From 4bb4622643855f09995ebb3a48d6e135a22cdd8a Mon Sep 17 00:00:00 2001
From: Joe Cheng <joe@posit.co>
Date: Mon, 1 Apr 2024 19:01:30 -0700
Subject: [PATCH 01/10] Add later dependency

---
 DESCRIPTION          | 4 ++++
 NAMESPACE            | 1 +
 R/nanonext-package.R | 1 +
 src/later_shim.cpp   | 5 +++++
 src/later_shim.h     | 7 +++++++
 5 files changed, 18 insertions(+)
 create mode 100644 src/later_shim.cpp
 create mode 100644 src/later_shim.h

diff --git a/DESCRIPTION b/DESCRIPTION
index fc3f85077..8ff2069de 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -30,6 +30,10 @@ SystemRequirements: 'libnng' >= 1.5 and 'libmbedtls' >= 2.5, or 'cmake' to
     compile NNG and/or Mbed TLS included in package sources
 Depends: 
     R (>= 3.5)
+Imports:
+    later
+LinkingTo: 
+    later
 Suggests: 
     knitr,
     markdown
diff --git a/NAMESPACE b/NAMESPACE
index a9f83b67f..d630e2792 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -96,6 +96,7 @@ export(until_)
 export(wait)
 export(wait_)
 export(write_cert)
+importFrom(later,later)
 importFrom(stats,start)
 importFrom(tools,md5sum)
 importFrom(utils,.DollarNames)
diff --git a/R/nanonext-package.R b/R/nanonext-package.R
index fff6f714a..d39594d39 100644
--- a/R/nanonext-package.R
+++ b/R/nanonext-package.R
@@ -95,6 +95,7 @@
 #' @importFrom stats start
 #' @importFrom tools md5sum
 #' @importFrom utils .DollarNames
+#' @importFrom later later
 #' @useDynLib nanonext, .registration = TRUE
 #'
 "_PACKAGE"
diff --git a/src/later_shim.cpp b/src/later_shim.cpp
new file mode 100644
index 000000000..62e90e173
--- /dev/null
+++ b/src/later_shim.cpp
@@ -0,0 +1,5 @@
+#include <later_api.h>
+
+extern "C" void later2(void (*func)(void*), void* data, double secs) {
+  later::later(func, data, secs);
+}
diff --git a/src/later_shim.h b/src/later_shim.h
new file mode 100644
index 000000000..7a9345b47
--- /dev/null
+++ b/src/later_shim.h
@@ -0,0 +1,7 @@
+#ifndef LATER_SHIM_H
+#define LATER_SHIM_H
+
+// This is simply a shim so that later::later can be accessed from C, not C++
+void later2(void (*func)(void*), void* data, double secs);
+
+#endif

From ce12e73621c2d0c08015e805b25d247cd451f6d6 Mon Sep 17 00:00:00 2001
From: Joe Cheng <joe@posit.co>
Date: Tue, 2 Apr 2024 11:00:12 -0700
Subject: [PATCH 02/10] Implement promises for recv_aio[_signal]

---
 NAMESPACE      |  2 ++
 R/aio.R        | 62 ++++++++++++++++++++++++++++++++++++++++++++++++--
 src/aio.c      | 34 +++++++++++++++++++++++----
 src/nanonext.h |  5 ++--
 4 files changed, 94 insertions(+), 9 deletions(-)

diff --git a/NAMESPACE b/NAMESPACE
index d630e2792..385c06dcc 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -33,6 +33,8 @@ S3method(print,recvAio)
 S3method(print,sendAio)
 S3method(print,tlsConfig)
 S3method(print,unresolvedValue)
+S3method(promises::as.promise,recvAio)
+S3method(promises::is.promising,recvAio)
 S3method(start,nanoDialer)
 S3method(start,nanoListener)
 export("%~>%")
diff --git a/R/aio.R b/R/aio.R
index b0a610412..6a8119f53 100644
--- a/R/aio.R
+++ b/R/aio.R
@@ -118,7 +118,14 @@ recv_aio <- function(con,
                               "integer", "logical", "numeric", "raw", "string"),
                      timeout = NULL,
                      n = 65536L)
-  data <- .Call(rnng_recv_aio, con, mode, timeout, n, environment())
+  data <- .Call(rnng_recv_aio, con, mode, timeout, n, environment(),
+    function() {
+      cb <- data$callback
+      if (!is.null(cb)) {
+        cb(data)
+      }
+    }
+  )
 
 #' Receive Async and Signal a Condition
 #'
@@ -157,7 +164,58 @@ recv_aio_signal <- function(con,
                                      "integer", "logical", "numeric", "raw", "string"),
                             timeout = NULL,
                             n = 65536L)
-  data <- .Call(rnng_recv_aio_signal, con, cv, mode, timeout, n, environment())
+  data <- .Call(rnng_recv_aio_signal, con, cv, mode, timeout, n, environment(),
+    function() {
+      cb <- data$callback
+      if (!is.null(cb)) {
+        cb(data)
+      }
+    }
+  )
+
+#' @exportS3Method promises::is.promising
+is.promising.recvAio <- function(x) {
+  TRUE
+}
+
+#' @exportS3Method promises::as.promise
+as.promise.recvAio <- function(x) {
+  prom <- x$promise
+
+  if (is.null(prom)) {
+    prom <- promises::promise(function(resolve, reject) {
+      assign("callback", function(...) {
+
+        # WARNING: x$data is heavily side-effecty!
+        value <- x$data
+
+        if (is_error_value(value)) {
+          reject(simpleError(nng_error(value)))
+        } else {
+          resolve(value)
+        }
+      }, x)
+    })
+
+    # WARNING: x$data is heavily side-effecty!
+    value <- x$data
+
+    if (!inherits(value, "unresolvedValue")) {
+      if (is_error_value(value)) {
+        prom <- promises::promise_reject(simpleError(nng_error(value)))
+      } else {
+        prom <- promises::promise_resolve(value)
+      }
+    }
+
+    # Save for next time. This is not just an optimization but essential for
+    # correct behavior if as.promise is called multiple times, because only one
+    # `callback` can exist on the recvAio object at a time.
+    assign("promise", prom, x)
+  }
+
+  prom
+}
 
 # Core aio functions -----------------------------------------------------------
 
diff --git a/src/aio.c b/src/aio.c
index 97606f517..eb80a7823 100644
--- a/src/aio.c
+++ b/src/aio.c
@@ -20,6 +20,7 @@
 #define NANONEXT_SUPPLEMENTALS
 #define NANONEXT_SIGNALS
 #include "nanonext.h"
+#include "later_shim.h"
 
 // internals -------------------------------------------------------------------
 
@@ -195,6 +196,21 @@ static void isaio_complete(void *arg) {
 
 }
 
+
+static void raio_invoke_cb(void* arg) {
+  nano_aio *raio = (nano_aio *) arg;
+  if (raio->cb == NULL || Rf_isNull(raio->cb)) return;
+  SEXP func = (SEXP)raio->cb;
+  SEXP callExpr, result;
+  if (!Rf_isNull(func)) {
+    PROTECT(callExpr = Rf_lcons(func, R_NilValue)); // Prepare call
+    PROTECT(result = Rf_eval(callExpr, R_GlobalEnv)); // Execute call
+
+    UNPROTECT(2);
+    R_ReleaseObject(func);
+  }
+}
+
 static void raio_complete(void *arg) {
 
   nano_aio *raio = (nano_aio *) arg;
@@ -210,6 +226,7 @@ static void raio_complete(void *arg) {
   raio->result = res - !res;
 #endif
 
+  later2(raio_invoke_cb, arg, 0);
 }
 
 static void raio_complete_signal(void *arg) {
@@ -229,6 +246,7 @@ static void raio_complete_signal(void *arg) {
   nng_cv_wake(cv);
   nng_mtx_unlock(mtx);
 
+  later2(raio_invoke_cb, arg, 0);
 }
 
 static void request_complete_signal(void *arg) {
@@ -709,7 +727,7 @@ SEXP rnng_send_aio(SEXP con, SEXP data, SEXP mode, SEXP timeout, SEXP clo) {
 }
 
 SEXP rnng_recv_aio_impl(const SEXP con, const SEXP mode, const SEXP timeout,
-                        const SEXP bytes, const SEXP clo, nano_cv *ncv) {
+                        const SEXP bytes, const SEXP clo, const SEXP cb, nano_cv *ncv) {
 
   const nng_duration dur = timeout == R_NilValue ? NNG_DURATION_DEFAULT : (nng_duration) Rf_asInteger(timeout);
   const int signal = ncv != NULL;
@@ -725,6 +743,12 @@ SEXP rnng_recv_aio_impl(const SEXP con, const SEXP mode, const SEXP timeout,
     raio->next = ncv;
     raio->type = RECVAIO;
     raio->mode = mod;
+    if (Rf_isNull(cb)) {
+      raio->cb = NULL;
+    } else {
+      R_PreserveObject(cb);
+      raio->cb = (void*)cb;
+    }
 
     if ((xc = nng_aio_alloc(&raio->aio, signal ? raio_complete_signal : raio_complete, raio)))
       goto exitlevel1;
@@ -791,19 +815,19 @@ SEXP rnng_recv_aio_impl(const SEXP con, const SEXP mode, const SEXP timeout,
 
 }
 
-SEXP rnng_recv_aio(SEXP con, SEXP mode, SEXP timeout, SEXP bytes, SEXP clo) {
+SEXP rnng_recv_aio(SEXP con, SEXP mode, SEXP timeout, SEXP bytes, SEXP clo, SEXP cb) {
 
