api: add get_unleveled_sstables to column family api

Adding to API function to return count of sstables in L0 if leveled
compaction strategy is enabled, 0 otherwise. Currently, we don't
support leveled compaction strategy, so function to return count of
sstables in L0 always return zero.

Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>

api/column_family.cc

@@ -97,6 +97,12 @@ static future<json::json_return_type> get_cf_histogram(http_context& ctx, utils:
     });
 }
 
+static future<json::json_return_type> get_cf_unleveled_sstables(http_context& ctx, const sstring& name) {
+    return map_reduce_cf(ctx, name, 0, [](const column_family& cf) {
+        return cf.get_unleveled_sstables();
+    }, std::plus<int64_t>());
+}
+
 static int64_t min_row_size(column_family& cf) {
     int64_t res = INT64_MAX;
     for (auto i: *cf.get_sstables() ) {
@@ -313,6 +319,10 @@ void set_column_family(http_context& ctx, routes& r) {
         return get_cf_stats(ctx, &column_family::stats::live_sstable_count);
     });
 
+    cf::get_unleveled_sstables.set(r, [&ctx] (std::unique_ptr<request> req) {
+        return get_cf_unleveled_sstables(ctx, req->param["name"]);
+    });
+
     cf::get_live_disk_space_used.set(r, [&ctx] (std::unique_ptr<request> req) {
         return get_cf_stats(ctx, req->param["name"], &column_family::stats::live_disk_space_used);
     });

database.cc

@@ -623,6 +623,13 @@ size_t column_family::sstables_count() {
     return _sstables->size();
 }
 
+int64_t column_family::get_unleveled_sstables() const {
+    // TODO: when we support leveled compaction, we should return the number of
+    // SSTables in L0. If leveled compaction is enabled in this column family,
+    // then we should return zero, as we currently do.
+    return 0;
+}
+
 lw_shared_ptr<sstable_list> column_family::get_sstables() {
     return _sstables;
 }

database.hh

@@ -190,6 +190,7 @@ public:
 
     lw_shared_ptr<sstable_list> get_sstables();
     size_t sstables_count();
+    int64_t get_unleveled_sstables() const;
 
     void start_compaction();
     void trigger_compaction();