The following question is almost exactly what I need: https://stackoverflow.com/a/2394783/456188
I'd like to run the following:
find_or_create_by_person_id(:person_id => 10, :some_other => expensive_query)
But more importantly, I'd like to defer the execution of expensive_query unless I actually have to create the object.
Is that possible with find_or_create_by?
Turns out find_or_create_by* accepts a block that only gets run in the create case.
find_or_create_by_person_id(10) do |item|
item.some_other = expensive_query
end
Related
#some_instance_var = Concurrent::Hash.new
(0...some.length).each do |idx|
fetch_requests[idx] = Concurrent::Promise.execute do
response = HTTP.get(EXTDATA_URL)
if response.status.success?
... # update #some_instance_var
end
# We're going to disregard GET failures here.
puts "I'm here"
end
end
Concurrent::Promise.all?(fetch_requests).execute.wait # let threads finish gathering all of the unique posts first
puts "how am i out already"
When I run this, the bottom line prints first, so it's not doing what I want of waiting for all the threads in the array to finish its work first, hence I keep getting an empty #some_instance_var to work with below this code. What am I writing wrong?
Never mind, I fixed this. That setup is correct, I just had to use the splat operator * for my fetch_requests array inside the all?().
Concurrent::Promise.all?(*fetch_requests).execute.wait
I guess it wanted multiple args instead of one array.
When a user uses my application, at one point they will get an array of arrays, that looks like this:
results = [["value",25], ["value2",30]...]
The sub arrays could be larger, and will be in a similar format. I want to allow my users to write their own custom transform function that will take an array of arrays, and return either an array of arrays, a string, or a number. A function should look like this:
def user_transform_function(array_of_arrays)
# eval users code, only let them touch the array of arrays
end
Is there a safe way to sandbox this function and eval so a user could not try and execute malicious code? For example, no web callouts, not database callouts, and so on.
First, if you will use eval, it will never be safe. You can at least have a look in the direction of taint method.
What I would recommend is creating your own DSL for that. There is a great framework in Ruby: http://treetop.rubyforge.org/index.html. Of course, it will require some effort from your side, but from the user prospective I think it could be even better.
WARNING: I can not guarantee that this is truly safe!
You might be able to run it as a separate process and use ruby $SAFE, however this does not guarantee that what you get is safe, but it makes it harder to mess things up.
What you then would do is something like this:
script = "arr.map{|e| e+2}" #from the user.
require "json"
array = [1, 2, 3, 4]
begin
results = IO.popen("ruby -e 'require \"json\"; $SAFE=3; arr = JSON.parse(ARGV[0]); puts (#{script}).to_json' #{array.to_json}") do |io|
io.read
end
rescue Exception => e
puts "Ohh, good Sir/Mam, your script caused an error."
end
if results.include?("Insecure operation")
puts "Ohh, good Sir/Mam, you cannot do such a thing"
else
begin
a = JSON.parse(results)
results = a
rescue Exception => e
puts "Ohh, good Sir/Mam, something is wrong with the results."
puts results
end
end
conquer_the_world(results) if results.is_a?(Array)
do_not_conquer_the_world(results) unless results.is_a?(Array)
OR
You could do this, it appears:
def evaluate_user_script(script)
Thread.start {
$SAFE = 4
eval(script)
}
end
But again: I do not know how to get the data out of there.
I have this action in my controller:
def ad
#koder = #side.reklamers.pluck(:id) - [session[:log]]
#reklame = Reklamer.find(#koder.sample)
session[:log] = #reklame.id
render :text => "<span class='bannerid' data-id='#{#reklame.id}'></span><p style='margin-bottom: 7px;margin-top: 7px;font-size: 9px;text-align: center !important;'>Ad</p>#{#reklame.kode}"
end
It renders an HTML ad. This code is really fast. The problem is when I do try to example count view the response becomes VERY slow. 3s. Compared to 200ms!
#koder = #side.reklamers.pluck(:id) - [session[:log]]
#reklame = Reklamer.find(#koder.sample)
session[:log] = #reklame.id
#reklame.views += 1
#reklame.save
render :text => "<span class='bannerid' data-id='#{#reklame.id}'></span><p style='margin-bottom: 7px;margin-top: 7px;font-size: 9px;text-align: center !important;'>Ad</p>#{#reklame.kode}"
I have tried to add a resque background job with the same result..