-  return rnng_recv_aio_impl(con, mode, timeout, bytes, clo, NULL);
+  return rnng_recv_aio_impl(con, mode, timeout, bytes, clo, cb, NULL);
 
 }
 
-SEXP rnng_recv_aio_signal(SEXP con, SEXP cvar, SEXP mode, SEXP timeout, SEXP bytes, SEXP clo) {
+SEXP rnng_recv_aio_signal(SEXP con, SEXP cvar, SEXP mode, SEXP timeout, SEXP bytes, SEXP clo, SEXP cb) {
 
   if (R_ExternalPtrTag(cvar) != nano_CvSymbol)
     Rf_error("'cv' is not a valid Condition Variable");
   nano_cv *ncv = (nano_cv *) R_ExternalPtrAddr(cvar);
 
-  return rnng_recv_aio_impl(con, mode, timeout, bytes, clo, ncv);
+  return rnng_recv_aio_impl(con, mode, timeout, bytes, clo, cb, ncv);
 
 }
 
diff --git a/src/nanonext.h b/src/nanonext.h
index 74c43e633..24a868975 100644
--- a/src/nanonext.h
+++ b/src/nanonext.h
@@ -88,6 +88,7 @@ typedef struct nano_aio_s {
   int result;
   void *data;
   void *next;
+  void *cb;
 } nano_aio;
 
 typedef struct nano_cv_s {
@@ -250,8 +251,8 @@ SEXP rnng_protocol_open(SEXP, SEXP);
 SEXP rnng_random(SEXP, SEXP);
 SEXP rnng_reap(SEXP);
 SEXP rnng_recv(SEXP, SEXP, SEXP, SEXP);
-SEXP rnng_recv_aio(SEXP, SEXP, SEXP, SEXP, SEXP);
-SEXP rnng_recv_aio_signal(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
+SEXP rnng_recv_aio(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
+SEXP rnng_recv_aio_signal(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_request(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_request_signal(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_send(SEXP, SEXP, SEXP, SEXP);

From 7e3284c1a48ed18555604f97fead1f5e58984b8e Mon Sep 17 00:00:00 2001
From: shikokuchuo <53399081+shikokuchuo@users.noreply.github.com>
Date: Thu, 11 Apr 2024 15:37:09 +0100
Subject: [PATCH 03/10] simplifications

---
 DESCRIPTION |  3 ++-
 R/aio.R     | 26 ++++++++++++++------------
 src/aio.c   | 24 ++++++------------------
 src/init.c  |  4 ++--
 4 files changed, 24 insertions(+), 33 deletions(-)

diff --git a/DESCRIPTION b/DESCRIPTION
index 8ff2069de..1a6380379 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -36,6 +36,7 @@ LinkingTo:
     later
 Suggests: 
     knitr,
-    markdown
+    markdown,
+    promises
 VignetteBuilder: knitr
 RoxygenNote: 7.3.1
diff --git a/R/aio.R b/R/aio.R
index 6a8119f53..c1db76198 100644
--- a/R/aio.R
+++ b/R/aio.R
@@ -120,8 +120,8 @@ recv_aio <- function(con,
                      n = 65536L)
   data <- .Call(rnng_recv_aio, con, mode, timeout, n, environment(),
     function() {
-      cb <- data$callback
-      if (!is.null(cb)) {
+      cb <- .subset2(data, "callback")
+      if (is.function(cb)) {
         cb(data)
       }
     }
@@ -166,8 +166,8 @@ recv_aio_signal <- function(con,
                             n = 65536L)
   data <- .Call(rnng_recv_aio_signal, con, cv, mode, timeout, n, environment(),
     function() {
-      cb <- data$callback
-      if (!is.null(cb)) {
+      cb <- .subset2(data, "callback")
+      if (is.function(cb)) {
         cb(data)
       }
     }
@@ -180,14 +180,15 @@ is.promising.recvAio <- function(x) {
 
 #' @exportS3Method promises::as.promise
 as.promise.recvAio <- function(x) {
-  prom <- x$promise
 
-  if (is.null(prom)) {
-    prom <- promises::promise(function(resolve, reject) {
+  promise <- .subset2(x, "promise")
+
+  if (is.null(promise)) {
+    promise <- promises::promise(function(resolve, reject) {
       assign("callback", function(...) {
 
         # WARNING: x$data is heavily side-effecty!
-        value <- x$data
+        value <- .subset2(x, "data")
 
         if (is_error_value(value)) {
           reject(simpleError(nng_error(value)))
@@ -202,19 +203,20 @@ as.promise.recvAio <- function(x) {
 
     if (!inherits(value, "unresolvedValue")) {
       if (is_error_value(value)) {
-        prom <- promises::promise_reject(simpleError(nng_error(value)))
+        promise <- promises::promise_reject(simpleError(nng_error(value)))
       } else {
-        prom <- promises::promise_resolve(value)
+        promise <- promises::promise_resolve(value)
       }
     }
 
     # Save for next time. This is not just an optimization but essential for
     # correct behavior if as.promise is called multiple times, because only one
     # `callback` can exist on the recvAio object at a time.
-    assign("promise", prom, x)
+    assign("promise", promise, x)
   }
 
-  prom
+  promise
+
 }
 
 # Core aio functions -----------------------------------------------------------
diff --git a/src/aio.c b/src/aio.c
index eb80a7823..6f332dbe7 100644
--- a/src/aio.c
+++ b/src/aio.c
@@ -196,19 +196,12 @@ static void isaio_complete(void *arg) {
 
 }
 
-
-static void raio_invoke_cb(void* arg) {
+static void raio_invoke_cb(void *arg) {
   nano_aio *raio = (nano_aio *) arg;
-  if (raio->cb == NULL || Rf_isNull(raio->cb)) return;
-  SEXP func = (SEXP)raio->cb;
-  SEXP callExpr, result;
-  if (!Rf_isNull(func)) {
-    PROTECT(callExpr = Rf_lcons(func, R_NilValue)); // Prepare call
-    PROTECT(result = Rf_eval(callExpr, R_GlobalEnv)); // Execute call
-
-    UNPROTECT(2);
-    R_ReleaseObject(func);
-  }
+  SEXP callExpr;
+  PROTECT(callExpr = Rf_lcons((SEXP) raio->cb, R_NilValue));
+  (void) Rf_eval(callExpr, R_GlobalEnv);
+  UNPROTECT(1);
 }
 
 static void raio_complete(void *arg) {
@@ -743,12 +736,7 @@ SEXP rnng_recv_aio_impl(const SEXP con, const SEXP mode, const SEXP timeout,
     raio->next = ncv;
     raio->type = RECVAIO;
     raio->mode = mod;
-    if (Rf_isNull(cb)) {
-      raio->cb = NULL;
-    } else {
-      R_PreserveObject(cb);
-      raio->cb = (void*)cb;
-    }
+    raio->cb = cb;
 
     if ((xc = nng_aio_alloc(&raio->aio, signal ? raio_complete_signal : raio_complete, raio)))
       goto exitlevel1;
diff --git a/src/init.c b/src/init.c
index 9bf9645f0..165b6ca6a 100644
--- a/src/init.c
+++ b/src/init.c
@@ -155,8 +155,8 @@ static const R_CallMethodDef callMethods[] = {
   {"rnng_random", (DL_FUNC) &rnng_random, 2},
   {"rnng_reap", (DL_FUNC) &rnng_reap, 1},
   {"rnng_recv", (DL_FUNC) &rnng_recv, 4},
-  {"rnng_recv_aio", (DL_FUNC) &rnng_recv_aio, 5},
-  {"rnng_recv_aio_signal", (DL_FUNC) &rnng_recv_aio_signal, 6},
+  {"rnng_recv_aio", (DL_FUNC) &rnng_recv_aio, 6},
+  {"rnng_recv_aio_signal", (DL_FUNC) &rnng_recv_aio_signal, 7},
   {"rnng_request", (DL_FUNC) &rnng_request, 6},
   {"rnng_request_signal", (DL_FUNC) &rnng_request_signal, 7},
   {"rnng_send", (DL_FUNC) &rnng_send, 4},

From 2ccc4d4df70bea72043b3a3cfcc9dffa94d6d4dc Mon Sep 17 00:00:00 2001
From: shikokuchuo <53399081+shikokuchuo@users.noreply.github.com>
Date: Wed, 17 Apr 2024 14:27:46 +0100
Subject: [PATCH 04/10] implements request_promise()

