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本文主要研究一下druid的return行为
close
com/alibaba/druid/pool/DruidPooledConnection.java
代码语言：javascript复制 @Override
public void close() throws SQLException {
if (this.disable) {
return;
}
DruidConnectionHolder holder = this.holder;
if (holder == null) {
if (dupCloseLogEnable) {
LOG.error("dup close");
}
return;
}
DruidAbstractDataSource dataSource = holder.getDataSource();
boolean isSameThread = this.getOwnerThread() == Thread.currentThread();
if (!isSameThread) {
dataSource.setAsyncCloseConnectionEnable(true);
}
if (dataSource.isAsyncCloseConnectionEnable()) {
syncClose();
return;
}
if (!CLOSING_UPDATER.compareAndSet(this, 0, 1)) {
return;
}
try {
for (ConnectionEventListener listener : holder.getConnectionEventListeners()) {
listener.connectionClosed(new ConnectionEvent(this));
}
List<Filter> filters = dataSource.getProxyFilters();
if (filters.size() > 0) {
FilterChainImpl filterChain = new FilterChainImpl(dataSource);
filterChain.dataSource_recycle(this);
} else {
recycle();
}
} finally {
CLOSING_UPDATER.set(this, 0);
}
this.disable = true;
}close方法先从holder获取当前的dataSource，然后判断ownerThread，若不是同一个线程则设置asyncCloseConnectionEnable为true，若asyncCloseConnectionEnable为true则执行syncClose(
这里语义貌似相反)，否则执行recycle方法
syncClose
com/alibaba/druid/pool/DruidPooledConnection.java
代码语言：javascript复制 public void syncClose() throws SQLException {
lock.lock();
try {
if (this.disable || CLOSING_UPDATER.get(this) != 0) {
return;
}
DruidConnectionHolder holder = this.holder;
if (holder == null) {
if (dupCloseLogEnable) {
LOG.error("dup close");
}
return;
}
if (!CLOSING_UPDATER.compareAndSet(this, 0, 1)) {
return;
}
for (ConnectionEventListener listener : holder.getConnectionEventListeners()) {
listener.connectionClosed(new ConnectionEvent(this));
}
DruidAbstractDataSource dataSource = holder.getDataSource();
List<Filter> filters = dataSource.getProxyFilters();
if (filters.size() > 0) {
FilterChainImpl filterChain = new FilterChainImpl(dataSource);
filterChain.dataSource_recycle(this);
} else {
recycle();
}
this.disable = true;
} finally {
CLOSING_UPDATER.set(this, 0);
lock.unlock();
}
}syncClose方法主要是加锁执行recycle
recycle
代码语言：javascript复制 public void recycle() throws SQLException {
if (this.disable) {
return;
}
DruidConnectionHolder holder = this.holder;
if (holder == null) {
if (dupCloseLogEnable) {
LOG.error("dup close");
}
return;
}
if (!this.abandoned) {
DruidAbstractDataSource dataSource = holder.getDataSource();
dataSource.recycle(this);
}
this.holder = null;
conn = null;
transactionInfo = null;
closed = true;
}recycle方法主要是执行dataSource.recycle(this)
DruidDataSource.recycle
com/alibaba/druid/pool/DruidDataSource.java
代码语言：javascript复制 protected void recycle(DruidPooledConnection pooledConnection) throws SQLException {
final DruidConnectionHolder holder = pooledConnection.holder;
if (holder == null) {
LOG.warn("connectionHolder is null");
return;
}
if (logDifferentThread //
&& (!isAsyncCloseConnectionEnable()) //
&& pooledConnection.ownerThread != Thread.currentThread()//
) {
LOG.warn("get/close not same thread");
}
final Connection physicalConnection = holder.conn;
if (pooledConnection.traceEnable) {
Object oldInfo = null;
activeConnectionLock.lock();
try {
if (pooledConnection.traceEnable) {
oldInfo = activeConnections.remove(pooledConnection);
pooledConnection.traceEnable = false;
}
} finally {
activeConnectionLock.unlock();
}
if (oldInfo == null) {
if (LOG.isWarnEnabled()) {
LOG.warn("remove abandonded failed. activeConnections.size " activeConnections.size());
}
}
}
final boolean isAutoCommit = holder.underlyingAutoCommit;
final boolean isReadOnly = holder.underlyingReadOnly;
final boolean testOnReturn = this.testOnReturn;
try {
// check need to rollback?
if ((!isAutoCommit) && (!isReadOnly)) {
pooledConnection.rollback();
}
// reset holder, restore default settings, clear warnings
boolean isSameThread = pooledConnection.ownerThread == Thread.currentThread();
if (!isSameThread) {
final ReentrantLock lock = pooledConnection.lock;
lock.lock();
try {
holder.reset();
} finally {
lock.unlock();
}
} else {
holder.reset();
}
if (holder.discard) {
return;
}
if (phyMaxUseCount > 0 && holder.useCount >= phyMaxUseCount) {
discardConnection(holder);
return;
}
if (physicalConnection.isClosed()) {
lock.lock();
try {
if (holder.active) {
activeCount--;
holder.active = false;
}
closeCount ;
} finally {
lock.unlock();
}
return;
}
if (testOnReturn) {
boolean validate = testConnectionInternal(holder, physicalConnection);
if (!validate) {
JdbcUtils.close(physicalConnection);
destroyCountUpdater.incrementAndGet(this);
lock.lock();
try {
if (holder.active) {
activeCount--;
holder.active = false;
}
closeCount ;
} finally {
lock.unlock();
}
return;
}
}
if (holder.initSchema != null) {
holder.conn.setSchema(holder.initSchema);
holder.initSchema = null;
}
if (!enable) {
discardConnection(holder);
return;
}
boolean result;
final long currentTimeMillis = System.currentTimeMillis();
if (phyTimeoutMillis > 0) {
long phyConnectTimeMillis = currentTimeMillis - holder.connectTimeMillis;
if (phyConnectTimeMillis > phyTimeoutMillis) {
discardConnection(holder);
return;
}
}
lock.lock();
try {
if (holder.active) {
activeCount--;
holder.active = false;
}
closeCount ;
result = putLast(holder, currentTimeMillis);
recycleCount ;
} finally {
lock.unlock();
}
if (!result) {
JdbcUtils.close(holder.conn);
LOG.info("connection recyle failed.");
}
} catch (Throwable e) {
holder.clearStatementCache();
if (!holder.discard) {
discardConnection(holder);
holder.discard = true;
}
LOG.error("recyle error", e);
recycleErrorCountUpdater.incrementAndGet(this);
}
}
boolean putLast(DruidConnectionHolder e, long lastActiveTimeMillis) {
if (poolingCount >= maxActive || e.discard || this.closed) {
return false;
}
e.lastActiveTimeMillis = lastActiveTimeMillis;
connections[poolingCount] = e;
incrementPoolingCount();
if (poolingCount > poolingPeak) {
poolingPeak = poolingCount;
poolingPeakTime = lastActiveTimeMillis;
}
notEmpty.signal();
notEmptySignalCount ;
return true;
}recycle方法先执行DruidConnectionHolder的reset方法，之后针对大于等于phyMaxUseCount的场景执行discardConnection；针对testOnReturn为true，则执行testConnectionInternal校验，校验失败则关闭连接；最后加锁执行putLast把连接放回连接池，若归还失败则关闭连接。
小结
close方法先从holder获取当前的dataSource，然后判断ownerThread，若不是同一个线程则设置asyncCloseConnectionEnable为true，若asyncCloseConnectionEnable为true则执行syncClose(这里语义貌似相反)，否则执行recycle方法。
