If the current job is the latest one in the loader pool and the job is deleted,
the job goes into an infinite cycle of load-fail-delete-reload-load-fail-delete.
So we need to prevent the infinite loop during XAI data loading failed.

From: @ouwenchang
Reviewed-by: @wangyue01,@tangjr14
Signed-off-by: @tangjr14

From: @shenghong96
Reviewed-by: @wenkai_dist,@lilongfei15
Signed-off-by: @wenkai_dist

1. delete the unused code, catch unknown error is unused in explain_parser.py
2. fix bug the lastest file size is unused
3. rename some variables and fix some spelling error

From: @ouwenchang
Reviewed-by: 
Signed-off-by:

From: @gzhcv
Reviewed-by: @wenkai_dist
Signed-off-by:

From: @xia_yi_fan1
Reviewed-by: @weiyanxi,@ouwenchang,@panhui3,@wangyue01,@wenkai_dist
Signed-off-by: @wenkai_dist

From: @liangtianshu
Reviewed-by: @liuchongming74,@wangyue01,@wenkai_dist
Signed-off-by: @wenkai_dist

Support to stop the loader that is currently loading data when add a new loader to cache by get_job method
Add the UT usecase to the stop mechanism

From: @weiyanxi
Reviewed-by: @xia_yi_fan1,@wangyue01,@panhui3,@wenkai_dist
Signed-off-by: @wenkai_dist

From: @feng_xue_feng
Reviewed-by: 
Signed-off-by:

From: @luopengting
Reviewed-by: @wenkai_dist,@wangyue01
Signed-off-by: @wangyue01

If the values for batch_size is 'choice: [1, 2, True]', it will raise
validation exception.

Additionally, use 'type(value) is int' will not pass pylint. so use
'isinstance(x, bool) or not isinstance(x, int)' to filter invalid
value(s).

From: @huang_wei_feng4
Reviewed-by: @weiyanxi,@wenkai_dist,@lilongfei15
Signed-off-by: @lilongfei15

From: @ouwenchang
Reviewed-by: @tangjr14,@wenkai_dist
Signed-off-by: @wenkai_dist

FIFO queue mechanism is adopted for loader cache

From: @yelihua
Reviewed-by: @wenkai_dist,@wangyue01
Signed-off-by: @wangyue01

From: @jiang-shuqiang
Reviewed-by: @wenkai_dist
Signed-off-by:

add "1", "0" for --enable-debugger
add default node for all kind of watch conditions

From: @liuchongming74
Reviewed-by: @lilongfei15,@heleiwang,@lilongfei15,@tangjr14
Signed-off-by:

From: @yelihua
Reviewed-by: @lilongfei15,@wangyue01
Signed-off-by: @wangyue01

From: @huang_wei_feng4
Reviewed-by: @feng_xue_feng,@wangyue01,@lilongfei15
Signed-off-by: @lilongfei15

From: @luopengting
Reviewed-by: @wenkai_dist,@lilongfei15
Signed-off-by: @lilongfei15

From: @liuchongming74
Reviewed-by: @wangyue01,@lilongfei15
Signed-off-by: @lilongfei15

From: @huang_wei_feng4
Reviewed-by: @panhui3,@lilongfei15,@wenkai_dist
Signed-off-by: @wenkai_dist

From: @liuchongming74
Reviewed-by: @lilongfei15,@tangjr14
Signed-off-by: @lilongfei15

From: @liangtianshu
Reviewed-by: 
Signed-off-by:

From: @gzhcv
Reviewed-by: @lilongfei15,@tangjr14
Signed-off-by: @lilongfei15

From: @liuchongming74
Reviewed-by: 
Signed-off-by:

Add pre-checking about the param type in choice. If user use batch_size:
[2, 4, ff] in optimizer config file, it will raise an Exception to tell
that it must be integer.

From: @jiang-shuqiang
Reviewed-by: @wenkai_dist,@lilongfei15
Signed-off-by: @lilongfei15

From: @liangtianshu
Reviewed-by: @lilongfei15
Signed-off-by:

From: @feng_xue_feng
Reviewed-by: 
Signed-off-by:

fix the shape checking that only check the second to fourth shape of user inputs

From: @liangyongxiong1024
Reviewed-by: @lilongfei15,@wenkai_dist
Signed-off-by: @wenkai_dist