From 35af40d8508b37ae00a35d1d8bc370f2a91dd530 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Mon, 3 Sep 2018 09:03:18 -0600
Subject: [PATCH] cs & thread: move places API to the thread layer

The Rumble layer provides a primitive `fork-place` operation and
`start-place` hook to tie in place initialization from other layers
(especially "io"), but the rest can live in the "thread" layer,
especially to handle place-channel synchronization.
---
 racket/src/cs/main.sps                        |   3 +-
 racket/src/cs/primitive/internal.ss           |   2 +
 racket/src/cs/rumble.sls                      |   8 +-
 racket/src/cs/rumble/place.ss                 |  41 +-----
 racket/src/cs/thread.sls                      |  18 ++-
 .../src/expander/compile/built-in-symbol.rkt  |  30 ++--
 racket/src/thread/atomic.rkt                  |   4 +-
 racket/src/thread/bootstrap.rkt               |  29 +++-
 racket/src/thread/continuation-mark.rkt       |   2 +-
 racket/src/thread/custodian.rkt               |   4 +-
 racket/src/thread/demo.rkt                    |   6 +
 racket/src/thread/future.rkt                  |   4 +-
 racket/src/thread/{engine.rkt => host.rkt}    |   8 +-
 racket/src/thread/main.rkt                    |  19 +++
 racket/src/thread/nested-thread.rkt           |   2 +-
 racket/src/thread/os-thread.rkt               |   2 +-
 racket/src/thread/parameter.rkt               |   2 +-
 racket/src/thread/place-local.rkt             |  20 +++
 racket/src/thread/place.rkt                   | 130 ++++++++++++++++++
 racket/src/thread/sandman.rkt                 |   2 +-
 racket/src/thread/schedule.rkt                |   4 +-
 racket/src/thread/thread-group.rkt            |   2 +-
 racket/src/thread/thread.rkt                  |   6 +-
 racket/src/thread/time.rkt                    |   4 +-
 racket/src/thread/will-executor.rkt           |   2 +-
 25 files changed, 272 insertions(+), 82 deletions(-)
 rename racket/src/thread/{engine.rkt => host.rkt} (93%)
 create mode 100644 racket/src/thread/place-local.rkt
 create mode 100644 racket/src/thread/place.rkt

diff --git a/racket/src/cs/main.sps b/racket/src/cs/main.sps
index 2b0815a36d..2c86e6a6db 100644
--- a/racket/src/cs/main.sps
+++ b/racket/src/cs/main.sps
@@ -488,7 +488,8 @@
       (regexp-place-init!)
       (expander-place-init!)
       (initialize-place!)
-      (dynamic-require mod sym)))
+      (lambda ()
+        (dynamic-require mod sym))))
 
    (when (getenv "PLT_STATS_ON_BREAK")
      (keyboard-interrupt-handler
diff --git a/racket/src/cs/primitive/internal.ss b/racket/src/cs/primitive/internal.ss
index c245c01a33..0243e6efbf 100644
--- a/racket/src/cs/primitive/internal.ss
+++ b/racket/src/cs/primitive/internal.ss
@@ -29,4 +29,6 @@
   [record-mutator (known-constant)]
   [unsafe-struct? (known-constant)]
 
+  [fork-place (known-procedure 1)]
+  [start-place (known-procedure 32)]
   [make-pthread-parameter (known-procedure 2)])
diff --git a/racket/src/cs/rumble.sls b/racket/src/cs/rumble.sls
index 0b2116b7b4..b7e2751d5d 100644
--- a/racket/src/cs/rumble.sls
+++ b/racket/src/cs/rumble.sls
@@ -570,12 +570,10 @@
           unsafe-extflvector-length unsafe-extflvector-ref unsafe-extflvector-set!
 
