Add statistics for CRUD operations on router

Add statistics module for collecting metrics of CRUD operations on
router. Wrap all CRUD operation calls in statistics collector.
Statistics must be enabled manually, and they can be disabled, restarted
or re-enabled later.

`crud.stats()` returns

---
- spaces:
    my_space:
      insert:
        ok:
          latency: 0.002
          count: 19800
          time: 39.6
        error:
          latency: 0.000001
          count: 4
          time: 0.000004
  space_not_found: 0
...

`spaces` section contains statistics for each observed space.
If operation has never been called for space, corresponding
field will be empty. If no operations has been called for a
space, it will not be represented. Operations called for
spaces not found both on storages and in statistics registry
(including cases when crud can't verify space existence)
will increment `space_not_found` counter.

Possible statistics operation labels are
`insert` (for `insert` and `insert_object` calls),
`get`, `replace`  (for `replace` and `replace_object` calls), `update`,
`upsert` (for `upsert` and `upsert_object` calls), `delete`,
`select` (for `select` and `pairs` calls), `truncate`, `len` and
`borders` (for `min` and `max` calls).

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,
`time` is total time of requests execution.

Part of #224

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [Unreleased]
 
 ### Added
+* Statistics for CRUD operations on router (#224).
 
 ### Changed
 

README.md

@@ -586,6 +586,77 @@ crud.len('customers')
 ...
 ```
 
+### Statistics
+
+`crud` routers can provide statistics on called operations.
+```lua
+-- Enable statistics collect.
+crud.enable_stats()
+
+-- Returns table with statistics information.
+crud.stats()
+
+-- Returns table with statistics information for specific space.
+crud.stats('my_space')
+
+-- Disables statistics collect and destroys all collectors.
+crud.disable_stats()
+
+-- Destroys all statistics collectors and creates them again.
+crud.reset_stats()
+```
+
+Format is as follows.
+```lua
+crud.stats()
+---
+- spaces:
+    my_space:
+      insert:
+        ok:
+          latency: 0.002
+          count: 19800
+          time: 39.6
+        error:
+          latency: 0.000001
+          count: 4
+          time: 0.000004
+  space_not_found: 0
+...
+crud.stats('my_space')
+---
+- insert:
+    ok:
+      latency: 0.002
+      count: 19800
+      time: 39.6
+    error:
+      latency: 0.000001
+      count: 4
+      time: 0.000004
+...
+```
+`spaces` section contains statistics for each observed space.
+If operation has never been called for space, corresponding
+field will be empty. If no operations has been called for a
+space, it will not be represented. Operations called for
+spaces not found both on storages and in statistics registry
+(including cases when crud can't verify space existence)
+will increment `space_not_found` counter.
+
+Possible statistics operation labels are
+`insert` (for `insert` and `insert_object` calls),
+`get`, `replace`  (for `replace` and `replace_object` calls), `update`,
+`upsert` (for `upsert` and `upsert_object` calls), `delete`,
+`select` (for `select` and `pairs` calls), `truncate`, `len` and
+`borders` (for `min` and `max` calls).
+
+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,
+`time` is total time of requests execution.
+
 ## Cartridge roles
 
 `cartridge.roles.crud-storage` is a Tarantool Cartridge role that depends on the

crud.lua

@@ -14,6 +14,7 @@ local len = require('crud.len')
 local borders = require('crud.borders')
 local sharding_key = require('crud.common.sharding_key')
 local utils = require('crud.common.utils')
+local stats = require('crud.stats.module')
 
 local crud = {}
 
@@ -22,67 +23,67 @@ local crud = {}
 
 -- @refer insert.tuple
 -- @function insert
-crud.insert = insert.tuple
+crud.insert = stats.wrap(insert.tuple, stats.op.INSERT)
 
 -- @refer insert.object
 -- @function insert_object
-crud.insert_object = insert.object
+crud.insert_object = stats.wrap(insert.object, stats.op.INSERT)
 
 -- @refer get.call
 -- @function get
-crud.get = get.call
+crud.get = stats.wrap(get.call, stats.op.GET)
 
 -- @refer replace.tuple
 -- @function replace
-crud.replace = replace.tuple
+crud.replace = stats.wrap(replace.tuple, stats.op.REPLACE)
 
 -- @refer replace.object
 -- @function replace_object
-crud.replace_object = replace.object
+crud.replace_object = stats.wrap(replace.object, stats.op.REPLACE)
 
 -- @refer update.call
 -- @function update
-crud.update = update.call
+crud.update = stats.wrap(update.call, stats.op.UPDATE)
 
 -- @refer upsert.tuple
 -- @function upsert
-crud.upsert = upsert.tuple
+crud.upsert = stats.wrap(upsert.tuple, stats.op.UPSERT)
 
 -- @refer upsert.object
 -- @function upsert
-crud.upsert_object = upsert.object
+crud.upsert_object = stats.wrap(upsert.object, stats.op.UPSERT)
 
