From 072064407a6699d1168b7ac8919fea3056501a77 Mon Sep 17 00:00:00 2001
From: Maxime Coste <mawww@kakoune.org>
Date: Sat, 28 Jan 2017 13:04:55 +0000
Subject: [PATCH] Remove hash from StringData

Maintaining the hash value of strings is not worth it as we only
use it for buffer reload, but pay for it on any buffer modifications.
---
 src/buffer.cc        |  4 ++--
 src/shared_string.hh | 17 ++---------------
 2 files changed, 4 insertions(+), 17 deletions(-)

diff --git a/src/buffer.cc b/src/buffer.cc
index 00506c7fa..275562629 100644
--- a/src/buffer.cc
+++ b/src/buffer.cc
@@ -249,7 +249,7 @@ void Buffer::reload(StringView data, timespec fs_timestamp)
         auto diff = find_diff(m_lines.begin(), m_lines.size(),
                               parsed_lines.lines.begin(), (int)parsed_lines.lines.size(),
                               [](const StringDataPtr& lhs, const StringDataPtr& rhs)
-                              { return lhs->hash == rhs->hash and lhs->strview() == rhs->strview(); });
+                              { return lhs->strview() == rhs->strview(); });
 
         auto it = m_lines.begin();
         for (auto& d : diff)
@@ -476,7 +476,7 @@ BufferCoord Buffer::do_insert(BufferCoord pos, StringView content)
 
     auto line_it = m_lines.begin() + (int)pos.line;
     auto new_lines_it = new_lines.begin();
-    if (not append_lines)
+    if (not append_lines) // replace first line with new first line
         *line_it++ = std::move(*new_lines_it++);
 
     m_lines.insert(line_it,
diff --git a/src/shared_string.hh b/src/shared_string.hh
index a13f042f3..a6522edb4 100644
--- a/src/shared_string.hh
+++ b/src/shared_string.hh
@@ -13,7 +13,6 @@ struct StringData : UseMemoryDomain<MemoryDomain::SharedString>
 {
     int refcount;
     int length;
-    uint32_t hash;
 
     StringData(int ref, int len) : refcount(ref), length(len) {}
 
@@ -26,8 +25,8 @@ struct StringData : UseMemoryDomain<MemoryDomain::SharedString>
 
     struct PtrPolicy
     {
-        static void inc_ref(StringData* r, void*) { ++r->refcount; }
-        static void dec_ref(StringData* r, void*) { if (--r->refcount == 0) delete r; }
+        static void inc_ref(StringData* r, void*) noexcept { ++r->refcount; }
+        static void dec_ref(StringData* r, void*) noexcept { if (--r->refcount == 0) destroy(r); }
         static void ptr_moved(StringData*, void*, void*) noexcept {}
     };
 
@@ -40,7 +39,6 @@ struct StringData : UseMemoryDomain<MemoryDomain::SharedString>
         if (back != 0)
             res->data()[len-1] = back;
         res->data()[len] = 0;
-        res->hash = hash_data(res->data(), res->length);
         return RefPtr<StringData, PtrPolicy>{res};
     }
 
@@ -48,17 +46,6 @@ struct StringData : UseMemoryDomain<MemoryDomain::SharedString>
     {
         StringData::operator delete(s, sizeof(StringData) + s->length + 1);
     }
-
-    friend void inc_ref_count(StringData* s, void*)
-    {
-        ++s->refcount;
-    }
-
-    friend void dec_ref_count(StringData* s, void*)
-    {
-        if (--s->refcount == 0)
-            StringData::destroy(s);
-    }
 };
 
 using StringDataPtr = RefPtr<StringData, StringData::PtrPolicy>;