Re: [Pharo-project] Replace ByteArray with a smaller one
if the chunks you wan to cut off are big enough you could potentially allocate a new object there which get's gc-ed. But I have no clue how to do that without VM / NB support ;) On 2012-11-07, at 14:39, Mariano Martinez Peck wrote: > Hi guys. I have a ByteArray of size N. > And I want now only the same ByteArray but from 1 to N-X. I am using > #copyFrom:to: but that one answers a new copy. If the ByteArray is large, > this takes time because it needs to allocate a large object. In my case I > don't care and I can modify the original ByteArray itself (lets say make it > smaller, null the remaining part and change the object header info). That > way I would avoid an extra allocation. Is there a primitive for that? > > Thanks! > > -- > Mariano > http://marianopeck.wordpress.com
Re: [Pharo-project] Replace ByteArray with a smaller one
On 7 November 2012 11:11, Camillo Bruni wrote: > if the chunks you wan to cut off are big enough you could > potentially allocate a new object there which get's gc-ed. > yes.. actually you can 'crop' the existing object by modifying its size field (so VM will know it) and then for the rest bytes, mark them as a 'free chunk', which designates a unused memory space in heap. actually, this could be a good candidate for a primitive. But imo, much better strategy is to not allocate too big arrays. :) Also, as alternative , you can create a 'ArraySlice' collection class, which is a view on existing array but with smaller number or elements. And pass it around as a valid collection. > But I have no clue how to do that without VM / NB support ;) > > > On 2012-11-07, at 14:39, Mariano Martinez Peck wrote: > >> Hi guys. I have a ByteArray of size N. >> And I want now only the same ByteArray but from 1 to N-X. I am using >> #copyFrom:to: but that one answers a new copy. If the ByteArray is large, >> this takes time because it needs to allocate a large object. In my case I >> don't care and I can modify the original ByteArray itself (lets say make it >> smaller, null the remaining part and change the object header info). That >> way I would avoid an extra allocation. Is there a primitive for that? >> >> Thanks! >> >> -- >> Mariano >> http://marianopeck.wordpress.com > > -- Best regards, Igor Stasenko.
Re: [Pharo-project] Replace ByteArray with a smaller one
On Thu, Nov 8, 2012 at 4:24 AM, Igor Stasenko wrote: > On 7 November 2012 11:11, Camillo Bruni wrote: >> if the chunks you wan to cut off are big enough you could >> potentially allocate a new object there which get's gc-ed. >> > yes.. > actually you can 'crop' the existing object by modifying its size > field (so VM will know it) > and then for the rest bytes, mark them as a 'free chunk', which designates a > unused memory space in heap. > actually, this could be a good candidate for a primitive. Exactlly. I was hoping there was already a primitive for that :( > But imo, much better strategy is to not allocate too big arrays. :) > > Also, as alternative , you can create a 'ArraySlice' collection class, > which is a view on existing array but with smaller number or elements. > And pass it around as a valid collection. > >> But I have no clue how to do that without VM / NB support ;) >> :( >> >> On 2012-11-07, at 14:39, Mariano Martinez Peck wrote: >> >>> Hi guys. I have a ByteArray of size N. >>> And I want now only the same ByteArray but from 1 to N-X. I am using >>> #copyFrom:to: but that one answers a new copy. If the ByteArray is large, >>> this takes time because it needs to allocate a large object. In my case I >>> don't care and I can modify the original ByteArray itself (lets say make it >>> smaller, null the remaining part and change the object header info). That >>> way I would avoid an extra allocation. Is there a primitive for that? >>> >>> Thanks! >>> >>> -- >>> Mariano >>> http://marianopeck.wordpress.com >> >> > > > > -- > Best regards, > Igor Stasenko. > -- Mariano http://marianopeck.wordpress.com
