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获取连接时序图
![](https://img.haomeiwen.com/i6425503/e55860800fce4f93.png)
初始化代码
HikariDataSource ds = new HikariDataSource();
ds.setJdbcUrl("jdbc:mysql://localhost:3306/test");
ds.setUsername("xx");
ds.setPassword("xxx");
...
getConnection()
@Override
public Connection getConnection() throws SQLException
{
if (isClosed()) {
throw new SQLException("HikariDataSource " + this + " has been closed.");
}
if (fastPathPool != null) {
return fastPathPool.getConnection();
}
// See http://en.wikipedia.org/wiki/Double-checked_locking#Usage_in_Java
HikariPool result = pool;
if (result == null) {
synchronized (this) {
result = pool;
if (result == null) {
validate();
LOGGER.info("{} - Starting...", getPoolName());
try {
pool = result = new HikariPool(this);
this.seal();
}
catch (PoolInitializationException pie) {
if (pie.getCause() instanceof SQLException) {
throw (SQLException) pie.getCause();
}
else {
throw pie;
}
}
LOGGER.info("{} - Start completed.", getPoolName());
}
}
}
return result.getConnection();
}
HikariPool 使用双重检查加锁初始化
具体的获取连接在HikarPool实现
public Connection getConnection() throws SQLException
{
return getConnection(connectionTimeout);
}
public Connection getConnection(final long hardTimeout) throws SQLException
{
suspendResumeLock.acquire();
final long startTime = currentTime();
try {
long timeout = hardTimeout;
do {
PoolEntry poolEntry = connectionBag.borrow(timeout, MILLISECONDS);
if (poolEntry == null) {
break; // We timed out... break and throw exception
}
final long now = currentTime();
if (poolEntry.isMarkedEvicted() || (elapsedMillis(poolEntry.lastAccessed, now) > aliveBypassWindowMs && !isConnectionAlive(poolEntry.connection))) {
closeConnection(poolEntry, poolEntry.isMarkedEvicted() ? EVICTED_CONNECTION_MESSAGE : DEAD_CONNECTION_MESSAGE);
timeout = hardTimeout - elapsedMillis(startTime);
}
else {
metricsTracker.recordBorrowStats(poolEntry, startTime);
return poolEntry.createProxyConnection(leakTaskFactory.schedule(poolEntry), now);
}
} while (timeout > 0L);
metricsTracker.recordBorrowTimeoutStats(startTime);
throw createTimeoutException(startTime);
}
catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new SQLException(poolName + " - Interrupted during connection acquisition", e);
}
finally {
suspendResumeLock.release();
}
}
connectionTimeout 获取连接的最大等待时间
从connectionBag借用连接,判断连接的有效性 如果无效连接则关闭连接
如果连接有效,通过ProxyFactory创建物理连接和poolEntry对应
poolEntry.createProxyConnection(leakTaskFactory.schedule(poolEntry), now);实现:
Connection createProxyConnection(final ProxyLeakTask leakTask, final long now)
{
return ProxyFactory.getProxyConnection(this, connection, openStatements, leakTask, now, isReadOnly, isAutoCommit);
}
static ProxyConnection getProxyConnection(final PoolEntry poolEntry,
final Connection connection,
final FastList<Statement> openStatements,
final ProxyLeakTask leakTask,
final long now,
final boolean isReadOnly,
final boolean isAutoCommit)
{
// Body is replaced (injected) by JavassistProxyFactory
throw new IllegalStateException("You need to run the CLI build and you need target/classes in your classpath to run.");
}
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