Mainly fix the following issues:
1. A null pointer exception is raised when a database or table is dropped. The expected behavior is that the routine load job is stopped.
2. Memory leaks. Batch routine load task submissions are no longer performed, and modifications are submitted separately for each task.
3. Unreasonable task timeout.
Routine load tasks should not be queued in the BE thread pool for execution. The task sent to the BE should be executed immediately, otherwise the task in the FE will be timeout first. Eventually leads to constant timeout for all subsequent tasks.
4. All routine load job should be scheduled once it being submitted. Not waiting the available BE slot. Otherwise, all later submitted jobs may not be scheduled forever.
1. Support specifying label to Insert Into stmt.
INSERT INTO tbl1 WITH LABEL label1 ...;
2. Return job' state corresponding to the existing label in result of stream load.
...
"Status": "Label Already Exists",
"ExistingJobStatus": "FINISHED"
...
3. Return the recent 2000 transactions in SHOW PROC '/transactions'
This config is used to control the max concurrent task num per be.
The cluster max concurrent task num = max_concurrent_task_num_per_be * number of be.
If strict mode is true, and at least one row is filtered, the insert operation will fail and a url will be given to get the error rows.
```
ERROR 1064 (HY000): all partitions have no load data. url: http://host:ip/api/_load_error_log?file=__shard_2/error_log_insert_stmt_e0a620e93dc54461-b89ec64768367d25_e0a620e93dc54461_b89ec64768367d25
```
If all rows are good, insert will return OK with affected rows:
```
Query OK, 1 row affected (0.26 sec)
```
If strict mode is false, and at least one row is good, the insert operation will return OK with affected rows and warnings. If has error row num, a label will be returned:
```
Query OK, 1 row affected, 1 warning (0.32 sec)
{'label':'7d66c457-658b-4a3e-bdcf-8beee872ef2c'}
```
* Broker load supports function
The commit support the column function in broker load.
The grammar of LoadStmt has not been changed.
Example:
columns terminated by ',' (tmp_c1, tmp_c2) set (c1=tmp_c1+tmp_c2)
Also, the old function is compatible such as default_value, strftime etc.
After this commit, there are no difference in column function between stream load and broker load except old function.
The catalogue of load docs:
---- load-manual.md
---- broker-load-manual.md
---- insert-into-manual.md
---- stream-load-manual.md
This commit also changes max/min_stream_load_timeout to max/min_load_timeout.
The old config named stream_load_timeout means the max timeout suited for all types of load.
So the config name has been changed.
This change adds a load property named strict_mode which is used to prohibit the incorrect data.
When it is set to false, the incorrect data will be loaded by NULL just like before.
When it is set to true, the incorrect data which belongs to a column without expr will be filtered.
The strict_mode is supported in broker load v2 now. It will be supported in stream load later.
1. Add Config.max_routine_load_concurrent_task_num instead of the old one
2. Fix a bug that SHOW ALTER TABLE COLUMN may throw Nullpointer exception
3. Fix some misspelling of docs
