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feat(split): register child partition #391

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merged 26 commits into from
Apr 24, 2020

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hycdong
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@hycdong hycdong commented Feb 11, 2020

Simple partition split process

  1. meta receives client partition split request, and change partition count split: meta start partition split #286
  2. replica notices partition count changed during on_config_sync
  3. parent partition create child partition split: parent replica create child replica #291
  4. parent prepare states for child to learn feat(split): parent replica prepare states #299
  5. child partition async learn states from parent feat(split): child replica learn parent prepare list and checkpoint #309 feat(split): child replica apply private logs, in-memory mutations and catch up parent #319
  6. child notify parent catch up feat(split): child notify parent catch up #390
  7. update child group partition count
  8. register child partition
  9. parent update group partition count and recover read and write

More partition split discussion in issue #69 and partition split design doc
This pr solves the part of fifth step of partition split, which is bold in process description.

What this pr solved

  • replica::register_child_on_meta: primary parent register child partition on meta_server and parent will reject read write client.
  • meta_split_service::register_child_on_meta: meta server update child partition_configuration structure on remote storage and local.
  • child_partition_active: when child registered, child of primary parent will be the primary of the child replica group, its status will turn from PS_PARTITION_SPLIT to PS_PRIMARY, child of secondary will update its status by group_check.

@hycdong hycdong marked this pull request as ready for review March 20, 2020 07:58
@hycdong hycdong changed the title feat(split): register child partition [WIP] feat(split): register child partition Mar 20, 2020
acelyc111
acelyc111 previously approved these changes Apr 16, 2020
src/dist/replication/lib/replica_split.cpp Show resolved Hide resolved
src/dist/replication/lib/replica_split.cpp Outdated Show resolved Hide resolved
src/dist/replication/lib/replica_split.cpp Show resolved Hide resolved
src/dist/replication/lib/replica_split.cpp Outdated Show resolved Hide resolved
Comment on lines +726 to +728
}

if (err == ERR_OK) {
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Suggested change
}
if (err == ERR_OK) {
} else {

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@hycdong hycdong Apr 17, 2020

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L752-L759 will always be executed, you can see comments in L751

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I see no comment:

// ThreadPool: THREAD_POOL_REPLICATION
void replica::child_partition_active(const partition_configuration &config) // on child
{
ddebug_replica("child partition become active");
_primary_states.last_prepare_decree_on_new_primary = _prepare_list->max_decree();
update_configuration(config);
}

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The line number changed after I wrote this comment.

// parent register child succeed or child partition has already resgitered
// in both situation, we should reset resgiter child task and child_gpid

const std::string &partition_path = _state->get_partition_path(request.child_config.pid);
blob value = dsn::json::json_forwarder<partition_configuration>::encode(request.child_config);
if (create_new) {
return _meta_svc->get_remote_storage()->create_node(
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use get_meta_storage() instead, which can auto-repeat on timeout, and assert on unexpected error.

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I tried to use get_meta_storage(), but I should handle ERR_TIMEOUT and ERR_NODE_ALREADY_EXIST specifically in callback function.

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OK. I will later write a utility of meta_storage for this case.

register_child_rpc rpc(std::move(request), RPC_CM_REGISTER_CHILD_REPLICA);
split_svc().register_child_on_meta(rpc);
wait_all();
if (wait_zk) {
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what's wait_zk used for? wait_all supposed to wait any tasks to complete.

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@hycdong hycdong Apr 17, 2020

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wait_all function will wait meta_service tasks, zk tasks are not included. The simple way is to sleep for several seconds to wait updating zk succeed.

@@ -369,6 +370,8 @@ void replica::update_configuration_on_meta_server(config_type::type type,
"");
dassert(
newConfig.primary == node, "%s VS %s", newConfig.primary.to_string(), node.to_string());
} else if (type == config_type::CT_REGISTER_CHILD) {
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Let me describe this code in pseudocode:

If the type is not CT_PRIMARY_FORCE_UPDATE_BALLOT, then it cannot be CT_REGISTER_CHILD.

What does it suppose to mean? Can you add a comment here? Is that CT_REGISTER_CHILD is impossible, or not-CT_PRIMARY_FORCE_UPDATE_BALLOT && CT_REGISTER_CHILD is impossible?

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There is no relationship between CT_PRIMARY_FORCE_UPDATE_BALLOT and CT_REGISTER_CHILD. I have updated the code.

Comment on lines +726 to +728
}

if (err == ERR_OK) {
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I see no comment:

// ThreadPool: THREAD_POOL_REPLICATION
void replica::child_partition_active(const partition_configuration &config) // on child
{
ddebug_replica("child partition become active");
_primary_states.last_prepare_decree_on_new_primary = _prepare_list->max_decree();
update_configuration(config);
}

const std::string &partition_path = _state->get_partition_path(request.child_config.pid);
blob value = dsn::json::json_forwarder<partition_configuration>::encode(request.child_config);
if (create_new) {
return _meta_svc->get_remote_storage()->create_node(
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OK. I will later write a utility of meta_storage for this case.

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4 participants