---
 DESCRIPTION          |   3 +-
 NAMESPACE            |   3 +-
 R/aio.R              |  64 +--------------------------
 R/context.R          |  16 +++++++
 R/nanonext-package.R |   2 +-
 man/request.Rd       |  11 +++++
 src/aio.c            | 100 ++++++++++++++++++++++++++++++++++---------
 src/init.c           |   5 ++-
 src/nanonext.h       |   5 ++-
 9 files changed, 117 insertions(+), 92 deletions(-)

diff --git a/DESCRIPTION b/DESCRIPTION
index 1a6380379..8ff2069de 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -36,7 +36,6 @@ LinkingTo:
     later
 Suggests: 
     knitr,
-    markdown,
-    promises
+    markdown
 VignetteBuilder: knitr
 RoxygenNote: 7.3.1
diff --git a/NAMESPACE b/NAMESPACE
index 385c06dcc..add71dece 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -33,8 +33,6 @@ S3method(print,recvAio)
 S3method(print,sendAio)
 S3method(print,tlsConfig)
 S3method(print,unresolvedValue)
-S3method(promises::as.promise,recvAio)
-S3method(promises::is.promising,recvAio)
 S3method(start,nanoDialer)
 S3method(start,nanoListener)
 export("%~>%")
@@ -77,6 +75,7 @@ export(recv_aio)
 export(recv_aio_signal)
 export(reply)
 export(request)
+export(request_promise)
 export(request_signal)
 export(send)
 export(send_aio)
diff --git a/R/aio.R b/R/aio.R
index c1db76198..b0a610412 100644
--- a/R/aio.R
+++ b/R/aio.R
@@ -118,14 +118,7 @@ recv_aio <- function(con,
                               "integer", "logical", "numeric", "raw", "string"),
                      timeout = NULL,
                      n = 65536L)
-  data <- .Call(rnng_recv_aio, con, mode, timeout, n, environment(),
-    function() {
-      cb <- .subset2(data, "callback")
-      if (is.function(cb)) {
-        cb(data)
-      }
-    }
-  )
+  data <- .Call(rnng_recv_aio, con, mode, timeout, n, environment())
 
 #' Receive Async and Signal a Condition
 #'
@@ -164,60 +157,7 @@ recv_aio_signal <- function(con,
                                      "integer", "logical", "numeric", "raw", "string"),
                             timeout = NULL,
                             n = 65536L)
-  data <- .Call(rnng_recv_aio_signal, con, cv, mode, timeout, n, environment(),
-    function() {
-      cb <- .subset2(data, "callback")
-      if (is.function(cb)) {
-        cb(data)
-      }
-    }
-  )
-
-#' @exportS3Method promises::is.promising
-is.promising.recvAio <- function(x) {
-  TRUE
-}
-
-#' @exportS3Method promises::as.promise
-as.promise.recvAio <- function(x) {
-
-  promise <- .subset2(x, "promise")
-
-  if (is.null(promise)) {
-    promise <- promises::promise(function(resolve, reject) {
-      assign("callback", function(...) {
-
-        # WARNING: x$data is heavily side-effecty!
-        value <- .subset2(x, "data")
-
-        if (is_error_value(value)) {
-          reject(simpleError(nng_error(value)))
-        } else {
-          resolve(value)
-        }
-      }, x)
-    })
-
-    # WARNING: x$data is heavily side-effecty!
-    value <- x$data
-
-    if (!inherits(value, "unresolvedValue")) {
-      if (is_error_value(value)) {
-        promise <- promises::promise_reject(simpleError(nng_error(value)))
-      } else {
-        promise <- promises::promise_resolve(value)
-      }
-    }
-
-    # Save for next time. This is not just an optimization but essential for
-    # correct behavior if as.promise is called multiple times, because only one
-    # `callback` can exist on the recvAio object at a time.
-    assign("promise", promise, x)
-  }
-
-  promise
-
-}
+  data <- .Call(rnng_recv_aio_signal, con, cv, mode, timeout, n, environment())
 
 # Core aio functions -----------------------------------------------------------
 
diff --git a/R/context.R b/R/context.R
index 0a70df53d..9f3285479 100644
--- a/R/context.R
+++ b/R/context.R
@@ -269,3 +269,19 @@ request_signal <- function(context,
                                          "integer", "logical", "numeric", "raw", "string"),
                            timeout = NULL)
   data <- .Call(rnng_request_signal, context, data, cv, send_mode, recv_mode, timeout, environment())
+
+#' @rdname request
+#' @export
+#'
+request_promise <- function(context,
+                            data,
+                            cv,
+                            send_mode = c("serial", "raw", "next"),
+                            recv_mode = c("serial", "character", "complex", "double",
+                                          "integer", "logical", "numeric", "raw", "string"),
+                            timeout = NULL)
+  data <- .Call(rnng_request_promise, context, data, cv, send_mode, recv_mode, timeout, environment(),
+                function() {
+                  cb <- .subset2(data, "callback")
+                  if (is.function(cb)) cb(data)
+                })
diff --git a/R/nanonext-package.R b/R/nanonext-package.R
index d39594d39..c5cf6c148 100644
--- a/R/nanonext-package.R
+++ b/R/nanonext-package.R
@@ -92,10 +92,10 @@
 #' @author Charlie Gao \email{charlie.gao@@shikokuchuo.net}
 #'     (\href{https://orcid.org/0000-0002-0750-061X}{ORCID})
 #'
+#' @importFrom later later
 #' @importFrom stats start
 #' @importFrom tools md5sum
 #' @importFrom utils .DollarNames
-#' @importFrom later later
 #' @useDynLib nanonext, .registration = TRUE
 #'
 "_PACKAGE"
diff --git a/man/request.Rd b/man/request.Rd
index dccf3fca7..61fb84056 100644
--- a/man/request.Rd
+++ b/man/request.Rd
@@ -3,6 +3,7 @@
 \name{request}
 \alias{request}
 \alias{request_signal}
+\alias{request_promise}
 \title{Request over Context (RPC Client for Req/Rep Protocol)}
 \usage{
 request(
@@ -23,6 +24,16 @@ request_signal(
     "numeric", "raw", "string"),
   timeout = NULL
 )
+
+request_promise(
+  context,
+  data,
+  cv,
+  send_mode = c("serial", "raw", "next"),
+  recv_mode = c("serial", "character", "complex", "double", "integer", "logical",
+    "numeric", "raw", "string"),
+  timeout = NULL
+)
 }
 \arguments{
 \item{context}{a Context.}
diff --git a/src/aio.c b/src/aio.c
index 6f332dbe7..2149ed139 100644
--- a/src/aio.c
+++ b/src/aio.c
@@ -196,14 +196,6 @@ static void isaio_complete(void *arg) {
 
 }
 
-static void raio_invoke_cb(void *arg) {
-  nano_aio *raio = (nano_aio *) arg;
-  SEXP callExpr;
-  PROTECT(callExpr = Rf_lcons((SEXP) raio->cb, R_NilValue));
-  (void) Rf_eval(callExpr, R_GlobalEnv);
-  UNPROTECT(1);
-}
-
 static void raio_complete(void *arg) {
 
   nano_aio *raio = (nano_aio *) arg;
@@ -219,7 +211,6 @@ static void raio_complete(void *arg) {
   raio->result = res - !res;
 #endif
 
-  later2(raio_invoke_cb, arg, 0);
 }
 
 static void raio_complete_signal(void *arg) {
@@ -239,7 +230,6 @@ static void raio_complete_signal(void *arg) {
   nng_cv_wake(cv);
   nng_mtx_unlock(mtx);
 
-  later2(raio_invoke_cb, arg, 0);
 }
 
 static void request_complete_signal(void *arg) {
@@ -262,6 +252,55 @@ static void request_complete_signal(void *arg) {
 
 }
 
+static void raio_invoke_cb(void *arg) {
+  SEXP callExpr;
+  PROTECT(callExpr = Rf_lcons((SEXP) arg, R_NilValue));
+  (void) Rf_eval(callExpr, R_GlobalEnv);
+  UNPROTECT(1);
+  R_ReleaseObject(arg);
+}
+
+static void raio_complete_cb(void *arg) {
+
+  nano_aio *raio = (nano_aio *) arg;
+  const int res = nng_aio_result(raio->aio);
+  if (res == 0)
+    raio->data = nng_aio_get_msg(raio->aio);
+
+#ifdef NANONEXT_LEGACY_NNG
+  nng_mtx_lock(shr_mtx);
+  raio->result = res - !res;
+  nng_mtx_unlock(shr_mtx);
+#else
+  raio->result = res - !res;
+#endif
+
+  later2(raio_invoke_cb, raio->cb, 0);
+
+}
+
+static void request_complete_cb(void *arg) {
+
+  nano_aio *raio = (nano_aio *) arg;
+  nano_aio *saio = (nano_aio *) raio->next;
+  nano_cv *ncv = (nano_cv *) saio->next;
+  nng_cv *cv = ncv->cv;
+  nng_mtx *mtx = ncv->mtx;
+
+  const int res = nng_aio_result(raio->aio);
+  if (res == 0)
+    raio->data = nng_aio_get_msg(raio->aio);
+
+  nng_mtx_lock(mtx);
+  raio->result = res - !res;
+  ncv->condition++;
+  nng_cv_wake(cv);
+  nng_mtx_unlock(mtx);
+
+  later2(raio_invoke_cb, raio->cb, 0);
+
+}
+
 static void iraio_complete(void *arg) {
 
   nano_aio *iaio = (nano_aio *) arg;
@@ -720,7 +759,7 @@ SEXP rnng_send_aio(SEXP con, SEXP data, SEXP mode, SEXP timeout, SEXP clo) {
 }
 
 SEXP rnng_recv_aio_impl(const SEXP con, const SEXP mode, const SEXP timeout,
-                        const SEXP bytes, const SEXP clo, const SEXP cb, nano_cv *ncv) {
+                        const SEXP bytes, const SEXP clo, nano_cv *ncv) {
 
   const nng_duration dur = timeout == R_NilValue ? NNG_DURATION_DEFAULT : (nng_duration) Rf_asInteger(timeout);
   const int signal = ncv != NULL;
@@ -736,7 +775,6 @@ SEXP rnng_recv_aio_impl(const SEXP con, const SEXP mode, const SEXP timeout,
     raio->next = ncv;
     raio->type = RECVAIO;
     raio->mode = mod;
-    raio->cb = cb;
 
     if ((xc = nng_aio_alloc(&raio->aio, signal ? raio_complete_signal : raio_complete, raio)))
       goto exitlevel1;
@@ -803,19 +841,19 @@ SEXP rnng_recv_aio_impl(const SEXP con, const SEXP mode, const SEXP timeout,
 
