[go-nuts] Re: Migrating from a classic OO pattern

[Wanton]

First link in my first reply didn't use encapsulation. It gave Dog as 
parameter. Also not sure how golang internals work but when you encapsulate 
something thats probably new heap allocation.
I know it's tempting to use OO patterns (classes) but golang has very powerful 
interface system and I think it should be used instead in most of the cases. 
Example every struct that has method Attack will automatically implement 
Attacker interface with Attack function.
If I where you I would first learn go way of doing things and adjust your code 
when migrating. You will win in the long run with readability and 
maintainability.

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[go-nuts] Should an input validation function correct the input?

[Tamás Gulácsi]

I treat all code on pointer as it may modify the data, and use pointers 
sparingly.

Maybe you could call it Correct instead of Verify, to be explicit.

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Re: [go-nuts] Looking for a SQLite statement parser

[Philip O'Toole]

Great -- thanks for the reference, I'll take a look.

Philip

On Tue, Jan 31, 2017 at 10:02 AM, Vasiliy Tolstov 
wrote:

> cznic/ql have own lexer for SQL and it syntax very similar.
>
> 31 Янв 2017 г. 16:33 пользователь  написал:
>
>> Hello,
>>
>> I am the creator of rqlite (https://github.com/rqlite/rqlite), a
>> distributed relational database built on SQLite.
>>
>> I'm looking for a lexer and parser for SQL -- specifically SQLite, to
>> improve the ease-of-use of rqlite. I've thought about looking into using
>> the C code exposed by the SQLite source itself (which is what
>> https://github.com/mattn/go-sqlite3 does more generally). But someone
>> might know of a lexer and parser written in Go. I know how to build it
>> myself, but would rather avoid the effort if possible.
>>
>> What I am really trying to do is to determine, for the end-user, whether
>> the Exec() (https://golang.org/pkg/database/sql/#DB.Exec)  or Query() (
>> https://golang.org/pkg/database/sql/#DB.Query) method should be called
>> on the standard Go SQL interface, given a user-supplied SQL statement.
>> Right now the user must know what type of statement she is executing, and
>> send the statements to the right endpoint. I'd really like rqlite to just
>> do the right thing, and determine this automatically. Hence my idea to
>> parse the SQLite command, create an AST, and work it out.
>>
>> Or perhaps there is another way of thinking about this?
>>
>> Thanks,
>>
>> Philip
>>
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>


-- 
Philip O'Toole
Director, Engineering
Get inspired. See what's new on the Percolate blog: blog.percolate.com

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Re: [go-nuts] Is there a reason go doesn't use the small string optomization

[Ian Lance Taylor]

On Tue, Jan 31, 2017 at 9:10 PM, Eliot Hedeman
 wrote:
> I was writing up a proposal about adding the small string
> optimization(putting strings on the heap if they will fit within the
> sringStruct)to the go runtime, and I realized there might be good reason why
> this has not been done yet. Are there any glaring reasons you can think of?
> Here is the really rough draft of the proposal. Thanks for the feedback!

The problem is that the concurrent garbage collector needs to be able
to determine reliably and safely whether a word in memory, including
on the stack, contains a pointer or not.  It's not OK to have a word
in memory that might or might contain a pointer.  It's a good thing
that Go doesn't have unions in the language, because they would be
very difficult to implement in the garbage collector.

Ian

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Re: [go-nuts] Re: How can I distribute incoming HTTP request to 5 asynchronous workers?

[Sairam Kunala]

If one incoming HTTP request should be sent to 5 workers async,
See *solution #5* for similar problem/solution -
http://rodaine.com/2015/04/async-split-io-reader-in-golang/ .
A video file is required to be processed in multiple formats where
io.MultiWriter is used to send all data asynchronously which are being
processed in separate Go routines.

You can use https://golang.org/pkg/io/#example_MultiWriter to copy the
content from the reader so that all 5 processes can read the content.

PubSub approach is suggested (as suggested in the previous thread) if you
are looking for a production/stable system.
There is *Kafka* in Go (https://github.com/travisjeffery/jocko) in case you
want to skip external deps (spec not fully complete).

