From a50996f376ee5aa6fc98b9f7a48bb1ac96a6e4db Mon Sep 17 00:00:00 2001
From: Glauber Costa <glauber@scylladb.com>
Date: Sun, 16 Oct 2016 11:35:19 -0400
Subject: [PATCH] commitlog: calculate segment-independent size of mutations

Goal is to calculate a size that is lesser or equal than the
segment-dependent size.

This was originally written by Tomasz, and featured in his submission
"commitlog: Handle overload more gracefully"

Extracted here so it sits clearly in a different patch.

Signed-off-by: Glauber Costa <glauber@scylladb.com>
---
 db/commitlog/commitlog.cc       | 4 ++++
 db/commitlog/commitlog.hh       | 2 ++
 db/commitlog/commitlog_entry.hh | 4 ++++
 3 files changed, 10 insertions(+)

diff --git a/db/commitlog/commitlog.cc b/db/commitlog/commitlog.cc
index dbd26a520e..85c924dd01 100644
--- a/db/commitlog/commitlog.cc
+++ b/db/commitlog/commitlog.cc
@@ -1424,6 +1424,7 @@ future<db::replay_position> db::commitlog::add(const cf_id_type& id,
             : _func(std::move(func)), _size(sz)
         { }
         virtual size_t size(segment&) override { return _size; }
+        virtual size_t size() override { return _size; }
         virtual void write(segment&, output& out) override {
             _func(out);
         }
@@ -1444,6 +1445,9 @@ future<db::replay_position> db::commitlog::add_entry(const cf_id_type& id, const
             _writer.set_with_schema(!seg.is_schema_version_known(_writer.schema()));
             return _writer.size();
         }
+        virtual size_t size() override {
+            return _writer.mutation_size();
+        }
         virtual void write(segment& seg, output& out) override {
             if (_writer.with_schema()) {
                 seg.add_schema_version(_writer.schema());
diff --git a/db/commitlog/commitlog.hh b/db/commitlog/commitlog.hh
index 5b56c486f3..786a96b663 100644
--- a/db/commitlog/commitlog.hh
+++ b/db/commitlog/commitlog.hh
@@ -321,6 +321,8 @@ private:
 
     struct entry_writer {
         virtual size_t size(segment&) = 0;
+        // Returns segment-independent size of the entry. Must be <= than segment-dependant size.
+        virtual size_t size() = 0;
         virtual void write(segment&, output&) = 0;
     };
 };
diff --git a/db/commitlog/commitlog_entry.hh b/db/commitlog/commitlog_entry.hh
index 925fbc0bfe..25149c951b 100644
--- a/db/commitlog/commitlog_entry.hh
+++ b/db/commitlog/commitlog_entry.hh
@@ -74,6 +74,10 @@ public:
         return _size;
     }
 
+    size_t mutation_size() const {
+        return _mutation.representation().size();
+    }
+
     void write(data_output& out) const;
 };