Expose the crud module in global scope (#58)

* Get rid of performing map-reduce for single-replicaset operations (introduced `call.rw_single`)
* Added `crud-router` Cartridge role
* CRUD-router functions are exposed to the global scope, so it's possible to call
  crud-operations via `net.box.call`
* `crud.init` is removed in favor to `crud.init_storage` and `crud.init_router`

Author: knazarov

.gitignore

@@ -3,3 +3,6 @@ build.luarocks/
 myapp/
 **.snap
 **.xlog
+.tarantool.cookie
+CMakeCache.txt
+CMakeFiles/

CHANGELOG.md

@@ -8,8 +8,20 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [Unreleased]
 
 ### Fixed
+
 * Select by primary index name
-* Fix error handling select with invalid type value 
+* Fix error handling select with invalid type value
+* Get rid of performing map-reduce for single-replicaset operations
+
+### Added
+
+* `crud-router` Cartridge role
+
+### Changed
+
+* CRUD-router functions are exposed to the global scope, so it's possible to call
+  crud-operations via `net.box.call`
+* `crud.init` is removed in favor to `crud.init_storage` and `crud.init_router`
 
 ## [0.2.0] - 2020-10-07
 

README.md

@@ -7,10 +7,12 @@ It also provides the `crud-storage` role for
 ## API
 
 The CRUD operations should be called from router.
-All storage replica sets should call `crud.init()`
+All storage replica sets should call `crud.init_storage()`
 (or enable the `crud-storage` role)
 first to initialize storage-side functions that are used to manipulate data
 across the cluster.
+All routers should call `crud.init_router()` (or enable the `crud-router` role)
+to make `crud` functions callable via `net.box`.
 
 **Notes:**
 
@@ -318,12 +320,17 @@ for _, object in crud.pairs('customers', {{'<=', 'age', 35}}, {use_tomap = true}
 end
 ```
 
-## Cartridge role
+## Cartridge roles
 
 `cartridge.roles.crud-storage` is a Tarantool Cartridge role that depends on the
 `vshard-storage` role, but also initializes functions that
 are used on the storage side to perform CRUD operations.
 
+`cartridge.roles.crud-router` is a role that depends on the
+`vshard-router` role, but also exposes public `crud` functions in the global
+scope, so that you can call them via `net.box`.
+
+
 ### Usage
 
 1. Add `crud` to dependencies in the project rockspec.
@@ -373,8 +380,17 @@ return {
     }
 ```
 
+```lua
+-- app.roles.customers-router.lua
+local cartridge = require('cartridge')
+return {
+        role_name = 'customers-router',
+        dependencies = {'cartridge.roles.crud-router'},
+    }
+```
+
 3. Start the application and create `customers-storage` and
-   `vshard-router` replica sets.
+   `customers-router` replica sets.
 
 4. Don't forget to bootstrap vshard.
 

cartridge/roles/crud-router.lua

@@ -0,0 +1,12 @@
+local crud = require('crud')
+
+-- removes routes that changed in config and adds new routes
+local function init()
+    crud.init_router()
+end
+
+return {
+    role_name = 'crud-router',
+    init = init,
+    dependencies = {'cartridge.roles.vshard-router'}
+}

cartridge/roles/crud-storage.lua

@@ -1,8 +1,7 @@
 local crud = require('crud')
 
--- removes routes that changed in config and adds new routes
 local function init()
-    crud.init()
+    crud.init_storage()
 end
 
 return {

crud.lua

@@ -2,8 +2,6 @@
 --
 -- @module crud
 
-local registry = require('crud.common.registry')
-local call = require('crud.common.call')
 local insert = require('crud.insert')
 local replace = require('crud.replace')
 local get = require('crud.get')
@@ -15,13 +13,6 @@ local utils = require('crud.common.utils')
 
 local crud = {}
 
---- Functions registry
--- @section registry
-
--- @refer registry.add
--- @function register
-crud.register = registry.add
-
 --- CRUD operations.
 -- @section crud
 
@@ -80,8 +71,11 @@ crud.unflatten_rows = utils.unflatten_rows
 --
 -- @function init
 --
-function crud.init()
-    call.init()
+function crud.init_storage()
+    if rawget(_G, '_crud') == nil then
+        rawset(_G, '_crud', {})
+    end
+
     insert.init()
     get.init()
     replace.init()
@@ -91,4 +85,8 @@ function crud.init()
     select.init()
 end
 
