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From "Mingjie Lai" <mjla...@gmail.com>
Subject Review Request: HBase-2001: Coprocessors: Colocate user code with regions
Date Mon, 20 Sep 2010 01:35:18 GMT

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This is an automatically generated e-mail. To reply, visit:
http://review.cloudera.org/r/876/
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Review request for hbase.


Summary
-------


The diff actually contains 2 seperate patches: HBase-2001 and the one for (HBASE-2002+HBASE-2321).
The reason is that HBase-2001's CommandTarget relies on HBASE-2002 + HBASE-2321 which patches
are still under review. I have to include Gary's HBASE-2002, HBASE-2321 with this diff, since
reviewboard is so powerful :) and it disallow my diff to be based on some unchecked in patch.


Both HBase-2001 and the dynamic RPC stuff are quite big patches. Total number of lines are
more than 7k. I turned back and forth, but still don't have a good idea to create the patch
in order to reduce the review pain. However right now I'm putting the whole patch for all
the 3 issues. Here the list of file which are only related to coprocessor:

src/main/java/org/apache/hadoop/hbase/coprocessor/BaseCommandTarget.java
src/main/java/org/apache/hadoop/hbase/coprocessor/BaseRegionObserver.java
src/main/java/org/apache/hadoop/hbase/coprocessor/Coprocessor.java
src/main/java/org/apache/hadoop/hbase/coprocessor/CoprocessorEnvironment.java
src/main/java/org/apache/hadoop/hbase/coprocessor/CoprocessorException.java
src/main/java/org/apache/hadoop/hbase/coprocessor/RegionObserver.java
src/main/java/org/apache/hadoop/hbase/coprocessor/package-info.java
src/main/java/org/apache/hadoop/hbase/regionserver/CoprocessorHost.java
src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
src/main/java/org/apache/hadoop/hbase/regionserver/SplitTransaction.java
src/main/resources/hbase-default.xml
src/test/java/org/apache/hadoop/hbase/coprocessor/TestClassloading.java
src/test/java/org/apache/hadoop/hbase/coprocessor/TestCommandTarget.java
src/test/java/org/apache/hadoop/hbase/coprocessor/TestCoprocessorInterface.java
src/test/java/org/apache/hadoop/hbase/coprocessor/TestRegionObserverInterface.java
src/test/java/org/apache/hadoop/hbase/coprocessor/TestRegionObserverStacking.java


==========================

(Here is a brief description. Please find much more details at the package-info.java in the
diff. I also post the package-info.html to https://issues.apache.org/jira/browse/HBASE-2001
as an attachment.)


Coprocessors are code that runs in-process on each region server. Regions contain references
to the coprocessor implementation classes associated with them. Coprocessor classes will be
loaded either from local jars on the region server's classpath or via the HDFS classloader.

Multiple types of coprocessors are provided to provide sufficient flexibility for potential
use cases. Right now there are:

* Coprocessor: provides region lifecycle management hooks, e.g., region open/close/split/flush/compact
operations.
* RegionObserver: provides hook for monitor table operations from client side, such as table
get/put/scan/delete, etc.
* CommandTarget: provides on demand triggers for any arbitrary function executed at a region.
One use case is column aggregation at region server.

Coprocessor:
A coprocessor is required to implement Coprocessor interface so that coprocessor framework
can manage it internally.

Another design goal of this interface is to provide simple features for making coprocessors
useful, while exposing no more internal state or control actions of the region server than
necessary and not exposing them directly. 

RegionObserver
If the coprocessor implements the RegionObserver interface it can observe and mediate client
actions on the region. 

CommandTarget:
Coprocessor and RegionObserver provide certain hooks for injecting user code running at each
region. These code will be triggerd with existing HTable and HBaseAdmin operations at the
certain hook points.

Through CommandTarget and dynamic RPC protocol, you can define your own interface communicated
between client and region server, i.e., you can specify new passed parameters and return types
for a method. And the new CommandTarget methods can be triggered by calling client side dynamic
RPC functions -- HTable.exec(...). 

Coprocess loading
A customized coprocessor can be loaded by two different ways, by configuration, or by HTableDescriptor
for a newly created table.

(Currently we don't really have an on demand coprocessor loading machanism for opened regions.
However it should be easy to create a dedicated CommandTarget for coprocessor loading) 


This addresses bug HBase-2001.
    http://issues.apache.org/jira/browse/HBase-2001


Diffs
-----

  src/main/java/org/apache/hadoop/hbase/client/Action.java 556ea81 
  src/main/java/org/apache/hadoop/hbase/client/Exec.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/client/ExecResult.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/client/HConnection.java 65f7618 
  src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java fbdec0b 
  src/main/java/org/apache/hadoop/hbase/client/HTable.java 0dbf263 
  src/main/java/org/apache/hadoop/hbase/client/MultiAction.java c6ea838 
  src/main/java/org/apache/hadoop/hbase/client/MultiResponse.java 91bd04b 
  src/main/java/org/apache/hadoop/hbase/client/RowRange.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/client/Scan.java 29b3cb0 
  src/main/java/org/apache/hadoop/hbase/coprocessor/BaseCommandTarget.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/coprocessor/BaseRegionObserver.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/coprocessor/Coprocessor.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/coprocessor/CoprocessorEnvironment.java PRE-CREATION

  src/main/java/org/apache/hadoop/hbase/coprocessor/CoprocessorException.java PRE-CREATION

  src/main/java/org/apache/hadoop/hbase/coprocessor/RegionObserver.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/coprocessor/package-info.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/io/HbaseObjectWritable.java 83f623d 
  src/main/java/org/apache/hadoop/hbase/ipc/ConnectionHeader.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/ipc/CoprocessorProtocol.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/ipc/ExecRPCInvoker.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/ipc/HBaseClient.java 2b5eeb6 
  src/main/java/org/apache/hadoop/hbase/ipc/HBaseRPC.java e23a629 
  src/main/java/org/apache/hadoop/hbase/ipc/HBaseServer.java e4c356d 
  src/main/java/org/apache/hadoop/hbase/ipc/HRegionInterface.java a4810a6 
  src/main/java/org/apache/hadoop/hbase/ipc/Invocation.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/ipc/RpcEngine.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/ipc/RpcServer.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/ipc/WritableRpcEngine.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/master/HMaster.java bccdc0e 
  src/main/java/org/apache/hadoop/hbase/regionserver/CoprocessorHost.java PRE-CREATION 
  src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java fdef130 
  src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java f2e4e7c 
  src/main/java/org/apache/hadoop/hbase/regionserver/SplitTransaction.java bb3b382 
  src/main/resources/hbase-default.xml 5452fd1 
  src/test/java/org/apache/hadoop/hbase/coprocessor/TestClassloading.java PRE-CREATION 
  src/test/java/org/apache/hadoop/hbase/coprocessor/TestCommandTarget.java PRE-CREATION 
  src/test/java/org/apache/hadoop/hbase/coprocessor/TestCoprocessorInterface.java PRE-CREATION

  src/test/java/org/apache/hadoop/hbase/coprocessor/TestRegionObserverInterface.java PRE-CREATION

  src/test/java/org/apache/hadoop/hbase/coprocessor/TestRegionObserverStacking.java PRE-CREATION

  src/test/java/org/apache/hadoop/hbase/regionserver/TestServerCustomProtocol.java PRE-CREATION


Diff: http://review.cloudera.org/r/876/diff


Testing
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Thanks,

Mingjie


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