- Sairam


On Wed, Feb 1, 2017 at 3:40 AM, Paweł Szczur  wrote:

> I read whole request body. Pack to some structure. Send to a message queue
> (RabbitMQ, Kafka, Google Pub/Sub). MQ services allow to configure a
> topic/channel to multiplex a msg to all receivers (in PubSub you would
> create multiple subscriptions for a given topic https://cloud.google.com/
> pubsub/architecture#the_basics_of_a_publishsubscribe_service).
>
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[go-nuts] Heap fragmentation: HeapProfile reported memory vs Memstats.HeapInUse

[Sarath Lakshman]

I am observing Memstats.HeapInUse of 50GB while a heap profile reports
only 24GB. I tried increasing the heapprofile rate to 1KB and still I
notice the same behavior.
I added an app level accounting of memory usage and that also reports
close to 24GB. This makes me think that this could be memory allocator
fragmentation.

Appreciate any ideas to debug this further.


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http://www.sarathlakshman.com

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[go-nuts] Re: Migrating from a classic OO pattern

[Henry]

Have you considered the possibility of splitting the prepare-and-attack method 
into prepare and attack respectively? Even in a OO language, I generally try to 
avoid a base class being dependent on its subclasses. The subclasses may depend 
on the base class, but not the other way around. 2-ways dependency is usually a 
design smell.

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[go-nuts] Re: Migrating from a classic OO pattern

[ojucie]

My approach to mimic OOP behavior would be something like this:
https://play.golang.org/p/QQvWxfOiMB

It's funny how hard was to learn OOP and how easy was to unlearn it.
To the present day I never had to do such gymnastic to program using Go. 
Not even once.

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Re: [go-nuts] Appending a path to an URL

[Andy Balholm]

The part being added is treated as an absolute path, because it starts with a 
slash, so it replaces the existing path.

Andy

> On Jan 31, 2017, at 2:09 PM, Manlio Perillo  wrote:
> 
> Il giorno martedì 31 gennaio 2017 18:35:02 UTC+1, Manlio Perillo ha scritto:
> Thanks, I was not aware of this behavior.
> 
> The documentation says:
> "Parse parses a URL in the context of the receiver. The provided URL may be 
> relative or absolute."
> 
> Probably an example should be added?
> 
> Manlio
> 
> Il giorno martedì 31 gennaio 2017 13:07:48 UTC+1, Martin Gallagher ha scritto:
> Is this what you want: https://play.golang.org/p/BW96Bk_sqJ 
> 
> 
> Unfortunately it does not work:
> https://play.golang.org/p/P0hNqnE9Ol
> 
> I'm not even sure to understand *why* it does not work for this case.
> 
> Manlio 
> 
> -- 
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[go-nuts] Re: How can I distribute incoming HTTP request to 5 asynchronous workers?

[Paweł Szczur]

I read whole request body. Pack to some structure. Send to a message queue 
(RabbitMQ, Kafka, Google Pub/Sub). MQ services allow to configure a 
topic/channel to multiplex a msg to all receivers (in PubSub you would 
create multiple subscriptions for a given topic 
https://cloud.google.com/pubsub/architecture#the_basics_of_a_publishsubscribe_service).

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Re: [go-nuts] How can I distribute incoming HTTP request to 5 asynchronous workers?

[Michael Banzon]

Read the content - wrap it up and start the five goroutines and pass it to
them?

On Tue, Jan 31, 2017 at 10:42 PM Onur Özer  wrote:

> No, results not sent back and yes workers rely on the content.
>
> On Wed, 1 Feb 2017 at 00:41, Michael Banzon  wrote:
>
> Does the processing result get returned to the client?
>
> Does the workers rely on the content of the request body?
>
> On Tue, Jan 31, 2017 at 10:38 PM oso  wrote:
>
> Hello, I have 5 workers to process asynchronous HTTP requests to the
> system. They all process the same HTTP request in different ways. Workers
> who finish their job are starting to process the HTTP request. How can I
> implement this system?
>
> Regards,
>
> --
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> --
> Michael Banzon
> https://michaelbanzon.com/
>
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[go-nuts] Re: Appending a path to an URL

[Manlio Perillo]

Il giorno martedì 31 gennaio 2017 18:35:02 UTC+1, Manlio Perillo ha scritto:
>
> Thanks, I was not aware of this behavior.
>
> The documentation says:
> "Parse parses a URL in the context of the receiver. The provided URL may 
> be relative or absolute."
>
> Probably an example should be added?
>
> Manlio
>
> Il giorno martedì 31 gennaio 2017 13:07:48 UTC+1, Martin Gallagher ha 
> scritto:
>>
>> Is this what you want: https://play.golang.org/p/BW96Bk_sqJ
>
>
Unfortunately it does not work:
https://play.golang.org/p/P0hNqnE9Ol

I'm not even sure to understand *why* it does not work for this case.

