Cache: Do not use random indexes when testing

It would seem that the likelyhood of different threads accessing
the same items at the same time is greater if each thread continuosly
loops across all items from beginning to finish. That will also ensure
that head and tail surely are accessed. In addition, some function names
have been disambiguated.

server/modules/filter/cache/test/testrawstorage.cc

@@ -67,6 +67,20 @@ GWBUF* create_gwbuf(const string& s)
 typedef unordered_map<CACHE_KEY, GWBUF*> StatementsByKey;
 typedef vector<pair<CACHE_KEY, GWBUF*> > Statements;
 
+enum storage_action_t
+{
+    STORAGE_PUT,
+    STORAGE_GET,
+    STORAGE_DEL
+};
+
+inline storage_action_t& operator++ (storage_action_t& action)
+{
+    action = static_cast<storage_action_t>((action + 1) % 3);
+    return action;
+}
+
+
 struct ThreadData
 {
     ThreadData()
@@ -75,6 +89,7 @@ struct ThreadData
         , thread(0)
         , terminate(false)
         , rv(EXIT_SUCCESS)
+        , start_action(STORAGE_PUT)
     {}
 
     Storage*          pStorage;
@@ -82,6 +97,7 @@ struct ThreadData
     pthread_t         thread;
     bool              terminate;
     int               rv;
+    storage_action_t  start_action;
 };
 
 void* thread_main(void* pData)
@@ -94,40 +110,37 @@ void* thread_main(void* pData)
     bool& terminate = pThreadData->terminate;
 
     size_t n = statements.size();
+    ss_dassert(n > 0);
 
-    enum action_t
-    {
-        PUT,
-        GET,
-        DEL
-    };
-
-    action_t action = PUT;
+    storage_action_t action = pThreadData->start_action;
 
     size_t n_puts = 0;
     size_t n_gets = 0;
     size_t n_dels = 0;
     size_t n_misses = 0;
 
+    size_t i = 0;
+
     while (!terminate)
     {
-        size_t i = n * ((double) random() / RAND_MAX);
-        ss_dassert(i < n);
+        if (i >= n)
+        {
+            i = 0;
+        }
 
         const Statements::value_type& statement = statements[i];
 
         switch (action)
         {
-        case PUT:
+        case STORAGE_PUT:
             {
                 cache_result_t result = storage.put_value(statement.first, statement.second);
                 ss_dassert(result == CACHE_RESULT_OK);
-                action = GET;
                 ++n_puts;
             }
             break;
 
-        case GET:
+        case STORAGE_GET:
             {
                 GWBUF* pQuery;
                 cache_result_t result = storage.get_value(statement.first, 0, &pQuery);
@@ -146,11 +159,10 @@ void* thread_main(void* pData)
                     ss_dassert(result == CACHE_RESULT_NOT_FOUND);
                     ++n_misses;
                 }
-                action = DEL;
             }
             break;
 
-        case DEL:
+        case STORAGE_DEL:
             {
                 cache_result_t result = storage.del_value(statement.first);
 
@@ -166,13 +178,14 @@ void* thread_main(void* pData)
                 {
                     ss_dassert(!true);
                 }
-                action = PUT;
             }
             break;
 
         default:
             ss_dassert(!true);
         }
+
+        ++action;
     }
 
     pThreadData->rv = EXIT_SUCCESS;
@@ -183,24 +196,29 @@ void* thread_main(void* pData)
     return 0;
 }
 
-int test(size_t n_threads, size_t seconds, Storage& storage, const Statements& statements)
+int test_storage(size_t n_threads, size_t seconds, Storage& storage, const Statements& statements)
 {
     int rv = EXIT_SUCCESS;
 
     ThreadData threadDatas[n_threads];
 
+    storage_action_t start_action = STORAGE_PUT;
+
     for (size_t i = 0; i < n_threads; ++i)
     {
         ThreadData* pThreadData = &threadDatas[i];
 
         pThreadData->pStorage = &storage;
         pThreadData->pStatements = &statements;
+        pThreadData->start_action = start_action;
 
         if (pthread_create(&pThreadData->thread, NULL, thread_main, pThreadData) != 0)
         {
             // This is impossible, so we just return.
             return EXIT_FAILURE;
         }
+
+        ++start_action;
     }
 
     stringstream ss;
@@ -228,7 +246,7 @@ int test(size_t n_threads, size_t seconds, Storage& storage, const Statements& s
     return rv;
 }
 
-int test(size_t n_threads, size_t seconds, Storage& storage, istream& in)
+int test_storage(size_t n_threads, size_t seconds, Storage& storage, istream& in)
 {
     int rv = EXIT_SUCCESS;
 
@@ -279,7 +297,7 @@ int test(size_t n_threads, size_t seconds, Storage& storage, istream& in)
 
     if (rv == EXIT_SUCCESS)
     {
-        rv = test(n_threads, seconds, storage, statements);
+        rv = test_storage(n_threads, seconds, storage, statements);
 
         for (Statements::iterator i = statements.begin(); i < statements.end(); ++i)
         {
@@ -290,7 +308,7 @@ int test(size_t n_threads, size_t seconds, Storage& storage, istream& in)
     return rv;
 }
 
-int test(size_t n_threads, size_t seconds, StorageFactory& factory, istream& in)
+int test_storagefactory(size_t n_threads, size_t seconds, StorageFactory& factory, istream& in)
 {
     int rv = EXIT_FAILURE;
 
@@ -303,7 +321,7 @@ int test(size_t n_threads, size_t seconds, StorageFactory& factory, istream& in)
 
     if (pStorage)
     {
-        rv = test(n_threads, seconds, *pStorage, in);
+        rv = test_storage(n_threads, seconds, *pStorage, in);
 
         delete pStorage;
     }
@@ -341,7 +359,7 @@ int main(int argc, char* argv[])
 
                     if (argc == 3)
                     {
-                        rv = test(n_threads, seconds, *pFactory, cin);
+                        rv = test_storagefactory(n_threads, seconds, *pFactory, cin);
                     }
                     else
                     {
@@ -349,7 +367,7 @@ int main(int argc, char* argv[])
 
                         if (in)
                         {
-                            rv = test(n_threads, seconds, *pFactory, in);
+                            rv = test_storagefactory(n_threads, seconds, *pFactory, in);
                         }
                         else
                         {