 }
 
-SEXP rnng_recv_aio(SEXP con, SEXP mode, SEXP timeout, SEXP bytes, SEXP clo, SEXP cb) {
+SEXP rnng_recv_aio(SEXP con, SEXP mode, SEXP timeout, SEXP bytes, SEXP clo) {
 
-  return rnng_recv_aio_impl(con, mode, timeout, bytes, clo, cb, NULL);
+  return rnng_recv_aio_impl(con, mode, timeout, bytes, clo, NULL);
 
 }
 
-SEXP rnng_recv_aio_signal(SEXP con, SEXP cvar, SEXP mode, SEXP timeout, SEXP bytes, SEXP clo, SEXP cb) {
+SEXP rnng_recv_aio_signal(SEXP con, SEXP cvar, SEXP mode, SEXP timeout, SEXP bytes, SEXP clo) {
 
   if (R_ExternalPtrTag(cvar) != nano_CvSymbol)
     Rf_error("'cv' is not a valid Condition Variable");
   nano_cv *ncv = (nano_cv *) R_ExternalPtrAddr(cvar);
 
-  return rnng_recv_aio_impl(con, mode, timeout, bytes, clo, cb, ncv);
+  return rnng_recv_aio_impl(con, mode, timeout, bytes, clo, ncv);
 
 }
 
@@ -1224,11 +1262,13 @@ SEXP rnng_ncurl_session_close(SEXP session) {
 // request ---------------------------------------------------------------------
 
 SEXP rnng_request_impl(const SEXP con, const SEXP data, const SEXP sendmode,
-                       const SEXP recvmode, const SEXP timeout, const SEXP clo, nano_cv *ncv) {
+                       const SEXP recvmode, const SEXP timeout, const SEXP clo,
+                       nano_cv *ncv, const SEXP cb) {
 
   const nng_duration dur = timeout == R_NilValue ? NNG_DURATION_DEFAULT : (nng_duration) Rf_asInteger(timeout);
   const int mod = nano_matcharg(recvmode);
   const int signal = ncv != NULL;
+  const int promises = cb != NULL;
   nng_ctx *ctx = (nng_ctx *) R_ExternalPtrAddr(con);
   SEXP aio, env, fun;
   nano_buf buf;
@@ -1267,8 +1307,15 @@ SEXP rnng_request_impl(const SEXP con, const SEXP data, const SEXP sendmode,
   raio->type = RECVAIO;
   raio->mode = mod;
   raio->next = saio;
-
-  if ((xc = nng_aio_alloc(&raio->aio, signal ? request_complete_signal : raio_complete, raio)))
+  if (promises)
+    R_PreserveObject(cb);
+  raio->cb = cb;
+
+  if ((xc = nng_aio_alloc(&raio->aio,
+                          promises ?
+                            (signal ? request_complete_cb : raio_complete_cb) :
+                            (signal ? request_complete_signal : raio_complete),
+                          raio)))
     goto exitlevel2;
 
   nng_aio_set_timeout(raio->aio, dur);
@@ -1306,7 +1353,7 @@ SEXP rnng_request(SEXP con, SEXP data, SEXP sendmode, SEXP recvmode, SEXP timeou
   if (R_ExternalPtrTag(con) != nano_ContextSymbol)
     Rf_error("'con' is not a valid Context");
 
-  return rnng_request_impl(con, data, sendmode, recvmode, timeout, clo, NULL);
+  return rnng_request_impl(con, data, sendmode, recvmode, timeout, clo, NULL, NULL);
 
 }
 
@@ -1318,7 +1365,18 @@ SEXP rnng_request_signal(SEXP con, SEXP data, SEXP cvar, SEXP sendmode, SEXP rec
     Rf_error("'cv' is not a valid Condition Variable");
   nano_cv *ncv = (nano_cv *) R_ExternalPtrAddr(cvar);
 
-  return rnng_request_impl(con, data, sendmode, recvmode, timeout, clo, ncv);
+  return rnng_request_impl(con, data, sendmode, recvmode, timeout, clo, ncv, NULL);
+
+}
+
+SEXP rnng_request_promise(SEXP con, SEXP data, SEXP cvar, SEXP sendmode, SEXP recvmode, SEXP timeout, SEXP clo, SEXP cb) {
+
+  if (R_ExternalPtrTag(con) != nano_ContextSymbol)
+    Rf_error("'con' is not a valid Context");
+
+  nano_cv *ncv = R_ExternalPtrTag(cvar) == nano_CvSymbol ? (nano_cv *) R_ExternalPtrAddr(cvar) : NULL;
+
+  return rnng_request_impl(con, data, sendmode, recvmode, timeout, clo, ncv, cb);
 
 }
 
diff --git a/src/init.c b/src/init.c
index 165b6ca6a..50c4c90da 100644
--- a/src/init.c
+++ b/src/init.c
@@ -155,9 +155,10 @@ static const R_CallMethodDef callMethods[] = {
   {"rnng_random", (DL_FUNC) &rnng_random, 2},
   {"rnng_reap", (DL_FUNC) &rnng_reap, 1},
   {"rnng_recv", (DL_FUNC) &rnng_recv, 4},
-  {"rnng_recv_aio", (DL_FUNC) &rnng_recv_aio, 6},
-  {"rnng_recv_aio_signal", (DL_FUNC) &rnng_recv_aio_signal, 7},
+  {"rnng_recv_aio", (DL_FUNC) &rnng_recv_aio, 5},
+  {"rnng_recv_aio_signal", (DL_FUNC) &rnng_recv_aio_signal, 6},
   {"rnng_request", (DL_FUNC) &rnng_request, 6},
+  {"rnng_request_promise", (DL_FUNC) &rnng_request_promise, 8},
   {"rnng_request_signal", (DL_FUNC) &rnng_request_signal, 7},
   {"rnng_send", (DL_FUNC) &rnng_send, 4},
   {"rnng_send_aio", (DL_FUNC) &rnng_send_aio, 5},
diff --git a/src/nanonext.h b/src/nanonext.h
index 24a868975..000ff9a50 100644
--- a/src/nanonext.h
+++ b/src/nanonext.h
@@ -251,9 +251,10 @@ SEXP rnng_protocol_open(SEXP, SEXP);
 SEXP rnng_random(SEXP, SEXP);
 SEXP rnng_reap(SEXP);
 SEXP rnng_recv(SEXP, SEXP, SEXP, SEXP);
-SEXP rnng_recv_aio(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
-SEXP rnng_recv_aio_signal(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
+SEXP rnng_recv_aio(SEXP, SEXP, SEXP, SEXP, SEXP);
+SEXP rnng_recv_aio_signal(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_request(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
+SEXP rnng_request_promise(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_request_signal(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_send(SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_send_aio(SEXP, SEXP, SEXP, SEXP, SEXP);

From b0533856a57529cfd7a5183b60f159f08f0366b0 Mon Sep 17 00:00:00 2001
From: shikokuchuo <53399081+shikokuchuo@users.noreply.github.com>
Date: Wed, 17 Apr 2024 15:05:57 +0100
Subject: [PATCH 05/10] R_UnwindProtect eval

---
 src/aio.c      | 13 +++++++++----
 src/core.c     |  2 +-
 src/nanonext.h |  1 +
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/aio.c b/src/aio.c
index 2149ed139..1ec1b9088 100644
--- a/src/aio.c
+++ b/src/aio.c
@@ -252,12 +252,17 @@ static void request_complete_signal(void *arg) {
 
 }
 
+static void release_object(void *data, Rboolean jump) {
+  if (jump)
+    R_ReleaseObject((SEXP) data);
+}
+
 static void raio_invoke_cb(void *arg) {
-  SEXP callExpr;
-  PROTECT(callExpr = Rf_lcons((SEXP) arg, R_NilValue));
-  (void) Rf_eval(callExpr, R_GlobalEnv);
+  SEXP call, data = (SEXP) arg;
+  PROTECT(call = Rf_lcons(data, R_NilValue));
+  (void) R_UnwindProtect(eval_safe, call, release_object, data, NULL);
   UNPROTECT(1);
-  R_ReleaseObject(arg);
+  R_ReleaseObject(data);
 }
 
 static void raio_complete_cb(void *arg) {
diff --git a/src/core.c b/src/core.c
index c6723da7b..07899210e 100644
--- a/src/core.c
+++ b/src/core.c
@@ -42,7 +42,7 @@ SEXP mk_error(const int xc) {
 
 }
 
-static SEXP eval_safe (void *call) {
+SEXP eval_safe (void *call) {
   return Rf_eval((SEXP) call, R_GlobalEnv);
 }
 
diff --git a/src/nanonext.h b/src/nanonext.h
index 000ff9a50..eac75336a 100644
--- a/src/nanonext.h
+++ b/src/nanonext.h
@@ -192,6 +192,7 @@ typedef struct nano_buf_s {
 
 SEXP mk_error(const int);
 SEXP mk_error_ncurl(const int);
+SEXP eval_safe(void *);
 nano_buf nano_char_buf(const SEXP);
 SEXP nano_decode(unsigned char *, const size_t, const int);
 void nano_encode(nano_buf *, const SEXP);

