Implementation of batch replace

Batch upsert is mostly used for operation with
one bucket / one Tarantool node in a transaction.
In this case batch replace is more efficient
then replacing tuple-by-tuple.
Right now CRUD cannot provide batch replace with full consistency.
CRUD offers batch upsert with partial consistency. That means
that full consistency can be provided only on single replicaset
using `box` transactions.

Part of #193

CHANGELOG.md

@@ -8,6 +8,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [Unreleased]
 
 ### Added
+* Batch insert/upsert operation
+  `crud.insert_many()`/`crud.insert_object_many()`/
+  `crud.upsert_many()`/`crud.upsert_object_many()`
+  `crud.replace_many()`/`crud.replace_object_many()`
+  with partial consistency
 
 ### Changed
 

README.md

@@ -21,6 +21,7 @@ It also provides the `crud-storage` and `crud-router` roles for
   - [Update](#update)
   - [Delete](#delete)
   - [Replace](#replace)
+  - [Replace many](#replace-many)
   - [Upsert](#upsert)
   - [Upsert many](#upsert-many)
   - [Select](#select)
@@ -520,6 +521,101 @@ crud.replace_object('customers', {
 ...
 ```
 
+### Replace many
+
+```lua
+-- Replace batch of tuples
+local result, err = crud.replace_many(space_name, tuples, opts)
+-- Replace batch of objects
+local result, err = crud.replace_object_many(space_name, objects, opts)
+```
+
+where:
+
+* `space_name` (`string`) - name of the space to insert/replace an object
+* `tuples` / `objects` (`table`) - array of tuples/objects to insert
+* `opts`:
+  * `timeout` (`?number`) - `vshard.call` timeout (in seconds)
+  * `fields` (`?table`) - field names for getting only a subset of fields
+  * `stop_on_error` (`?boolean`) - stop on a first error and report error
+    regarding the failed operation and error about what tuples were not
+    performed, default is `false`
+  * `rollback_on_error` (`?boolean`) - any failed operation will lead to
+    rollback on a storage, where the operation is failed, report error
+    about what tuples were rollback, default is `false`
+
+Returns metadata and array contains inserted rows, array of errors.
+Error object can contain field `operation_data`.
+
+This field can contain:
+* tuple for which the error occurred;
+* object with an incorrect format;
+* tuple the operation on which was performed but
+  operation was rollback;
+* tuple the operation on which was not performed
+  because operation was stopped by error.
+
+Right now CRUD cannot provide batch replace with full consistency.
+CRUD offers batch replace with partial consistency. That means
+that full consistency can be provided only on single replicaset
+using `box` transactions.
+
+**Example:**
+
+```lua
+crud.replace_many('developers', {
+  {1, box.NULL, 'Elizabeth', 'lizaaa'},
+  {2, box.NULL, 'Anastasia', 'iamnewdeveloper'},
+})
+---
+- metadata:
+  - {'name': 'id', 'type': 'unsigned'}
+  - {'name': 'bucket_id', 'type': 'unsigned'}
+  - {'name': 'name', 'type': 'string'}
+  - {'name': 'login', 'type': 'string'}
+  rows:
+  - [1, 477, 'Elizabeth', 'lizaaa']
+  - [2, 401, 'Anastasia', 'iamnewdeveloper']
+...
+crud.replace_object_many('developers', {
+    {id = 1, name = 'Inga', login = 'mylogin'},
+    {id = 10, name = 'Anastasia', login = 'qwerty'},
+})
+---
+- metadata:
+  - {'name': 'id', 'type': 'unsigned'}
+  - {'name': 'bucket_id', 'type': 'unsigned'}
+  - {'name': 'name', 'type': 'string'}
+  - {'name': 'age', 'type': 'number'}
+  rows:
+  - [1, 477, 'Inga', 'mylogin']
+  - [10, 569, 'Anastasia', 'qwerty']
+
+-- Partial success
+-- Let's say login has unique secondary index
+local res, errs = crud.replace_object_many('developers', {
+    {id = 22, name = 'Alex', login = 'pushkinn'},
+    {id = 3, name = 'Anastasia', login = 'qwerty'},
+    {id = 5, name = 'Sergey', login = 's.petrenko'},
+})
+---
+res
+- metadata:
+  - {'name': 'id', 'type': 'unsigned'}
+  - {'name': 'bucket_id', 'type': 'unsigned'}
+  - {'name': 'name', 'type': 'string'}
+  - {'name': 'age', 'type': 'number'}
+  rows:
+  - [5, 1172, 'Sergey', 'crudisthebest'],
+  - [22, 655, 'Alex', 'pushkinn'],
+
+#errs              -- 1
+errs[1].class_name -- ReplaceManyError
+errs[1].err        -- 'Duplicate key exists <...>'
+errs[1].tuple      -- {3, 2804, 'Anastasia', 'qwerty'}
+...
+```
+
 ### Upsert
 
 ```lua

crud.lua

@@ -6,6 +6,7 @@ local cfg = require('crud.cfg')
 local insert = require('crud.insert')
 local insert_many = require('crud.insert_many')
 local replace = require('crud.replace')
+local replace_many = require('crud.replace_many')
 local get = require('crud.get')
 local update = require('crud.update')
 local upsert = require('crud.upsert')
@@ -53,6 +54,14 @@ crud.replace = stats.wrap(replace.tuple, stats.op.REPLACE)
 -- @function replace_object
 crud.replace_object = stats.wrap(replace.object, stats.op.REPLACE)
 
+-- @refer replace_many.tuples
+-- @function replace_many
+crud.replace_many = replace_many.tuples
+
+-- @refer replace_many.objects
+-- @function replace_object_many
+crud.replace_object_many = replace_many.objects
+
 -- @refer update.call
 -- @function update
 crud.update = stats.wrap(update.call, stats.op.UPDATE)
@@ -145,6 +154,7 @@ function crud.init_storage()
     insert_many.init()
     get.init()
     replace.init()
+    replace_many.init()
     update.init()
     upsert.init()
     upsert_many.init()