This question involves Rook, but I think the answer will be general
enough that it pays to post here. At any rate, I don't know enough to
know whether this is a Rook only issue or a general R issue.
Here's what I'd like to do (and indeed, have code that should do this):
1. Start R, Rook
2. Start an analysis via a HTTP request to Rook. This analysis uses
.Call() to some compiled C code, if that matters. The C code calls a
callback function to update a variable with its progress.
3. While the analysis is happening, use Rook to obtain current status
with an HTTP request
The problem is that once the analysis starts, Rook does not respond to
requests. All of the status requests to Rook pile up, and then are
answered when the analysis (step 2) is done. Here is some example code
to demonstrate what the issue:
##########
library(Rook)
s <- Rhttpd$new()
s$add(
name="pingpong",
app=Rook::URLMap$new(
'/ping' = function(env){
req <- Rook::Request$new(env)
res <- Rook::Response$new()
res$write('This is ping.')
Sys.sleep(20)
res$finish()
},
'/pong' = function(env){
req <- Rook::Request$new(env)
res <- Rook::Response$new()
res$write("This is pong.")
res$finish()
},
'/?' = function(env){
req <- Rook::Request$new(env)
res <- Rook::Response$new()
res$redirect(req$to_url('/pong'))
res$finish()
}
)
)
s$start(quiet=TRUE)
s$browse('pingpong')
#############################
If you request /ping, R runs Sys.sleep() for 20 seconds. This is where
my .Call() statement would be. While the .Call() (Sys.sleep()) function
is doing its thing, I need to get Rook to respond on /pong (which would
simply respond with the progress), but if you run this code, request
/ping, then immediately request /pong, you'll see that the /pong request
will not be answered until the Sys.sleep() is done.
Of course, for a progress report to be useful, the requests have to be
answered immediately. Is this a Rook issue, or an R issue? Or am I
asking something unreasonable?
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