Manlio 

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Re: [go-nuts] How can I distribute incoming HTTP request to 5 asynchronous workers?

[Onur Özer]

No, results not sent back and yes workers rely on the content.

On Wed, 1 Feb 2017 at 00:41, Michael Banzon  wrote:

> Does the processing result get returned to the client?
>
> Does the workers rely on the content of the request body?
>
> On Tue, Jan 31, 2017 at 10:38 PM oso  wrote:
>
> Hello, I have 5 workers to process asynchronous HTTP requests to the
> system. They all process the same HTTP request in different ways. Workers
> who finish their job are starting to process the HTTP request. How can I
> implement this system?
>
> Regards,
>
> --
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> "golang-nuts" group.
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> email to golang-nuts+unsubscr...@googlegroups.com.
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>
> --
> Michael Banzon
> https://michaelbanzon.com/
>

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Re: [go-nuts] How can I distribute incoming HTTP request to 5 asynchronous workers?

[Michael Banzon]

Does the processing result get returned to the client?

Does the workers rely on the content of the request body?

On Tue, Jan 31, 2017 at 10:38 PM oso  wrote:

> Hello, I have 5 workers to process asynchronous HTTP requests to the
> system. They all process the same HTTP request in different ways. Workers
> who finish their job are starting to process the HTTP request. How can I
> implement this system?
>
> Regards,
>
> --
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>
-- 
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https://michaelbanzon.com/

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[go-nuts] How can I distribute incoming HTTP request to 5 asynchronous workers?

[oso]

Hello, I have 5 workers to process asynchronous HTTP requests to the 
system. They all process the same HTTP request in different ways. Workers 
who finish their job are starting to process the HTTP request. How can I 
implement this system?

Regards,

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Re: [go-nuts] Looking for a SQLite statement parser

[Vasiliy Tolstov]

cznic/ql have own lexer for SQL and it syntax very similar.

31 Янв 2017 г. 16:33 пользователь  написал:

> Hello,
>
> I am the creator of rqlite (https://github.com/rqlite/rqlite), a
> distributed relational database built on SQLite.
>
> I'm looking for a lexer and parser for SQL -- specifically SQLite, to
> improve the ease-of-use of rqlite. I've thought about looking into using
> the C code exposed by the SQLite source itself (which is what
> https://github.com/mattn/go-sqlite3 does more generally). But someone
> might know of a lexer and parser written in Go. I know how to build it
> myself, but would rather avoid the effort if possible.
>
> What I am really trying to do is to determine, for the end-user, whether
> the Exec() (https://golang.org/pkg/database/sql/#DB.Exec)  or Query() (
> https://golang.org/pkg/database/sql/#DB.Query) method should be called on
> the standard Go SQL interface, given a user-supplied SQL statement. Right
> now the user must know what type of statement she is executing, and send
> the statements to the right endpoint. I'd really like rqlite to just do the
> right thing, and determine this automatically. Hence my idea to parse the
> SQLite command, create an AST, and work it out.
>
> Or perhaps there is another way of thinking about this?
>
> Thanks,
>
> Philip
>
> --
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[go-nuts] Re: Appending a path to an URL

[Manlio Perillo]

Thanks, I was not aware of this behavior.

The documentation says:
"Parse parses a URL in the context of the receiver. The provided URL may be 
relative or absolute."

Probably an example should be added?

Manlio

Il giorno martedì 31 gennaio 2017 13:07:48 UTC+1, Martin Gallagher ha 
scritto:
>
> Is this what you want: https://play.golang.org/p/BW96Bk_sqJ

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[go-nuts] Should an input validation function correct the input?

