Shulou(Shulou.com)06/02 Report--

This article introduces what is the role of ReferenceCountedACLCache in zk, the content is very detailed, interested friends can refer to, hope to be helpful to you.

Function: complete the conversion between LIst and Long. Acl in DataNode is a long value, not an ACL list.

Spatial complexity: inner class AtomicLongWithEquals

Attributes:

/ / log information private static final Logger LOG = LoggerFactory.getLogger (ReferenceCountedACLCache.class); / / long ACL list correspondence final Map longKeyMap = new HashMap (); / / ACL list long correspondence final Map aclKeyMap = new HashMap (); final Map referenceCounter = new HashMap (); private static final long OPEN_UNSAFE_ACL_ID =-1L * * these are the number of acls that we have in the datatree * / long aclIndex = 0

Methods:

Record the number of references

Private static class AtomicLongWithEquals extends AtomicLong {private static final long serialVersionUID = 3355155896813725462L; public AtomicLongWithEquals (long I) {super (I);} @ Override public boolean equals (Object o) {if (this = = o) {return true;} if (o = = null | | getClass ()! = o.getClass ()) {return false;} return equals ((AtomicLongWithEquals) o) } public boolean equals (AtomicLongWithEquals that) {return get () = = that.get ();} @ Override public int hashCode () {return 31 * Long.valueOf (get ()). HashCode ();}} add use public synchronized void addUsage (Long acl) {if (acl = = OPEN_UNSAFE_ACL_ID) {return } if (! longKeyMap.containsKey (acl)) {LOG.info ("Ignoring acl" + acl + "as it does not exist in the cache"); return;} AtomicLong count = referenceCounter.get (acl); if (count = = null) {referenceCounter.put (acl, new AtomicLongWithEquals (1));} else {count.incrementAndGet () }} / / remove reference public synchronized void removeUsage (Long acl) {if (acl = = OPEN_UNSAFE_ACL_ID) {return;} if (! longKeyMap.containsKey (acl)) {LOG.info ("Ignoring acl" + acl + "as it does not exist in the cache"); return;} long newCount = referenceCounter.get (acl). DecrementAndGet (); if (newCount)

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