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/*
Copyright (c) 2014-2016 DataStax
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include "pool.hpp"
#include "connection.hpp"
#include "error_response.hpp"
#include "io_worker.hpp"
#include "logger.hpp"
#include "prepare_handler.hpp"
#include "session.hpp"
#include "set_keyspace_handler.hpp"
#include "request_handler.hpp"
#include "result_response.hpp"
#include "timer.hpp"
#include <algorithm>
namespace cass {
static bool least_busy_comp(Connection* a, Connection* b) {
return a->pending_request_count() < b->pending_request_count();
}
Pool::Pool(IOWorker* io_worker,
const Host::ConstPtr& host,
bool is_initial_connection)
: io_worker_(io_worker)
, host_(host)
, loop_(io_worker->loop())
, config_(io_worker->config())
, metrics_(io_worker->metrics())
, state_(POOL_STATE_NEW)
, error_code_(Connection::CONNECTION_OK)
, available_connection_count_(0)
, is_available_(false)
, is_initial_connection_(is_initial_connection)
, is_pending_flush_(false)
, cancel_reconnect_(false) { }
Pool::~Pool() {
LOG_DEBUG("Pool(%p) dtor with %u pending requests",
static_cast<void*>(this),
static_cast<unsigned int>(pending_requests_.size()));
while (!pending_requests_.is_empty()) {
RequestHandler* request_handler
= static_cast<RequestHandler*>(pending_requests_.front());
pending_requests_.remove(request_handler);
request_handler->stop_timer();
request_handler->next_host();
request_handler->retry();
}
}
void Pool::connect() {
if (state_ == POOL_STATE_NEW ||
state_ == POOL_STATE_WAITING_TO_CONNECT) {
LOG_DEBUG("Connect pool(%p) for host %s",
static_cast<void*>(this),
host_->address_string().c_str());
connect_timer.stop(); // There could be a delayed connect waiting
for (unsigned i = 0; i < config_.core_connections_per_host(); ++i) {
spawn_connection();
}
state_ = POOL_STATE_CONNECTING;
maybe_notify_ready();
}
}
void Pool::delayed_connect() {
if (state_ == POOL_STATE_NEW) {
state_ = POOL_STATE_WAITING_TO_CONNECT;
connect_timer.start(loop_,
config_.reconnect_wait_time_ms(),
this, on_wait_to_connect);
}
}
void Pool::close(bool cancel_reconnect) {
if (state_ != POOL_STATE_CLOSING && state_ != POOL_STATE_CLOSED) {
LOG_DEBUG("Closing pool(%p) for host %s",
static_cast<void*>(this),
host_->address_string().c_str());
connect_timer.stop();
// We're closing before we've connected (likely because of an error), we need
// to notify we're "ready"
if (state_ == POOL_STATE_CONNECTING) {
state_ = POOL_STATE_CLOSING;
io_worker_->notify_pool_ready(this);
} else {
state_ = POOL_STATE_CLOSING;
}
set_is_available(false);
cancel_reconnect_ = cancel_reconnect;
for (ConnectionVec::iterator it = connections_.begin(),
end = connections_.end();
it != end; ++it) {
(*it)->close();
}
for (ConnectionVec::iterator it = pending_connections_.begin(),
end = pending_connections_.end();
it != end; ++it) {
(*it)->close();
}
}
maybe_close();
}
Connection* Pool::borrow_connection() {
if (connections_.empty()) {
for (unsigned i = 0; i < config_.core_connections_per_host(); ++i) {
maybe_spawn_connection();
}
return NULL;
}
Connection* connection = find_least_busy();
if (connection == NULL ||
connection->pending_request_count() >=
config_.max_concurrent_requests_threshold()) {
maybe_spawn_connection();
}
return connection;
}
void Pool::return_connection(Connection* connection) {
if (!connection->is_ready() || pending_requests_.is_empty()) return;
RequestHandler* request_handler
= static_cast<RequestHandler*>(pending_requests_.front());
remove_pending_request(request_handler);
request_handler->stop_timer();
if (!write(connection, request_handler)) {
request_handler->next_host();
request_handler->retry();
}
}
void Pool::add_pending_request(RequestHandler* request_handler) {
pending_requests_.add_to_back(request_handler);
if (pending_requests_.size() % 10 == 0) {
LOG_DEBUG("%u request%s pending on %s pool(%p)",
static_cast<unsigned int>(pending_requests_.size() + 1),
pending_requests_.size() > 0 ? "s":"",
host_->address_string().c_str(),
static_cast<void*>(this));
}
if (pending_requests_.size() > config_.pending_requests_high_water_mark()) {
