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136 lines
5.0 KiB
C++
136 lines
5.0 KiB
C++
#include <mysqlxx/PoolWithFailover.h>
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/// Duplicate of code from StringUtils.h. Copied here for less dependencies.
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static bool startsWith(const std::string & s, const char * prefix)
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{
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return s.size() >= strlen(prefix) && 0 == memcmp(s.data(), prefix, strlen(prefix));
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}
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using namespace mysqlxx;
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PoolWithFailover::PoolWithFailover(const Poco::Util::AbstractConfiguration & config_,
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const std::string & config_name_, const unsigned default_connections_,
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const unsigned max_connections_, const size_t max_tries_)
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: max_tries(max_tries_)
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{
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shareable = config_.getBool(config_name_ + ".share_connection", false);
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if (config_.has(config_name_ + ".replica"))
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{
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Poco::Util::AbstractConfiguration::Keys replica_keys;
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config_.keys(config_name_, replica_keys);
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for (const auto & replica_config_key : replica_keys)
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{
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/// There could be another elements in the same level in configuration file, like "password", "port"...
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if (startsWith(replica_config_key, "replica"))
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{
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std::string replica_name = config_name_ + "." + replica_config_key;
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int priority = config_.getInt(replica_name + ".priority", 0);
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replicas_by_priority[priority].emplace_back(
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std::make_shared<Pool>(config_, replica_name, default_connections_, max_connections_, config_name_.c_str()));
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}
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}
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}
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else
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{
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replicas_by_priority[0].emplace_back(
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std::make_shared<Pool>(config_, config_name_, default_connections_, max_connections_));
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}
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}
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PoolWithFailover::PoolWithFailover(const std::string & config_name_, const unsigned default_connections_,
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const unsigned max_connections_, const size_t max_tries_)
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: PoolWithFailover{
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Poco::Util::Application::instance().config(), config_name_,
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default_connections_, max_connections_, max_tries_}
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{
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}
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PoolWithFailover::PoolWithFailover(const PoolWithFailover & other)
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: max_tries{other.max_tries}, shareable{other.shareable}
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{
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if (shareable)
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{
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replicas_by_priority = other.replicas_by_priority;
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}
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else
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{
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for (const auto & priority_replicas : other.replicas_by_priority)
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{
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Replicas replicas;
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replicas.reserve(priority_replicas.second.size());
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for (const auto & pool : priority_replicas.second)
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replicas.emplace_back(std::make_shared<Pool>(*pool));
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replicas_by_priority.emplace(priority_replicas.first, std::move(replicas));
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}
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}
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}
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PoolWithFailover::Entry PoolWithFailover::get()
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{
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Poco::Util::Application & app = Poco::Util::Application::instance();
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std::lock_guard<std::mutex> locker(mutex);
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/// If we cannot connect to some replica due to pool overflow, than we will wait and connect.
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PoolPtr * full_pool = nullptr;
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for (size_t try_no = 0; try_no < max_tries; ++try_no)
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{
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full_pool = nullptr;
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for (auto & priority_replicas : replicas_by_priority)
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{
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Replicas & replicas = priority_replicas.second;
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for (size_t i = 0, size = replicas.size(); i < size; ++i)
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{
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PoolPtr & pool = replicas[i];
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try
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{
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Entry entry = shareable ? pool->get() : pool->tryGet();
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if (!entry.isNull())
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{
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/// Move all traversed replicas to the end of queue.
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/// (No need to move replicas with another priority)
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std::rotate(replicas.begin(), replicas.begin() + i + 1, replicas.end());
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return entry;
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}
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}
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catch (const Poco::Exception & e)
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{
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if (e.displayText().find("mysqlxx::Pool is full") != std::string::npos) /// NOTE: String comparison is trashy code.
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{
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full_pool = &pool;
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}
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app.logger().warning("Connection to " + pool->getDescription() + " failed: " + e.displayText());
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continue;
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}
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app.logger().warning("Connection to " + pool->getDescription() + " failed.");
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}
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}
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app.logger().error("Connection to all replicas failed " + std::to_string(try_no + 1) + " times");
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}
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if (full_pool)
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{
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app.logger().error("All connections failed, trying to wait on a full pool " + (*full_pool)->getDescription());
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return (*full_pool)->get();
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}
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std::stringstream message;
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message << "Connections to all replicas failed: ";
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for (auto it = replicas_by_priority.begin(); it != replicas_by_priority.end(); ++it)
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for (auto jt = it->second.begin(); jt != it->second.end(); ++jt)
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message << (it == replicas_by_priority.begin() && jt == it->second.begin() ? "" : ", ") << (*jt)->getDescription();
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throw Poco::Exception(message.str());
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}
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