           install-start-place!       ; not exported to Racket
-          place-enabled? place? place-channel? place-break
-          place-channel-get place-channel-put place-sleep
-          place-channel place-dead-evt place-kill place-message-allowed?
-          dynamic-place place-wait place-pumper-threads place-shared?
+          fork-place                 ; not exported to Racket
+          start-place                ; not exported to Racket
+          place-enabled?
           unsafe-get-place-table
-          unsafe-add-post-custodian-shutdown
           unsafe-make-place-local unsafe-place-local-ref unsafe-place-local-set!
           place-local-register-ref   ; not exported to Racket
           place-local-register-set!  ; not exported to Racket
diff --git a/racket/src/cs/rumble/place.ss b/racket/src/cs/rumble/place.ss
index 455b08a9c6..4fffecf9b9 100644
--- a/racket/src/cs/rumble/place.ss
+++ b/racket/src/cs/rumble/place.ss
@@ -54,8 +54,6 @@
 
 ;; ----------------------------------------
 
-(define-record place (thread))
-
 (meta-cond
  [(threaded?)
   (define (place-enabled?) #f) ;; FIXME
@@ -68,40 +66,9 @@
   (define (place-enabled?) #f)
   (define (fork-place thunk) #f)])
 
-(define start-place void)
+(define do-start-place void)
 (define (install-start-place! proc)
-  (set! start-place proc))
+  (set! do-start-place proc))
 
-(define (dynamic-place path sym in out err)
-  (make-place
-   (fork-place (lambda ()
-                 (start-place path sym in out err)))))
-
-(define (place-channel? v)
-  #f)
-
-(define-syntax define-place-not-yet-available
-  (syntax-rules ()
-    [(_ id)
-     (define (id . args)
-       (error 'id "place API not yet supported"))]
-    [(_ id ...)
-     (begin (define-place-not-yet-available id) ...)]))
-
-;; This operation adds shutdown thunks to a non-main place, so it's a
-;; no-op for now:
-(define (unsafe-add-post-custodian-shutdown proc)
-  (void))
-
-(define-place-not-yet-available
-  place-break
-  place-channel-get
-  place-channel-put
-  place-sleep
-  place-channel
-  place-dead-evt
-  place-kill
-  place-message-allowed?
-  place-wait
-  place-pumper-threads
-  place-shared?)
+(define (start-place path sym in out err)
+  (do-start-place path sym in out err))
diff --git a/racket/src/cs/thread.sls b/racket/src/cs/thread.sls
index 8bfdf340f9..89d610bdec 100644
--- a/racket/src/cs/thread.sls
+++ b/racket/src/cs/thread.sls
@@ -26,6 +26,8 @@
                   [mutex-acquire rumble:mutex-acquire]
                   [mutex-release rumble:mutex-release]
                   [pthread? rumble:thread?]
+                  [fork-place rumble:fork-place]
+                  [start-place rumble:start-place]
                   [fork-pthread rumble:fork-thread]
                   [threaded? rumble:threaded?]
                   [get-thread-id rumble:get-thread-id]
@@ -39,7 +41,8 @@
   ;; Special handling of `current-atomic`: use the last virtual register;
   ;; we rely on the fact that the register's default value is 0.
   (define-syntax (define stx)
-    (syntax-case stx (current-atomic make-pthread-parameter)
+    (syntax-case stx (current-atomic make-pthread-parameter unsafe-make-place-local)
+      ;; Recognize definition of `current-atomic`:
       [(_ current-atomic (make-pthread-parameter 0))
        (with-syntax ([(_ id _) stx]
                      [n (datum->syntax #'here (sub1 (virtual-register-count)))])
@@ -47,6 +50,9 @@
              (syntax-rules ()
                [(_) (virtual-register n)]
                [(_ v) (set-virtual-register! n v)])))]
+      ;; Workaround for redirected access of `unsafe-make-place-local` from engine:
+      [(_ alias-id unsafe-make-place-local) #'(begin)]
+      ;; Chain to place-register handling:
       [(_ . rest) #'(place:define . rest)]))
 
