On Jun 13, 2013, at 2:45 PM, Isaac Schlueter <[email protected]> wrote:
> All the arguments are optional. Only the order matters. So,
> actually, you can just do:
>
> stream.end(function() { 'finished' })
>
> That function is just added as a listener on the "finish" event.
>
Thank you Isaac. I noticed I have a typo below (I wrote “final” instead of
“finish”). The above is good to know.
> If you find a bug in the `bytesWritten` field, then please provide a test
> case.
With regard to my code fragment below, it turns out bytesWritten is in fact the
correct value of the bytes on disk! So something else is going on:
I see:
Sending x1 bytes to be written…
Sending x2 bytes to be written…
Sending x3 bytes to be written…
Each of these log messages is followed up by a stream.write() so the data is
being pushed to the buffer. x1 + x2 + x3 equals the bytes sent from the client.
So far so good.
I call stream.end() (at some point) and the callback/listener prints that Y
bytes were written to disk. And indeed the size of the file on disk is Y bytes.
However, Y < x1 + x2 + x3.
The only way I can explain this is that stream.end() causes some part of
pending stream.write()s to be discarded and not written to disk.
Or I am doing something very wrong.
I will write a test case.
—ravi
>
> On Thu, Jun 13, 2013 at 10:40 AM, // ravi <[email protected]> wrote:
>>
>> Howdy all,
>>
>> humour me another round. My question today:
>>
>> The writable.end() call takes three arguments: (1) chunk to write if any,
>> (2) encoding, (3) callback for when all writing is done.
>>
>> Assuming there is nothing left to write, I am hoping it is okay to pass
>> null, null to the first two arguments.
>>
>> And I am guessing it is also safe to assume that the end() will be queued up
>> after any pending write()s.
>>
>> With regard to the callback argument, the docs say:
>>
>>> callback Function Optional. Called when the final chunk is successfully
>>> written.
>>
>> My question is what does “successfully written” really mean? In particular,
>> can the callback rely on fs’s file.bytesWritten to have the correct value?
>> The doc for the latter says:
>>
>>> The number of bytes written so far. Does not include data that is still
>>> queued for writing.
>>
>> These two bits suggest the below is safe to do:
>>
>> req.on
>> (
>> ‘data’,
>> function(chunk)
>> {
>> console.log(“Sending “ + chunk.length + “ bytes to be written.”);
>> write_stream.write(chunk);
>> }
>> );
>>
>> req.on
>> (
>> ‘end’,
>> write_stream.end
>> (
>> null, null,
>> function()
>> {
>> console.log(“Yay, the file is written. Size is “ +
>> write_stream.bytesWritten);
>> }
>> );
>> );
>>
>> But in my experience, it does not seem to be. If I send 1000 bytes, the
>> first log prints, say, 4 times with 250 byte writes, as expected. But the
>> bytesWritten value is much smaller than the 1000 bytes sent (all numbers are
>> made up).
>>
>> I can post more fleshed out sample code if/once you confirm my assumptions
>> are correct. I realise there are other ways to do this (e.g: pipe, or listen
>> to the ‘final’ event for the writeable, etc), but I am curious if the above
>> is even expected behaviour.
>>
>> Thank you,
>>
>> —ravi
>>
>>
>> --
>> --
>> Job Board: http://jobs.nodejs.org/
>> Posting guidelines:
>> https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
>> You received this message because you are subscribed to the Google
>> Groups "nodejs" group.
>> To post to this group, send email to [email protected]
>> To unsubscribe from this group, send email to
>> [email protected]
>> For more options, visit this group at
>> http://groups.google.com/group/nodejs?hl=en?hl=en
>>
>> ---
>> You received this message because you are subscribed to the Google Groups
>> "nodejs" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to [email protected].
>> For more options, visit https://groups.google.com/groups/opt_out.
>>
>>
>
> --
> --
> Job Board: http://jobs.nodejs.org/
> Posting guidelines:
> https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
> You received this message because you are subscribed to the Google
> Groups "nodejs" group.
> To post to this group, send email to [email protected]
> To unsubscribe from this group, send email to
> [email protected]
> For more options, visit this group at
> http://groups.google.com/group/nodejs?hl=en?hl=en
>
> ---
> You received this message because you are subscribed to the Google Groups
> "nodejs" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to [email protected].
> For more options, visit https://groups.google.com/groups/opt_out.
>
>
--
--
Job Board: http://jobs.nodejs.org/
Posting guidelines:
https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
You received this message because you are subscribed to the Google
Groups "nodejs" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/nodejs?hl=en?hl=en
---
You received this message because you are subscribed to the Google Groups
"nodejs" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/groups/opt_out.
