAppsHashCode());
}
return result;
}
read-only cache
The read-only cache is refreshed periodically, also in ResponseCacheImplthe constructor of
if (shouldUseReadOnlyResponseCache) {
timer.schedule(getCacheUpdateTask(),
new Date(((System.currentTimeMillis() / responseCacheUpdateIntervalMs) * responseCacheUpdateIntervalMs)
+ responseCacheUpdateIntervalMs),
responseCacheUpdateIntervalMs);
}
This refresh task is like this
private TimerTask getCacheUpdateTask() {
return new TimerTask() {
@Override
public void run() {
logger.debug("Updating the client cache from response cache");
for (Key key : readOnlyCacheMap.keySet()) {
if (logger.isDebugEnabled()) {
logger.debug("Updating the client cache from response cache for key : {} {} {} {}",
key.getEntityType(), key.getName(), key.getVersion(), key.getType());
}
try {
CurrentRequestVersion.set(key.getVersion());
Value cacheValue = readWriteCacheMap.get(key);
Value currentCacheValue = readOnlyCacheMap.get(key);
if (cacheValue != currentCacheValue) {
readOnlyCacheMap.put(key, cacheValue);
}
} catch (Throwable th) {
logger.error("Error while updating the client cache from response cache for key {}", key.toStringCompact(), th);
}
}
}
};
}
Observe the content in the for loop and find that the content of the read-only cache is based on the read-write cache
Incremental pull
The thread scheduling of incremental pulling and the thread scheduling of sending heartbeats initScheduledTasksare executed in one method. The code is as follows:
int registryFetchIntervalSeconds = clientConfig.getRegistryFetchIntervalSeconds();
int expBackOffBound = clientConfig.getCacheRefreshExecutorExponentialBackOffBound();
scheduler.schedule(
new TimedSupervisorTask(
"cacheRefresh",
scheduler,
cacheRefreshExecutor,
registryFetchIntervalSeconds,
TimeUnit.SECONDS,
expBackOffBound,
new CacheRefreshThread()
),
registryFetchIntervalSeconds, TimeUnit.SECONDS);
take a look at the threadCacheRefreshThread
class CacheRefreshThread implements Runnable {
public void run() {
refreshRegistry();
}
}
void refreshRegistry() {
try {
boolean isFetchingRemoteRegionRegistries = isFetchingRemoteRegionRegistries();
boolean remoteRegionsModified = false;
//省略了一部分无关代码
//核心
boolean success = fetchRegistry(remoteRegionsModified);
if (success) {
registrySize = localRegionApps.get().size();
lastSuccessfulRegistryFetchTimestamp = System.currentTimeMillis();
}
if (logger.isDebugEnabled()) {
StringBuilder allAppsHashCodes = new StringBuilder();
allAppsHashCodes.append("Local region apps hashcode: ");
allAppsHashCodes.append(localRegionApps.get().getAppsHashCode());
allAppsHashCodes.append(", is fetching remote regions? ");
allAppsHashCodes.append(isFetchingRemoteRegionRegistries);
for (Map.Entry<String, Applications> entry : remoteRegionVsApps.entrySet()) {
allAppsHashCodes.append(", Remote region: ");
allAppsHashCodes.append(entry.getKey());
allAppsHashCodes.append(" , apps hashcode: ");
allAppsHashCodes.append(entry.getValue().getAppsHashCode());
}
logger.debug("Completed cache refresh task for discovery. All Apps hash code is {} ",
allAppsHashCodes);
}
} catch (Throwable e) {
logger.error("Cannot fetch registry from server", e);
}
}
The core lies in the fetchRegistrymethod, which has been mentioned above, but the interface for partial pull and get calls is getAndUpdateDeltaonly
private void getAndUpdateDelta(Applications applications) throws Throwable {
long currentUpdateGeneration = fetchRegistryGeneration.get();
Applications delta = null;
EurekaHttpResponse<Applications> httpResponse = eurekaTransport.queryClient.getDelta(remoteRegionsRef.get());
if (httpResponse.getStatusCode() == Status.OK.getStatusCode()) {
delta = httpResponse.getEntity();
}
if (delta == null) {
logger.warn("The server does not allow the delta revision to be applied because it is not safe. "
+ "Hence got the full registry.");
getAndStoreFullRegistry();
} else if (fetchRegistryGeneration.compareAndSet(currentUpdateGeneration, currentUpdateGeneration + 1)) {
logger.debug("Got delta update with apps hashcode {}", delta.getAppsHashCode());
String reconcileHashCode = "";
if (fetchRegistryUpdateLock.tryLock()) {
try {
updateDelta(delta);
reconcileHashCode = getReconcileHashCode(applications);
} finally {
fetchRegistryUpdateLock.unlock();
}
} else {
logger.warn("Cannot acquire update lock, aborting getAndUpdateDelta");
}
// There is a diff in number of instances for some reason
if (!reconcileHashCode.equals(delta.getAppsHashCode()) || clientConfig.shouldLogDeltaDiff()) {
reconcileAndLogDifference(delta, reconcileHashCode); // this makes a remoteCall
}
} else {
logger.warn("Not updating application delta as another thread is updating it already");
logger.debug("Ignoring delta update with apps hashcode {}, as another thread is updating it already", delta.getAppsHashCode());
}
}
Let's look at the server-side processing first, and then see how to process the results.
