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Net-Hadoop-WebHDFS-0.8
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/ Net::Hadoop::WebHDFS

NAME

Net::Hadoop::WebHDFS - Client library for Hadoop WebHDFS and HttpFs

SYNOPSIS


            

              
              
use Net::Hadoop::WebHDFS;
my $client = Net::Hadoop::WebHDFS->new( host => 'hostname.local', port => 50070 );
my $statusArrayRef = $client->list('/');
my $contentData = $client->read('/data.txt');
$client->create('/foo/bar/data.bin', $bindata);

DESCRIPTION

This module supports WebHDFS v1 on Hadoop 1.x (and CDH4.0.0 or later), and HttpFs on Hadoop 2.x (and CDH4 or later). WebHDFS/HttpFs has two authentication methods: pseudo authentication and Kerberos, but this module supports pseudo authentication only.

METHODS

Net::Hadoop::WebHDFS class method and instance methods.

CLASS METHODS

Net::Hadoop::WebHDFS->new( %args ) :Net::Hadoop::WebHDFS

Creates and returns a new client instance with %args. If you are using HttpFs, set httpfs_mode => 1 and port => 14000.

%args might be:

host :Str = "namenode.local"
port :Int = 50070
standby_host :Str = "standby.namenode.local"
standby_port :Int = 50070
username :Str = "hadoop"
doas :Str = "hdfs"
httpfs_mode :Bool = 0/1

INSTANCE METHODS

$client->create($path, $body, %options) :Bool

Creates file on HDFS with $body data. If you want to create blank file, pass blank string.

%options might be:

overwrite :Str = "true" or "false"
blocksize :Int
replication :Int
permission :Str = "0600"
buffersize :Int

$client->append($path, $body, %options) :Bool

Append $body data to $path file.

%options might be:

buffersize :Int

$client->read($path, %options) :Str

Open file of $path and returns its content. Alias: open.

%options might be:

offset :Int
length :Int
buffersize :Int

$client->mkdir($path, [permission => '0644']) :Bool

Make directory $path on HDFS. Alias: mkdirs.

$client->rename($path, $dest) :Bool

Rename file or directory as $dest.

$client->delete($path, [recursive => 0/1]) :Bool

Delete file $path from HDFS. With optional recursive => 1, files and directories are removed recursively (default false).

$client->stat($path) :HashRef

Get and returns file status object for $path. Alias: getfilestatus.

$client->list($path) :ArrayRef

Get list of files in directory $path, and returns these status objects arrayref. Alias: liststatus.

$client->content_summary($path) :HashRef

Get 'content summary' object and returns it. Alias: getcontentsummary.

$client->checksum($path) :HashRef

Get checksum information object for $path. Alias: getfilechecksum.

$client->homedir() :Str

Get accessing user's home directory path. Alias: gethomedirectory.

$client->chmod($path, $mode) :Bool

Set permission of $path as octal $mode. Alias: setpermission.

$client->chown($path, [owner => 'username', group => 'groupname']) :Bool

Set owner or group of $path. One of owner/group must be specified. Alias: setowner.

$client->replication($path, $replnum) :Bool

Set replica number for $path. Alias: setreplication.

$client->touch($path, [modificationtime => $mtime, accesstime => $atime]) :Bool

Set mtime/atime of $path. Alias: settimes.

$client->touchz($path) :Bool

Create a zero length file.

$client->checkaccess( $path, $fsaction ) :Bool

Test if the user has the rights to do a file system action.

$client->concat( $path, @source_paths ) :Bool

Concatenate paths.

$client->truncate( $path, $newlength ) :Bool

Truncate a path contents.

$client->delegation_token( $action, $path, @args )

This is a method wrapping the multiple methods for delegation token handling.