What should I do?
Since views is really a counter maybe you should take a look at:
http://apidock.com/rails/v3.2.13/ActiveRecord/CounterCache/increment_counter
In your case it should look like this
Reklamer.increment_counter(:views, #reklame.id)
It should update only views column, don't run validations, callbacks etc. which will make it faster. But on the other hand 3s on simple save indicates that there is something else going wrong also.
First, try:
#reklame.update_attribute :views, #reklame.views + 1
See if that helps. If so, then you have some costly data validations going on that are slowing you down, but at least you know the source of the problem.
If that doesn't work, try wrapping that statement in
Thread.new { //code }
If it's still slow doing the save, then it's probably how your database is set up or something along those lines.
I am retrieving results from NCBI's online Blast tool with 'net/http' and 'uri'. To do this I have to search through an html page to check if one of the lines is "Status=WAITING" or "Status=READY". When the Blast tool has finished the status will change to ready and results will be posted on the html page.
I have a working version to check the status and then retrieve the information that I need, but it is inefficient and is broken into two methods when I believe that there could be some way to put them into one.
def waitForBlast(rid)
get = Net::HTTP.post_form(URI.parse('http://www.ncbi.nlm.nih.gov/blast/Blast.cgi?'), {:RID => "#{rid}", :CMD => 'Get'})
get.body.each{|line| (waitForBlast(rid) if line.strip == "Status=WAITING") if line[/Status=/]}
end
def returnBlast(rid)
blast_array = Array.new
get = Net::HTTP.post_form(URI.parse('http://www.ncbi.nlm.nih.gov/blast/Blast.cgi?'), {:RID => "#{rid}", :CMD => 'Get'})
get.body.each{|line| blast_array.push(line[/<a href=#\d+>/][/\d+/]) if line[/<a href=#\d+>/]}
return blast_array
end
The first method checks the status and is my main concern because it is recursive. I believe(and correct me if I'm wrong) that designed as is takes too much computing power when all that I need is some way to recheck the results within the same method(adding in a time delay is a bonus). The second method is fine, but I would prefer if it was combined with the first somehow. Any help appreciated.
Take a look at this implementation. This is what he does:
res='http://www.ncbi.nlm.nih.gov/blast/Blast.cgi?CMD=Get&FORMAT_OBJECT=SearchInfo&RID=' + #rid
while status = open(res).read.scan(/Status=(.*?)$/).to_s=='WAITING'
#logger.debug("Status=WAITING")
sleep(3)
end
I think using the string scanner might be a bit more efficient than iterating over every line in the page, but I haven't looked at it's implementation so I may be wrong.
I'm trying to call two lengthy commands in a when statement, but for some reason, because of its syntax, it performs two of the commands twice when it is called :
#email = Email.find(params[:id])
delivery = case #email.mail_type
# when "magic_email" these two delayed_jobs perform 2x instead of 1x. Why is that?
when "magic_email" then Delayed::Job.enqueue MagicEmail.new(#email.subject, #email.body)
Delayed::Job.enqueue ReferredEmail.new(#email.subject, #email.body)
when "org_magic_email" then Delayed::Job.enqueue OrgMagicEmail.new(#email.subject, #email.body)
when "all_orgs" then Delayed::Job.enqueue OrgBlast.new(#email.subject, #email.body)
when "all_card_holders" then Delayed::Job.enqueue MassEmail.new(#email.subject, #email.body)
end
return delivery
How can I make it so that when I hit when "magic_email", it only renders both those delayed jobs once ?
I have tried this with following example:
q = []
a = case 1
when 1 then q.push 'ashish'
q.push 'kumar'
when 2 then q.push 'test'
when 4 then q.push 'another test'
end
puts a.inspect #######["ashish", "kumar"]
This is working fine. It means your case-when syntax is ok. It might be you have aome other problem.
You are calling return delivery and delivery varible may be having the value to call the delayed job again. It depends on what the then statement returns, so try not to return anything if possible. I believe you want to do the delayed job and not return anything by using the function.
Perhaps you should just have the case and dont store it in any variable. I mean delivery variable has no purpose here.