From 163a416366d8ac98171429a07f4fe460ea16af9d Mon Sep 17 00:00:00 2001
From: Amos Bird <amosbird@gmail.com>
Date: Sat, 28 Aug 2021 11:43:43 +0800
Subject: [PATCH] Refactor

---
 src/Common/StackTrace.cpp                   | 22 ++++++++++++---------
 src/Common/StackTrace.h                     |  3 ++-
 src/Common/SymbolIndex.cpp                  | 22 +++++++++++++--------
 src/Common/SymbolIndex.h                    |  4 +++-
 src/Interpreters/InterpreterSystemQuery.cpp |  2 +-
 5 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/src/Common/StackTrace.cpp b/src/Common/StackTrace.cpp
index 3fae1df0bfa..a9d4700490e 100644
--- a/src/Common/StackTrace.cpp
+++ b/src/Common/StackTrace.cpp
@@ -431,16 +431,20 @@ std::string StackTrace::toString(void ** frame_pointers_, size_t offset, size_t
     return toStringStatic(frame_pointers_copy, offset, size);
 }
 
-std::string StackTrace::toStringStatic(const StackTrace::FramePointers & frame_pointers, size_t offset, size_t size, bool reload)
+static SimpleCache<decltype(toStringImpl), &toStringImpl> & cacheInstance()
+{
+    static SimpleCache<decltype(toStringImpl), &toStringImpl> cache;
+    return cache;
+}
+
+std::string StackTrace::toStringStatic(const StackTrace::FramePointers & frame_pointers, size_t offset, size_t size)
 {
     /// Calculation of stack trace text is extremely slow.
     /// We use simple cache because otherwise the server could be overloaded by trash queries.
-    static SimpleCache<decltype(toStringImpl), &toStringImpl> func_cached;
-    /// Reload cached stacktrace instead.
-    if (reload)
-    {
-        func_cached.drop();
-        return "";
-    }
-    return func_cached(frame_pointers, offset, size);
+    return cacheInstance()(frame_pointers, offset, size);
+}
+
+void StackTrace::dropCache()
+{
+    cacheInstance().drop();
 }
diff --git a/src/Common/StackTrace.h b/src/Common/StackTrace.h
index 7e6edabaf0d..62acb70563f 100644
--- a/src/Common/StackTrace.h
+++ b/src/Common/StackTrace.h
@@ -61,7 +61,8 @@ public:
     std::string toString() const;
 
     static std::string toString(void ** frame_pointers, size_t offset, size_t size);
-    static std::string toStringStatic(const FramePointers & frame_pointers, size_t offset, size_t size, bool reload = false);
+    static std::string toStringStatic(const FramePointers & frame_pointers, size_t offset, size_t size);
+    static void dropCache();
     static void symbolize(const FramePointers & frame_pointers, size_t offset, size_t size, StackTrace::Frames & frames);
 
     void toStringEveryLine(std::function<void(const std::string &)> callback) const;
diff --git a/src/Common/SymbolIndex.cpp b/src/Common/SymbolIndex.cpp
index 72ce51cccd0..2d875b7042d 100644
--- a/src/Common/SymbolIndex.cpp
+++ b/src/Common/SymbolIndex.cpp
@@ -462,16 +462,22 @@ String SymbolIndex::getBuildIDHex() const
     return build_id_hex;
 }
 
-MultiVersion<SymbolIndex>::Version SymbolIndex::instance(bool reload)
+MultiVersion<SymbolIndex> & SymbolIndex::instanceImpl()
 {
     static MultiVersion<SymbolIndex> instance(std::unique_ptr<SymbolIndex>(new SymbolIndex));
-    if (reload)
-    {
-        instance.set(std::unique_ptr<SymbolIndex>(new SymbolIndex));
-        /// Also reload stacktrace cache.
-        StackTrace::toStringStatic({}, 0, 0, true);
-    }
-    return instance.get();
+    return instance;
+}
+
+MultiVersion<SymbolIndex>::Version SymbolIndex::instance()
+{
+    return instanceImpl().get();
+}
+
+void SymbolIndex::reload()
+{
+    instanceImpl().set(std::unique_ptr<SymbolIndex>(new SymbolIndex));
+    /// Also drop stacktrace cache.
+    StackTrace::dropCache();
 }
 
 }
diff --git a/src/Common/SymbolIndex.h b/src/Common/SymbolIndex.h
index 65e446a7fc4..37862987bd2 100644
--- a/src/Common/SymbolIndex.h
+++ b/src/Common/SymbolIndex.h
@@ -22,7 +22,8 @@ protected:
     SymbolIndex() { update(); }
 
 public:
-    static MultiVersion<SymbolIndex>::Version instance(bool reload = false);
+    static MultiVersion<SymbolIndex>::Version instance();
+    static void reload();
 
     struct Symbol
     {
@@ -60,6 +61,7 @@ private:
     Data data;
 
     void update();
+    static MultiVersion<SymbolIndex> & instanceImpl();
 };
 
 }
diff --git a/src/Interpreters/InterpreterSystemQuery.cpp b/src/Interpreters/InterpreterSystemQuery.cpp
index d4ac555add0..31c04a7b431 100644
--- a/src/Interpreters/InterpreterSystemQuery.cpp
+++ b/src/Interpreters/InterpreterSystemQuery.cpp
@@ -337,7 +337,7 @@ BlockIO InterpreterSystemQuery::execute()
         {
 #if defined(__ELF__) && !defined(__FreeBSD__)
             getContext()->checkAccess(AccessType::SYSTEM_RELOAD_SYMBOLS);
-            (void)SymbolIndex::instance(true);
+            SymbolIndex::reload();
             break;
 #else
             throw Exception("SYSTEM RELOAD SYMBOLS is not supported on current platform", ErrorCodes::NOT_IMPLEMENTED);