From 0af45c36c58519991ba47dea19de7629eef3f7ce Mon Sep 17 00:00:00 2001
From: shikokuchuo <53399081+shikokuchuo@users.noreply.github.com>
Date: Wed, 17 Apr 2024 15:21:36 +0100
Subject: [PATCH 06/10] add credit

---
 README.Rmd | 1 +
 README.md  | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/README.Rmd b/README.Rmd
index 381fba95f..730cd8ea3 100644
--- a/README.Rmd
+++ b/README.Rmd
@@ -169,6 +169,7 @@ We would like to acknowledge in particular:
 
 - [Garrett D'Amore](https://github.com/gdamore), author of the NNG library, for generous advice and for implementing a feature request specifically for a more efficient 'aio' implementation in `nanonext`.
 - The [R Consortium](https://www.r-consortium.org/) for funding the development of the secure TLS capabilities in the package, and [Henrik Bengtsson](https://github.com/HenrikBengtsson) and [Will Landau](https://github.com/wlandau/)'s roles in making this possible.
+- [Joe Cheng](https://github.com/jcheng5/) for prototyping the integration of `nanonext` with `later` to support the next generation of completely event-driven promises in `mirai`.
 - [R Core](https://www.r-project.org/contributors.html) for various auxiliary functions for serialisation and raw / character conversion, which have been adopted by the package.
 - [Luke Tierney](https://github.com/ltierney/) and [Mike Cheng](https://github.com/coolbutuseless) for meticulous documentation of the R serialization mechanism, which led to the package's own implementation of a low-level interface to R serialization.
 - [Jeroen Ooms](https://github.com/jeroen) - for his 'Anticonf (tm)' configure script, on which our original 'configure' was based, although much modified since.
diff --git a/README.md b/README.md
index 7533e483d..8408c6d50 100644
--- a/README.md
+++ b/README.md
@@ -221,6 +221,9 @@ We would like to acknowledge in particular:
   development of the secure TLS capabilities in the package, and [Henrik
   Bengtsson](https://github.com/HenrikBengtsson) and [Will
   Landau](https://github.com/wlandau/)’s roles in making this possible.
+- [Joe Cheng](https://github.com/jcheng5/) for prototyping the
+  integration of `nanonext` with `later` to support the next generation
+  of completely event-driven promises in `mirai`.
 - [R Core](https://www.r-project.org/contributors.html) for various
   auxiliary functions for serialisation and raw / character conversion,
   which have been adopted by the package.

From f379cb0386fadb71459bb7cc754bd6113429c6db Mon Sep 17 00:00:00 2001
From: shikokuchuo <53399081+shikokuchuo@users.noreply.github.com>
Date: Wed, 17 Apr 2024 21:57:35 +0100
Subject: [PATCH 07/10] simplify

---
 R/context.R    |  6 +-----
 src/aio.c      | 35 +++++++++++++++++++----------------
 src/init.c     |  2 +-
 src/nanonext.h |  2 +-
 4 files changed, 22 insertions(+), 23 deletions(-)

diff --git a/R/context.R b/R/context.R
index 9f3285479..525cfb6d3 100644
--- a/R/context.R
+++ b/R/context.R
@@ -280,8 +280,4 @@ request_promise <- function(context,
                             recv_mode = c("serial", "character", "complex", "double",
                                           "integer", "logical", "numeric", "raw", "string"),
                             timeout = NULL)
-  data <- .Call(rnng_request_promise, context, data, cv, send_mode, recv_mode, timeout, environment(),
-                function() {
-                  cb <- .subset2(data, "callback")
-                  if (is.function(cb)) cb(data)
-                })
+  data <- .Call(rnng_request_promise, context, data, cv, send_mode, recv_mode, timeout, environment())
diff --git a/src/aio.c b/src/aio.c
index 1ec1b9088..fa68226c2 100644
--- a/src/aio.c
+++ b/src/aio.c
@@ -258,11 +258,11 @@ static void release_object(void *data, Rboolean jump) {
 }
 
 static void raio_invoke_cb(void *arg) {
-  SEXP call, data = (SEXP) arg;
-  PROTECT(call = Rf_lcons(data, R_NilValue));
-  (void) R_UnwindProtect(eval_safe, call, release_object, data, NULL);
+  SEXP call, env = (SEXP) arg;
+  PROTECT(call = Rf_lcons(CADR(ATTRIB(env)), R_NilValue));
+  (void) R_UnwindProtect(eval_safe, call, release_object, env, NULL);
   UNPROTECT(1);
-  R_ReleaseObject(data);
+  R_ReleaseObject(env);
 }
 
 static void raio_complete_cb(void *arg) {
@@ -280,7 +280,8 @@ static void raio_complete_cb(void *arg) {
   raio->result = res - !res;
 #endif
 
-  later2(raio_invoke_cb, raio->cb, 0);
+  if (CADR(ATTRIB(raio->cb)) != R_NilValue)
+    later2(raio_invoke_cb, raio->cb, 0);
 
 }
 
@@ -302,7 +303,8 @@ static void request_complete_cb(void *arg) {
   nng_cv_wake(cv);
   nng_mtx_unlock(mtx);
 
-  later2(raio_invoke_cb, raio->cb, 0);
+  if (CADR(ATTRIB(raio->cb)) != R_NilValue)
+    later2(raio_invoke_cb, raio->cb, 0);
 
 }
 
@@ -1268,12 +1270,11 @@ SEXP rnng_ncurl_session_close(SEXP session) {
 
 SEXP rnng_request_impl(const SEXP con, const SEXP data, const SEXP sendmode,
                        const SEXP recvmode, const SEXP timeout, const SEXP clo,
-                       nano_cv *ncv, const SEXP cb) {
+                       nano_cv *ncv, const int promises) {
 
   const nng_duration dur = timeout == R_NilValue ? NNG_DURATION_DEFAULT : (nng_duration) Rf_asInteger(timeout);
   const int mod = nano_matcharg(recvmode);
   const int signal = ncv != NULL;
-  const int promises = cb != NULL;
   nng_ctx *ctx = (nng_ctx *) R_ExternalPtrAddr(con);
   SEXP aio, env, fun;
   nano_buf buf;
@@ -1309,12 +1310,14 @@ SEXP rnng_request_impl(const SEXP con, const SEXP data, const SEXP sendmode,
   nng_ctx_send(*ctx, saio->aio);
 
   raio = R_Calloc(1, nano_aio);
+  PROTECT(env = Rf_allocSExp(ENVSXP));
   raio->type = RECVAIO;
   raio->mode = mod;
   raio->next = saio;
-  if (promises)
-    R_PreserveObject(cb);
-  raio->cb = cb;
+  if (promises) {
+    R_PreserveObject(env);
+    raio->cb = env;
+  }
 
   if ((xc = nng_aio_alloc(&raio->aio,
                           promises ?
@@ -1330,7 +1333,6 @@ SEXP rnng_request_impl(const SEXP con, const SEXP data, const SEXP sendmode,
   PROTECT(aio = R_MakeExternalPtr(raio, nano_AioSymbol, R_NilValue));
   R_RegisterCFinalizerEx(aio, request_finalizer, TRUE);
 
-  PROTECT(env = Rf_allocSExp(ENVSXP));
   NANO_CLASS(env, "recvAio");
   Rf_defineVar(nano_AioSymbol, aio, env);
 
@@ -1344,6 +1346,7 @@ SEXP rnng_request_impl(const SEXP con, const SEXP data, const SEXP sendmode,
   return env;
 
   exitlevel2:
+  UNPROTECT(1);
   R_Free(raio);
   nng_aio_free(saio->aio);
   exitlevel1:
@@ -1358,7 +1361,7 @@ SEXP rnng_request(SEXP con, SEXP data, SEXP sendmode, SEXP recvmode, SEXP timeou
   if (R_ExternalPtrTag(con) != nano_ContextSymbol)
     Rf_error("'con' is not a valid Context");
 
-  return rnng_request_impl(con, data, sendmode, recvmode, timeout, clo, NULL, NULL);
+  return rnng_request_impl(con, data, sendmode, recvmode, timeout, clo, NULL, 0);
 
 }
 
@@ -1370,18 +1373,18 @@ SEXP rnng_request_signal(SEXP con, SEXP data, SEXP cvar, SEXP sendmode, SEXP rec
     Rf_error("'cv' is not a valid Condition Variable");
   nano_cv *ncv = (nano_cv *) R_ExternalPtrAddr(cvar);
 
-  return rnng_request_impl(con, data, sendmode, recvmode, timeout, clo, ncv, NULL);
+  return rnng_request_impl(con, data, sendmode, recvmode, timeout, clo, ncv, 0);
 
 }
 
-SEXP rnng_request_promise(SEXP con, SEXP data, SEXP cvar, SEXP sendmode, SEXP recvmode, SEXP timeout, SEXP clo, SEXP cb) {
+SEXP rnng_request_promise(SEXP con, SEXP data, SEXP cvar, SEXP sendmode, SEXP recvmode, SEXP timeout, SEXP clo) {
 
   if (R_ExternalPtrTag(con) != nano_ContextSymbol)
     Rf_error("'con' is not a valid Context");
 
   nano_cv *ncv = R_ExternalPtrTag(cvar) == nano_CvSymbol ? (nano_cv *) R_ExternalPtrAddr(cvar) : NULL;
 
