Integrate CRUD statistics with metrics rock

If `metrics` [1] found, you can use metrics collectors to store
statistics. It is required to use `>= 0.9.0` to support age buckets in
summary and crucial bugfixes under high load [2]. The metrics are part
of global registry and can be exported together (e.g. to Prometheus)
with default tools without any additional configuration. Disabling
stats destroys the collectors.

Metrics collectors are used by default if supported. To explicitly set
driver, call `crud.enable_stats{ driver = driver }` ('local' or
'metrics').

If `metrics` used, `latency` statistics are changed to 0.99 quantile
of request execution time (with aging).

Add CI matrix to run tests with `metrics` installed. To get full
coverage on coveralls, #248 must be resolved.

1. https://github.com/tarantool/metrics
2. tarantool/metrics#235

Closes #224

.github/workflows/test_on_push.yaml

@@ -13,13 +13,19 @@ jobs:
       matrix:
         # We need 1.10.6 here to check that module works with
         # old Tarantool versions that don't have "tuple-keydef"/"tuple-merger" support.
-        tarantool-version: ["1.10.6", "1.10", "2.2", "2.3", "2.4", "2.5", "2.6", "2.7"]
+        tarantool-version: ["1.10.6", "1.10", "2.2", "2.3", "2.4", "2.5", "2.6", "2.7", "2.8"]
+        metrics-version: [""]
         remove-merger: [false]
         include:
           - tarantool-version: "2.7"
             remove-merger: true
+          - tarantool-version: "2.8"
+            metrics-version: "0.1.8"
+          - tarantool-version: "2.8"
+            metrics-version: "0.9.0"
           - tarantool-version: "2.8"
             coveralls: true
+            metrics-version: "0.12.0"
       fail-fast: false
     runs-on: [ubuntu-latest]
     steps:
@@ -47,6 +53,10 @@ jobs:
           tarantool --version
           ./deps.sh
 
+      - name: Install metrics
+        if: matrix.metrics-version != ''
+        run: tarantoolctl rocks install metrics ${{ matrix.metrics-version }}
+
       - name: Remove external merger if needed
         if: ${{ matrix.remove-merger }}
         run: rm .rocks/lib/tarantool/tuple/merger.so

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Added
 * Statistics for CRUD operations on router (#224).
+* Integrate CRUD statistics with [`metrics`](https://github.com/tarantool/metrics) (#224).
 
 ### Changed
 

README.md

@@ -606,8 +606,19 @@ crud.disable_stats()
 crud.reset_stats()
 ```
 
-Format is as follows.
+If [`metrics`](https://github.com/tarantool/metrics) `0.9.0` or greater
+found, metrics collectors will be used by default to store statistics
+instead of local collectors. You can manually choose driver if needed.
 ```lua
+-- Use metrics collectors.
+crud.enable_stats({ driver = 'metrics' })
+
+-- Use simple local collectors.
+crud.enable_stats({ driver = 'local' })
+```
+
+Format is as follows.
+```
 crud.stats()
 ---
 - spaces:
@@ -654,11 +665,44 @@ Possible statistics operation labels are
 Each operation section contains of different collectors
 for success calls and error (both error throw and `nil, err`)
 returns. `count` is total requests count since instance start
-or stats restart. `latency` is average time of requests execution,
+or stats restart. `latency` is 0.99 quantile of request execution
+time if `metrics` driver used, otherwise `latency` is total average.
 `time` is total time of requests execution.
 
+In [`metrics`](https://www.tarantool.io/en/doc/latest/book/monitoring/)
+registry statistics are stored as `tnt_crud_stats` metrics
+with `operation`, `status` and `name` labels. Collector
+`tnt_crud_space_not_found` stores count of calls to unknown spaces.
+```
+metrics:collect()
+---
+- - label_pairs:
+      status: ok
+      operation: insert
+      name: customers
+    value: 221411
+    metric_name: tnt_crud_stats_count
+  - label_pairs:
+      status: ok
+      operation: insert
+      name: customers
+    value: 10.49834896344692
+    metric_name: tnt_crud_stats_sum
+  - label_pairs:
+      status: ok
+      operation: insert
+      name: customers
+      quantile: 0.99
+    value: 0.00023606420935973
+    metric_name: tnt_crud_stats
+  - label_pairs: []
+    value: 3
+    metric_name: tnt_crud_space_not_found
+...
+```
+
 `select` section additionally contains `details` collectors.
-```lua
+```
 crud.stats('my_space').select.details
 ---
 - map_reduces: 4
@@ -671,6 +715,10 @@ crud.stats('my_space').select.details
 is a count of tuples fetched from storages during execution,
 `tuples_lookup` is a count of tuples looked up on storages
 while collecting response for call.
+In [`metrics`](https://www.tarantool.io/en/doc/latest/book/monitoring/)
+registry they are stored as `tnt_crud_map_reduces`,
+`tnt_crud_tuples_fetched` and `tnt_crud_tuples_lookup` metrics
+with `{ operation = 'select', name = space_name }` labels.
 
 ## Cartridge roles