From 97e5bfa8152aff690457b4ee733929b9108e7dbb Mon Sep 17 00:00:00 2001
From: Vlad Zolotarov <vladz@cloudius-systems.com>
Date: Tue, 12 Apr 2016 14:49:08 +0300
Subject: [PATCH] database: add metrics for total writes and reads

This patch adds a counter of total writes and reads
for each shard.

It seems that nothing ensures that all database queries are
ready before database object is destroyed.
Make _stats lw_shared_ptr in order to ensure that the object is
alive when lambda gets to incrementing it.

Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
---
 database.cc | 28 ++++++++++++++++++++++++++--
 database.hh |  7 +++++++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/database.cc b/database.cc
index eef6d16347..bba8b58a14 100644
--- a/database.cc
+++ b/database.cc
@@ -1201,6 +1201,8 @@ database::database(const db::config& cfg)
     : _streaming_dirty_memory_region_group(&_dirty_memory_region_group)
     , _cfg(std::make_unique<db::config>(cfg))
     , _memtable_total_space([this] {
+        _stats = make_lw_shared<db_stats>();
+
         auto memtable_total_space = size_t(_cfg->memtable_total_space_in_mb()) << 20;
         if (!memtable_total_space) {
             return memory::stats().total_memory() / 2;
@@ -1246,6 +1248,20 @@ database::setup_collectd() {
                 , "bytes", "pending_flushes")
                 , scollectd::make_typed(scollectd::data_type::GAUGE, _cf_stats.pending_memtables_flushes_bytes)
     ));
+
+    _collectd.push_back(
+        scollectd::add_polled_metric(scollectd::type_instance_id("database"
+                , scollectd::per_cpu_plugin_instance
+                , "total_operations", "total_writes")
+                , scollectd::make_typed(scollectd::data_type::DERIVE, _stats->total_writes)
+    ));
+
+    _collectd.push_back(
+        scollectd::add_polled_metric(scollectd::type_instance_id("database"
+                , scollectd::per_cpu_plugin_instance
+                , "total_operations", "total_reads")
+                , scollectd::make_typed(scollectd::data_type::DERIVE, _stats->total_reads)
+    ));
 }
 
 database::~database() {
@@ -1814,13 +1830,19 @@ column_family::as_mutation_source() const {
 future<lw_shared_ptr<query::result>>
 database::query(schema_ptr s, const query::read_command& cmd, query::result_request request, const std::vector<query::partition_range>& ranges) {
     column_family& cf = find_column_family(cmd.cf_id);
-    return cf.query(std::move(s), cmd, request, ranges);
+    return cf.query(std::move(s), cmd, request, ranges).then([this, s = _stats] (auto&& res) {
+        ++s->total_reads;
+        return std::move(res);
+    });
 }
 
 future<reconcilable_result>
 database::query_mutations(schema_ptr s, const query::read_command& cmd, const query::partition_range& range) {
     column_family& cf = find_column_family(cmd.cf_id);
-    return mutation_query(std::move(s), cf.as_mutation_source(), range, cmd.slice, cmd.row_limit, cmd.timestamp);
+    return mutation_query(std::move(s), cf.as_mutation_source(), range, cmd.slice, cmd.row_limit, cmd.timestamp).then([this, s = _stats] (auto&& res) {
+        ++s->total_reads;
+        return std::move(res);
+    });
 }
 
 std::unordered_set<sstring> database::get_initial_tokens() {
@@ -1997,6 +2019,8 @@ future<> database::apply(schema_ptr s, const frozen_mutation& m) {
     }
     return _memtables_throttler.throttle().then([this, &m, s = std::move(s)] {
         return do_apply(std::move(s), m);
+    }).then([this, s = _stats] {
+        ++s->total_writes;
     });
 }
 
diff --git a/database.hh b/database.hh
index 9aa621fab8..3d6b8b2f7e 100644
--- a/database.hh
+++ b/database.hh
@@ -781,6 +781,13 @@ public:
 
 class database {
     ::cf_stats _cf_stats;
+    struct db_stats {
+        uint64_t total_writes = 0;
+        uint64_t total_reads = 0;
+    };
+
+    lw_shared_ptr<db_stats> _stats;
+
     logalloc::region_group _dirty_memory_region_group;
     logalloc::region_group _streaming_dirty_memory_region_group;
     std::unordered_map<sstring, keyspace> _keyspaces;