nse/client: Allow disconnecting.

* gnu/gnunet/nse/client.scm
  (<server>)[request-close-condition]: New field
  (disconnect!): New procedure.
  (reconnect): Add 'request-close-condition' argument.
  (reconnect)[request-close-handler]: New procedure.
  (reconnect): Spawn 'request-close-handler'.
  (connect)[request-close-condition]: New variable.
  (connect): Use new variable.
* tests/utils.scm: Export 'call-with-temporary-directory'.
* tests/network-size.scm
  ("close, not connected --> all fibers stop, no callbacks called"):
  New test.

1 files changed, 32 insertions, 9 deletions

diff --git a/gnu/gnunet/nse/client.scm b/gnu/gnunet/nse/client.scm
index f19f06c..92e8d77 100644
--- a/gnu/gnunet/nse/client.scm
+++ b/gnu/gnunet/nse/client.scm
@@ -32,7 +32,7 @@
           estimate:timestamp
           server?
           connect
-          ;; TODO: disconnect
+          disconnect!
           estimate)
   (import (only (rnrs base)
                 begin define quote lambda case values expt = else apply)
@@ -45,7 +45,9 @@
           (only (fibers)
                 spawn-fiber)
           (only (fibers conditions)
-                make-condition wait signal-condition!)
+                make-condition wait wait-operation signal-condition!)
+          (only (fibers operations)
+                choice-operation perform-operation)
           (only (gnu extractor enum)
                 symbol-value value->index)
           (only (guile)
@@ -60,7 +62,7 @@
                 message-handler
                 message-handlers)
           (only (gnu gnunet mq)
-                send-message!)
+                send-message! close-queue!)
           (only (gnu gnunet mq-impl stream)
                 connect/fibers)
           (gnu gnunet message protocols)
@@ -76,7 +78,9 @@
       (opaque #t))
 
     (define-record-type (<server> %make-server server?)
-      (fields (immutable estimate/box server-estimate/box))) ; atomic box of flonum
+      (fields (immutable estimate/box server-estimate/box) ; atomic box of flonum
+              (immutable request-close-condition
+                         server-request-close-condition)))
 
     (define (estimate server)
       "Return the current estimate of the number of peers on the network,
@@ -114,8 +118,14 @@ Maybe +inf.0 as well?"
 timestamp."
       (%estimate:timestamp estimate))
 
+    (define (disconnect! server)
+      "Asynchronuously disconnect from the NSE server and stop reconnecting,
+even if not connected.  This is an idempotent operation."
+      (signal-condition! (server-request-close-condition server)))
+
     ;; See 'connect'.
-    (define* (reconnect estimate/box config #:key updated connected disconnected
+    (define* (reconnect estimate/box request-close-condition config #:key
+                        updated connected disconnected
                         (spawn spawn-fiber) #:rest rest)
       (define (handle-estimate! estimate-slice)
         (define estimate
@@ -144,6 +154,7 @@ timestamp."
                (value->index (symbol-value message-type msg:nse:start)))
         (send-message! mq s))
       (define mq-defined (make-condition))
+      (define mq-closed (make-condition))
       (define (error-handler error)
         (case error
           ;; TODO report input errors?
@@ -161,11 +172,22 @@ timestamp."
            ;; it is possible that 'connected' is called twice without
            ;; a call to 'disconnected' in-between, which would presumably
            ;; be confusing.
+           (signal-condition! mq-closed)
            (when disconnected (disconnected))
-           (apply reconnect estimate/box config rest))))
+           (apply reconnect estimate/box request-close-condition config rest))))
+      ;; Only started after 'mq' is defined, so no need to wait for
+      ;; 'mq-defined'.
+      (define (request-close-handler)
+        (perform-operation
+         (choice-operation
+          (wait-operation request-close-condition)
+          ;; Make sure the fiber exits after a reconnect.
+          (wait-operation mq-closed)))
+        (close-queue! mq))
       (define mq (connect/fibers config "nse" handlers error-handler
                                  #:spawn spawn))
-      (signal-condition! mq-defined))
+      (signal-condition! mq-defined)
+      (spawn-fiber request-close-handler))
 
     (define* (connect config #:key updated connected disconnected
                       (spawn spawn-fiber) #:rest rest)
@@ -181,5 +203,6 @@ shortly after calling @var{disconnected}.
 
 The procedures @var{updated}, @var{connected} and @var{disconnected} are optional."
       (define estimate/box (make-atomic-box #f))
-      (apply reconnect estimate/box config rest)
-      (%make-server estimate/box))))
+      (define request-close-condition (make-condition))
+      (apply reconnect estimate/box request-close-condition config rest)
+      (%make-server estimate/box request-close-condition))))