-  return rnng_request_impl(con, data, sendmode, recvmode, timeout, clo, ncv, cb);
+  return rnng_request_impl(con, data, sendmode, recvmode, timeout, clo, ncv, 1);
 
 }
 
diff --git a/src/init.c b/src/init.c
index 50c4c90da..f13e0cf33 100644
--- a/src/init.c
+++ b/src/init.c
@@ -158,7 +158,7 @@ static const R_CallMethodDef callMethods[] = {
   {"rnng_recv_aio", (DL_FUNC) &rnng_recv_aio, 5},
   {"rnng_recv_aio_signal", (DL_FUNC) &rnng_recv_aio_signal, 6},
   {"rnng_request", (DL_FUNC) &rnng_request, 6},
-  {"rnng_request_promise", (DL_FUNC) &rnng_request_promise, 8},
+  {"rnng_request_promise", (DL_FUNC) &rnng_request_promise, 7},
   {"rnng_request_signal", (DL_FUNC) &rnng_request_signal, 7},
   {"rnng_send", (DL_FUNC) &rnng_send, 4},
   {"rnng_send_aio", (DL_FUNC) &rnng_send_aio, 5},
diff --git a/src/nanonext.h b/src/nanonext.h
index eac75336a..2a36bbfa5 100644
--- a/src/nanonext.h
+++ b/src/nanonext.h
@@ -255,7 +255,7 @@ SEXP rnng_recv(SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_recv_aio(SEXP, SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_recv_aio_signal(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_request(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
-SEXP rnng_request_promise(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
+SEXP rnng_request_promise(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_request_signal(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_send(SEXP, SEXP, SEXP, SEXP);
 SEXP rnng_send_aio(SEXP, SEXP, SEXP, SEXP, SEXP);

From 3233638e3d96e47bd188ad787eba9aea517bd46e Mon Sep 17 00:00:00 2001
From: shikokuchuo <53399081+shikokuchuo@users.noreply.github.com>
Date: Thu, 18 Apr 2024 08:59:42 +0100
Subject: [PATCH 08/10] document

---
 DESCRIPTION    |  2 +-
 NAMESPACE      |  2 +-
 NEWS.md        |  5 ++++-
 R/context.R    | 20 +++++++++++++-------
 man/request.Rd | 10 +++++++---
 5 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/DESCRIPTION b/DESCRIPTION
index 8ff2069de..6653bea49 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: nanonext
 Type: Package
 Title: NNG (Nanomsg Next Gen) Lightweight Messaging Library
-Version: 0.13.6.9000
+Version: 0.13.6.9002
 Description: R binding for NNG (Nanomsg Next Gen), a successor to ZeroMQ. NNG is
     a socket library implementing 'Scalability Protocols', a reliable,
     high-performance standard for common communications patterns including
diff --git a/NAMESPACE b/NAMESPACE
index add71dece..f66fa746b 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -75,7 +75,7 @@ export(recv_aio)
 export(recv_aio_signal)
 export(reply)
 export(request)
-export(request_promise)
+export(request2)
 export(request_signal)
 export(send)
 export(send_aio)
diff --git a/NEWS.md b/NEWS.md
index 032f74ee3..4e12142ae 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,4 +1,7 @@
-# nanonext 0.13.6 (development)
+# nanonext 0.13.6.9002 (development)
+
+* Integrates with the `later` package to provide the foundation for truly event-driven (non-polling) promises (thanks @jcheng5 for the initial prototype in #28), where side-effects are enacted asynchronously upon aio completion.
+* Adds `request2()` for creating a request that may be turned into an event-driven promise.
 
 # nanonext 0.13.6
 
diff --git a/R/context.R b/R/context.R
index 525cfb6d3..6aa92551d 100644
--- a/R/context.R
+++ b/R/context.R
@@ -270,14 +270,20 @@ request_signal <- function(context,
                            timeout = NULL)
   data <- .Call(rnng_request_signal, context, data, cv, send_mode, recv_mode, timeout, environment())
 
+#' Request2 (RPC Client for Req/Rep Protocol)
+#'
+#' \strong{request2} is the next generation request function that optionally
+#'     takes a condition variable for signalling, and supports event-driven
+#'     promises.
+#'
 #' @rdname request
 #' @export
 #'
-request_promise <- function(context,
-                            data,
-                            cv,
-                            send_mode = c("serial", "raw", "next"),
-                            recv_mode = c("serial", "character", "complex", "double",
-                                          "integer", "logical", "numeric", "raw", "string"),
-                            timeout = NULL)
+request2 <- function(context,
+                     data,
+                     cv = NULL,
+                     send_mode = c("serial", "raw", "next"),
+                     recv_mode = c("serial", "character", "complex", "double",
+                                   "integer", "logical", "numeric", "raw", "string"),
+                     timeout = NULL)
   data <- .Call(rnng_request_promise, context, data, cv, send_mode, recv_mode, timeout, environment())
diff --git a/man/request.Rd b/man/request.Rd
index 61fb84056..c1c1c475c 100644
--- a/man/request.Rd
+++ b/man/request.Rd
@@ -3,7 +3,7 @@
 \name{request}
 \alias{request}
 \alias{request_signal}
-\alias{request_promise}
+\alias{request2}
 \title{Request over Context (RPC Client for Req/Rep Protocol)}
 \usage{
 request(
@@ -25,10 +25,10 @@ request_signal(
   timeout = NULL
 )
 
-request_promise(
+request2(
   context,
   data,
-  cv,
+  cv = NULL,
   send_mode = c("serial", "raw", "next"),
   recv_mode = c("serial", "character", "complex", "double", "integer", "logical",
     "numeric", "raw", "string"),
@@ -68,6 +68,10 @@ Implements a caller/client for the req node of the req/rep protocol. Sends
 
 A signalling version of the function takes a 'conditionVariable' as an
     additional argument and signals it when the async receive is complete.
+
+\strong{request2} is the next generation request function that optionally
+    takes a condition variable for signalling, and supports event-driven
+    promises.
 }
 \details{
 Sending the request and receiving the result are both performed

From b8ed2360e13e7c32e22bb089442d3851be43a283 Mon Sep 17 00:00:00 2001
From: shikokuchuo <53399081+shikokuchuo@users.noreply.github.com>
Date: Thu, 18 Apr 2024 09:35:07 +0100
Subject: [PATCH 09/10] more efficient aio structure; remove legacy nng compat;
 requires nng >= 1.6.0

---
 DESCRIPTION    |  2 +-
 NEWS.md        |  1 +
 README.Rmd     |  2 +-
 README.md      |  2 +-
 configure      |  4 +--
 src/aio.c      | 83 ++++----------------------------------------------
 src/core.c     | 52 -------------------------------
 src/init.c     | 10 ------
 src/nanonext.h |  8 -----
 9 files changed, 12 insertions(+), 152 deletions(-)

diff --git a/DESCRIPTION b/DESCRIPTION
index 6653bea49..06c3155d5 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -26,7 +26,7 @@ License: GPL (>= 3)
 BugReports: https://github.com/shikokuchuo/nanonext/issues
 URL: https://shikokuchuo.net/nanonext/, https://github.com/shikokuchuo/nanonext/
 Encoding: UTF-8
-SystemRequirements: 'libnng' >= 1.5 and 'libmbedtls' >= 2.5, or 'cmake' to
+SystemRequirements: 'libnng' >= 1.6 and 'libmbedtls' >= 2.5, or 'cmake' to
     compile NNG and/or Mbed TLS included in package sources
 Depends: 
     R (>= 3.5)
diff --git a/NEWS.md b/NEWS.md
index 4e12142ae..817704246 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -2,6 +2,7 @@
 
 * Integrates with the `later` package to provide the foundation for truly event-driven (non-polling) promises (thanks @jcheng5 for the initial prototype in #28), where side-effects are enacted asynchronously upon aio completion.
 * Adds `request2()` for creating a request that may be turned into an event-driven promise.
+* Updates minimum 'libnng' version requirement to v1.6.0 (if a suitable system-installed version is not found, the bundled version is compiled from source).
 
 # nanonext 0.13.6
 
diff --git a/README.Rmd b/README.Rmd
index 730cd8ea3..55312b09c 100644
--- a/README.Rmd
+++ b/README.Rmd
@@ -149,7 +149,7 @@ vignette("nanonext", package = "nanonext")
 
 #### Linux / Mac / Solaris
 
-Installation from source requires 'libnng' >= v1.5.0 and 'libmbedtls' >= 2.5.0 (suitable installations are automatically detected), or else 'cmake' to compile 'libnng' v1.7.3 and 'libmbedtls' v3.6.0 LTS included within the package sources.
+Installation from source requires 'libnng' >= v1.6.0 and 'libmbedtls' >= 2.5.0 (suitable installations are automatically detected), or else 'cmake' to compile 'libnng' v1.7.3 and 'libmbedtls' v3.6.0 LTS included within the package sources.
 
