lock graph when close()

[javeme]

also fix scheduleOrExecuteJob and closeScheduler dead lock:
when main thread catched lock in closeScheduler() then call closeSchedulerTx()
and wait for schedulerExecutor, at the same time scheduler thread call
scheduleOrExecuteJob() but can't get synchronized lock, caused dead lock.

fix #1075
Change-Id: I47e7d4bbb87dd1330dd33616b6d2c33b2a39a89e

[javeme]

calling initialized() cause reopen tx when graph is closed hugegraph@dc7b924#diff-a7ddfcbed05d0ca6b726444d2184723fR304

[ERROR] Tests run: 673, Failures: 3, Errors: 1, Skipped: 13, Time elapsed: 868.376 s <<< FAILURE! - in com.baidu.hugegraph.core.CoreTestSuite
[ERROR] testCreateGraphsWithDifferentNameDifferentBackends(com.baidu.hugegraph.core.MultiGraphsTest)  Time elapsed: 48.688 s  <<< FAILURE!
java.lang.AssertionError: java.lang.IllegalStateException: Ensure tx closed in all threads when closing graph 'g1'
	at com.baidu.hugegraph.core.MultiGraphsTest.destoryGraphs(MultiGraphsTest.java:352)
	at com.baidu.hugegraph.core.MultiGraphsTest.testCreateGraphsWithDifferentNameDifferentBackends(MultiGraphsTest.java:301)
[ERROR] testCreateGraphsWithMultiDisksForRocksDB(com.baidu.hugegraph.core.MultiGraphsTest)  Time elapsed: 0.734 s  <<< FAILURE!
java.lang.AssertionError: No exception was thrown(expected com.baidu.hugegraph.backend.BackendException)
	at com.baidu.hugegraph.core.MultiGraphsTest.testCreateGraphsWithMultiDisksForRocksDB(MultiGraphsTest.java:315)
[ERROR] testCreateGraphWithSameNameDifferentBackends(com.baidu.hugegraph.core.MultiGraphsTest)  Time elapsed: 0.003 s  <<< ERROR!
java.lang.RuntimeException: GraphFactory could not instantiate this Graph implementation [class com.baidu.hugegraph.HugeFactory]
	at com.baidu.hugegraph.core.MultiGraphsTest.openGraphWithBackend(MultiGraphsTest.java:373)
	at com.baidu.hugegraph.core.MultiGraphsTest.testCreateGraphWithSameNameDifferentBackends(MultiGraphsTest.java:279)
Caused by: java.lang.reflect.InvocationTargetException
	at com.baidu.hugegraph.core.MultiGraphsTest.openGraphWithBackend(MultiGraphsTest.java:373)
	at com.baidu.hugegraph.core.MultiGraphsTest.testCreateGraphWithSameNameDifferentBackends(MultiGraphsTest.java:279)
Caused by: java.lang.IllegalStateException: Graph name 'graph' has been used by backend 'hbase'
	at com.baidu.hugegraph.core.MultiGraphsTest.openGraphWithBackend(MultiGraphsTest.java:373)
	at com.baidu.hugegraph.core.MultiGraphsTest.testCreateGraphWithSameNameDifferentBackends(MultiGraphsTest.java:279)
[ERROR] testCopySchemaWithMultiGraphs(com.baidu.hugegraph.core.MultiGraphsTest)  Time elapsed: 105.285 s  <<< FAILURE!
java.lang.AssertionError: java.lang.IllegalStateException: Ensure tx closed in all threads when closing graph 'schema_g1'
	at com.baidu.hugegraph.core.MultiGraphsTest.destoryGraphs(MultiGraphsTest.java:352)
	at com.baidu.hugegraph.core.MultiGraphsTest.testCopySchemaWithMultiGraphs(MultiGraphsTest.java:185)

[codecov]

Codecov Report

Merging #1104 into master will increase coverage by 9.04%.
The diff coverage is 86.66%.

@@             Coverage Diff              @@
##             master    #1104      +/-   ##
============================================
+ Coverage     60.35%   69.40%   +9.04%     
- Complexity     4709     5625     +916     
============================================
  Files           331      331              
  Lines         26997    27116     +119     
  Branches       3865     3896      +31     
============================================
+ Hits          16295    18819    +2524     
+ Misses         8915     6448    -2467     
- Partials       1787     1849      +62     

Impacted Files	Coverage Δ	Complexity Δ
...in/java/com/baidu/hugegraph/StandardHugeGraph.java	80.40% <ø> (+1.27%)	108.00 <0.00> (+6.00)
...ain/java/com/baidu/hugegraph/task/TaskManager.java	74.32% <85.18%> (+1.40%)	30.00 <5.00> (+6.00)
...va/com/baidu/hugegraph/task/ServerInfoManager.java	70.05% <100.00%> (+1.09%)	48.00 <2.00> (+4.00)
...om/baidu/hugegraph/backend/query/QueryResults.java	71.15% <0.00%> (-10.48%)	40.00% <0.00%> (+1.00%)	⬇️
...n/java/com/baidu/hugegraph/config/CoreOptions.java	99.04% <0.00%> (+0.02%)	2.00% <0.00%> (ø%)
.../baidu/hugegraph/backend/tx/SchemaTransaction.java	91.54% <0.00%> (+0.49%)	70.00% <0.00%> (+1.00%)
...om/baidu/hugegraph/task/StandardTaskScheduler.java	79.39% <0.00%> (+0.50%)	90.00% <0.00%> (+9.00%)
...n/java/com/baidu/hugegraph/structure/HugeEdge.java	74.74% <0.00%> (+0.51%)	85.00% <0.00%> (+4.00%)
...ava/com/baidu/hugegraph/structure/HugeElement.java	70.52% <0.00%> (+0.52%)	70.00% <0.00%> (+3.00%)
...aidu/hugegraph/backend/store/mysql/MysqlTable.java	81.54% <0.00%> (+0.55%)	96.00% <0.00%> (+1.00%)
... and 134 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 125b2ef...d69b5fa. Read the comment docs.