split experimental_feature flag (vesoft-inc#1429)

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## What type of PR is this?
- [ ] bug
- [ ] feature
- [x] enhancement

## What problem(s) does this PR solve?
#### Issue(s) number: 

vesoft-inc#4729

#### Description:

experimental flags control toss and data balance at the same time.


## How do you solve it?

add 2 sub flag, current config only allow data balance.

```
# if use experimental features
--enable_experimental_feature=false
# if use toss feature, only work if enable_experimental_feature is true
--enable_toss=false
# if use balance data feature, only work if enable_experimental_feature is true
--enable_data_balance=true
```

## Special notes for your reviewer, ex. impact of this fix, design document, etc:



## Checklist:
Tests:
- [ ] Unit test(positive and negative cases)
- [ ] Function test
- [ ] Performance test
- [ ] N/A

Affects:
- [x] Documentation affected (Please add the label if documentation needs to be modified.)
- [ ] Incompatibility (If it breaks the compatibility, please describe it and add the label.）
- [ ] If it's needed to cherry-pick (If cherry-pick to some branches is required, please label the destination version(s).)
- [ ] Performance impacted: Consumes more CPU/Memory


## Release notes:

Please confirm whether to be reflected in release notes and how to describe:
> add new flag to support only open toss（not suggest）/ data balance feature

Migrated from vesoft-inc#4728

Co-authored-by: Alex Xing <[email protected]>

conf/nebula-graphd.conf.default

@@ -136,6 +136,9 @@
 # if use experimental features
 --enable_experimental_feature=false
 
+# if use toss feature, only work if enable_experimental_feature is true
+--enable_toss=false
+
 ########## Black box ########
 # Enable black box
 --ng_black_box_switch=true

conf/nebula-graphd.conf.production

@@ -135,6 +135,9 @@
 # if use experimental features
 --enable_experimental_feature=false
 
+# if use toss feature, only work if enable_experimental_feature is true
+--enable_toss=false
+
 ########## session ##########
 # Maximum number of sessions that can be created per IP and per user
 --max_sessions_per_ip_per_user=300

conf/nebula-standalone.conf.default

@@ -93,6 +93,9 @@
 # if use experimental features
 --enable_experimental_feature=false
 
+# if use toss feature, only work if enable_experimental_feature is true
+--enable_toss=false
+
 ######### Raft #########
 # Raft election timeout
 --raft_heartbeat_interval_secs=30

src/graph/executor/mutate/DeleteExecutor.cpp

@@ -200,7 +200,7 @@ folly::Future<Status> DeleteEdgesExecutor::deleteEdges() {
   auto plan = qctx()->plan();
   StorageClient::CommonRequestParam param(
       spaceId, qctx()->rctx()->session()->id(), plan->id(), plan->isProfileEnabled());
-  param.useExperimentalFeature = FLAGS_enable_experimental_feature;
+  param.useExperimentalFeature = FLAGS_enable_experimental_feature && FLAGS_enable_toss;
   return qctx()
       ->getStorageClient()
       ->deleteEdges(param, std::move(edgeKeys))

src/graph/executor/mutate/InsertExecutor.cpp

@@ -54,7 +54,7 @@ folly::Future<Status> InsertEdgesExecutor::insertEdges() {
   auto plan = qctx()->plan();
   StorageClient::CommonRequestParam param(
       ieNode->getSpace(), qctx()->rctx()->session()->id(), plan->id(), plan->isProfileEnabled());
-  param.useExperimentalFeature = FLAGS_enable_experimental_feature;
+  param.useExperimentalFeature = FLAGS_enable_experimental_feature && FLAGS_enable_toss;
   return qctx()
       ->getStorageClient()
       ->addEdges(param,

src/graph/executor/mutate/UpdateExecutor.cpp

@@ -98,7 +98,7 @@ folly::Future<Status> UpdateEdgeExecutor::execute() {
   auto plan = qctx()->plan();
   StorageClient::CommonRequestParam param(
       ueNode->getSpaceId(), qctx()->rctx()->session()->id(), plan->id(), plan->isProfileEnabled());
-  param.useExperimentalFeature = FLAGS_enable_experimental_feature;
+  param.useExperimentalFeature = FLAGS_enable_experimental_feature && FLAGS_enable_toss;
   return qctx()
       ->getStorageClient()
       ->updateEdge(param,

src/graph/service/GraphFlags.cpp

@@ -74,6 +74,7 @@ DEFINE_bool(disable_octal_escape_char,
             " in next version to ensure compatibility with cypher.");
 
 DEFINE_bool(enable_experimental_feature, false, "Whether to enable experimental feature");
+DEFINE_bool(enable_toss, false, "Whether to enable toss feature");
 
 // LDAP authentication common parameters
 DEFINE_string(ldap_server,

src/graph/service/GraphFlags.h

@@ -54,6 +54,7 @@ DECLARE_bool(optimize_appendvertice);
 DECLARE_int64(max_allowed_connections);
 
 DECLARE_bool(enable_experimental_feature);
+DECLARE_bool(enable_toss);
 
 // LDAP authentication common parameters
 DECLARE_string(ldap_server);

src/graph/validator/MutateValidator.cpp

@@ -216,7 +216,8 @@ Status InsertEdgesValidator::check() {
 // Check validity of vertices data.
 // Check edge key type, check properties value, fill to NewEdge structure.
 Status InsertEdgesValidator::prepareEdges() {
-  auto size = FLAGS_enable_experimental_feature ? rows_.size() : rows_.size() * 2;
+  auto size =
+      FLAGS_enable_experimental_feature && FLAGS_enable_toss ? rows_.size() : rows_.size() * 2;
   edges_.reserve(size);
 
   size_t fieldNum = schema_->getNumFields();
@@ -301,7 +302,7 @@ Status InsertEdgesValidator::prepareEdges() {
     edge.key_ref() = key;
     edge.props_ref() = std::move(entirePropValues);
     edges_.emplace_back(edge);
-    if (!FLAGS_enable_experimental_feature) {
+    if (!(FLAGS_enable_experimental_feature && FLAGS_enable_toss)) {
       // inbound
       key.src_ref() = dstId;
       key.dst_ref() = srcId;
@@ -870,7 +871,7 @@ Status UpdateEdgeValidator::toPlan() {
                                    {},
                                    condition_,
                                    {});
-  if (FLAGS_enable_experimental_feature) {
+  if ((FLAGS_enable_experimental_feature && FLAGS_enable_toss)) {
     root_ = outNode;
     tail_ = root_;
   } else {