HBASE-22623 - Add RegionObserver coprocessor hook for preWALAppend

[gjacoby126]

This is the branch-1 backport of PR #390 , for HBASE-22623. Since it's a slightly non-trivial backport, opening up a separate PR for ease of review / chance for HBase Robot to pass judgement.

[gjacoby126]

@apurtell@Apache9@anoopsjohn , fyi. The branch-1 backport.

[Apache-HBase]

💔 -1 overall

Vote	Subsystem	Runtime	Comment
0	reexec	73	Docker mode activated.
		_ Prechecks _
+1	dupname	0	No case conflicting files found.
+1	hbaseanti	0	Patch does not have any anti-patterns.
+1	@author	0	The patch does not contain any @author tags.
+1	test4tests	0	The patch appears to include 2 new or modified test files.
		_ branch-1 Compile Tests _
+1	mvninstall	600	branch-1 passed
+1	compile	57	branch-1 passed with JDK v1.8.0_222
+1	compile	55	branch-1 passed with JDK v1.7.0_232
+1	checkstyle	126	branch-1 passed
+1	shadedjars	217	branch has no errors when building our shaded downstream artifacts.
+1	javadoc	47	branch-1 passed with JDK v1.8.0_222
+1	javadoc	49	branch-1 passed with JDK v1.7.0_232
0	spotbugs	220	Used deprecated FindBugs config; considering switching to SpotBugs.
+1	findbugs	216	branch-1 passed
		_ Patch Compile Tests _
+1	mvninstall	143	the patch passed
+1	compile	51	the patch passed with JDK v1.8.0_222
+1	javac	51	the patch passed
+1	compile	54	the patch passed with JDK v1.7.0_232
+1	javac	54	the patch passed
-1	checkstyle	114	hbase-server: The patch generated 1 new + 636 unchanged - 1 fixed = 637 total (was 637)
+1	whitespace	0	The patch has no whitespace issues.
+1	shadedjars	220	patch has no errors when building our shaded downstream artifacts.
+1	hadoopcheck	357	Patch does not cause any errors with Hadoop 2.8.5 2.9.2.
+1	javadoc	40	the patch passed with JDK v1.8.0_222
+1	javadoc	50	the patch passed with JDK v1.7.0_232
+1	findbugs	215	the patch passed
		_ Other Tests _
-1	unit	9456	hbase-server in the patch failed.
+1	asflicense	30	The patch does not generate ASF License warnings.
		12423

Reason	Tests
Failed junit tests	hadoop.hbase.client.TestAdmin1

Subsystem	Report/Notes
Docker	Client=19.03.1 Server=19.03.1 base: https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-470/2/artifact/out/Dockerfile
GITHUB PR	#470
Optional Tests	dupname asflicense javac javadoc unit spotbugs findbugs shadedjars hadoopcheck hbaseanti checkstyle compile
uname	Linux 519955c246bd 4.4.0-154-generic #181-Ubuntu SMP Tue Jun 25 05:29:03 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	/home/jenkins/jenkins-slave/workspace/HBase-PreCommit-GitHub-PR_PR-470/out/precommit/personality/provided.sh
git revision	branch-1 / e7114f7
Default Java	1.7.0_232
Multi-JDK versions	/usr/lib/jvm/java-8-openjdk-amd64:1.8.0_222 /usr/lib/jvm/java-7-openjdk-amd64:1.7.0_232
checkstyle	https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-470/2/artifact/out/diff-checkstyle-hbase-server.txt
unit	https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-470/2/artifact/out/patch-unit-hbase-server.txt
Test Results	https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-470/2/testReport/
Max. process+thread count	4179 (vs. ulimit of 10000)
modules	C: hbase-server U: hbase-server
Console output	https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-470/2/console
versions	git=1.9.1 maven=3.0.5 findbugs=3.0.1
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[Apache-HBase]

💔 -1 overall

Vote	Subsystem	Runtime	Comment
0	reexec	1206	Docker mode activated.
		_ Prechecks _
+1	dupname	0	No case conflicting files found.
+1	hbaseanti	0	Patch does not have any anti-patterns.
+1	@author	0	The patch does not contain any @author tags.
+1	test4tests	0	The patch appears to include 2 new or modified test files.
		_ branch-1 Compile Tests _
+1	mvninstall	554	branch-1 passed
+1	compile	41	branch-1 passed with JDK v1.8.0_222
+1	compile	45	branch-1 passed with JDK v1.7.0_232
+1	checkstyle	101	branch-1 passed
+1	shadedjars	181	branch has no errors when building our shaded downstream artifacts.
+1	javadoc	40	branch-1 passed with JDK v1.8.0_222
+1	javadoc	40	branch-1 passed with JDK v1.7.0_232
0	spotbugs	180	Used deprecated FindBugs config; considering switching to SpotBugs.
+1	findbugs	177	branch-1 passed
		_ Patch Compile Tests _
+1	mvninstall	110	the patch passed
+1	compile	38	the patch passed with JDK v1.8.0_222
+1	javac	38	the patch passed
+1	compile	42	the patch passed with JDK v1.7.0_232
+1	javac	42	the patch passed
-1	checkstyle	95	hbase-server: The patch generated 1 new + 636 unchanged - 1 fixed = 637 total (was 637)
+1	whitespace	0	The patch has no whitespace issues.
+1	shadedjars	167	patch has no errors when building our shaded downstream artifacts.
+1	hadoopcheck	304	Patch does not cause any errors with Hadoop 2.8.5 2.9.2.
+1	javadoc	31	the patch passed with JDK v1.8.0_222
+1	javadoc	40	the patch passed with JDK v1.7.0_232
+1	findbugs	181	the patch passed
		_ Other Tests _
-1	unit	9446	hbase-server in the patch failed.
+1	asflicense	30	The patch does not generate ASF License warnings.
		13097

Reason	Tests
Failed junit tests	hadoop.hbase.master.TestMasterBalanceThrottling

Subsystem	Report/Notes
Docker	Client=19.03.1 Server=19.03.1 base: https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-470/1/artifact/out/Dockerfile
GITHUB PR	#470
Optional Tests	dupname asflicense javac javadoc unit spotbugs findbugs shadedjars hadoopcheck hbaseanti checkstyle compile
uname	Linux 0eeb20ca9e17 4.4.0-139-generic #165-Ubuntu SMP Wed Oct 24 10:58:50 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	/home/jenkins/jenkins-slave/workspace/HBase-PreCommit-GitHub-PR_PR-470/out/precommit/personality/provided.sh
git revision	branch-1 / e7114f7
Default Java	1.7.0_232
Multi-JDK versions	/usr/lib/jvm/java-8-openjdk-amd64:1.8.0_222 /usr/lib/jvm/java-7-openjdk-amd64:1.7.0_232
checkstyle	https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-470/1/artifact/out/diff-checkstyle-hbase-server.txt
unit	https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-470/1/artifact/out/patch-unit-hbase-server.txt
Test Results	https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-470/1/testReport/
Max. process+thread count	4992 (vs. ulimit of 10000)
modules	C: hbase-server U: hbase-server
Console output	https://builds.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-470/1/console
versions	git=1.9.1 maven=3.0.5 findbugs=3.0.1
Powered by	Apache Yetus 0.10.0 http://yetus.apache.org

This message was automatically generated.

[apurtell]

TestMasterBalanceThrottling is showing up in a couple of PRs, passes locally.