 **It is recommended for optimal performance and stability to let the package automatically compile bundled versions of 'libmbedtls' and 'libnng' during installation.** To ensure the libraries are compiled from source even if system installations are present, set the `NANONEXT_LIBS` environment variable prior to installation e.g. by `Sys.setenv(NANONEXT_LIBS = 1)`.
 
diff --git a/README.md b/README.md
index 8408c6d50..995103e9f 100644
--- a/README.md
+++ b/README.md
@@ -178,7 +178,7 @@ vignette("nanonext", package = "nanonext")
 
 #### Linux / Mac / Solaris
 
-Installation from source requires ‘libnng’ \>= v1.5.0 and ‘libmbedtls’
+Installation from source requires ‘libnng’ \>= v1.6.0 and ‘libmbedtls’
 \>= 2.5.0 (suitable installations are automatically detected), or else
 ‘cmake’ to compile ‘libnng’ v1.7.3 and ‘libmbedtls’ v3.6.0 LTS included
 within the package sources.
diff --git a/configure b/configure
index 88a9e1be4..5c8ab0809 100755
--- a/configure
+++ b/configure
@@ -128,7 +128,7 @@ fi
 
 echo "#include <nng/nng.h>
 int main() {
-#if NNG_MAJOR_VERSION < 1 || NNG_MAJOR_VERSION == 1 && NNG_MINOR_VERSION < 5
+#if NNG_MAJOR_VERSION < 1 || NNG_MAJOR_VERSION == 1 && NNG_MINOR_VERSION < 6
     *(void *) 0 = 0;
 #endif
 }" | ${CC} ${NNG_CFLAGS} -xc - -o /dev/null > /dev/null 2>&1
@@ -140,7 +140,7 @@ fi
 
 if [ $? -ne 0 ]
 then
-  echo "No existing 'libnng' >= 1.5 found"
+  echo "No existing 'libnng' >= 1.6 found"
   echo "Detecting 'cmake'..."
   which cmake
   if [ $? -ne 0 ]
diff --git a/src/aio.c b/src/aio.c
index fa68226c2..d86e96adf 100644
--- a/src/aio.c
+++ b/src/aio.c
@@ -160,14 +160,7 @@ static void saio_complete(void *arg) {
   const int res = nng_aio_result(saio->aio);
   if (res)
     nng_msg_free(nng_aio_get_msg(saio->aio));
-
-#ifdef NANONEXT_LEGACY_NNG
-  nng_mtx_lock(shr_mtx);
-  saio->result = res - !res;
-  nng_mtx_unlock(shr_mtx);
-#else
   saio->result = res - !res;
-#endif
 
 }
 
@@ -185,14 +178,7 @@ static void isaio_complete(void *arg) {
   const int res = nng_aio_result(iaio->aio);
   if (iaio->data != NULL)
     R_Free(iaio->data);
-
-#ifdef NANONEXT_LEGACY_NNG
-  nng_mtx_lock(shr_mtx);
   iaio->result = res - !res;
-  nng_mtx_unlock(shr_mtx);
-#else
-  iaio->result = res - !res;
-#endif
 
 }
 
@@ -203,13 +189,7 @@ static void raio_complete(void *arg) {
   if (res == 0)
     raio->data = nng_aio_get_msg(raio->aio);
 
-#ifdef NANONEXT_LEGACY_NNG
-  nng_mtx_lock(shr_mtx);
-  raio->result = res - !res;
-  nng_mtx_unlock(shr_mtx);
-#else
   raio->result = res - !res;
-#endif
 
 }
 
@@ -271,17 +251,11 @@ static void raio_complete_cb(void *arg) {
   const int res = nng_aio_result(raio->aio);
   if (res == 0)
     raio->data = nng_aio_get_msg(raio->aio);
-
-#ifdef NANONEXT_LEGACY_NNG
-  nng_mtx_lock(shr_mtx);
   raio->result = res - !res;
-  nng_mtx_unlock(shr_mtx);
-#else
-  raio->result = res - !res;
-#endif
 
-  if (CADR(ATTRIB(raio->cb)) != R_NilValue)
-    later2(raio_invoke_cb, raio->cb, 0);
+  nano_aio *saio = (nano_aio *) raio->next;
+  if (CADR(ATTRIB((SEXP) saio->data)) != R_NilValue)
+    later2(raio_invoke_cb, saio->data, 0);
 
 }
 
@@ -303,8 +277,8 @@ static void request_complete_cb(void *arg) {
   nng_cv_wake(cv);
   nng_mtx_unlock(mtx);
 
-  if (CADR(ATTRIB(raio->cb)) != R_NilValue)
-    later2(raio_invoke_cb, raio->cb, 0);
+  if (CADR(ATTRIB((SEXP) saio->data)) != R_NilValue)
+    later2(raio_invoke_cb, saio->data, 0);
 
 }
 
@@ -312,14 +286,7 @@ static void iraio_complete(void *arg) {
 
   nano_aio *iaio = (nano_aio *) arg;
   const int res = nng_aio_result(iaio->aio);
-
-#ifdef NANONEXT_LEGACY_NNG
-  nng_mtx_lock(shr_mtx);
-  iaio->result = res - !res;
-  nng_mtx_unlock(shr_mtx);
-#else
   iaio->result = res - !res;
-#endif
 
 }
 
@@ -367,9 +334,6 @@ static void request_finalizer(SEXP xptr) {
   if (R_ExternalPtrAddr(xptr) == NULL) return;
   nano_aio *xp = (nano_aio *) R_ExternalPtrAddr(xptr);
   nano_aio *saio = (nano_aio *) xp->next;
-#ifdef NANONEXT_LEGACY_NNG
-  nng_ctx_close(*(nng_ctx *) saio->data);
-#endif
   nng_aio_free(saio->aio);
   nng_aio_free(xp->aio);
   if (xp->data != NULL)
@@ -447,15 +411,7 @@ SEXP rnng_aio_result(SEXP env) {
 
   nano_aio *saio = (nano_aio *) R_ExternalPtrAddr(aio);
 
-#ifdef NANONEXT_LEGACY_NNG
-  int res;
-  nng_mtx_lock(shr_mtx);
-  res = saio->result;
-  nng_mtx_unlock(shr_mtx);
-  if (res == 0)
-#else
   if (nng_aio_busy(saio->aio))
-#endif
     return nano_unresolved;
 
   if (saio->result > 0)
@@ -479,15 +435,7 @@ SEXP rnng_aio_get_msg(SEXP env) {
 
   nano_aio *raio = (nano_aio *) R_ExternalPtrAddr(aio);
 
-#ifdef NANONEXT_LEGACY_NNG
-  int res;
-  nng_mtx_lock(shr_mtx);
-  res = raio->result;
-  nng_mtx_unlock(shr_mtx);
-  if (res == 0)
-#else
   if (nng_aio_busy(raio->aio))
-#endif
     return nano_unresolved;
 
   if (raio->result > 0)
@@ -652,15 +600,7 @@ SEXP rnng_unresolved2(SEXP aio) {
 
   nano_aio *aiop = (nano_aio *) R_ExternalPtrAddr(coreaio);
 
-#ifdef NANONEXT_LEGACY_NNG
-  int res;
-  nng_mtx_lock(shr_mtx);
-  res = aiop->result;
-  nng_mtx_unlock(shr_mtx);
-  return Rf_ScalarLogical(!res);
-#else
   return Rf_ScalarLogical(nng_aio_busy(aiop->aio));
-#endif
 
 }
 
@@ -1004,15 +944,7 @@ SEXP rnng_aio_http(SEXP env, SEXP response, SEXP type) {
 
   nano_aio *haio = (nano_aio *) R_ExternalPtrAddr(aio);
 
-#ifdef NANONEXT_LEGACY_NNG
-  int res;
-  nng_mtx_lock(shr_mtx);
-  res = haio->result;
-  nng_mtx_unlock(shr_mtx);
-  if (res == 0)
-#else
   if (nng_aio_busy(haio->aio))
-#endif
     return nano_unresolved;
 
   if (haio->result > 0)
@@ -1292,9 +1224,6 @@ SEXP rnng_request_impl(const SEXP con, const SEXP data, const SEXP sendmode,
   }
 
   saio = R_Calloc(1, nano_aio);
-#ifdef NANONEXT_LEGACY_NNG
-  saio->data = ctx;
-#endif
   saio->next = ncv;
 
   if ((xc = nng_msg_alloc(&msg, 0)))
@@ -1316,7 +1245,7 @@ SEXP rnng_request_impl(const SEXP con, const SEXP data, const SEXP sendmode,
   raio->next = saio;
   if (promises) {
     R_PreserveObject(env);
-    raio->cb = env;
+    saio->data = env;
   }
 
   if ((xc = nng_aio_alloc(&raio->aio,
diff --git a/src/core.c b/src/core.c
index 07899210e..81d053e92 100644
--- a/src/core.c
+++ b/src/core.c
@@ -982,30 +982,6 @@ SEXP rnng_send(SEXP con, SEXP data, SEXP mode, SEXP block) {
     nng_ctx *ctxp = (nng_ctx *) R_ExternalPtrAddr(con);
     nng_msg *msgp;
 
-#ifdef NANONEXT_LEGACY_NNG
-
-    nng_aio *aiop;
-
-    if ((xc = nng_msg_alloc(&msgp, 0)))
-      goto exitlevel1;
-
-    if ((xc = nng_msg_append(msgp, buf.buf, buf.cur)) ||
-        (xc = nng_aio_alloc(&aiop, NULL, NULL))) {
-      nng_msg_free(msgp);
-      goto exitlevel1;
-    }
-
-    nng_aio_set_msg(aiop, msgp);
-    nng_aio_set_timeout(aiop, flags < 0 ? 0 : flags > 0 ? flags : (*NANO_INTEGER(block) == 1) * NNG_DURATION_DEFAULT);
-    nng_ctx_send(*ctxp, aiop);
-    NANO_FREE(buf);
-    nng_aio_wait(aiop);
-    if ((xc = nng_aio_result(aiop)))
-      nng_msg_free(nng_aio_get_msg(aiop));
-    nng_aio_free(aiop);
-
-#else
-
     if (flags <= 0) {
 
       if ((xc = nng_msg_alloc(&msgp, 0)))
@@ -1043,8 +1019,6 @@ SEXP rnng_send(SEXP con, SEXP data, SEXP mode, SEXP block) {
 
