[Fix] TwoQ crashes when the LRU cache is empty (#295)

* [Fix] pkgconf should be installed explicitly on macos

* [Fix] TwoQ crashes when the LRU cache is empty

When `TwoQ_evict` is called while Ain is within the size limit, the function
will try to do eviction on Am. But when Am is empty, an assertion failure will
be encountered. This commit fix the issue by checking whether the Am is able
to evict elements.

Author: LauYeeYu

libCacheSim/cache/eviction/TwoQ.c

@@ -259,19 +259,19 @@ static void TwoQ_evict(cache_t *cache, const request_t *req) {
   cache_t *Aout = params->Aout;
   cache_t *Am = params->Am;
 
-  if (Ain->get_occupied_byte(Ain) > params->Ain_cache_size) {
+  if (Am->get_occupied_byte(Am) > 0 &&
+      Ain->get_occupied_byte(Ain) <= params->Ain_cache_size) {
+    // evict from Am
+    Am->evict(Am, req);
+  } else {
     // evict from Ain cache
     cache_obj_t *obj = Ain->to_evict(Ain, req);
     assert(obj != NULL);
     // need to copy the object before it is evicted
     copy_cache_obj_to_request(params->req_local, obj);
     Aout->get(Aout, params->req_local);
     Ain->evict(Ain, req);
-    return;
   }
-
-  // evict from Am
-  Am->evict(Am, req);
 }
 
 /**

scripts/install_dependency.sh

@@ -124,7 +124,7 @@ setup_macOS() {
 		log_error "Homebrew is not installed. Please install Homebrew first."
 		exit 1
 	fi
-	brew install glib google-perftools argp-standalone xxhash llvm wget cmake ninja zstd xgboost lightgbm
+	brew install glib google-perftools argp-standalone xxhash llvm wget cmake ninja zstd xgboost lightgbm pkgconf
 }
 
 # Install CMake