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Make worker-local data lookups faster

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By using a std::vector to store the keys, the cost of key lookup goes down
in comparison with std::unordered_map. The downside is the increase in
memory use in certain situations but given the fact that the intended
purpose of worker-local data is to store global data, this is unlikely to
have observable negative side-effects. Depending on the implementations of
std::vector and std::unordered_map, the use of std::vector could even
result in a smaller memory footprint.
This commit is contained in:
Markus Mäkelä
2019-03-19 10:23:36 +02:00
parent 494a8a660a
commit 8ed192892a
1 changed files with 20 additions and 18 deletions
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38
include/maxscale/routingworker.hh
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@ -185,8 +185,8 @@ public:
typedef Registry<MXS_SESSION> SessionsById;
typedef std::vector<DCB*> Zombies;
typedef std::unordered_map<uint64_t, void*> LocalData;
typedef std::unordered_map<uint64_t, void (*)(void*)> DataDeleters;
typedef std::vector<void*> LocalData;
typedef std::vector<void (*)(void*)> DataDeleters;
/**
* Initialize the routing worker mechanism.
@ -475,8 +475,8 @@ public:
*/
static uint64_t create_key()
{
static uint64_t id_generator = 0;
return mxb::atomic::add(&id_generator, 1, mxb::atomic::RELAXED);
static std::atomic<uint64_t> id_generator {0};
return id_generator.fetch_add(1, std::memory_order_relaxed);
}
/**
@ -487,6 +487,12 @@ public:
*/
void set_data(uint64_t key, void* data, void (* callback)(void*))
{
if (m_local_data.size() <= key)
{
m_local_data.resize(key + 1, nullptr);
m_data_deleters.resize(key + 1, nullptr);
}
if (callback)
{
m_data_deleters[key] = callback;
@ -502,10 +508,9 @@ public:
*
* @return Data previously stored
*/
void* get_data(uint64_t key)
void* get_data(uint64_t key) const
{
auto it = m_local_data.find(key);
return it != m_local_data.end() ? it->second : NULL;
return key < m_local_data.size() ? m_local_data[key] : nullptr;
}
/**
@ -517,19 +522,15 @@ public:
*/
void delete_data(uint64_t key)
{
auto data = m_local_data.find(key);
if (data != m_local_data.end())
if (key < m_local_data.size())
{
auto deleter = m_data_deleters.find(key);
if (deleter != m_data_deleters.end())
if (auto deleter = m_data_deleters[key])
{
deleter->second(data->second);
m_data_deleters.erase(deleter);
deleter(m_local_data[key]);
}
m_local_data.erase(data);
m_data_deleters[key] = nullptr;
m_local_data[key] = nullptr;
}
}
@ -766,7 +767,8 @@ private:
T* get_local_value() const
{
T* my_value = static_cast<T*>(mxs_rworker_get_data(m_handle));
auto worker = RoutingWorker::get_current();
T* my_value = static_cast<T*>(worker->get_data(m_handle));
if (my_value == nullptr)
{
@ -775,7 +777,7 @@ private:
my_value = new T(m_value);
guard.unlock();
mxs_rworker_set_data(m_handle, my_value, destroy_value);
worker->set_data(m_handle, my_value, destroy_value);
}
mxb_assert(my_value);