+function crud.init_router()
+   rawset(_G, 'crud', crud)
+end
+
 return crud

crud/common/call.lua

@@ -3,55 +3,25 @@ local vshard = require('vshard')
 local errors = require('errors')
 
 local dev_checks = require('crud.common.dev_checks')
-local registry = require('crud.common.registry')
 local utils = require('crud.common.utils')
 
 local CallError = errors.new_class('Call')
 local NotInitializedError = errors.new_class('NotInitialized')
 
 local call = {}
 
-local CALL_FUNC_NAME = '__call'
-
 local DEFAULT_VSHARD_CALL_TIMEOUT = 2
 
---- Initializes call on node
---
--- Wrapper function is registered to call functions remotely.
---
--- @function init
---
-function call.init()
-    local function call(opts)
-        dev_checks({
-            func_name = 'string',
-            func_args = '?table',
-        })
-
-        local func = registry.get(opts.func_name) or rawget(_G, opts.func_name)
-
-        if type(func) ~= 'function' then
-            return nil, CallError:new('Function %s is not registered', opts.func_name)
-        end
-
-        return func(unpack(opts.func_args or {}))
-    end
-
-    -- register global function
-    rawset(_G, CALL_FUNC_NAME, call)
-end
-
 local function call_on_replicaset(replicaset, channel, vshard_call, func_name, func_args, opts)
-    local elect_call_arg = {
-        func_name = func_name,
-        func_args = func_args,
-    }
-
     -- replicaset:<vshard_call>(func_name,...)
-    local func_ret, err = replicaset[vshard_call](replicaset, CALL_FUNC_NAME, {elect_call_arg}, opts)
+    local func_ret, err = replicaset[vshard_call](replicaset, func_name, func_args, opts)
     if type(err) == 'table' and err.type == 'ClientError' and type(err.message) == 'string' then
-        if err.message == string.format("Procedure '%s' is not defined", CALL_FUNC_NAME) then
-            err = NotInitializedError:new("crud isn't initialized on replicaset")
+        if err.message == string.format("Procedure '%s' is not defined", func_name) then
+            if func_name:startswith('_crud.') then
+                err = NotInitializedError:new("crud isn't initialized on replicaset")
+            else
+                err = NotInitializedError:new("Function %s is not registered", func_name)
+            end
         end
     end
 
@@ -165,4 +135,41 @@ function call.ro(func_name, func_args, opts)
     return call_impl('callro', func_name, func_args, opts)
 end
 
+--- Calls specified function on a node according to bucket_id.
+--
+-- Exactly mimics the contract of vshard.router.callrw, but adds
+-- better error hangling
+--
+-- @function rw_single
+--
+function call.rw_single(bucket_id, func_name, func_args, options)
+    local res, err = vshard.router.callrw(bucket_id, func_name, func_args, options)
+
+    -- This is a workaround, until vshard supports telling us where the error happened
+    if err ~= nil then
+        if type(err) == 'table' and err.type == 'ClientError' and type(err.message) == 'string' then
+            if err.message == string.format("Procedure '%s' is not defined", func_name) then
+               err = NotInitializedError:new("crud isn't initialized on replicaset")
+            end
+        end
+
+        local replicaset, _ = vshard.router.route(bucket_id)
+        if replicaset == nil then
+            return nil, CallError:new(
+                "Function returned an error, but we couldn't figure out the replicaset: %s", err
+            )
+        end
+
+        return nil, CallError:new(utils.format_replicaset_error(
+             replicaset.uuid, "Function returned an error: %s", err
+        ))
+    end
+
+    if res == box.NULL then
+        return nil
+    end
+
+    return res
+end
+
 return call

crud/common/registry.lua

@@ -3,17 +3,16 @@ local errors = require('errors')
 local vshard = require('vshard')
 
 local call = require('crud.common.call')
-local registry = require('crud.common.registry')
 local utils = require('crud.common.utils')
 local dev_checks = require('crud.common.dev_checks')
 
 local DeleteError = errors.new_class('Delete',  {capture_stack = false})
 
 local delete = {}
 
-local DELETE_FUNC_NAME = '__delete'
+local DELETE_FUNC_NAME = '_crud.delete_on_storage'
 
-local function call_delete_on_storage(space_name, key)
+local function delete_on_storage(space_name, key)
     dev_checks('string', '?')
 
     local space = box.space[space_name]
@@ -26,9 +25,7 @@ local function call_delete_on_storage(space_name, key)
 end
 
 function delete.init()
-    registry.add({
-        [DELETE_FUNC_NAME] = call_delete_on_storage,
-    })
+   _G._crud.delete_on_storage = delete_on_storage
 end
 
 --- Deletes tuple from the specified space by key
@@ -66,24 +63,18 @@ function delete.call(space_name, key, opts)
     end
 
     local bucket_id = vshard.router.bucket_id_strcrc32(key)
-    local replicaset, err = vshard.router.route(bucket_id)
-    if replicaset == nil then
-        return nil, DeleteError:new("Failed to get replicaset for bucket_id %s: %s", bucket_id, err.err)
-    end
-
-    local results, err = call.rw(DELETE_FUNC_NAME, {space_name, key}, {
-        replicasets = {replicaset},
-        timeout = opts.timeout,
-    })
+    local result, err = call.rw_single(
+        bucket_id, DELETE_FUNC_NAME,
+        {space_name, key}, {timeout = opts.timeout}
+    )
 
     if err ~= nil then
         return nil, DeleteError:new("Failed to delete: %s", err)
     end
 
-    local tuple = results[replicaset.uuid]
     return {
         metadata = table.copy(space:format()),
-        rows = {tuple},
+        rows = {result},
     }
 end