The server handles incremental pulls
@Path("delta")
@GET
public Response getContainerDifferential(
@PathParam("version") String version,
@HeaderParam(HEADER_ACCEPT) String acceptHeader,
@HeaderParam(HEADER_ACCEPT_ENCODING) String acceptEncoding,
@HeaderParam(EurekaAccept.HTTP_X_EUREKA_ACCEPT) String eurekaAccept,
@Context UriInfo uriInfo, @Nullable @QueryParam("regions") String regionsStr) {
boolean isRemoteRegionRequested = null != regionsStr && !regionsStr.isEmpty();
// If the delta flag is disabled in discovery or if the lease expiration
// has been disabled, redirect clients to get all instances
if ((serverConfig.shouldDisableDelta()) || (!registry.shouldAllowAccess(isRemoteRegionRequested))) {
return Response.status(Status.FORBIDDEN).build();
}
String[] regions = null;
if (!isRemoteRegionRequested) {
EurekaMonitors.GET_ALL_DELTA.increment();
} else {
regions = regionsStr.toLowerCase().split(",");
Arrays.sort(regions); // So we don't have different caches for same regions queried in different order.
EurekaMonitors.GET_ALL_DELTA_WITH_REMOTE_REGIONS.increment();
}
CurrentRequestVersion.set(Version.toEnum(version));
KeyType keyType = Key.KeyType.JSON;
String returnMediaType = MediaType.APPLICATION_JSON;
if (acceptHeader == null || !acceptHeader.contains(HEADER_JSON_VALUE)) {
keyType = Key.KeyType.XML;
returnMediaType = MediaType.APPLICATION_XML;
}
Key cacheKey = new Key(Key.EntityType.Application,
ResponseCacheImpl.ALL_APPS_DELTA,
keyType, CurrentRequestVersion.get(), EurekaAccept.fromString(eurekaAccept), regions
);
if (acceptEncoding != null
&& acceptEncoding.contains(HEADER_GZIP_VALUE)) {
return Response.ok(responseCache.getGZIP(cacheKey))
.header(HEADER_CONTENT_ENCODING, HEADER_GZIP_VALUE)
.header(HEADER_CONTENT_TYPE, returnMediaType)
.build();
} else {
return Response.ok(responseCache.get(cacheKey))
.build();
}
}
The processing logic here is the same as most of the logic for full acquisition, with only a few differences:
- hashKey是ApplicationALL_APPS_DELTAJSONV2full
- When getting the instance list, the following branch is taken
if (ALL_APPS.equals(key.getName())) {
if (isRemoteRegionRequested) {
tracer = serializeAllAppsWithRemoteRegionTimer.start();
payload = getPayLoad(key, registry.getApplicationsFromMultipleRegions(key.getRegions()));
} else {
tracer = serializeAllAppsTimer.start();
payload = getPayLoad(key, registry.getApplications());
}
} else if (ALL_APPS_DELTA.equals(key.getName())) {
if (isRemoteRegionRequested) {
tracer = serializeDeltaAppsWithRemoteRegionTimer.start();
versionDeltaWithRegions.incrementAndGet();
versionDeltaWithRegionsLegacy.incrementAndGet();
payload = getPayLoad(key,
registry.getApplicationDeltasFromMultipleRegions(key.getRegions()));
} else {
tracer = serializeDeltaAppsTimer.start();
versionDelta.incrementAndGet();
versionDeltaLegacy.incrementAndGet();
payload = getPayLoad(key, registry.getApplicationDeltas());
}
}
getApplicationDeltasLet's see how
public Applications getApplicationDeltas() {
GET_ALL_CACHE_MISS_DELTA.increment();
Applications apps = new Applications();
apps.setVersion(responseCache.getVersionDelta().get());
Map<String, Application> applicationInstancesMap = new HashMap<String, Application>();
try {
write.lock();
Iterator<RecentlyChangedItem> iter = this.recentlyChangedQueue.iterator();
logger.debug("The number of elements in the delta queue is : {}",
this.recentlyChangedQueue.size());
while (iter.hasNext()) {
Lease<InstanceInfo> lease = iter.next().getLeaseInfo();
InstanceInfo instanceInfo = lease.getHolder();
logger.debug(
"The instance id {} is found with status {} and actiontype {}",
instanceInfo.getId(), instanceInfo.getStatus().name(), instanceInfo.getActionType().name());
Application app = applicationInstancesMap.get(instanceInfo
.getAppName());
if (app == null) {
app = new Application(instanceInfo.getAppName());
applicationInstancesMap.put(instanceInfo.getAppName(), app);
apps.addApplication(app);
}
app.addInstance(decorateInstanceInfo(lease));
}
boolean disableTransparentFallback = serverConfig.disableTransparentFallbackToOtherRegion();
if (!disableTransparentFallback) {
Applications allAppsInLocalRegion = getApplications(false);
