From 16c26613f19ee00d88ddd6ab93f44f7ac09267e3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <pawel.bylica@imapp.pl>
Date: Wed, 18 Mar 2015 12:20:04 +0100
Subject: [PATCH] Additional cache options: readonly, writeonly and clear.

---
 libevmjit/Cache.cpp           | 23 ++++++++++++++++++++++-
 libevmjit/Cache.h             | 14 +++++++++++++-
 libevmjit/ExecutionEngine.cpp | 14 ++++++++++++--
 3 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/libevmjit/Cache.cpp b/libevmjit/Cache.cpp
index 6b140dd84..d3cda1098 100644
--- a/libevmjit/Cache.cpp
+++ b/libevmjit/Cache.cpp
@@ -22,6 +22,7 @@ namespace jit
 
 namespace
 {
+	CacheMode g_mode;
 	llvm::MemoryBuffer* g_lastObject;
 	ExecutionEngineListener* g_listener;
 	static const size_t c_versionStampLength = 32;
@@ -38,15 +39,31 @@ namespace
 	}
 }
 
-ObjectCache* Cache::getObjectCache(ExecutionEngineListener* _listener)
+ObjectCache* Cache::getObjectCache(CacheMode _mode, ExecutionEngineListener* _listener)
 {
 	static ObjectCache objectCache;
+	g_mode = _mode;
 	g_listener = _listener;
 	return &objectCache;
 }
 
+void Cache::clear()
+{
+	using namespace llvm::sys;
+	llvm::SmallString<256> cachePath;
+	path::system_temp_directory(false, cachePath);
+	path::append(cachePath, "evm_objs");
+
+	std::error_code err;
+	for (auto it = fs::directory_iterator{cachePath.str(), err}; it != fs::directory_iterator{}; it.increment(err))
+		fs::remove(it->path());
+}
+
 std::unique_ptr<llvm::Module> Cache::getObject(std::string const& id)
 {
+	if (g_mode != CacheMode::on && g_mode != CacheMode::read)
+		return nullptr;
+
 	if (g_listener)
 		g_listener->stateChanged(ExecState::CacheLoad);
 
@@ -88,6 +105,10 @@ std::unique_ptr<llvm::Module> Cache::getObject(std::string const& id)
 
 void ObjectCache::notifyObjectCompiled(llvm::Module const* _module, llvm::MemoryBuffer const* _object)
 {
+	// Only in "on" and "write" mode
+	if (g_mode != CacheMode::on && g_mode != CacheMode::write)
+		return;
+
 	if (g_listener)
 		g_listener->stateChanged(ExecState::CacheWrite);
 
diff --git a/libevmjit/Cache.h b/libevmjit/Cache.h
index e8f01d38d..b0d26d080 100644
--- a/libevmjit/Cache.h
+++ b/libevmjit/Cache.h
@@ -12,6 +12,15 @@ namespace jit
 {
 class ExecutionEngineListener;
 
+enum class CacheMode
+{
+	on,
+	off,
+	read,
+	write,
+	clear
+};
+
 class ObjectCache : public llvm::ObjectCache
 {
 public:
@@ -29,8 +38,11 @@ public:
 class Cache
 {
 public:
-	static ObjectCache* getObjectCache(ExecutionEngineListener* _listener);
+	static ObjectCache* getObjectCache(CacheMode _mode, ExecutionEngineListener* _listener);
 	static std::unique_ptr<llvm::Module> getObject(std::string const& id);
+
+	/// Clears cache storage
+	static void clear();
 };
 
 }
diff --git a/libevmjit/ExecutionEngine.cpp b/libevmjit/ExecutionEngine.cpp
index e1c0780d9..f9588fbea 100644
--- a/libevmjit/ExecutionEngine.cpp
+++ b/libevmjit/ExecutionEngine.cpp
@@ -67,7 +67,14 @@ void printVersion()
 
 namespace cl = llvm::cl;
 cl::opt<bool> g_optimize{"O", cl::desc{"Optimize"}};
-cl::opt<bool> g_cache{"cache", cl::desc{"Cache compiled EVM code on disk"}, cl::init(true)};
+cl::opt<CacheMode> g_cache{"cache", cl::desc{"Cache compiled EVM code on disk"},
+	cl::values(
+		clEnumValN(CacheMode::on,    "1", "Enabled"),
+		clEnumValN(CacheMode::off,   "0", "Disabled"),
+		clEnumValN(CacheMode::read,  "r", "Read only. No new objects are added to cache."),
+		clEnumValN(CacheMode::write, "w", "Write only. No objects are loaded from cache."),
+		clEnumValN(CacheMode::clear, "c", "Clear the cache storage. Cache is disabled."),
+		clEnumValEnd)};
 cl::opt<bool> g_stats{"st", cl::desc{"Statistics"}};
 cl::opt<bool> g_dump{"dump", cl::desc{"Dump LLVM IR module"}};
 
@@ -89,11 +96,14 @@ ReturnCode ExecutionEngine::run(RuntimeData* _data, Env* _env)
 	std::unique_ptr<ExecStats> listener{new ExecStats};
 	listener->stateChanged(ExecState::Started);
 
-	auto objectCache = g_cache ? Cache::getObjectCache(listener.get()) : nullptr;
+	auto objectCache = (g_cache != CacheMode::off && g_cache != CacheMode::clear) ? Cache::getObjectCache(g_cache, listener.get()) : nullptr;
 
 	static std::unique_ptr<llvm::ExecutionEngine> ee;
 	if (!ee)
 	{
+		if (g_cache == CacheMode::clear)
+			Cache::clear();
+
 		llvm::InitializeNativeTarget();
 		llvm::InitializeNativeTargetAsmPrinter();