From cfd4d0f680dbb44c5f0cecc2cfccfad9cf573df2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Dziepak?= <pdziepak@scylladb.com>
Date: Tue, 29 Nov 2016 15:24:58 +0000
Subject: [PATCH] db: add metrics for short reads and memory used for results
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
---
 database.cc     | 27 +++++++++++++++++++++++++++
 database.hh     |  3 +++
 query-result.hh |  8 +++++++-
 3 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/database.cc b/database.cc
index b7e22bc44a..2341908007 100644
--- a/database.cc
+++ b/database.cc
@@ -1813,6 +1813,27 @@ database::setup_collectd() {
                 , "queue_length", "queued_reads_system_keyspace")
                 , scollectd::make_typed(scollectd::data_type::GAUGE, [this] { return _system_read_concurrency_sem.waiters(); })
     ));
+
+    _collectd.push_back(
+        scollectd::add_polled_metric(scollectd::type_instance_id("database"
+                , scollectd::per_cpu_plugin_instance
+                , "bytes", "total_result_memory")
+                , scollectd::make_typed(scollectd::data_type::GAUGE, [this] {
+                    return get_result_memory_limiter().total_used_memory();
+                })
+    ));
+    _collectd.push_back(
+        scollectd::add_polled_metric(scollectd::type_instance_id("database"
+                , scollectd::per_cpu_plugin_instance
+                , "total_operations", "short_data_queries")
+                , scollectd::make_typed(scollectd::data_type::DERIVE, _stats->short_data_queries)
+    ));
+    _collectd.push_back(
+        scollectd::add_polled_metric(scollectd::type_instance_id("database"
+                , scollectd::per_cpu_plugin_instance
+                , "total_operations", "short_mutation_queries")
+                , scollectd::make_typed(scollectd::data_type::DERIVE, _stats->short_mutation_queries)
+    ));
 }
 
 database::~database() {
@@ -2413,6 +2434,9 @@ database::query(schema_ptr s, const query::read_command& cmd, query::result_requ
             ++s->total_reads_failed;
         } else {
             ++s->total_reads;
+            auto result = f.get0();
+            s->short_data_queries += bool(result->is_short_read());
+            return make_ready_future<lw_shared_ptr<query::result>>(std::move(result));
         }
         return f;
     });
@@ -2428,6 +2452,9 @@ database::query_mutations(schema_ptr s, const query::read_command& cmd, const qu
             ++s->total_reads_failed;
         } else {
             ++s->total_reads;
+            auto result = f.get0();
+            s->short_mutation_queries += bool(result.is_short_read());
+            return make_ready_future<reconcilable_result>(std::move(result));
         }
         return f;
     });
diff --git a/database.hh b/database.hh
index 47eb01cd84..7d39610197 100644
--- a/database.hh
+++ b/database.hh
@@ -1049,6 +1049,9 @@ private:
         uint64_t total_reads = 0;
         uint64_t total_reads_failed = 0;
         uint64_t sstable_read_queue_overloaded = 0;
+
+        uint64_t short_data_queries = 0;
+        uint64_t short_mutation_queries = 0;
     };
 
     lw_shared_ptr<db_stats> _stats;
diff --git a/query-result.hh b/query-result.hh
index 91c526ca79..ee2e7c51c2 100644
--- a/query-result.hh
+++ b/query-result.hh
@@ -49,18 +49,24 @@ namespace query {
 class result_memory_accounter;
 
 class result_memory_limiter {
+    const size_t _maximum_total_result_memory;
     semaphore _memory_limiter;
 public:
     static constexpr size_t minimum_result_size = 4 * 1024;
     static constexpr size_t maximum_result_size = 1 * 1024 * 1024;
 public:
     result_memory_limiter()
-        : _memory_limiter(memory::stats().total_memory() / 10)
+        : _maximum_total_result_memory(memory::stats().total_memory() / 10)
+        , _memory_limiter(_maximum_total_result_memory)
     { }
 
     result_memory_limiter(const result_memory_limiter&) = delete;
     result_memory_limiter(result_memory_limiter&&) = delete;
 
+    ssize_t total_used_memory() const {
+        return _maximum_total_result_memory - _memory_limiter.available_units();
+    }
+
     // Reserves minimum_result_size and creates new memory accounter.
     future<result_memory_accounter> new_read();