            

              
              
my $token = $client->delegation_token( get => $path );
print "Token: $token\n";
my $milisec = $client->delegation_token( renew => $token );
printf "Token expiration renewed until %s\n", scalar localtime $milisec / 1000;
if ( $client->delegation_token( cancel => $token ) ) {
    print "Token cancelled. There will be a new one created.\n";
    my $token_new = $client->delegation_token( get => $path );
    print "New token: $token_new\n";
    printf "New token is %s\n", $token_new eq $token ? 'the same' : 'different';
}
else {
    warn "Failed to cancel token $token!";
}

$client->delegation_token( get => $path, [renewer => $username, service => $service, kind => $kind ] ) :Str )

Returns the delegation token id for the specified path.

$client->delegation_token( renew => $token ) :Int

Returns the new expiration time for the specified delegation token in miliseconds.

$client->delegation_token( cancel => $token ) :Bool

Cancels the specified delegation token (which will force a new one to be created.

$client->snapshot( $path, $action => @args )

This is a method wrapping the multiple methods for snapshot handling.

$client->snapshot( $path, create => [, $snapshotname ] ) :Str

Creates a new snaphot on the specified path and returns the name of the snapshot.

$client->snapshot( $path, rename => $oldsnapshotname, $snapshotname ) :Bool

Renames the snaphot.

$client->snapshot( $path, delete => $snapshotname ) :Bool

Deletes the specified snapshot.

$client->xattr( $path, $action, @args )

This is a method wrapping the multiple methods for extended attributes handling.


            

              
              
my @attr_names = $client->xattr( $path, 'list' );
my %attr = $client->xattr( $path, get => flatten => 1 );
if ( ! exists $attr{'user.bar'} ) {
    warn "set user.bar = 42\n";
    $client->xattr( $path, create => 'user.bar' => 42 )
        || warn "Failed to create user.bar";
}
else {
    warn "alter user.bar = 24\n";
    $client->xattr( $path, replace => 'user.bar' => 24 )
        || warn "Failed to replace user.bar";
    ;
}
if ( exists $attr{'user.foo'} ) {
    warn "No more foo\n";
    $client->xattr( $path, remove => 'user.foo')
        || warn "Failed to remove user.foo";
    ;
}

$client->xattr( $path, get => [, names => \@attr_names] [, flatten => 1 ] [, encoding => $enc ] ) :Struct

Returns the extended attribute key/value pairs on a path. The default data set is an array of hashrefs with the pairs, however if you set <flatten> to a true value then a simple hash will be returned.

It is also possible to fetch a subset of the attributes if you specify the names of them with the <names> option.

$client->xattr( $path, 'list' ) :List

This method will return the names of all the attributes set on <$path>.

$client->xattr( $path, create => $attr_name => $value ) :Bool

It is possible to create a new extended attribute on a path with this method.

$client->xattr( $path, replace => $attr_name => $value ) :Bool

It is possible to replace the value of an existing extended attribute on a path with this method.

$client->xattr( $path, remove => $attr_name ) :Bool

Deletes the speficied attribute on <$path>.

EXTENSIONS

$client->exists($path) :Bool

Returns the stat() hash if successful, and false otherwise. Dies on interface errors.

$client->find($path, $callback, $options_hash)

Loops recursively over the specified path:


            

              
              
$client->find(
    '/user',
    sub {
        my($cwd, $path) = @_;
        my $date = localtime $path->{modificationTime};
        my $type = $path->{type} eq q{DIRECTORY} ? "[dir ]" : "[file]";
        my $size = sprintf "% 10s",
                            $path->{blockSize}
                                ? sprintf "%.2f MB", $path->{blockSize} / 1024**2
                                : 0;
        print "$type $size $path->{permission} $path->{owner}:$path->{group} $cwd/$path->{pathSuffix}\n";
    },
    { # optional
        re_ignore => qr{
                        \A      # Filter some filenames out even before reaching the callback
                            [_] # logs and meta data, java junk, _SUCCESS files, etc.
                    }xms,
    }
);

AUTHOR

TAGOMORI Satoshi <tagomoris {at} gmail.com>

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.