   (define (exit n)
@@ -67,7 +73,13 @@
        ;; expander, and they need to be listed in
        ;; "primitives/internal.ss".
        (hash
-        'make-pthread-parameter make-pthread-parameter)]
+        'make-pthread-parameter make-pthread-parameter
+        ;; These are actually redirected by "place-register.ss", but
+        ;; we list them here for compatibility with the bootstrapping
+        ;; variant of `#%pthread`
+        'unsafe-make-place-local rumble:unsafe-make-place-local
+        'unsafe-place-local-ref rumble:unsafe-place-local-ref
+        'unsafe-place-local-set! rumble:unsafe-place-local-set!)]
       [(|#%engine|)
        (hash
         'make-engine rumble:make-engine
@@ -93,6 +105,8 @@
         'poll-async-callbacks poll-async-callbacks
         'disable-interrupts disable-interrupts
         'enable-interrupts enable-interrupts
+        'fork-place rumble:fork-place
+        'start-place rumble:start-place
         'fork-pthread rumble:fork-thread
         'pthread? rumble:thread?
         'get-thread-id rumble:get-thread-id
diff --git a/racket/src/expander/compile/built-in-symbol.rkt b/racket/src/expander/compile/built-in-symbol.rkt
index 6821d2d35e..a26a7a1fa0 100644
--- a/racket/src/expander/compile/built-in-symbol.rkt
+++ b/racket/src/expander/compile/built-in-symbol.rkt
@@ -48,18 +48,18 @@
 
    ;; Linklet compilation on Chez Scheme 
    (for-each register-built-in-symbol!
-             '(let
-                  letrec*
-                define
-                or
-                and
-                pariah
-                variable-set!
-                variable-ref
-                variable-ref/no-check
-                make-instance-variable-reference
-                annotation?
-                annotation-expression
-                #%app
-                #%call-with-values
-                make-pthread-parameter))))
+             '(or
+               and
+               let
+               letrec*
+               define
+               pariah
+               variable-set!
+               variable-ref
+               variable-ref/no-check
+               make-instance-variable-reference
+               annotation?
+               annotation-expression
+               #%app
+               #%call-with-values
+               make-pthread-parameter))))
diff --git a/racket/src/thread/atomic.rkt b/racket/src/thread/atomic.rkt
index 9dc2ee15a5..c24b395ddd 100644
--- a/racket/src/thread/atomic.rkt
+++ b/racket/src/thread/atomic.rkt
@@ -1,6 +1,6 @@
 #lang racket/base
-(require racket/private/place-local
-         "engine.rkt"
+(require "host.rkt"
+         "place-local.rkt"
          "internal-error.rkt"
          "debug.rkt")
 
diff --git a/racket/src/thread/bootstrap.rkt b/racket/src/thread/bootstrap.rkt
index dfd95ad157..34742d4620 100644
--- a/racket/src/thread/bootstrap.rkt
+++ b/racket/src/thread/bootstrap.rkt
@@ -140,9 +140,34 @@
     [() x]
     [(v) (set! x v)]))
 
+(define place-local-table (make-thread-cell (make-hasheq)))
+
+(define (unsafe-make-place-local v)
+  (define key (vector v 'place-locale))
+  (hash-set! (thread-cell-ref place-local-table) key v)
+  key)
+
+(define (unsafe-place-local-ref key)
+  (hash-ref (thread-cell-ref place-local-table) key (vector-ref key 0)))
+
+(define (unsafe-place-local-set! key val)
+  (hash-set! (thread-cell-ref place-local-table) key val))
+
+(define (fork-place thunk)
+  (thread (lambda ()
+            (thread-cell-set! place-local-table (make-hasheq))
+            (thunk))))
+
+(define (start-place mod sym in out err)
+  (lambda (finish)
+    (void)))
+
 (primitive-table '#%pthread
                  (hash
-                  'make-pthread-parameter make-pthread-parameter))
+                  'make-pthread-parameter make-pthread-parameter
+                  'unsafe-make-place-local unsafe-make-place-local
+                  'unsafe-place-local-ref unsafe-place-local-ref
+                  'unsafe-place-local-set! unsafe-place-local-set!))
 (primitive-table '#%engine
                  (hash 
                   'make-engine make-engine
@@ -168,6 +193,8 @@
                   'poll-async-callbacks (lambda () null)
                   'disable-interrupts void
                   'enable-interrupts void
+                  'fork-place fork-place
+                  'start-place start-place
                   'fork-pthread (lambda args
                                   (error "fork-pthread: not ready"))
                   'pthread? (lambda args
diff --git a/racket/src/thread/continuation-mark.rkt b/racket/src/thread/continuation-mark.rkt
index efc8b3f1fe..e277a8921a 100644
--- a/racket/src/thread/continuation-mark.rkt
+++ b/racket/src/thread/continuation-mark.rkt
@@ -1,7 +1,7 @@
 #lang racket/base
 (require "check.rkt"
          (submod "thread.rkt" scheduling)
-         "engine.rkt")
+         "host.rkt")
 
