The Trunk: Files-tpr.156.mcz

> tim Rowledge uploaded a new version of Files to project The Trunk:
> http://source.squeak.org/trunk/Files-tpr.156.mcz
>
> ==================== Summary ====================
>
> Name: Files-tpr.156
> Author: tpr
> Time: 24 May 2016, 10:00:21.788027 am
> UUID: a9fad8c9-8c36-480a-8c66-1521c4e1bf16
> Ancestors: Files-cmm.155
>
> Add call to the fsync file flushing/synchronising primitive, plus a #sync method to use it.
>
> =============== Diff against Files-cmm.155 ===============
>
> Item was added:
> + ----- Method: FileStream>>sync (in category 'file open/close') -----
> + sync
> + "sync the current buffer out to disk."
> +
> + self subclassResponsibility
> + !
>
> Item was added:
> + ----- Method: StandardFileStream>>primSync: (in category 'primitives') -----
> + primSync: id
> + "Call fsync to really, really, flush pending changes to the disk"
> + | p |
> + <primitive: 'primitiveFileSync' module: 'FilePlugin'>
> + "In some OS's seeking to 0 and back will do a flush. Maybe that will help if we dont have the primitives"
> + p := self position.
> + self position: 0; position: p!
>
> Item was added:
> + ----- Method: StandardFileStream>>sync (in category 'read, write, position') -----
> + sync
> + "Really, really, flush pending changes"
> + ^self primSync: fileID!
>
>
>

> tim Rowledge uploaded a new version of Files to project The Trunk:
> http://source.squeak.org/trunk/Files-tpr.156.mcz
>
> ==================== Summary ====================
>
> Name: Files-tpr.156
> Author: tpr
> Time: 24 May 2016, 10:00:21.788027 am
> UUID: a9fad8c9-8c36-480a-8c66-1521c4e1bf16
> Ancestors: Files-cmm.155
>
> Add call to the fsync file flushing/synchronising primitive, plus a #sync method to use it.
>
> =============== Diff against Files-cmm.155 ===============
>
> Item was added:
> + ----- Method: FileStream>>sync (in category 'file open/close') -----
> + sync
> +       "sync the current buffer out to disk."
> +
> +       self subclassResponsibility
> + !
>
> Item was added:
> + ----- Method: StandardFileStream>>primSync: (in category 'primitives') -----
> + primSync: id
> +       "Call fsync to really, really, flush pending changes to the disk"
> +       | p |
> +       <primitive: 'primitiveFileSync' module: 'FilePlugin'>
> +       "In some OS's seeking to 0 and back will do a flush. Maybe that will help if we dont have the primitives"
> +       p := self position.
> +       self position: 0; position: p!
>
> Item was added:
> + ----- Method: StandardFileStream>>sync (in category 'read, write, position') -----
> + sync
> +       "Really, really, flush pending changes"
> +       ^self primSync: fileID!
>
>

> On 24-05-2016, at 12:32 PM, Chris Muller <[hidden email]> wrote:
>
> Since I'm not a systems programmer, I wasn't really following the
> other discussion.  But this does interest me since Magma employs a
> complex logging / playback mechanism which does depend on the idea
> that returning from #flush assures all my puts on that Filestreams are
> truly written to the disk.
>
> Should I be using #sync, instead of #flush?  Could you succinctly
> summarize the difference between the two for a lay-person like myself?

>
>> On 24-05-2016, at 12:32 PM, Chris Muller <[hidden email]> wrote:
>>
>> Since I'm not a systems programmer, I wasn't really following the
>> other discussion.  But this does interest me since Magma employs a
>> complex logging / playback mechanism which does depend on the idea
>> that returning from #flush assures all my puts on that Filestreams are
>> truly written to the disk.
>>
>> Should I be using #sync, instead of #flush?  Could you succinctly
>> summarize the difference between the two for a lay-person like myself?
>
> My level of understanding of this is roughly that flush is spelt f-l-u-s-h and sync is spelt s-y-n-c. I don’t understand why a system would ever let things get so out of sync that you would ever need to think of it. When you close a file it seems to me that everything should be cleaned up.
>
>
> tim
> --
> tim Rowledge; [hidden email]; http://www.rowledge.org/tim
> Useful random insult:- Hypnotized as a child and couldn't be woken.
>
>
>

> A little research suggests #sync is a blocking operation, whereas
> #flush is non-blocking.
>
> So I should probably change Magma's atomic-writing to use #sync..
>
>
> On Tue, May 24, 2016 at 2:45 PM, tim Rowledge <[hidden email]> wrote:
>>
>>> On 24-05-2016, at 12:32 PM, Chris Muller <[hidden email]> wrote:
>>>
>>> Since I'm not a systems programmer, I wasn't really following the
>>> other discussion.  But this does interest me since Magma employs a
>>> complex logging / playback mechanism which does depend on the idea
>>> that returning from #flush assures all my puts on that Filestreams are
>>> truly written to the disk.
>>>
>>> Should I be using #sync, instead of #flush?  Could you succinctly
>>> summarize the difference between the two for a lay-person like myself?
>>
>> My level of understanding of this is roughly that flush is spelt f-l-u-s-h and sync is spelt s-y-n-c. I don’t understand why a system would ever let things get so out of sync that you would ever need to think of it. When you close a file it seems to me that everything should be cleaned up.
>>
>>
>> tim
>> --
>> tim Rowledge; [hidden email]; http://www.rowledge.org/tim
>> Useful random insult:- Hypnotized as a child and couldn't be woken.
>>
>>
>>
>
>