So, my suspicion was correct, I am using DataView methods like this
(https://github.com/Ayms/abstract-tls/blob/master/lib/abstract-tls.js#l280-332
here and on other projects) for historical reasons, because I started
from node.js's buffers methods and then switched to ArrayBuffers with
node.js's like methods, because in some cases I needed to use both at
the same time or to be able to switch easily from one to another.
Then the use is not correct in theory, now performances seem to be OK
(except node.js), so maybe most of the implementations are instantiating
once a DataView for a given ArrayBuffer and keeping reference to it when
you call it again?
Regards,
Le 03/04/2013 00:52, Kenneth Russell a écrit :
Yes: API consistency. An ArrayBuffer is opaque; to work with the data
it contains, instantiate a view.
On Tue, Apr 2, 2013 at 3:36 PM, Kevin Gadd <kevin.g...@gmail.com> wrote:
Is there a reason why DataView wasn't specified as static methods that take
an ArrayBuffer in the first place? That would solve the problem of figuring
out when/how often to create DataView instances, and eliminate the garbage
created by using DataViews.
On Tue, Apr 2, 2013 at 3:23 PM, Kenneth Russell <k...@google.com> wrote:
On Tue, Apr 2, 2013 at 3:03 PM, Aymeric Vitte <vitteayme...@gmail.com>
wrote:
Le 02/04/2013 04:24, Kenneth Russell a écrit :
Agreed. DataView's methods are all simple and should be easy to
optimize. Because they include a conditional byte swap, they can't run
quite as fast as the typed arrays' accessors -- but they shouldn't
need to. DataView was designed to support file and network I/O, where
throughput is limited by the disk or network connection. The typed
array views were designed for in-memory assembly of data to be
submitted to the graphics card, sound card, etc., and must run as fast
as possible.
When you are streaming things, what's the correct use of DataViews?
ie : you are supposed to create each time you want to read some bytes a
DataView (which can be optimized or whatever, but still with some
costs)?
Maybe it's outside of the scope of this discussion, I have already
provided
examples, I still suspect that I am using it wrongly or that
ArrayBuffers
are more adapted to webgl (ie static buffer manipulation) than network
streaming (ie dynamic buffer manipulation).
Probably I am wrong but really would like to know then what's the
correct
use.
If I understand your question, then the correct use of DataView is:
upon receiving an ArrayBuffer, create a DataView referring to it. When
iterating down the contents of the ArrayBuffer, continue to use the
same DataView instance, just incrementing the offset. In
abstract-tls/lib/abstract-tls.js there are some operations which
create a new DataView just to read or write a single element; this
isn't the correct usage.
http://www.html5rocks.com/en/tutorials/webgl/typed_arrays/ may be a
useful reference.
If you're handling streaming data then presumably you're receiving
multiple ArrayBuffers, one after the other. You should create one
DataView per buffer. The only challenge is properly handling the
boundary from one buffer to the next, if the boundary is within an
element like a uint16 or uint32.
-Ken
--
-kg
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