Trouble installing luarock dependencies

[Phrogz]

1. You might want to note that you need libssl-dev installed in order to build cqueues.
2. After clearing that hurdle, I run into this:

Using http://luarocks.org/dev/fifo-scm-0.src.rock... switching to 'build' mode
Warning: /usr/local/share/lua/5.1/fifo.lua is not tracked by this installation of LuaRocks. Moving it to /usr/local/share/lua/5.1/fifo.lua~
Updating manifest for /usr/local/lib/luarocks/rocks
fifo scm-0 is now built and installed in /usr/local (license: MIT/X11)

Error: Unknown protocol git+https

[daurnimator]

You might want to note that you need libssl-dev installed in order to build cqueues.

I'm not sure if that belongs here? That should be an issue for the cqueues project/rockspec...

I run into this: Error: Unknown protocol git+https

That's a symptom of an old version of luarocks. You should try upgrading to >2.2.0 This wouldn't be an issue if I made an actual release; it's just an issue for using git HEAD with an old luarocks.

[daurnimator]

@Phrogz did you get this figured out?

[Phrogz]

@daurnimator I did, thank you. FWIW I ended up bailing and having an engineer write me a Lua binding using hiredis because I needed non-blocking subscriptions for multiple different signatures.

[daurnimator]

because I needed non-blocking subscriptions for multiple different signatures.

I'm not sure what you mean by this? lredis allows you to call subscribe and/or psubscribe as many times as you desire.

[daurnimator]

lredis allows you to call subscribe and/or psubscribe as many times as you desire.

Example:

local r=require "lredis.cqueues".connect_tcp()
r:subscribe("foo")
r:psubscribe("b*")
for item in r.get_next, r do
    local message_type = item[1]
    if message_type == "message" then
        print("Channel:", item[2], "Message:", item[3])
    elseif message_type == "pmessage" then
        print("Channel:", item[3], "Message:", item[4])
    end
end

[Phrogz]

lredis allows you to call subscribe and/or psubscribe as many times as you desire.

Does it? I don't have the code I tried at the moment (they're at work), but what I ran into, IIRC, was that a call to wait for a callback from a subscribe was synchronous. I needed to write code like the following (using totally made up methods):

local client = require'lredis'
client:connect'localhost'
client:subscribe( "foo.*", function(evt,data)
  print( "Got "..evt.." with some data: "..tostring(data) )
  -- JavaScript-style setInterval() that publishes new events
  -- at 60Hz for 3 seconds
end )

client:subscribe( "bar.*", function(evt,data)
  print( "Handling "..evt.." differently" )
  client:publish("some.response", data*42 )
end )

client:subscribe( "quit", function() client:close() end )

client:continueHandlingEventsUntilClosed()

As a suggestion: your library seems to fill a nice void, but is sorely missing in documentation and sample code.

[daurnimator]

Does it? I don't have the code I tried at the moment (they're at work), but what I ran into, IIRC, was that a call to wait for a callback from a subscribe was synchronous.

All lredis functions become asynchronous when run inside a cqueues managed coroutine. They "fake" being blocking when run outside a cqueues coroutine.

local lrc = require "lredis.cqueues"
local cqueues = require "cqueues"
-- Make a new cqueues scheduler
local cq = cqueues.new()
-- Make a thread that prints published messages to stdout
cq:wrap(function()
    local r = lrc.connect_tcp()
    r:subscribe("foo")
    r:psubscribe("b*")
    for item in r.get_next, r do
        local message_type = item[1]
        if message_type == "message" then
            print("Channel:", item[2], "Message:", item[3])
        elseif message_type == "pmessage" then
            print("Channel:", item[3], "Message:", item[4])
        end
    end
end)
-- Make a second thread that publishes events on an interval
cq:wrap(function()
    local r = lrc.connect_tcp()
    for i=1, 10000 do
        cqueues.sleep(1)
        r:call("publish", "bar", tostring(i))
    end
end)
-- Start 'main' loop
assert(cq:loop())

[Phrogz]

Thanks for the example code. I can see now how I might be able to make an event loop that handled read only. The problem comes when I'm not sure if a new get_next message will come in before I need to asynchronously publish a new event. So I can't write an event loop that could block forever waiting for the next incoming response, I need to be able to time out if no event comes in.

Edit: That cqueues looks wonderful. Hadn't seen it. I'll use what you've given me here soon to see if I can move away from the custom-embedded solution we're using on one side, and the Python scripts we're using on the other.

[daurnimator]

That cqueues looks wonderful. Hadn't seen it.

Glad to help out. cqueues is an underappreciated library! You may be interested in https://github.com/wahern/cqueues/wiki/Integrations-with-other-main-loops if you're doing this inside another program.

I'll use what you've given me here soon to see if I can move away from the custom-embedded solution we're using on one side, and the Python scripts we're using on the other.

let me know how you go :)

[daurnimator]

As a suggestion: your library seems to fill a nice void, but is sorely missing in documentation and sample code.

Indeed! It definitely needs some love. I just haven't had the time to take it beyond the 'works for me' stage. If you are using the library, please do contribute links, examples and/or docs :)

[daurnimator]

I just added the code from my above comment (slightly modified) as an example: https://github.com/daurnimator/lredis/blob/master/examples/pubsub.lua

[daurnimator]

@Phrogz get a chance to try things out?