[Freeswitch-users] Javascript FileIO

Sun Jun 25 19:17:00 UTC 2017

On Sun, Jun 25, 2017 at 1:29 PM Raymond <xxxman2008 at 126.com> wrote:

>
> OK， firstly ，where's the new documentation of new V8 js module ?
>

Use the source luke.  Maybe you can join the volunteer docs team and help
them.  The module itself was donated by a community member.

> Secondly, I think,  loop read small piece of  file will cause  too much
> I/O request . SO , i usually do read in following way.
> open the file ----> get file size --> read the whole file ( OS will charge
> the "one time " read size).
>

That is completely relevant to the size of the file and the size of the
chunk.  There is no one answer.

> and in real-life , real-project , there's not so many big files.  So, just
>  open the file ,and  read all.    in 99.99% situation , it's safe.
>

Um, ok..... That does not sound very wise but sure.  I'd say At least test
the size of the file first.

> in some situation , you cann't open the "incomplete file"  , you even
> cann't "see" them. There's too much detail when we talk about file read
> ,we can discuss file-system in rest of our life.
>  For Faruq , i think  just read whole file is  ok .  if you warry about "incomplete
> file" ,just wait 1 second ,and  read the file size again. it's  may casuse
> delay ,but useful if you have lots of files to read .
>
> In my opinion, when linux  do file read ,it read 1 block one time . A
> block is a sequence of bit or Bytes with a fixed length ie 512 bytes, 4kB,
> 8kB, 16kB, 32kB etc.  So , please not use strange number as your read size.
> it's not a good idea.  And  ......I really hate "while (.....)"  code ,it's
> really really bad.
>

Shaming coding constructs, in my opinion, is the path to mistakes.  Every
code element exists for a reason and there is always a case for any of
them.  I hate coding construct x is not helpful.

> Raymond
>
>
> At 2017-06-24 04:00:36, "Anthony Minessale" <anthony.minessale at gmail.com>
> wrote:
>
> That wiki documentation is from the old spidermonkey js module not the new
> v8 one.
>
> I believe that putting a very large number will not cause any problems as
> the data read cannot exceed the total bytes in the file so it should not be
> a problem.
> You can always do an append loop.  Its usually a good practice to have a
> precise max size to read because what if the file was accidentally 2gb.
>
> On Fri, Jun 23, 2017 at 3:36 AM, Raymond <xxxman2008 at 126.com> wrote:
>
>> Hi ,
>>
>>    This will help you  . https://wiki.freeswitch.org/wiki/File
>>
>> Raymond
>>
>> At 2017-06-22 21:49:33, "Faruq Ahmad" <afarooqa at gmail.com> wrote:
>>
>> Hi,
>>
>> I have a FS dialplan that fetches callflow from a JSON file. File is read
>> using
>>
>> var JsonFd = new FileIO(JsonPath, 'r');
>> JsonFd.read(2048);
>> result = JsonFd.data();
>> var menu = JSON.parse(result),
>>
>> Is there anyway I can read the whole file in one attempt, i.e. when a
>> smaller size was given to the .read() function it wouldn't read the
>> complete file. I have increased the value of size for read function however
>> my concern is in the long run file size might increase and parse would get
>> an incomplete JSON.
>>
>> Is there anyway I can get filesize from FileIO object or detect EOF from
>> the read buffer to make sure the whole file is loaded?
>> Also if I increase the size for read fucntion buffer way over the
>> estimated filesizes, is there any guarantee that no garbage values will be
>> read from the disk after the EOF?
>>
>>
>>
>>
>>
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>
>
>
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