keep good passphrases in cache

passphrase_cache.cc

@@ -12,9 +12,11 @@ namespace pEp {
         std::lock_guard<std::mutex> lock(_mtx);
         cleanup();
 
-        for (auto entry : _cache) {
-            if (callee(entry.passphrase))
+        for (auto entry=_cache.begin(); entry!=_cache.end(); ++entry) {
+            if (callee(entry->passphrase)) {
+                refresh(entry);
                 return true;
+            }
         }
 
         return false;
@@ -27,5 +29,11 @@ namespace pEp {
         while (_cache.size() > _max_size)
             _cache.pop_front();
     }
+
+    void PassphraseCache::refresh(cache::iterator entry)
+    {
+        entry->tp = clock::now();
+        _cache.splice(_cache.end(), _cache, entry);
+    }
 };
 

passphrase_cache.hh

@@ -16,8 +16,9 @@ namespace pEp {
             std::string passphrase;
             time_point tp;
         };
+        using cache = std::list<cache_entry>;
 
-        std::list<cache_entry> _cache;   
+        cache _cache;   
         std::mutex _mtx;
         int _max_size;
         duration _timeout;
@@ -40,6 +41,7 @@ namespace pEp {
 
     protected:
         void cleanup();
+        void refresh(cache::iterator entry);
     };
 };
 

test/test_passphrase_cache.cc

@@ -17,6 +17,9 @@ int main()
     std::cout << "expected: one passphrase\n";
     cache.for_each_passphrase([&](std::string passphrase){std::cout << passphrase << "\n"; return true;});
 
+    std::cout << "expected: two passphrases but reverse order\n";
+    cache.for_each_passphrase([&](std::string passphrase){std::cout << passphrase << "\n"; return false;});
+
     sleep(2);
 
     std::cout << "expected: no passphrase\n";