[tahoe-dev] 回复: Re: 回复: Re: hello

[han zheng]

Thank you very much. I have done some simple test, the results showed it seemed less efficient...

 I call the funtion "c.startService" before uploading a file, and I put off calling "uploader.upload(uploadable)" to make sure Server is finished starting up...

It seems can work right, but there is an need to do more work to optimize it.


2012-11-07



Regards,
han zheng



发件人：Zooko Wilcox-O'Hearn
发送时间：2012-11-06 00:11
主题：Re: [tahoe-dev] 回复: Re: hello
收件人："Tahoe-LAFS development"<tahoe-dev at tahoe-lafs.org>
抄送：

Dear Han Zheng: 

I'm glad you are learning how to write Python code to extend the 
Tahoe-LAFS gateway. 


On Fri, Nov 2, 2012 at 9:29 PM, han zheng <z.han0903 at gmail.com> wrote: 
> if __name__ == "__main__": 
>     c = client.Client("/home/nick/.tahoe") 
>     uploader = c.getServiceNamed("uploader") 
>     uploadable = FileName("/home/nick/test.tar.gz",None) 
>     d = uploader.upload(uploadable) 
>     d.addCallback(printSuccess) 
>     d.addErrback(printError) 
> 
>     reactor.callLater(10,reactor.stop) 
>     reactor.run() 
> ---------------------------------------------------------------------------- 
> 
> When I ran "python test.py"(the file located in "/home/nick/.tahoe"), there 
> was an Failure instance like this: "client gave us zero servers" 
> 
> Should I do some initialization work? and how? 

I'm not sure, but I think the key might be that you need to invoke 
"startService" on the client object: 

https://tahoe-lafs.org/trac/tahoe-lafs/browser/git/src/allmydata/node.py?annotate=blame&rev=26d3869076f02351a821a3e4dd7049fd234f6bb6#L287 

It looks like there isn't a way for your Python code to tell *when* 
the service is finished starting up. Perhaps you'll need to extend the 
current code to return a Deferred from the startService method and 
trigger that Deferred once it has done everything it needs to do. Then 
your new code that wants to use a started-up client can attach a 
callback to that Deferred to do whatever your new code wants to do 
after the client is ready. 


> I ran "tahoe start" before I ran "test.py" 

The shell command "tahoe start" won't help! That starts a separate 
operating system process in which Python runs and in that Python 
interpreter, the tahoe "client.Client" object gets constructed and 
started. Then when you run "python test.py", another, separate 
operating system process is created with its own Python interpreter 
and its own "client.Client" object. The two processes have completely 
separate Python interpreters, so what Python code you run in one will 
not have any direct effect on the other. 


> If I only use tahoe as backup system, I think uploading a file directly to the cloud is more efficient 

Hm, you know what? I was about to write that I think you're wrong — 
that uploading the file by "tahoe put" through the web API will be 
just as efficient as your Python code that uploads a file from within 
the client. But, maybe it *will* be different. The webapi has to store 
a copy of the uploaded file in temp space on disk before beginning to 
upload it. The inside-the-Python-interpreter code would instead just 
make a pre-pass over the file, reading all of its contents, before 
beginning to upload it. 

In any case, you should measure how much difference it makes in 
performance. It might be a big difference, a little difference, or no 
difference. Your in-the-Python-interpreter code might even be *less* 
efficient than code that goes through the webapi. Measure! 


Regards, 

Zooko 
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