聊聊artemis的ClientProducerCreditManager
序
本文主要研究一下artemis的ClientProducerCreditManager
ClientProducerCreditManager
activemq-artemis-2.11.0/artemis-core-client/src/main/java/org/apache/activemq/artemis/core/client/impl/ClientProducerCreditManager.java
public interface ClientProducerCreditManager { ClientProducerCredits getCredits(SimpleString address, boolean anon, SessionContext context);
void returnCredits(SimpleString address);
void receiveCredits(SimpleString address, int credits);
void receiveFailCredits(SimpleString address, int credits);
void reset();
void close();
int creditsMapSize();
int unReferencedCreditsSize();
/** This will determine the flow control as asynchronous,
* no actual block should happen instead a callback will be sent whenever blockages change */
void setCallback(ClientProducerFlowCallback callback);
}
- ClientProducerCreditManager接口定义了getCredits、returnCredits、receiveCredits、receiveFailCredits、reset、close、creditsMapSize、unReferencedCreditsSize、setCallback方法
ClientProducerCreditManagerImpl
activemq-artemis-2.11.0/artemis-core-client/src/main/java/org/apache/activemq/artemis/core/client/impl/ClientProducerCreditManagerImpl.java
public class ClientProducerCreditManagerImpl implements ClientProducerCreditManager { public static final int MAX_UNREFERENCED_CREDITS_CACHE_SIZE = 1000;
private final Map<SimpleString, ClientProducerCredits> producerCredits = new LinkedHashMap<>();
private final Map<SimpleString, ClientProducerCredits> unReferencedCredits = new LinkedHashMap<>();
private final ClientSessionInternal session;
private int windowSize;
private ClientProducerFlowCallback callback;
public ClientProducerCreditManagerImpl(final ClientSessionInternal session, final int windowSize) {
this.session = session;
this.windowSize = windowSize;
}
/** This will determine the flow control as asynchronous,
* no actual block should happen instead a callback will be sent whenever blockages change */
@Override
public void setCallback(ClientProducerFlowCallback callback) {
this.callback = callback;
}
@Override
public synchronized ClientProducerCredits getCredits(final SimpleString address,
final boolean anon,
SessionContext context) {
if (windowSize == -1) {
return ClientProducerCreditsNoFlowControl.instance;
} else {
boolean needInit = false;
ClientProducerCredits credits;
synchronized (this) {
credits = producerCredits.get(address);
if (credits == null) {
// Doesn"t need to be fair since session is single threaded
credits = build(address);
needInit = true;
producerCredits.put(address, credits);
}
if (!anon) {
credits.incrementRefCount();
// Remove from anon credits (if there)
unReferencedCredits.remove(address);
} else {
addToUnReferencedCache(address, credits);
}
}
// The init is done outside of the lock
// otherwise packages may arrive with flow control
// while this is still sending requests causing a dead lock
if (needInit) {
credits.init(context);
}
return credits;
}
}
private ClientProducerCredits build(SimpleString address) {
if (callback != null) {
return new AsynchronousProducerCreditsImpl(session, address, windowSize, callback);
} else {
return new ClientProducerCreditsImpl(session, address, windowSize);
}
}
@Override
public synchronized void returnCredits(final SimpleString address) {
ClientProducerCredits credits = producerCredits.get(address);
if (credits != null && credits.decrementRefCount() == 0) {
addToUnReferencedCache(address, credits);
}
}
@Override
public synchronized void receiveCredits(final SimpleString address, final int credits) {
ClientProducerCredits cr = producerCredits.get(address);
if (cr != null) {
cr.receiveCredits(credits);
}
}
@Override
public synchronized void receiveFailCredits(final SimpleString address, int credits) {
ClientProducerCredits cr = producerCredits.get(address);
if (cr != null) {
cr.receiveFailCredits(credits);
}
}
@Override
public synchronized void reset() {
for (ClientProducerCredits credits : producerCredits.values()) {
credits.reset();
}
}
@Override
public synchronized void close() {
windowSize = -1;
for (ClientProducerCredits credits : producerCredits.values()) {
credits.close();
}
producerCredits.clear();
unReferencedCredits.clear();
}
@Override
public synchronized int creditsMapSize() {
return producerCredits.size();
}
@Override
public synchronized int unReferencedCreditsSize() {
return unReferencedCredits.size();
}
private void addToUnReferencedCache(final SimpleString address, final ClientProducerCredits credits) {
unReferencedCredits.put(address, credits);
if (unReferencedCredits.size() > MAX_UNREFERENCED_CREDITS_CACHE_SIZE) {
// Remove the oldest entry
Iterator<Map.Entry<SimpleString, ClientProducerCredits>> iter = unReferencedCredits.entrySet().iterator();
Map.Entry<SimpleString, ClientProducerCredits> oldest = iter.next();
iter.remove();
removeEntry(oldest.getKey(), oldest.getValue());
}
}
private void removeEntry(final SimpleString address, final ClientProducerCredits credits) {
producerCredits.remove(address);
credits.releaseOutstanding();
credits.close();
}
//......
}
- ClientProducerCreditManagerImpl实现了ClientProducerCreditManager接口，它的构造器接收session及windowSize参数；其getCredits方法在windowSize为-1时返回ClientProducerCreditsNoFlowControl.instance，否则根据address从producerCredits获取或创建ClientProducerCredits，若是新建的则needInit为true会执行credits.init(context)
- returnCredits方法从producerCredits获取ClientProducerCredits，然后递减refCount，若为0则执行addToUnReferencedCache；receiveCredits方法从producerCredits获取ClientProducerCredits，然后执行cr.receiveCredits(credits)；receiveFailCredits方法从producerCredits获取ClientProducerCredits，然后执行cr.receiveFailCredits(credits)
- reset方法遍历producerCredits.values()挨个执行ClientProducerCredits的reset方法；close方法遍历producerCredits.values()挨个执行ClientProducerCredits的close方法，然后清空producerCredits、unReferencedCredits
ClientProducerCreditsNoFlowControl
activemq-artemis-2.11.0/artemis-core-client/src/main/java/org/apache/activemq/artemis/core/client/impl/ClientProducerCreditManagerImpl.java
static class ClientProducerCreditsNoFlowControl implements ClientProducerCredits { static ClientProducerCreditsNoFlowControl instance = new ClientProducerCreditsNoFlowControl();
@Override
public void acquireCredits(int credits) {
}
@Override
public void receiveCredits(int credits) {
}
@Override
public void receiveFailCredits(int credits) {
}
@Override
public boolean isBlocked() {
return false;
}
@Override
public void init(SessionContext ctx) {
}
@Override
public void reset() {
}
@Override
public void close() {
}
@Override
public void incrementRefCount() {
}
@Override
public int decrementRefCount() {
return 1;
}
@Override
public void releaseOutstanding() {
}
@Override
public SimpleString getAddress() {
return SimpleString.toSimpleString("");
}
}
- ClientProducerCreditsNoFlowControl实现了ClientProducerCredits接口，其isBlocked方法返回false，decrementRefCount方法返回1，getAddress方法返回SimpleString.toSimpleString("")，其余方法都是空操作
小结
ClientProducerCreditManager接口定义了getCredits、returnCredits、receiveCredits、receiveFailCredits、reset、close、creditsMapSize、unReferencedCreditsSize、setCallback方法
doc
- ClientProducerCreditManager
以上是 聊聊artemis的ClientProducerCreditManager 的全部内容， 来源链接： utcz.com/z/512691.html