LOG_WARN("Exceeded pending requests water mark (current: %u water mark: %u) for host %s",
static_cast<unsigned int>(pending_requests_.size()),
config_.pending_requests_high_water_mark(),
host_->address_string().c_str());
set_is_available(false);
metrics_->exceeded_pending_requests_water_mark.inc();
}
}
void Pool::remove_pending_request(RequestHandler* request_handler) {
pending_requests_.remove(request_handler);
set_is_available(true);
}
void Pool::set_is_available(bool is_available) {
if (is_available) {
if (!is_available_ &&
available_connection_count_ > 0 &&
pending_requests_.size() < config_.pending_requests_low_water_mark()) {
io_worker_->set_host_is_available(host_->address(), true);
is_available_ = true;
}
} else {
if (is_available_) {
io_worker_->set_host_is_available(host_->address(), false);
is_available_ = false;
}
}
}
bool Pool::write(Connection* connection, RequestHandler* request_handler) {
request_handler->set_pool(this);
if (*io_worker_->keyspace() == connection->keyspace()) {
if (!connection->write(request_handler, false)) {
return false;
}
} else {
LOG_DEBUG("Setting keyspace %s on connection(%p) pool(%p)",
io_worker_->keyspace()->c_str(),
static_cast<void*>(connection),
static_cast<void*>(this));
if (!connection->write(new SetKeyspaceHandler(connection, *io_worker_->keyspace(),
request_handler), false)) {
return false;
}
}
if (!is_pending_flush_) {
io_worker_->add_pending_flush(this);
}
is_pending_flush_ = true;
return true;
}
void Pool::flush() {
is_pending_flush_ = false;
for (ConnectionVec::iterator it = connections_.begin(),
end = connections_.end(); it != end; ++it) {
(*it)->flush();
}
}
void Pool::maybe_notify_ready() {
// This will notify ready even if all the connections fail.
// it is up to the holder to inspect state
if (state_ == POOL_STATE_CONNECTING && pending_connections_.empty()) {
LOG_DEBUG("Pool(%p) connected to host %s",
static_cast<void*>(this),
host_->address_string().c_str());
state_ = POOL_STATE_READY;
io_worker_->notify_pool_ready(this);
}
}
void Pool::maybe_close() {
if (state_ == POOL_STATE_CLOSING && connections_.empty() &&
pending_connections_.empty()) {
LOG_DEBUG("Pool(%p) closed connections to host %s",
static_cast<void*>(this),
host_->address_string().c_str());
state_ = POOL_STATE_CLOSED;
io_worker_->notify_pool_closed(this);
}
}
void Pool::spawn_connection() {
if (state_ != POOL_STATE_CLOSING && state_ != POOL_STATE_CLOSED) {
Connection* connection =
new Connection(loop_, config_, metrics_,
host_,
*io_worker_->keyspace(),
io_worker_->protocol_version(),
this);
LOG_DEBUG("Spawning new connection to host %s for pool(%p)",
host_->address_string().c_str(),
static_cast<void*>(this));
connection->connect();
pending_connections_.push_back(connection);
}
}
void Pool::maybe_spawn_connection() {
if (pending_connections_.size() >= config_.max_concurrent_creation()) {
return;
}
if (connections_.size() + pending_connections_.size() >=
config_.max_connections_per_host()) {
return;
}
if (state_ != POOL_STATE_READY) {
return;
}
spawn_connection();
}
Connection* Pool::find_least_busy() {
ConnectionVec::iterator it = std::min_element(
connections_.begin(), connections_.end(), least_busy_comp);
if ((*it)->is_ready() && (*it)->available_streams() > 0) {
return *it;
}
return NULL;
}
void Pool::on_ready(Connection* connection) {
pending_connections_.erase(std::remove(pending_connections_.begin(), pending_connections_.end(), connection),
pending_connections_.end());
connections_.push_back(connection);
return_connection(connection);
maybe_notify_ready();
metrics_->total_connections.inc();
}
void Pool::on_close(Connection* connection) {
pending_connections_.erase(std::remove(pending_connections_.begin(), pending_connections_.end(), connection),
pending_connections_.end());
ConnectionVec::iterator it =
std::find(connections_.begin(), connections_.end(), connection);
if (it != connections_.end()) {
connections_.erase(it);
metrics_->total_connections.dec();
}
// For timeouts, if there are any valid connections left then don't close the
// entire pool, but attempt to reconnect the timed out connections.
