Table of Contents
This chapter will be of interest only to those building and developing HBase (i.e., as opposed to just downloading the latest distribution).
See HBASE-3678 Add Eclipse-based Apache Formatter to HBase Wiki for an Eclipse formatter to help ensure your code conforms to HBase'y coding convention. The issue includes instructions for loading the attached formatter.
Also, no @author tags - that's a rule. Quality Javadoc comments are appreciated. And include the Apache license.
Download and install the Subversive plugin.
Set up an SVN Repository target from Section 1.1.1, “SVN”, then check out the code.
mvn eclipse:eclipse... from your local HBase project directory in your workspace to generate some new
.project
and .classpath
files. Then reopen Eclipse.
Download and install the Maven plugin. For example, Help -> Install New Software -> (search for Maven Plugin)
The M2_REPO
classpath variable needs to be set up for the project. This needs to be set to
your local Maven repository, which is usually ~/.m2/repository
Description Resource Path Location Type The project cannot be built until build path errors are resolved hbase Unknown Java Problem Unbound classpath variable: 'M2_REPO/asm/asm/3.1/asm-3.1.jar' in project 'hbase' hbase Build path Build Path Problem Unbound classpath variable: 'M2_REPO/com/github/stephenc/high-scale-lib/high-scale-lib/1.1.1/high-scale-lib-1.1.1.jar' in project 'hbase' hbase Build path Build Path Problem Unbound classpath variable: 'M2_REPO/com/google/guava/guava/r09/guava-r09.jar' in project 'hbase' hbase Build path Build Path Problem Unbound classpath variable: 'M2_REPO/com/google/protobuf/protobuf-java/2.3.0/protobuf-java-2.3.0.jar' in project 'hbase' hbase Build path Build Path Problem Unbound classpath variable:
If you install the m2eclipse and import the HBase pom.xml in your workspace, you will have to fix your eclipse Build Path.
Remove target
folder, add target/generated-jamon
and target/generated-sources/java
folders. You may also remove from your Build Path
the exclusions on the src/main/resources
and src/test/resources
to avoid error message in the console 'Failed to execute goal org.apache.maven.plugins:maven-antrun-plugin:1.6:run (default) on project hbase:
'An Ant BuildException has occured: Replace: source file .../target/classes/hbase-default.xml doesn't exist'. This will also
reduce the eclipse build cycles and make your life easier when developing.
Eclipse will currently complain about Bytes.java
. It is not possible to turn these errors off.
Description Resource Path Location Type Access restriction: The method arrayBaseOffset(Class) from the type Unsafe is not accessible due to restriction on required library /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/classes.jar Bytes.java /hbase/src/main/java/org/apache/hadoop/hbase/util line 1061 Java Problem Access restriction: The method arrayIndexScale(Class) from the type Unsafe is not accessible due to restriction on required library /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/classes.jar Bytes.java /hbase/src/main/java/org/apache/hadoop/hbase/util line 1064 Java Problem Access restriction: The method getLong(Object, long) from the type Unsafe is not accessible due to restriction on required library /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/classes.jar Bytes.java /hbase/src/main/java/org/apache/hadoop/hbase/util line 1111 Java Problem
For additional information on setting up Eclipse for HBase development on Windows, see Michael Morello's blog on the topic.
This section will be of interest only to those building HBase from source.
Pass -Dsnappy
to trigger the snappy maven profile for building
snappy native libs into hbase.
Follow the instructions at
Publishing Maven Artifacts.
The 'trick' to making it all work is answering the questions put to you by the mvn release plugin properly,
making sure it is using the actual branch AND before doing the mvn release:perform step,
VERY IMPORTANT, hand edit the release.properties file that was put under ${HBASE_HOME}
by the previous step, release:perform. You need to edit it to make it point at
right locations in SVN.
If you see run into the below, its because you need to edit version in the pom.xml and add
-SNAPSHOT
to the version (and commit).
[INFO] Scanning for projects... [INFO] Searching repository for plugin with prefix: 'release'. [INFO] ------------------------------------------------------------------------ [INFO] Building HBase [INFO] task-segment: [release:prepare] (aggregator-style) [INFO] ------------------------------------------------------------------------ [INFO] [release:prepare {execution: default-cli}] [INFO] ------------------------------------------------------------------------ [ERROR] BUILD FAILURE [INFO] ------------------------------------------------------------------------ [INFO] You don't have a SNAPSHOT project in the reactor projects list. [INFO] ------------------------------------------------------------------------ [INFO] For more information, run Maven with the -e switch [INFO] ------------------------------------------------------------------------ [INFO] Total time: 3 seconds [INFO] Finished at: Sat Mar 26 18:11:07 PDT 2011 [INFO] Final Memory: 35M/423M [INFO] -----------------------------------------------------------------------
All commands executed from the local HBase project directory.
Note: use Maven 3 (Maven 2 may work but we suggest you use Maven 3).