     }
 
-#endif
-
   } else if (ptrtag == nano_StreamSymbol) {
 
     nano_encode(&buf, data);
@@ -1136,30 +1110,6 @@ SEXP rnng_recv(SEXP con, SEXP mode, SEXP block, SEXP bytes) {
     nng_ctx *ctxp = (nng_ctx *) R_ExternalPtrAddr(con);
     nng_msg *msgp;
 
-#ifdef NANONEXT_LEGACY_NNG
-
-    nng_aio *aiop;
-
-    if ((xc = nng_aio_alloc(&aiop, NULL, NULL)))
-      goto exitlevel1;
-    nng_aio_set_timeout(aiop, flags < 0 ? 0 : flags > 0 ? flags : (*NANO_INTEGER(block) == 1) * NNG_DURATION_DEFAULT);
-    nng_ctx_recv(*ctxp, aiop);
-
-    nng_aio_wait(aiop);
-    if ((xc = nng_aio_result(aiop))) {
-      nng_aio_free(aiop);
-      goto exitlevel1;
-    }
-
-    msgp = nng_aio_get_msg(aiop);
-    nng_aio_free(aiop);
-    buf = nng_msg_body(msgp);
-    sz = nng_msg_len(msgp);
-    res = nano_decode(buf, sz, mod);
-    nng_msg_free(msgp);
-
-#else
-
     if (flags <= 0) {
 
       xc = nng_ctx_recvmsg(*ctxp, &msgp, (flags < 0 || *NANO_INTEGER(block) != 1) * NNG_FLAG_NONBLOCK);
@@ -1195,8 +1145,6 @@ SEXP rnng_recv(SEXP con, SEXP mode, SEXP block, SEXP bytes) {
 
     }
 
-#endif
-
   } else if (ptrtag == nano_StreamSymbol) {
 
     mod = nano_matchargs(mode);
diff --git a/src/init.c b/src/init.c
index f13e0cf33..b2d4c26c0 100644
--- a/src/init.c
+++ b/src/init.c
@@ -50,10 +50,6 @@ SEXP nano_refHook;
 SEXP nano_success;
 SEXP nano_unresolved;
 
-#ifdef NANONEXT_LEGACY_NNG
-nng_mtx *shr_mtx;
-#endif
-
 static void RegisterSymbols(void) {
   nano_AioSymbol = Rf_install("aio");
   nano_ContextSymbol = Rf_install("context");
@@ -193,9 +189,6 @@ static const R_ExternalMethodDef externalMethods[] = {
 void attribute_visible R_init_nanonext(DllInfo* dll) {
   RegisterSymbols();
   PreserveObjects();
-#ifdef NANONEXT_LEGACY_NNG
-  nng_mtx_alloc(&shr_mtx);
-#endif
   R_registerRoutines(dll, NULL, callMethods, NULL, externalMethods);
   R_useDynamicSymbols(dll, FALSE);
   R_forceSymbols(dll, TRUE);
@@ -203,7 +196,4 @@ void attribute_visible R_init_nanonext(DllInfo* dll) {
 
 void attribute_visible R_unload_nanonext(DllInfo *info) {
   ReleaseObjects();
-#ifdef NANONEXT_LEGACY_NNG
-  nng_mtx_free(shr_mtx);
-#endif
 }
diff --git a/src/nanonext.h b/src/nanonext.h
index 2a36bbfa5..f0abad23d 100644
--- a/src/nanonext.h
+++ b/src/nanonext.h
@@ -21,10 +21,6 @@
 
 #include <nng/nng.h>
 
-#if NNG_MAJOR_VERSION == 1 && NNG_MINOR_VERSION < 6
-#define NANONEXT_LEGACY_NNG
-#endif
-
 #ifdef NANONEXT_PROTOCOLS
 #include <nng/protocol/bus0/bus.h>
 #include <nng/protocol/pair0/pair.h>
@@ -45,9 +41,6 @@
 #ifdef NANONEXT_SUPPLEMENTALS
 #include <nng/supplemental/tls/tls.h>
 #include <nng/supplemental/util/platform.h>
-#ifdef NANONEXT_LEGACY_NNG
-extern nng_mtx *shr_mtx;
-#endif
 
 typedef struct nano_listener_s {
   nng_listener list;
@@ -88,7 +81,6 @@ typedef struct nano_aio_s {
   int result;
   void *data;
   void *next;
-  void *cb;
 } nano_aio;
 
 typedef struct nano_cv_s {

From e8226fbec713340860e485c18064bc81ffa52f4f Mon Sep 17 00:00:00 2001
From: shikokuchuo <53399081+shikokuchuo@users.noreply.github.com>
Date: Thu, 18 Apr 2024 10:06:03 +0100
Subject: [PATCH 10/10] safer and more efficient to release cb object in
 request finalizer

---
 NEWS.md        |  5 +++++
 src/aio.c      | 24 +++++++++++-------------
 src/core.c     |  5 +++--
 src/nanonext.h |  1 -
 4 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/NEWS.md b/NEWS.md
index 817704246..4aeb74dd6 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,7 +1,12 @@
 # nanonext 0.13.6.9002 (development)
 
+#### New Features
+
 * Integrates with the `later` package to provide the foundation for truly event-driven (non-polling) promises (thanks @jcheng5 for the initial prototype in #28), where side-effects are enacted asynchronously upon aio completion.
 * Adds `request2()` for creating a request that may be turned into an event-driven promise.
+
+#### Updates
+
 * Updates minimum 'libnng' version requirement to v1.6.0 (if a suitable system-installed version is not found, the bundled version is compiled from source).
 
 # nanonext 0.13.6
diff --git a/src/aio.c b/src/aio.c
index d86e96adf..d8dc8b2a1 100644
--- a/src/aio.c
+++ b/src/aio.c
@@ -232,17 +232,11 @@ static void request_complete_signal(void *arg) {
 
 }
 
-static void release_object(void *data, Rboolean jump) {
-  if (jump)
-    R_ReleaseObject((SEXP) data);
-}
-
 static void raio_invoke_cb(void *arg) {
-  SEXP call, env = (SEXP) arg;
-  PROTECT(call = Rf_lcons(CADR(ATTRIB(env)), R_NilValue));
-  (void) R_UnwindProtect(eval_safe, call, release_object, env, NULL);
+  SEXP call, cb = (SEXP) arg;
+  PROTECT(call = Rf_lcons(cb, R_NilValue));
+  (void) Rf_eval(call, R_GlobalEnv);
   UNPROTECT(1);
-  R_ReleaseObject(env);
 }
 
 static void raio_complete_cb(void *arg) {
@@ -254,8 +248,9 @@ static void raio_complete_cb(void *arg) {
   raio->result = res - !res;
 
   nano_aio *saio = (nano_aio *) raio->next;
-  if (CADR(ATTRIB((SEXP) saio->data)) != R_NilValue)
-    later2(raio_invoke_cb, saio->data, 0);
+  SEXP ax = CADR(ATTRIB((SEXP) saio->data));
+  if (ax != R_NilValue)
+    later2(raio_invoke_cb, ax, 0);
 
 }
 
@@ -277,8 +272,9 @@ static void request_complete_cb(void *arg) {
   nng_cv_wake(cv);
   nng_mtx_unlock(mtx);
 
-  if (CADR(ATTRIB((SEXP) saio->data)) != R_NilValue)
-    later2(raio_invoke_cb, saio->data, 0);
+  SEXP ax = CADR(ATTRIB((SEXP) saio->data));
+  if (ax != R_NilValue)
+    later2(raio_invoke_cb, ax, 0);
 
 }
 
@@ -338,6 +334,8 @@ static void request_finalizer(SEXP xptr) {
   nng_aio_free(xp->aio);
   if (xp->data != NULL)
     nng_msg_free((nng_msg *) xp->data);
+  if (saio->data != NULL)
+    R_ReleaseObject((SEXP) saio->data);
   R_Free(saio);
   R_Free(xp);
 
diff --git a/src/core.c b/src/core.c
index 81d053e92..73d44abcb 100644
--- a/src/core.c
+++ b/src/core.c
@@ -42,12 +42,13 @@ SEXP mk_error(const int xc) {
 
 }
 
-SEXP eval_safe (void *call) {
+static SEXP eval_safe (void *call) {
   return Rf_eval((SEXP) call, R_GlobalEnv);
 }
 
 static void rl_reset(void *data, Rboolean jump) {
-  if (jump && data == NULL)
+  (void) data;
+  if (jump)
     SET_TAG(nano_refHook, R_NilValue);
 }
 
diff --git a/src/nanonext.h b/src/nanonext.h
index f0abad23d..566ac8028 100644
--- a/src/nanonext.h
+++ b/src/nanonext.h
@@ -184,7 +184,6 @@ typedef struct nano_buf_s {
 
 SEXP mk_error(const int);
 SEXP mk_error_ncurl(const int);
-SEXP eval_safe(void *);
 nano_buf nano_char_buf(const SEXP);
 SEXP nano_decode(unsigned char *, const size_t, const int);
 void nano_encode(nano_buf *, const SEXP);