[Tarantool-patches] [PATCH vshard 1/1] rebalancer: give more info at bucket_recv() fail

[Vladislav Shpilevoy]

vshard.storage.bucket_recv() used to raise the natural
space:insert(...) error without any additional info when it
failed. For instance, due to incorrect format, or a duplicate key.

When such an error happens, it is very useful to know what was the
problematic space and what was the failed tuple. This patch
enriches the space insertion error with that information.

The new detailed error object and its message should help to fix
the rebalancing issues, which quite often are about schema
mismatch in different replicasets. Especially hard to debug when
number of spaces is tens of even hundreds.

The old way was fine for errors like "duplicate key" because on
the newest version of Tarantool it contains the space name, the
old and the new tuples. But errors like tuple format mismatch
still are not very informative. VShard now tries to enrich all the
possible errors.

Closes #275
---
Branch: http://github.com/tarantool/vshard/tree/gerold103/gh-275-bucket_recv-detailed-error
Issue: https://github.com/tarantool/vshard/issues/275

 test/storage/storage.result   | 47 +++++++++++++++++++++++++++++++++++
 test/storage/storage.test.lua | 17 +++++++++++++
 vshard/error.lua              |  5 ++++
 vshard/storage/init.lua       |  8 +++++-
 4 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/test/storage/storage.result b/test/storage/storage.result
index 570d9c6..5372059 100644
--- a/test/storage/storage.result
+++ b/test/storage/storage.result
@@ -521,6 +521,53 @@ while box.space._bucket:get{4} do vshard.storage.recovery_wakeup() fiber.sleep(0
 ---
 ...
 --
+-- gh-275: detailed info when couldn't insert into a space.
+--
+res, err = vshard.storage.bucket_recv(                                          \
+    4, util.replicasets[2], {{box.space.test.id, {{9, 4}, {10, 4}, {1, 4}}}})
+---
+...
+assert(not res)
+---
+- true
+...
+assert(err.space == 'test')
+---
+- true
+...
+assert(err.bucket_id == 4)
+---
+- true
+...
+assert(tostring(err.tuple) == '[1, 4]')
+---
+- true
+...
+assert(err.reason:match('Duplicate key exists') ~= nil)
+---
+- true
+...
+err = err.message
+---
+...
+assert(err:match('bucket 4 data in space "test" at tuple %[1, 4%]') ~= nil)
+---
+- true
+...
+assert(err:match('Duplicate key exists') ~= nil)
+---
+- true
+...
+while box.space._bucket:get{4} do                                               \
+    vshard.storage.recovery_wakeup() fiber.sleep(0.01)                          \
+end
+---
+...
+assert(box.space.test:get{9} == nil and box.space.test:get{10} == nil)
+---
+- true
+...
+--
 -- Bucket transfer
 --
 -- Transfer to unknown replicaset.
diff --git a/test/storage/storage.test.lua b/test/storage/storage.test.lua
index 494e2e8..d1f3f50 100644
--- a/test/storage/storage.test.lua
+++ b/test/storage/storage.test.lua
@@ -125,6 +125,23 @@ vshard.storage.bucket_recv(100, 'from_uuid', {{1000, {{1}}}})
 res, err = vshard.storage.bucket_recv(4, util.replicasets[2], {{1000, {{1}}}})
 util.portable_error(err)
 while box.space._bucket:get{4} do vshard.storage.recovery_wakeup() fiber.sleep(0.01) end
+--
+-- gh-275: detailed info when couldn't insert into a space.
+--
+res, err = vshard.storage.bucket_recv(                                          \
+    4, util.replicasets[2], {{box.space.test.id, {{9, 4}, {10, 4}, {1, 4}}}})
+assert(not res)
+assert(err.space == 'test')
+assert(err.bucket_id == 4)
+assert(tostring(err.tuple) == '[1, 4]')
+assert(err.reason:match('Duplicate key exists') ~= nil)
+err = err.message
+assert(err:match('bucket 4 data in space "test" at tuple %[1, 4%]') ~= nil)
+assert(err:match('Duplicate key exists') ~= nil)
+while box.space._bucket:get{4} do                                               \
+    vshard.storage.recovery_wakeup() fiber.sleep(0.01)                          \
+end
+assert(box.space.test:get{9} == nil and box.space.test:get{10} == nil)
 
 --
 -- Bucket transfer
diff --git a/vshard/error.lua b/vshard/error.lua
index b02bfe9..bcbcd71 100644
--- a/vshard/error.lua
+++ b/vshard/error.lua
@@ -149,6 +149,11 @@ local error_message_template = {
         msg = 'Can not delete a storage ref: %s',
         args = {'reason'},
     },
+    [30] = {
+        name = 'BUCKET_RECV_DATA_ERROR',
+        msg = 'Can not receive the bucket %s data in space "%s" at tuple %s: %s',
+        args = {'bucket_id', 'space', 'tuple', 'reason'},
+    }
 }
 
 --
diff --git a/vshard/storage/init.lua b/vshard/storage/init.lua
index 63e0398..7045d91 100644
--- a/vshard/storage/init.lua
+++ b/vshard/storage/init.lua
@@ -1254,7 +1254,13 @@ local function bucket_recv_xc(bucket_id, from, data, opts)
         end
         box.begin()
         for _, tuple in ipairs(space_data) do
-            space:insert(tuple)
+            local ok, err = pcall(space.insert, space, tuple)
+            if not ok then
+                box.rollback()
+                return nil, lerror.vshard(lerror.code.BUCKET_RECV_DATA_ERROR,
+                                          bucket_id, space.name,
+                                          box.tuple.new(tuple), err)
+            end
             limit = limit - 1
             if limit == 0 then
                 box.commit()
-- 
2.24.3 (Apple Git-128)