 (provide continuation-marks)
 
diff --git a/racket/src/thread/custodian.rkt b/racket/src/thread/custodian.rkt
index b8f4252cc2..51bb1cbf71 100644
--- a/racket/src/thread/custodian.rkt
+++ b/racket/src/thread/custodian.rkt
@@ -1,8 +1,8 @@
 #lang racket/base
-(require racket/private/place-local
+(require "place-local.rkt"
          "check.rkt"
          "atomic.rkt"
-         "engine.rkt"
+         "host.rkt"
          "evt.rkt"
          "semaphore.rkt")
 
diff --git a/racket/src/thread/demo.rkt b/racket/src/thread/demo.rkt
index c1f215bd9f..e517cfeae4 100644
--- a/racket/src/thread/demo.rkt
+++ b/racket/src/thread/demo.rkt
@@ -500,6 +500,12 @@
    (thread (lambda () (sync (system-idle-evt)) (collect-garbage)))
    (check #t (symbol? (will-execute we)))
 
+   ;; Check places, where the various export symbols passed to
+   ;; `dynamic-place` are built into "bootstrap.rkt"
+   (define pl (dynamic-place 'dummy 'no-op #f #f #f))
+   (check #t (place? pl))
+   (sleep 1)
+
    (set! done? #t)))
 
 (unless done?
diff --git a/racket/src/thread/future.rkt b/racket/src/thread/future.rkt
index 728da5da89..76cc10df17 100644
--- a/racket/src/thread/future.rkt
+++ b/racket/src/thread/future.rkt
@@ -1,9 +1,9 @@
 #lang racket/base
 
-(require racket/private/place-local
+(require "place-local.rkt"
          "check.rkt"
          "internal-error.rkt"
-         "engine.rkt"
+         "host.rkt"
          "atomic.rkt"
          "parameter.rkt"
          "../common/queue.rkt"
diff --git a/racket/src/thread/engine.rkt b/racket/src/thread/host.rkt
similarity index 93%
rename from racket/src/thread/engine.rkt
rename to racket/src/thread/host.rkt
index 5601f4ec77..1f9bedb999 100644
--- a/racket/src/thread/engine.rkt
+++ b/racket/src/thread/host.rkt
@@ -24,7 +24,10 @@
 ;; This `#%pthread` table's entries are linked more directly
 ;; than `#%engine` entries:
 (bounce #%pthread
-        make-pthread-parameter)
+        make-pthread-parameter
+        unsafe-make-place-local
+        unsafe-place-local-ref
+        unsafe-place-local-set!)
 
