Improvements to Hadoop Thrift bindings
--------------------------------------
Key: HADOOP-4707
URL: https://issues.apache.org/jira/browse/HADOOP-4707
Project: Hadoop Core
Issue Type: Improvement
Components: contrib/thiftfs
Affects Versions: 0.20.0
Environment: Tested under Linux x86-64
Reporter: Carlos Valiente
Priority: Minor
Fix For: 0.20.0
Attachments: hadoopfs_thrift.diff
I have made the following changes to hadoopfs.thrift:
# Added namespaces for Python, Perl and C++.
# Renamed parameters and struct members to camelCase versions to keep them
consistent (in particular FileStatus{blockReplication,blockSize} vs
FileStatus.{block_replication,blocksize}).
# Renamed ThriftHadoopFileSystem to FileSystem. From the perspective of a
Perl/Python/C++ user, 1) it is already clear that we're using Thrift, and 2)
the fact that we're dealing with Hadoop is already explicit in the namespace.
The usage of generated code is more compact and (in my opinion) clearer:
{quote}
*Perl*:
use HadoopFS;
my $client = HadoopFS::FileSystemClient->new(..);
_instead of:_
my $client = HadoopFS::ThriftHadoopFileSystemClient->new(..);
*Python*:
from hadoopfs import FileSystem
client = FileSystem.Client(..)
_instead of_
from hadoopfs import ThriftHadoopFileSystem
client = ThriftHadoopFileSystem.Client(..)
(See also the attached diff [^scripts_hdfs_py.diff] for the
new version of 'scripts/hdfs.py').
*C++*:
hadoopfs::FileSystemClient client(..);
_instead of_:
hadoopfs::ThriftHadoopFileSystemClient client(..);
{quote}
# Renamed ThriftHandle to FileHandle: As in 3, it is clear that we're dealing
with a Thrift object, and its purpose (to act as a handle for file operations)
is clearer.
# Renamed ThriftIOException to IOException, to keep it simpler, and consistent
with MalformedInputException.
# Added explicit version tags to fields of ThriftHandle/FileHandle, Pathname,
MalformedInputException and ThriftIOException/IOException, to improve
compatibility of existing clients with future versions of the interface which
might add new fields to those objects (like stack traces for the exception
types, for instance).
Those changes are reflected in the attachment [^hadoopfs_thrift.diff].
Changes in generated Java, Python, Perl and C++ code are also attached in
[^gen.diff]. They were generated by a Thrift checkout from trunk
([http://svn.apache.org/repos/asf/incubator/thrift/trunk/]) as of revision
719697, plus the following Perl-related patches:
* [https://issues.apache.org/jira/browse/THRIFT-190]
* [https://issues.apache.org/jira/browse/THRIFT-193]
* [https://issues.apache.org/jira/browse/THRIFT-199]
The Thrift jar file [^libthrift.jar] built from that Thrift checkout is also
attached, since it's needed to run the Java Thrift server.
I have also added a new target to src/contrib/thriftfs/build.xml to build the
Java bindings needed for org.apache.hadoop.thriftfs.HadoopThriftServer.java
(see attachment [^build_xml.diff] and modified HadoopThriftServer.java to make
use of the new bindings (see attachment [^HadoopThriftServer_java.diff]).
The jar file [^lib/hadoopthriftapi.jar] is also included, although it can be
regenerated from the stuff under 'gen-java' and the new 'compile-gen' Ant
target.
The whole changeset is also included as [^all.diff].
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