/ 
Data-TxnBuffer-0.05
River stage zero No dependents
/ Data::TxnBuffer

NAME

Data::TxnBuffer - binary read/write buffer supporting transaction read

SYNOPSIS

use Data::TxnBuffer;

# create buffer
my $buf = Data::TxnBuffer->new;
# or create buffer from some data
my $buf = Data::TxnBuffer->new($data);

# read some data
use Try::Tiny;
try {
    my $u32   = $buf->read_u32; # read unsigned int
    my $bytes = $buf->read(10); # read 10 bytes

    $buf->spin; # all data received. clear these data from buffer.
} catch {
    $buf->reset; # reset read cursor. try again later
};

# or more easy way. this way automatically call spin or reset method like above.
try {
    $buf->txn_read(sub {
        my $u32   = $buf->read_u32; # read unsigned int
        my $bytes = $buf->read(10); # read 10 bytes
    });
} catch {
    # try again later
};


# write some data to filehandle or buffer
$buf->write_u32(100);
$buf->write("Hello World");

# got written data
my $data = $buf->data;

# clear all data from buffer
$buf->clear;

DESCRIPTION

Data::TxnBuffer provides some binary buffering functions, such as basic read/write function for buffer, more convenience r/w methods (read_u32/write_u32, etc), and transaction read method.

XS implementation

This module use XS implementation by default, but fallback to ::PP implementation in pure perl environment or PERL_ONLY environment variable is set.

XS implementation is several times faster than PP implementation.

CLASS METHOD

my $buf = Data::TxnBuffer->new($data);

Create a Data::TxnBuffer object. If you passed some $data, create buffer from the data.

ACCESSORS

$buf->cursor

Return buffer read cursor point. This value increase by read methods automatically and reset to 0 by reset method.

$buf->data

Return buffer's whole data.

$buf->length

Return buffer's data length. (bytes)

BASIC METHODS

$buf->read($bytes)

Read $bytes data from buffer and return the data. If there's not enough data in buffer, throw exception.

$buf->write($data)

Write $data into buffer.

$buf->spin

$buf->write('foo');
$buf->write('bar');

my $foo = $buf->read(3); # foo
$buf->spin; # clear only foo

$buf->data; # == 'bar'

Clear *only* read data from buffer. When read cursor == 0, this method does nothing.

And also, this method returns cleared data. For example $buf->spin in above example returns 'foo';

$buf->reset

Reset read cursor to 0.

$buf->clear

Clear all data from buffer.

TRANSACTION READ

By combination of read, spin, and reset methods, you can read some data like transaction:

use Try::Tiny;

try {
    my $foo = $buf->read(3);
    my $bar = $buf->read(3);
    $buf->spin; # clear read data 'foobar'
} catch {
    $buf->reset;
};

read method throw exception if there's not enough data in buffer, catch this exception and reset read cursor, then you can read first data again after some seconds.

$buf->txn_read($code)

Shortcut method for above transaction read example.

use Try::Tiny;

try {
    $buf->txn_read(sub {
        my $foo = $buf->read(3);
        my $bar = $buf->read(3);
    });
    # spin automatically called
} catch {
    # reset automatically called
    # try later
};

This method automatically call spin method and returns spin'ed data if all data successfully read, or throw exception not enough data in buffer and call reset method automatically. This method is very useful for typical transaction read functions.

READ/WRITE HELPER METHODS

This module provides not only basic read($bytes) method but also useful methods to read integer values easily.

$buf->read_u32

$buf->read_u24

$buf->read_u16

$buf->read_u8

Read unsigned integers. uXX is bit length. (ex: u32 is 32bit unsigned int)

$buf->read_i32

$buf->read_i24

$buf->read_i16

$buf->read_i8

Read singed integers.

$buf->write_u32

$buf->write_u24

$buf->write_u16

$buf->write_u8

Write unsigned integers

$buf->write_i32

$buf->write_i24

$buf->write_i16

$buf->write_i8

Write signed integers

(In XS implementation, this is just an alias to write_uXX)

$buf->read_n32

$buf->read_n24

$buf->read_n16

$buf->write_n32

$buf->write_n24

$buf->write_n16

Read/Write unsigned integers in network byte order.

$buf->read_float

$buf->read_double

$buf->write_float

$buf->write_double

Read/Write floating points (float = 32bit single precision float, double = 64bit double precision float)

AUTHOR

Daisuke Murase <typester@cpan.org>

COPYRIGHT AND LICENSE

Copyright (c) 2011 by KAYAC Inc.

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

The full text of the license can be found in the LICENSE file included with this module.