[JohnGB]

In each of the handlers in an API I have, I first unmarshal the JSON 
request, and then validate the resulting struct.  There are a few cases 
where I am able to pick up a correctable error in the validation code, but 
I'm not sure whether it's good practice to correct the error in the input 
data, or whether it's generally better to simply log the mistake (so that 
the client can be corrected), and return an error.

As a side note, I have a validator interface which is implemented on a 
pointer to each of the structs that I decode into, so it's technically 
quite easy to modify the struct.  However, it will likely not be clear in 
the code that the validator is also modifying data.

What is considered the best practice in this situation? 

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[go-nuts] Question on lib/pq CopyInSchema

[Mandolyte]

I have a date column which isn't fully populated. I tried to use "\N" per 
(1) and also just an empty string. Neither worked, both giving this error: 

invalid input syntax for type date


Is there a way to supply null values for CopyInSchema?

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[go-nuts] Re: About "Declaring Empty Slices" of CodeReviewComments

[James Bardin]

None of those values are escaping or being used. Your only allocation is 
probably the call to fmt.Fprint.

This isn't something that really needs a benchmark, it should be obvious 
that t is nil in `var t []string`, and t is not nil in `t := []string{}`. 
The former doesn't allocate a slice header, while the latter does (though 
it may be in the stack). 



On Tuesday, January 31, 2017 at 12:15:40 AM UTC-5, Keiji Yoshida wrote:
>
> Hi,
>
> "Declaring Empty Slices" of CodeReviewComments ( 
> https://github.com/golang/go/wiki/CodeReviewComments#declaring-empty-slices 
> ) says as below:
>
> ```
> When declaring a slice, use
>
> var t []string
>
> rather than
>
> t := []string{}
>
> The former avoids allocating memory if the slice is never appended to.
> ```
>
> I executed a benchmark test against above code but I could not see any 
> difference between them as for the results.
>
> My benchmark test code and its results can be seen here: 
> https://github.com/keijiyoshida/go-code-snippets/blob/master/empty-slice-declaration/main_test.go
>
> Is there something wrong in my benchmark test code or procedure?
>
> Thanks,
> Keiji Yoshida
>

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[go-nuts] Looking for a SQLite statement parser

[philip]

Hello,

I am the creator of rqlite (https://github.com/rqlite/rqlite), a 
distributed relational database built on SQLite.

I'm looking for a lexer and parser for SQL -- specifically SQLite, to 
improve the ease-of-use of rqlite. I've thought about looking into using 
the C code exposed by the SQLite source itself (which is what 
https://github.com/mattn/go-sqlite3 does more generally). But someone might 
know of a lexer and parser written in Go. I know how to build it myself, 
but would rather avoid the effort if possible.

What I am really trying to do is to determine, for the end-user, whether 
the Exec() (https://golang.org/pkg/database/sql/#DB.Exec)  or Query() 
(https://golang.org/pkg/database/sql/#DB.Query) method should be called on 
the standard Go SQL interface, given a user-supplied SQL statement. Right 
now the user must know what type of statement she is executing, and send 
the statements to the right endpoint. I'd really like rqlite to just do the 
right thing, and determine this automatically. Hence my idea to parse the 
SQLite command, create an AST, and work it out.

Or perhaps there is another way of thinking about this?

Thanks,

Philip

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[go-nuts] Appending a path to an URL

[Martin Gallagher]

Is this what you want: https://play.golang.org/p/BW96Bk_sqJ

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RE: [go-nuts] Is Go too strict for nesting function callings?

[John Souvestre]

Interesting!  Thanks.

 

John

John Souvestre - New Orleans LA

 

From: golang-nuts@googlegroups.com [mailto:golang-nuts@googlegroups.com] On 
Behalf Of Jonas August
Sent: 2017 January 30, Mon 04:25
To: golang-nuts
Subject: Re: [go-nuts] Is Go too strict for nesting function callings?

 



On Wednesday, January 25, 2017 at 5:48:44 PM UTC-5, John Souvestre wrote:

Does this mean that there is no way to call this function? 

   func h(func()(int, bool)) {} 

 

No, you can call it by passing in a function value f itself instead of its 
result values f(). Using f in the top post:

 

h(f)// OK

h(f())  // bad

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