com.github.ambry.account

Class HelixAccountService

java.lang.Object

com.github.ambry.account.HelixAccountService

All Implemented Interfaces:

com.github.ambry.account.AccountService, java.io.Closeable, java.lang.AutoCloseable

public class HelixAccountService
extends java.lang.Object
implements com.github.ambry.account.AccountService

An implementation of AccountService that employs a HelixPropertyStore as its underlying storage. It's in the middle of transitioning from using old helix path to the new path. In old way, it internally stores the full set of Account metadata in a store-relative path defined in LegacyMetadataStore. In the new way, it internally stores the list of blob ids that point to different versions of Account metadata. In both way, the latest full Account metadata will be cached locally, so serving an Account query will not incur any calls to remote ZooKeeper or AmbryServer.

After transition, this implementation would not only save the latest set of Account metadata, but also save several previous versions. It keeps a list of blob ids in HelixPropertyStore and remove the earliest one when it reaches the limit of the version numbers. There are several benefits from this approach.

• Reverting changes would be much easier.
• There will no be size limit for Account metadata

When a HelixAccountService starts up, it will automatically fetch a full set of Account metadata and store them in its local cache. It also takes a Notifier, and subscribes to a ACCOUNT_METADATA_CHANGE_TOPIC. Each time when receiving a FULL_ACCOUNT_METADATA_CHANGE_MESSAGE, it will fetch the updated full Account metadata, and refresh its local cache. After every successful operation for updating a collection of Accounts, it publishes a FULL_ACCOUNT_METADATA_CHANGE_MESSAGE for ACCOUNT_METADATA_CHANGE_TOPIC through the Notifier. If the remote Account metadata is corrupted or has conflict, HelixAccountService will not update its local cache.

The full set of the Account metadata are stored in a single ZNRecord or a single blob in the new way, as a simple map from a string account id to the Account content in json as a string.

Limited by HelixPropertyStore, the total size of Account data stored on a single ZNRecord cannot exceed 1MB before the transition.

Field Summary

Fields

Modifier and Type	Field and Description
protected java.util.concurrent.atomic.AtomicReference<com.github.ambry.account.AccountInfoMap>	accountInfoMapRef
protected AccountServiceMetrics	accountServiceMetrics
protected java.util.concurrent.locks.ReentrantLock	lock
protected java.util.concurrent.atomic.AtomicBoolean	open

Method Summary

Modifier and Type	Method and Description
boolean	addAccountUpdateConsumer(java.util.function.Consumer<java.util.Collection<com.github.ambry.account.Account>> accountUpdateConsumer)
protected void	checkOpen() Ensures the account service is ready to process requests.
void	close()
com.github.ambry.account.Account	getAccountById(short id)
com.github.ambry.account.Account	getAccountByName(java.lang.String accountName)
java.util.Collection<com.github.ambry.account.Account>	getAllAccounts()
protected void	notifyAccountUpdateConsumers(com.github.ambry.account.AccountInfoMap newAccountInfoMap, com.github.ambry.account.AccountInfoMap oldAccountInfoMap, boolean isCalledFromListener) Logs and notifies account update Consumers about any new account changes/creations.
boolean	removeAccountUpdateConsumer(java.util.function.Consumer<java.util.Collection<com.github.ambry.account.Account>> accountUpdateConsumer)
void	setupRouter(com.github.ambry.router.Router router) set the router to the given one.
boolean	updateAccounts(java.util.Collection<com.github.ambry.account.Account> accounts)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.github.ambry.account.AccountService

addAccountUpdateConsumer, getAccountById, getAccountByName, getAllAccounts, getContainersByStatus, removeAccountUpdateConsumer

Field Detail

open

protected final java.util.concurrent.atomic.AtomicBoolean open

accountInfoMapRef

protected final java.util.concurrent.atomic.AtomicReference<com.github.ambry.account.AccountInfoMap> accountInfoMapRef

lock

protected final java.util.concurrent.locks.ReentrantLock lock

accountServiceMetrics

protected final AccountServiceMetrics accountServiceMetrics

Method Detail

setupRouter

public void setupRouter(com.github.ambry.router.Router router)
                 throws java.lang.IllegalStateException

set the router to the given one. This is a blocking call. This function would block until it fetches the Account metadata from ambry server.

Parameters:

router - The router to set.

Throws:

java.lang.IllegalStateException - when the router already set up.

updateAccounts

public boolean updateAccounts(java.util.Collection<com.github.ambry.account.Account> accounts)

This call is blocking until it completes the operation of updating account metadata to HelixPropertyStore.

There is a slight chance that an Account could be updated successfully, but its value was set based on an outdated Account. This can be fixed after generationId is introduced to Account.

Specified by:

updateAccounts in interface com.github.ambry.account.AccountService

close

public void close()

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

checkOpen

protected void checkOpen()

Ensures the account service is ready to process requests. Throws an unchecked exception (for example IllegalStateException) if the account service is not ready to process requests.

getAccountByName

public com.github.ambry.account.Account getAccountByName(java.lang.String accountName)

Specified by:

getAccountByName in interface com.github.ambry.account.AccountService

getAccountById

public com.github.ambry.account.Account getAccountById(short id)

Specified by:

getAccountById in interface com.github.ambry.account.AccountService

getAllAccounts

public java.util.Collection<com.github.ambry.account.Account> getAllAccounts()

Specified by:

getAllAccounts in interface com.github.ambry.account.AccountService

addAccountUpdateConsumer

public boolean addAccountUpdateConsumer(java.util.function.Consumer<java.util.Collection<com.github.ambry.account.Account>> accountUpdateConsumer)

Specified by:

addAccountUpdateConsumer in interface com.github.ambry.account.AccountService

removeAccountUpdateConsumer

public boolean removeAccountUpdateConsumer(java.util.function.Consumer<java.util.Collection<com.github.ambry.account.Account>> accountUpdateConsumer)

Specified by:

removeAccountUpdateConsumer in interface com.github.ambry.account.AccountService

notifyAccountUpdateConsumers

protected void notifyAccountUpdateConsumers(com.github.ambry.account.AccountInfoMap newAccountInfoMap,
                                            com.github.ambry.account.AccountInfoMap oldAccountInfoMap,
                                            boolean isCalledFromListener)

Logs and notifies account update Consumers about any new account changes/creations.

Parameters:

newAccountInfoMap - the new AccountInfoMap that has been set.

oldAccountInfoMap - the AccountInfoMap that was cached before this change.

isCalledFromListener - true if the caller is the account update listener, otherwise.