HBase 0.92 added a verify
maven target. Invoking it with run all the phases up to and including the verify phase via the maven failsafe plugin, running all the unit tests as well as the long running unit and integration tests.
mvn verify
HBase gets better only when people contribute!
As HBase is an Apache Software Foundation project, see ??? for more information about how the ASF functions.
Sign up for the dev-list and the user-list. See the mailing lists page. Posing questions - and helping to answer other people's questions - is encouraged! There are varying levels of experience on both lists so patience and politeness are encouraged (and please stay on topic.)
Check for existing issues in Jira. If it's either a new feature request, enhancement, or a bug, file a ticket.
The following is a guideline on setting Jira issue priorities:
Most development is done on TRUNK. However, there are branches for minor releases (e.g., 0.90.1, 0.90.2, and 0.90.3 are on the 0.90 branch).
If you have any questions on this just send an email to the dev dist-list.
In HBase we use JUnit 4.
If you need to run miniclusters of HDFS, ZooKeeper, HBase, or MapReduce testing,
be sure to checkout the HBaseTestingUtility
.
Alex Baranau of Sematext describes how it can be used in
HBase Case-Study: Using HBaseTestingUtility for Local Testing and Development (2010).
Sometimes you don't need a full running server
unit testing. For example, some methods can make do with a
a org.apache.hadoop.hbase.Server
instance
or a org.apache.hadoop.hbase.master.MasterServices
Interface reference rather than a full-blown
org.apache.hadoop.hbase.master.HMaster
.
In these cases, you maybe able to get away with a mocked
Server
instance. For example:
TODO...
Patch files can be easily generated from Eclipse, for example by selecting "Team -> Create Patch". Patches can also be created by git diff and svn diff.
Please submit one patch-file per Jira. For example, if multiple files are changed make sure the selected resource when generating the patch is a directory. Patch files can reflect changes in multiple files.
Make sure you review Section 1.2.1.1, “Code Formatting” for code style.
The patch file should have the HBase Jira ticket in the name. For example, if a patch was submitted for Foo.java
, then
a patch file called Foo_HBASE_XXXX.patch
would be acceptable where XXXX is the HBase Jira number.
If you generating from a branch, then including the target branch in the filename is advised, e.g., HBASE-XXXX-0.90.patch
.
Yes, please. Please try to include unit tests with every code patch (and especially new classes and large changes). Make sure unit tests pass locally before submitting the patch.
Also, see Section 1.6.2.1, “Mockito”.
The patch should be attached to the associated Jira ticket "More Actions -> Attach Files". Make sure you click the ASF license inclusion, otherwise the patch can't be considered for inclusion.
Once attached to the ticket, click "Submit Patch" and the status of the ticket will change. Committers will review submitted patches for inclusion into the codebase. Please understand that not every patch may get committed, and that feedback will likely be provided on the patch. Fear not, though, because the HBase community is helpful!
The following items are representative of common patch feedback. Your patch process will go faster if these are taken into account before submission.
See the Java coding standards for more information on coding conventions in Java.
Rather than do this...
if ( foo.equals( bar ) ) { // don't do this
... do this instead...
if (foo.equals(bar)) {
Also, rather than do this...
foo = barArray[ i ]; // don't do this
... do this instead...
foo = barArray[i];
Auto-generated code in Eclipse often looks like this...
public void readFields(DataInput arg0) throws IOException { // don't do this foo = arg0.readUTF(); // don't do this
... do this instead ...
public void readFields(DataInput di) throws IOException { foo = di.readUTF();
See the difference? 'arg0' is what Eclipse uses for arguments by default.
Keep lines less than 80 characters.
Bar bar = foo.veryLongMethodWithManyArguments(argument1, argument2, argument3, argument4, argument5); // don't do this
... do this instead ...
Bar bar = foo.veryLongMethodWithManyArguments(argument1, argument2, argument3,argument4, argument5);
... or this, whichever looks better ...
Bar bar = foo.veryLongMethodWithManyArguments( argument1, argument2, argument3,argument4, argument5);
This happens more than people would imagine.
Bar bar = foo.getBar(); <--- imagine there's an extra space(s) after the semicolon instead of a line break.
Make sure there's a line-break after the end of your code, and also avoid lines that have nothing but whitespace.
Every class returned by RegionServers must implement Writable
. If you
are creating a new class that needs to implement this interface, don't forget the default constructor.
Don't just leave the @param arguments the way your IDE generated them. Don't do this...
/** * * @param bar <---- don't do this!!!! * @return <---- or this!!!! */ public Foo getFoo(Bar bar);
... either add something descriptive to the @param and @return lines, or just remove them. But the preference is to add something descriptive and useful.
If you submit a patch for one thing, don't do auto-reformatting or unrelated reformatting of code on a completely different area of code.
Likewise, don't add unrelated cleanup or refactorings outside the scope of your Jira.
Larger patches should go through ReviewBoard.
For more information on how to use ReviewBoard, see the ReviewBoard documentation.
Committers do this. See How To Commit in the HBase wiki.
Commiters will also resolve the Jira, typically after the patch passes a build.