if (connection->is_timeout_error() && !connections_.empty()) {
if (!connect_timer.is_running()) {
connect_timer.start(loop_,
config_.reconnect_wait_time_ms(),
this, on_partial_reconnect);
}
maybe_notify_ready();
} else if (connection->is_defunct()) {
// Log only the first connection failure as an error or warning.
if (state_ != POOL_STATE_CLOSING) {
// Log as an error if the connection pool was either estabilished or
// it's the first attempt, otherwise log as a warning.
if (state_ == POOL_STATE_READY) {
LOG_ERROR("Closing established connection pool to host %s because of the following error: %s",
host_->address_string().c_str(),
connection->error_message().c_str());
} else if (is_initial_connection_) {
LOG_ERROR("Connection pool was unable to connect to host %s because of the following error: %s",
host_->address_string().c_str(),
connection->error_message().c_str());
} else {
LOG_WARN("Connection pool was unable to reconnect to host %s because of the following error: %s",
host_->address_string().c_str(),
connection->error_message().c_str());
}
}
// If at least one connection has a critical failure then don't try to
// reconnect automatically. Also, don't set the error to something else if
// it has already been set to something critical.
if (!is_critical_failure()) {
error_code_ = connection->error_code();
}
close();
} else {
maybe_notify_ready();
maybe_close();
}
}
void Pool::on_availability_change(Connection* connection) {
if (connection->is_available()) {
++available_connection_count_;
set_is_available(true);
metrics_->available_connections.inc();
} else {
--available_connection_count_;
assert(available_connection_count_ >= 0);
if (available_connection_count_ == 0) {
set_is_available(false);
}
metrics_->available_connections.dec();
}
}
void Pool::on_pending_request_timeout(Timer* timer) {
RequestHandler* request_handler = static_cast<RequestHandler*>(timer->data());
Pool* pool = request_handler->pool();
pool->metrics_->pending_request_timeouts.inc();
pool->remove_pending_request(request_handler);
request_handler->next_host();
request_handler->retry();
LOG_DEBUG("Timeout waiting for connection to %s pool(%p)",
pool->host_->address_string().c_str(),
static_cast<void*>(pool));
pool->maybe_close();
}
void Pool::wait_for_connection(RequestHandler* request_handler) {
request_handler->set_pool(this);
request_handler->start_timer(loop_,
config_.connect_timeout_ms(),
request_handler,
Pool::on_pending_request_timeout);
add_pending_request(request_handler);
}
void Pool::on_partial_reconnect(Timer* timer) {
Pool* pool = static_cast<Pool*>(timer->data());
size_t current = pool->connections_.size() +
pool->pending_connections_.size();
size_t want = pool->config_.core_connections_per_host();
if (current < want) {
size_t need = want - current;
for (size_t i = 0; i < need; ++i) {
pool->spawn_connection();
}
}
}
void Pool::on_wait_to_connect(Timer* timer) {
Pool* pool = static_cast<Pool*>(timer->data());
pool->connect();
}
} // namespace cass
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