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Cache: Collect LRU statistics

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This commit is contained in:
Johan Wikman 2016-12-07 14:31:19 +02:00
parent e0bedad46e
commit 941f0f9001
2 changed files with 78 additions and 31 deletions
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83
server/modules/filter/cache/lrustorage.cc vendored
View File

@ -18,8 +18,6 @@ LRUStorage::LRUStorage(Storage* pstorage, size_t max_count, size_t max_size)
: pstorage_(pstorage)
, max_count_(max_count)
, max_size_(max_size)
, count_(0)
, size_(0)
, phead_(NULL)
, ptail_(NULL)
{
@ -36,17 +34,6 @@ cache_result_t LRUStorage::get_key(const char* zdefault_db,
return pstorage_->get_key(zdefault_db, pquery, pkey);
}
static void set_integer(json_t* pobject, const char* zname, size_t value)
{
json_t* pvalue = json_integer(value);
if (pvalue)
{
json_object_set(pobject, zname, pvalue);
json_decref(pvalue);
}
}
cache_result_t LRUStorage::do_get_info(uint32_t what,
json_t** ppinfo) const
{
@ -58,8 +45,7 @@ cache_result_t LRUStorage::do_get_info(uint32_t what,
if (plru)
{
set_integer(plru, "size", size_);
set_integer(plru, "count", count_);
stats_.fill(plru);
json_object_set(*ppinfo, "lru", plru);
json_decref(plru);
@ -88,6 +74,8 @@ cache_result_t LRUStorage::do_get_value(const CACHE_KEY& key,
if (result == CACHE_RESULT_OK)
{
++stats_.hits;
if (existed)
{
if (ptail_ == i->second)
@ -102,6 +90,15 @@ cache_result_t LRUStorage::do_get_value(const CACHE_KEY& key,
MXS_ERROR("Item found in storage, but not in key mapping.");
}
}
else
{
++stats_.misses;
if (existed && (result == CACHE_RESULT_NOT_FOUND))
{
MXS_ERROR("Item was not found in storage, but was found in key mapping.");
}
}
return result;
}
@ -112,7 +109,7 @@ cache_result_t LRUStorage::do_put_value(const CACHE_KEY& key,
cache_result_t result = CACHE_RESULT_ERROR;
size_t value_size = GWBUF_LENGTH(pvalue);
size_t new_size = size_ + value_size;
size_t new_size = stats_.size + value_size;
Node* pnode = NULL;
@ -126,7 +123,7 @@ cache_result_t LRUStorage::do_put_value(const CACHE_KEY& key,
}
else
{
if ((new_size > max_size_) || (count_ == max_count_))
if ((new_size > max_size_) || (stats_.items == max_count_))
{
if (new_size > max_size_)
{
@ -137,7 +134,7 @@ cache_result_t LRUStorage::do_put_value(const CACHE_KEY& key,
}
else
{
ss_dassert(count_ == max_count_);
ss_dassert(stats_.items == max_count_);
MXS_NOTICE("Max count %lu reached, removing least recently used.", max_count_);
pnode = free_lru();
}
@ -174,15 +171,17 @@ cache_result_t LRUStorage::do_put_value(const CACHE_KEY& key,
{
if (existed)
{
size_ -= pnode->size();
++stats_.updates;
ss_dassert(stats_.size >= pnode->size());
stats_.size -= pnode->size();
}
else
{
++count_;
++stats_.items;
}
pnode->reset(&i->first, value_size);
size_ += pnode->size();
stats_.size += pnode->size();
if (ptail_ == pnode)
{
@ -215,15 +214,17 @@ cache_result_t LRUStorage::do_del_value(const CACHE_KEY& key)
if (result == CACHE_RESULT_OK)
{
++stats_.deletes;
if (i == nodes_per_key_.end())
{
Node* pnode = i->second;
ss_dassert(size_ > pnode->size());
ss_dassert(count_ > 0);
ss_dassert(stats_.size > pnode->size());
ss_dassert(stats_.items > 0);
size_ -= pnode->size();
--count_;
stats_.size -= pnode->size();
--stats_.items;
phead_ = pnode->remove();
delete pnode;
@ -339,11 +340,12 @@ bool LRUStorage::free_node_data(Node* pnode)
nodes_per_key_.erase(i);
}
ss_dassert(size_ >= pnode->size());
ss_dassert(count_ > 0);
ss_dassert(stats_.size >= pnode->size());
ss_dassert(stats_.items > 0);
size_ -= pnode->size();
count_ -= 1;
stats_.size -= pnode->size();
stats_.items -= 1;
stats_.evictions += 1;
break;
default:
@ -354,3 +356,26 @@ bool LRUStorage::free_node_data(Node* pnode)
return success;
}
static void set_integer(json_t* pobject, const char* zname, size_t value)
{
json_t* pvalue = json_integer(value);
if (pvalue)
{
json_object_set(pobject, zname, pvalue);
json_decref(pvalue);
}
}
void LRUStorage::Stats::fill(json_t* pbject) const
{
set_integer(pbject, "size", size);
set_integer(pbject, "items", items);
set_integer(pbject, "hits", hits);
set_integer(pbject, "misses", misses);
set_integer(pbject, "updates", updates);
set_integer(pbject, "deletes", deletes);
set_integer(pbject, "evictions", evictions);
}

26
server/modules/filter/cache/lrustorage.h vendored
View File

@ -176,11 +176,33 @@ private:
private:
typedef std::tr1::unordered_map<CACHE_KEY, Node*> NodesPerKey;
struct Stats
{
Stats()
: size(0)
, items(0)
, hits(0)
, misses(0)
, updates(0)
, deletes(0)
, evictions(0)
{}
void fill(json_t* pbject) const;
uint64_t size; /*< The total size of the stored values. */
uint64_t items; /*< The number of stored items. */
uint64_t hits; /*< How many times a key was found in the cache. */
uint64_t misses; /*< How many times a key was not found in the cache. */
uint64_t updates; /*< How many times an existing key in the cache was updated. */
uint64_t deletes; /*< How many times an existing key in the cache was deleted. */
uint64_t evictions; /*< How many times an item has been evicted from the cache. */
};
Storage* pstorage_; /*< The actual storage. */
size_t max_count_; /*< The maximum number of items in the LRU list, */
size_t max_size_; /*< The maximum size of all cached items. */
size_t count_; /*< The current count of cached items. */
size_t size_; /*< The current size of all cached items. */
Stats stats_; /*< Cache statistics. */
NodesPerKey nodes_per_key_; /*< Mapping from cache keys to corresponding Node. */
Node* phead_; /*< The node at the LRU list. */
Node* ptail_; /*< The node at bottom of the LRU list.*/