Implements event-driven (non-polling) promises

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: mirai
 Type: Package
 Title: Minimalist Async Evaluation Framework for R
-Version: 0.13.2.9001
+Version: 0.13.2.9002
 Description: Lightweight parallel code execution and distributed computing.
     Designed for simplicity, a 'mirai' evaluates an R expression asynchronously,
     on local or network resources, resolving automatically upon completion.
@@ -23,13 +23,12 @@ Encoding: UTF-8
 Depends: 
     R (>= 3.6)
 Imports: 
-    nanonext (>= 0.13.3)
+    nanonext (>= 0.13.6.9002)
 Enhances: 
     parallel,
     promises
 Suggests: 
     knitr,
-    later,
     markdown
 VignetteBuilder: knitr
 RoxygenNote: 7.3.1

NAMESPACE

@@ -65,6 +65,7 @@ importFrom(nanonext,reap)
 importFrom(nanonext,recv)
 importFrom(nanonext,recv_aio_signal)
 importFrom(nanonext,request)
+importFrom(nanonext,request2)
 importFrom(nanonext,request_signal)
 importFrom(nanonext,send)
 importFrom(nanonext,socket)

NEWS.md

@@ -1,6 +1,7 @@
-# mirai 0.13.2.9001 (development)
+# mirai 0.13.2.9002 (development)
 
-* `stop_mirai()` now returns a 'miraiInterrupt' in the case the asynchronous task was still ongoing (thanks @jcheng #110).
+* Re-implements the promises method with completely event-driven (non-polling) promises (possible thanks to improvements in `nanonext` implemented with the help of @jcheng5)
+* `stop_mirai()` now returns a 'miraiInterrupt' in the case the asynchronous task was still ongoing (thanks @jcheng5 #110).
 
 # mirai 0.13.2
 

R/mirai-package.R

@@ -44,8 +44,9 @@
 #'
 #' @importFrom nanonext call_aio call_aio_ .context cv cv_value dial
 #'     is_error_value listen lock mclock msleep next_config opt opt<- parse_url
-#'     pipe_notify random reap recv recv_aio_signal request request_signal send
-#'     socket stat stop_aio strcat tls_config unresolved until wait write_cert
+#'     pipe_notify random reap recv recv_aio_signal request request2
+#'     request_signal send socket stat stop_aio strcat tls_config unresolved
+#'     until wait write_cert
 #' @importFrom parallel nextRNGStream
 #' @importFrom stats rexp
 #' @importFrom utils .DollarNames

R/mirai.R

@@ -145,10 +145,10 @@ mirai <- function(.expr, ..., .args = list(), .timeout = NULL, .compute = "defau
   envir <- ..[[.compute]]
   if (is.null(envir)) {
     sock <- ephemeral_daemon(local_url())
-    aio <- request(.context(sock), data = data, send_mode = 1L, recv_mode = 1L, timeout = .timeout)
+    aio <- request2(.context(sock), data = data, send_mode = 1L, recv_mode = 1L, timeout = .timeout)
     `attr<-`(.subset2(aio, "aio"), "sock", sock)
   } else {
-    aio <- request_signal(.context(envir[["sock"]]), data = data, cv = envir[["cv"]], send_mode = 3L, recv_mode = 1L, timeout = .timeout)
+    aio <- request2(.context(envir[["sock"]]), data = data, cv = envir[["cv"]], send_mode = 3L, recv_mode = 1L, timeout = .timeout)
   }
 
   `class<-`(aio, c("mirai", "recvAio"))

R/promises.R

@@ -64,22 +64,33 @@
 #'
 as.promise.mirai <- function(x) {
 
-  force(x)
-  promises::then(
-    promise = promises::promise(
-      function(resolve, reject) {
-        query <- function()
-          if (unresolved(x))
-            later::later(query, delay = 0.1) else
-              resolve(.subset2(x, "value"))
-        query()
-      }
-    ),
-    onFulfilled = function(value)
-      if (is_error_value(value) && !is_mirai_interrupt(value))
-        stop(value) else
-          value
-  )
+  promise <- .subset2(x, "promise")
+
+  if (is.null(promise)) {
+
+    promise <- promises::then(
+      promises::promise(
+        function(resolve, reject)
+          attr(x, "callback") <- function() resolve(.subset2(x, "data"))
+      ),
+      onFulfilled = function(value)
+        if (is_error_value(value) && !is_mirai_interrupt(value))
+          stop(value) else
+            value
+    )
+
+    if (!unresolved(x)) {
+      value <- .subset2(x, "value")
+      promise <- if (is_error_value(value) && !is_mirai_interrupt(value))
+        promises::promise_reject(value) else
+          promises::promise_resolve(value)
+    }
+
+    assign("promise", promise, x)
+
+  }
+
+  promise
 
 }
 

README.Rmd

@@ -152,7 +152,7 @@ We would like to thank in particular:
 
 [Will Landau](https://github.com/wlandau/), for being instrumental in shaping development of the package, from initiating the original request for persistent daemons, through to orchestrating robustness testing for the high performance computing requirements of `crew` and `targets`.
 
-[Joe Cheng](https://github.com/jcheng5/), for optimising the `promises` method to make `mirai` work seamlessly within Shiny, and guidance for implementing error stack traces.
+[Joe Cheng](https://github.com/jcheng5/), for optimising the `promises` method to make `mirai` work seamlessly within Shiny, prototyping non-polling promises and guidance on implementing error stack traces.
 
 [Luke Tierney](https://github.com/ltierney/), R Core, for discussion on R's implementation of L'Ecuyer-CMRG streams, used to ensure statistical independence in parallel processing, and collaboration in 'providing an alternative communications backend for R'.
 

README.md

@@ -88,17 +88,17 @@ result.
 
 ``` r
 m$data
-#>  [1]  1.8451625 -0.2165991 -1.2117962  0.4428216  1.3387124  0.7469864
-#>  [7]  2.2582459 -0.8252213 -4.6168235  0.5419577
+#>  [1]  2.4181337  1.8674723  6.6228207 -1.0355541  0.8055614  1.2413703
+#>  [7] -0.9656666  0.1509931  0.5354832  0.4135421
 ```
 
 Alternatively, explicitly call and wait for the result using
 `call_mirai()`.
 
 ``` r
 call_mirai(m)$data
-#>  [1]  1.8451625 -0.2165991 -1.2117962  0.4428216  1.3387124  0.7469864
-#>  [7]  2.2582459 -0.8252213 -4.6168235  0.5419577
+#>  [1]  2.4181337  1.8674723  6.6228207 -1.0355541  0.8055614  1.2413703
+#>  [7] -0.9656666  0.1509931  0.5354832  0.4135421
 ```
 
 ### Daemons
@@ -184,8 +184,8 @@ for persistent daemons, through to orchestrating robustness testing for
 the high performance computing requirements of `crew` and `targets`.
 
 [Joe Cheng](https://github.com/jcheng5/), for optimising the `promises`
-method to make `mirai` work seamlessly within Shiny, and guidance for
-implementing error stack traces.
+method to make `mirai` work seamlessly within Shiny, prototyping
+non-polling promises and guidance on implementing error stack traces.
 
 [Luke Tierney](https://github.com/ltierney/), R Core, for discussion on
 R’s implementation of L’Ecuyer-CMRG streams, used to ensure statistical