for (RemoteRegionRegistry remoteRegistry : this.regionNameVSRemoteRegistry.values()) {
Applications applications = remoteRegistry.getApplicationDeltas();
for (Application application : applications.getRegisteredApplications()) {
Application appInLocalRegistry =
allAppsInLocalRegion.getRegisteredApplications(application.getName());
if (appInLocalRegistry == null) {
apps.addApplication(application);
}
}
}
}
Applications allApps = getApplications(!disableTransparentFallback);
apps.setAppsHashCode(allApps.getReconcileHashCode());
return apps;
} finally {
write.unlock();
}
}
Unlike the full acquisition, the final result is from the recent lease change record queue recentlyChangedQueue, and the other processes are similar
Handling incremental pull results
result processing code
if (delta == null) {
logger.warn("The server does not allow the delta revision to be applied because it is not safe. "
+ "Hence got the full registry.");
getAndStoreFullRegistry();
} else if (fetchRegistryGeneration.compareAndSet(currentUpdateGeneration, currentUpdateGeneration + 1)) {
logger.debug("Got delta update with apps hashcode {}", delta.getAppsHashCode());
String reconcileHashCode = "";
if (fetchRegistryUpdateLock.tryLock()) {
try {
updateDelta(delta);
reconcileHashCode = getReconcileHashCode(applications);
} finally {
fetchRegistryUpdateLock.unlock();
}
} else {
logger.warn("Cannot acquire update lock, aborting getAndUpdateDelta");
}
// There is a diff in number of instances for some reason
if (!reconcileHashCode.equals(delta.getAppsHashCode()) || clientConfig.shouldLogDeltaDiff()) {
reconcileAndLogDifference(delta, reconcileHashCode); // this makes a remoteCall
}
}
updateDelta
private void updateDelta(Applications delta) {
int deltaCount = 0;
for (Application app : delta.getRegisteredApplications()) {
for (InstanceInfo instance : app.getInstances()) {
Applications applications = getApplications();
String instanceRegion = instanceRegionChecker.getInstanceRegion(instance);
if (!instanceRegionChecker.isLocalRegion(instanceRegion)) {
Applications remoteApps = remoteRegionVsApps.get(instanceRegion);
if (null == remoteApps) {
remoteApps = new Applications();
remoteRegionVsApps.put(instanceRegion, remoteApps);
}
applications = remoteApps;
}
++deltaCount;
if (ActionType.ADDED.equals(instance.getActionType())) {
Application existingApp = applications.getRegisteredApplications(instance.getAppName());
if (existingApp == null) {
applications.addApplication(app);
}
logger.debug("Added instance {} to the existing apps in region {}", instance.getId(), instanceRegion);
applications.getRegisteredApplications(instance.getAppName()).addInstance(instance);
} else if (ActionType.MODIFIED.equals(instance.getActionType())) {
Application existingApp = applications.getRegisteredApplications(instance.getAppName());
if (existingApp == null) {
applications.addApplication(app);
}
logger.debug("Modified instance {} to the existing apps ", instance.getId());
applications.getRegisteredApplications(instance.getAppName()).addInstance(instance);
} else if (ActionType.DELETED.equals(instance.getActionType())) {
Application existingApp = applications.getRegisteredApplications(instance.getAppName());
if (existingApp == null) {
applications.addApplication(app);
}
logger.debug("Deleted instance {} to the existing apps ", instance.getId());
applications.getRegisteredApplications(instance.getAppName()).removeInstance(instance);
}
}
}
logger.debug("The total number of instances fetched by the delta processor : {}", deltaCount);
getApplications().setVersion(delta.getVersion());
getApplications().shuffleInstances(clientConfig.shouldFilterOnlyUpInstances());
for (Applications applications : remoteRegionVsApps.values()) {
applications.setVersion(delta.getVersion());
applications.shuffleInstances(clientConfig.shouldFilterOnlyUpInstances());
}
}
The general processing flow is:
- Get local cache instance
- If there is no partition of the remotely pulled instance
remoteRegionVsApps, create a new partition key in the object - Update the local instance state according to the state of the remote instance (add, modify, delete)
- instance filtering
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