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Optimize CacheMap concurrency with std::shared_mutex #2454

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Optimize CacheMap concurrency with std::shared_mutex #2454

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23a7b61
perf(utils): optimize CacheMap concurrency with std::shared_mutex
levi42x Feb 13, 2026
dea1f1f
resolve race condition
levi42x Feb 13, 2026
59c11d2
style: fix formatting in CacheMap.h
levi42x Feb 13, 2026
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25 changes: 14 additions & 11 deletions lib/inc/drogon/CacheMap.h
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
#include <deque>
#include <map>
#include <mutex>
#include <shared_mutex>
#include <set>
#include <unordered_map>
#include <unordered_set>
Expand Down Expand Up @@ -222,14 +223,14 @@ class CacheMap
if (timeout > 0)
{
MapValue v{std::move(value), timeout, std::move(timeoutCallback)};
std::lock_guard<std::mutex> lock(mtx_);
std::unique_lock<std::shared_mutex> lock(mtx_);
map_.insert(std::make_pair(key, std::move(v)));
eraseAfter(timeout, key);
}
else
{
MapValue v{std::move(value)};
std::lock_guard<std::mutex> lock(mtx_);
std::unique_lock<std::shared_mutex> lock(mtx_);
map_.insert(std::make_pair(key, std::move(v)));
}
if (fnOnInsert_)
Expand All @@ -254,14 +255,14 @@ class CacheMap
if (timeout > 0)
{
MapValue v{value, timeout, std::move(timeoutCallback)};
std::lock_guard<std::mutex> lock(mtx_);
std::unique_lock<std::shared_mutex> lock(mtx_);
map_.insert(std::make_pair(key, std::move(v)));
eraseAfter(timeout, key);
}
else
{
MapValue v{value};
std::lock_guard<std::mutex> lock(mtx_);
std::unique_lock<std::shared_mutex> lock(mtx_);
map_.insert(std::make_pair(key, std::move(v)));
}
if (fnOnInsert_)
Expand All @@ -280,7 +281,7 @@ class CacheMap
T2 operator[](const T1 &key)
{
size_t timeout = 0;
std::lock_guard<std::mutex> lock(mtx_);
std::unique_lock<std::shared_mutex> lock(mtx_);
auto iter = map_.find(key);
if (iter != map_.end())
{
Expand Down Expand Up @@ -312,7 +313,7 @@ class CacheMap
void modify(const T1 &key, Callable &&handler, size_t timeout = 0)
{
{
std::lock_guard<std::mutex> lock(mtx_);
std::unique_lock<std::shared_mutex> lock(mtx_);
auto iter = map_.find(key);
if (iter != map_.end())
{
Expand Down Expand Up @@ -341,7 +342,9 @@ class CacheMap
size_t timeout = 0;
bool flag = false;

std::lock_guard<std::mutex> lock(mtx_);
// We use unique_lock here because eraseAfter modifies the internal map
// state
std::unique_lock<std::shared_mutex> lock(mtx_);
auto iter = map_.find(key);
if (iter != map_.end())
{
Expand All @@ -364,7 +367,7 @@ class CacheMap
{
size_t timeout = 0;
bool flag = false;
std::lock_guard<std::mutex> lock(mtx_);
std::unique_lock<std::shared_mutex> lock(mtx_);
auto iter = map_.find(key);
if (iter != map_.end())
{
Expand All @@ -388,7 +391,7 @@ class CacheMap
{
// in this case,we don't evoke the timeout callback;
{
std::lock_guard<std::mutex> lock(mtx_);
std::unique_lock<std::shared_mutex> lock(mtx_);
map_.erase(key);
}
if (fnOnErase_)
Expand Down Expand Up @@ -453,7 +456,7 @@ class CacheMap

std::atomic<size_t> ticksCounter_{0};

std::mutex mtx_;
std::shared_mutex mtx_;
std::mutex bucketMutex_;
trantor::TimerId timerId_;
trantor::EventLoop *loop_;
Expand Down Expand Up @@ -529,7 +532,7 @@ class CacheMap
bool erased{false};
std::function<void()> timeoutCallback;
{
std::lock_guard<std::mutex> lock(mtx_);
std::unique_lock<std::shared_mutex> lock(mtx_);
auto iter = map_.find(key);
if (iter != map_.end())
{
Expand Down
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