 -- @refer delete.call
 -- @function delete
-crud.delete = delete.call
+crud.delete = stats.wrap(delete.call, stats.op.DELETE)
 
 -- @refer select.call
 -- @function select
-crud.select = select.call
+crud.select = stats.wrap(select.call, stats.op.SELECT)
 
 -- @refer select.pairs
 -- @function pairs
-crud.pairs = select.pairs
+crud.pairs = stats.wrap(select.pairs, stats.op.SELECT, { pairs = true })
 
 -- @refer utils.unflatten_rows
 -- @function unflatten_rows
 crud.unflatten_rows = utils.unflatten_rows
 
 -- @refer truncate.call
 -- @function truncate
-crud.truncate = truncate.call
+crud.truncate = stats.wrap(truncate.call, stats.op.TRUNCATE)
 
 -- @refer len.call
 -- @function len
-crud.len = len.call
+crud.len = stats.wrap(len.call, stats.op.LEN)
 
 -- @refer borders.min
 -- @function min
-crud.min = borders.min
+crud.min = stats.wrap(borders.min, stats.op.BORDERS)
 
 -- @refer borders.max
 -- @function max
-crud.max = borders.max
+crud.max = stats.wrap(borders.max, stats.op.BORDERS)
 
 -- @refer utils.cut_rows
 -- @function cut_rows
@@ -92,6 +93,22 @@ crud.cut_rows = utils.cut_rows
 -- @function cut_objects
 crud.cut_objects = utils.cut_objects
 
+-- @refer stats.enable
+-- @function enable_stats
+crud.enable_stats = stats.enable
+
+-- @refer stats.get
+-- @function stats
+crud.stats = stats.get
+
+-- @refer stats.disable
+-- @function disable_stats
+crud.disable_stats = stats.disable
+
+-- @refer stats.reset
+-- @function reset_stats
+crud.reset_stats = stats.reset
+
 --- Initializes crud on node
 --
 -- Exports all functions that are used for calls

crud/stats/local_registry.lua

@@ -0,0 +1,124 @@
+local dev_checks = require('crud.common.dev_checks')
+local registry_common = require('crud.stats.registry_common')
+
+local registry = {}
+local internal_registry = {}
+
+--- Initialize local metrics registry
+--
+--  Registries are not meant to used explicitly
+--  by users, init is not guaranteed to be idempotent.
+--
+-- @function init
+--
+-- @treturn boolean Returns true.
+--
+function registry.init()
+    internal_registry.spaces = {}
+    internal_registry.space_not_found = 0
+
+    return true
+end
+
+--- Destroy local metrics registry
+--
+--  Registries are not meant to used explicitly
+--  by users, destroy is not guaranteed to be idempotent.
+--
+-- @function destroy
+--
+-- @treturn boolean Returns true.
+--
+function registry.destroy()
+    internal_registry = {}
+
+    return true
+end
+
+--- Get copy of local metrics registry
+--
+--  Registries are not meant to used explicitly
+--  by users, get is not guaranteed to work without init.
+--
+-- @function get
+--
+-- @tparam string space_name
+--  (Optional) If specified, returns table with statistics
+--  of operations on table, separated by operation type and
+--  execution status. If there wasn't any requests for table,
+--  returns {}. In not specified, returns table with statistics
+--  about all existing spaces and count of calls to spaces
+--  that wasn't found.
+--
+-- @treturn table Returns copy of metrics registry (or registry section).
+--
+function registry.get(space_name)
+    dev_checks('?string')
+
+    if space_name ~= nil then
+        return table.deepcopy(internal_registry.spaces[space_name]) or {}
+    end
+
+    return table.deepcopy(internal_registry)
+end
+
+--- Check if space statistics are present in registry
+--
+-- @function is_unknown_space
+--
+-- @tparam string space_name
+--  Name of space.
+--
+-- @treturn boolean True, if space stats found. False otherwise.
+--
+function registry.is_unknown_space(space_name)
+    dev_checks('string')
+
+    return internal_registry.spaces[space_name] == nil
+end
+
+--- Increase requests count and update latency info
+--
+-- @function observe
+--
+-- @tparam string space_name
+--  Name of space.
+--
+-- @tparam number latency
+--  Time of call execution.
+--
+-- @tparam string op
+--  Label of registry collectors.
+--  Use `require('crud.common.const').OP` to pick one.
+--
+-- @tparam string success
+--  'ok' if no errors on execution, 'error' otherwise.
+--
+-- @treturn boolean Returns true.
+--
+function registry.observe(latency, space_name, op, status)
+    dev_checks('number', 'string', 'string', 'string')
+
+    registry_common.init_collectors_if_required(internal_registry.spaces, space_name, op)
+    local collectors = internal_registry.spaces[space_name][op][status]
+
+    collectors.count = collectors.count + 1
+    collectors.time = collectors.time + latency
+    collectors.latency = collectors.time / collectors.count
+
+    return true
+end
+
+--- Increase count of "space not found" collector by one
+--
+-- @function observe_space_not_found
+--
+-- @treturn boolean Returns true.
+--
+function registry.observe_space_not_found()
+    internal_registry.space_not_found = internal_registry.space_not_found + 1
+
+    return true
+end
+
+return registry