private E getPoolEntryBlocking( final T route, final Object state, final long timeout, final TimeUnit tunit, final PoolEntryFuture<E> future) throws IOException, InterruptedException, TimeoutException { Date deadline = null; if (timeout > 0) { deadline = new Date (System.currentTimeMillis() + tunit.toMillis(timeout)); } this.lock.lock(); try { final RouteSpecificPool<T, C, E> pool = getPool(route);//这是每一个路由细分出来的连接池 E entry = null; while (entry == null) { Asserts.check(!this.isShutDown, "Connection pool shut down"); //从池子中获取一个可用连接并返回 for (;;) { entry = pool.getFree(state); if (entry == null) { break; } if (entry.isExpired(System.currentTimeMillis())) { entry.close(); } else if (this.validateAfterInactivity > 0) { if (entry.getUpdated() + this.validateAfterInactivity <= System.currentTimeMillis()) { if (!validate(entry)) { entry.close(); } } } if (entry.isClosed()) { this.available.remove(entry); pool.free(entry, false); } else { break; } } if (entry != null) { this.available.remove(entry); this.leased.add(entry); onReuse(entry); return entry; } //创建新的连接 // New connection is needed final int maxPerRoute = getMax(route);//获取当前路由最大并发数 // Shrink the pool prior to allocating a new connection final int excess = Math.max(0, pool.getAllocatedCount() + 1 - maxPerRoute); if (excess > 0) {//如果当前路由对应的连接池的连接超过最大路由并发数，获取到最后使用的一次连接，释放掉 for (int i = 0; i < excess; i++) { final E lastUsed = pool.getLastUsed(); if (lastUsed == null) { break; } lastUsed.close(); this.available.remove(lastUsed); pool.remove(lastUsed); } } //尝试创建新的连接 if (pool.getAllocatedCount() < maxPerRoute) {//当前路由对应的连接池可用空闲连接数+当前路由对应的连接池已用连接数 < 当前路由对应的连接池最大并发数 final int totalUsed = this.leased.size(); final int freeCapacity = Math.max(this.maxTotal - totalUsed, 0); if (freeCapacity > 0) { final int totalAvailable = this.available.size(); if (totalAvailable > freeCapacity - 1) {//线程池中可用空闲连接数 > (线程池中最大连接数 - 线程池中已用连接数 - 1) if (!this.available.isEmpty()) { final E lastUsed = this.available.removeLast(); lastUsed.close(); final RouteSpecificPool<T, C, E> otherpool = getPool(lastUsed.getRoute()); otherpool.remove(lastUsed); } } final C conn = this.connFactory.create(route); entry = pool.add(conn); this.leased.add(entry); return entry; } } boolean success = false; try { pool.queue(future); this.pending.add(future); success = future.await(deadline); } finally { // In case of ‘success‘, we were woken up by the // connection pool and should now have a connection // waiting for us, or else we‘re shutting down. // Just continue in the loop, both cases are checked. pool.unqueue(future); this.pending.remove(future); } // check for spurious wakeup vs. timeout if (!success && (deadline != null) && (deadline.getTime() <= System.currentTimeMillis())) { break; } } throw new TimeoutException("Timeout waiting for connection"); } finally { this.lock.unlock(); } }