public Connection borrowConnection(long timeout, TimeUnit unit)
throws ConnectionException, TimeoutException {
if (isShutdown.get())
// Note: throwing a ConnectionException is probably fine in practice as it will trigger the
// creation of a new host.
// That being said, maybe having a specific exception could be cleaner.
throw new ConnectionException(host.getAddress(), "Pool is shutdown");
if (connections.isEmpty()) {
for (int i = 0; i < options().getCoreConnectionsPerHost(hostDistance); i++) {
// We don't respect MAX_SIMULTANEOUS_CREATION here because it's only to
// protect against creating connection in excess of core too quickly
scheduledForCreation.incrementAndGet();
manager.executor().submit(newConnectionTask);
}
Connection c = waitForConnection(timeout, unit);
c.setKeyspace(manager.poolsState.keyspace);
return c;
}
int minInFlight = Integer.MAX_VALUE;
Connection leastBusy = null;
for (Connection connection : connections) {
int inFlight = connection.inFlight.get();
if (inFlight < minInFlight) {
minInFlight = inFlight;
leastBusy = connection;
}
}
if (minInFlight >= options().getMaxSimultaneousRequestsPerConnectionThreshold(hostDistance)
&& connections.size() < options().getMaxConnectionsPerHost(hostDistance))
maybeSpawnNewConnection();
while (true) {
int inFlight = leastBusy.inFlight.get();
if (inFlight >= Connection.MAX_STREAM_PER_CONNECTION) {
leastBusy = waitForConnection(timeout, unit);
break;
}
if (leastBusy.inFlight.compareAndSet(inFlight, inFlight + 1)) break;
}
leastBusy.setKeyspace(manager.poolsState.keyspace);
return leastBusy;
}
public void returnConnection(Connection connection) {
int inFlight = connection.inFlight.decrementAndGet();
if (connection.isDefunct()) {
if (host.getMonitor().signalConnectionFailure(connection.lastException())) shutdown();
else replace(connection);
} else {
if (trash.contains(connection) && inFlight == 0) {
if (trash.remove(connection)) close(connection);
return;
}
if (connections.size() > options().getCoreConnectionsPerHost(hostDistance)
&& inFlight <= options().getMinSimultaneousRequestsPerConnectionThreshold(hostDistance)) {
trashConnection(connection);
} else {
signalAvailableConnection();
}
}
}
private boolean addConnectionIfUnderMaximum() {
// First, make sure we don't cross the allowed limit of open connections
for (; ; ) {
int opened = open.get();
if (opened >= options().getMaxConnectionsPerHost(hostDistance)) return false;
if (open.compareAndSet(opened, opened + 1)) break;
}
if (isShutdown()) {
open.decrementAndGet();
return false;
}
// Now really open the connection
try {
connections.add(manager.connectionFactory().open(host));
signalAvailableConnection();
return true;
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
// Skip the open but ignore otherwise
open.decrementAndGet();
return false;
} catch (ConnectionException e) {
open.decrementAndGet();
logger.debug("Connection error to {} while creating additional connection", host);
if (host.getMonitor().signalConnectionFailure(e)) shutdown();
return false;
} catch (AuthenticationException e) {
// This shouldn't really happen in theory
open.decrementAndGet();
logger.error(
"Authentication error while creating additional connection (error is: {})",
e.getMessage());
shutdown();
return false;
}
}
private Connection waitForConnection(long timeout, TimeUnit unit)
throws ConnectionException, TimeoutException {
long start = System.nanoTime();
long remaining = timeout;
do {
try {
awaitAvailableConnection(remaining, unit);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
// If we're interrupted fine, check if there is a connection available but stop waiting
// otherwise
timeout = 0; // this will make us stop the loop if we don't get a connection right away
}
if (isShutdown()) throw new ConnectionException(host.getAddress(), "Pool is shutdown");
int minInFlight = Integer.MAX_VALUE;
Connection leastBusy = null;
for (Connection connection : connections) {
int inFlight = connection.inFlight.get();
if (inFlight < minInFlight) {
minInFlight = inFlight;
leastBusy = connection;
}
}
while (true) {
int inFlight = leastBusy.inFlight.get();
if (inFlight >= Connection.MAX_STREAM_PER_CONNECTION) break;
if (leastBusy.inFlight.compareAndSet(inFlight, inFlight + 1)) return leastBusy;
}
remaining = timeout - Cluster.timeSince(start, unit);
} while (remaining > 0);
throw new TimeoutException();
}