 (bounce #%engine
         make-engine
@@ -63,6 +66,9 @@
         [disable-interrupts host:disable-interrupts]
         [enable-interrupts host:enable-interrupts]
 
+        [fork-place host:fork-place]
+        [start-place host:start-place]
+
         fork-pthread
         pthread?
         [get-thread-id get-pthread-id]
diff --git a/racket/src/thread/main.rkt b/racket/src/thread/main.rkt
index db8cd4f6fc..d29d96a3ea 100644
--- a/racket/src/thread/main.rkt
+++ b/racket/src/thread/main.rkt
@@ -25,6 +25,7 @@
          "time.rkt"
          "stats.rkt"
          "stack-size.rkt"
+         "place.rkt"
          "future.rkt"
          "fsemaphore.rkt"
          "os-thread.rkt")
@@ -157,6 +158,24 @@
          unsafe-custodian-register
          unsafe-custodian-unregister
 
+         dynamic-place  ; not the one from `racket/place`
+         place?
+         place-break
+         place-kill
+         place-wait
+         place-dead-evt
+         place-sleep
+
+         place-channel
+         place-channel? 
+         place-channel-get
+         place-channel-put
+         place-message-allowed?
+
+         place-pumper-threads
+         place-shared?
+         unsafe-add-post-custodian-shutdown
+
          futures-enabled?
          processor-count
          future
diff --git a/racket/src/thread/nested-thread.rkt b/racket/src/thread/nested-thread.rkt
index 1f2bc244e6..07340c4c47 100644
--- a/racket/src/thread/nested-thread.rkt
+++ b/racket/src/thread/nested-thread.rkt
@@ -1,7 +1,7 @@
 #lang racket/base
 (require "check.rkt"
          "atomic.rkt"
-         "engine.rkt"
+         "host.rkt"
          "thread.rkt"
          (except-in (submod "thread.rkt" scheduling)
                     thread
diff --git a/racket/src/thread/os-thread.rkt b/racket/src/thread/os-thread.rkt
index d43f76b337..18289801ce 100644
--- a/racket/src/thread/os-thread.rkt
+++ b/racket/src/thread/os-thread.rkt
@@ -1,6 +1,6 @@
 #lang racket/base
 (require "check.rkt"
-         "engine.rkt"
+         "host.rkt"
          "atomic.rkt")
 
 (provide unsafe-os-thread-enabled?
diff --git a/racket/src/thread/parameter.rkt b/racket/src/thread/parameter.rkt
index 5a8b235fec..8e64f50484 100644
--- a/racket/src/thread/parameter.rkt
+++ b/racket/src/thread/parameter.rkt
@@ -1,5 +1,5 @@
 #lang racket/base
-(require "engine.rkt")
+(require "host.rkt")
 
 (provide current-thread)
 
diff --git a/racket/src/thread/place-local.rkt b/racket/src/thread/place-local.rkt
new file mode 100644
index 0000000000..fc9c91745b
--- /dev/null
+++ b/racket/src/thread/place-local.rkt
@@ -0,0 +1,20 @@
+#lang racket/base
+(require (for-syntax racket/base)
+         "host.rkt")
+
+(provide define-place-local)
+
+;; Just like the one from `racket/private/place-local`, but using the
+;; exports of "host.rkt" so we can test in bootstrapping mode.
+
+(define-syntax-rule (define-place-local id v)
+  (begin
+    (define cell (unsafe-make-place-local v))
+    (define-syntax id
+      (make-set!-transformer
+       (lambda (stx)
+         (...
+          (syntax-case stx (set!)
+            [(set! _ r) #'(unsafe-place-local-set! cell r)]
+            [(_ e ...) #'((unsafe-place-local-ref cell) e ...)]
+            [_ #'(unsafe-place-local-ref cell)])))))))
diff --git a/racket/src/thread/place.rkt b/racket/src/thread/place.rkt
new file mode 100644
index 0000000000..a1f83aa03a
--- /dev/null
+++ b/racket/src/thread/place.rkt
@@ -0,0 +1,130 @@
+#lang racket/base
+(require (only-in '#%unsafe unsafe-abort-current-continuation/no-wind)
+         "place-local.rkt"
+         "check.rkt"
+         "host.rkt"
+         "schedule.rkt"
+         "atomic.rkt"
+         "thread.rkt"
+         "custodian.rkt"
+         "plumber.rkt"
+         "exit.rkt"
+         "sync.rkt"
+         "evt.rkt")
+
+(provide dynamic-place
+         place?
+         place-break
+         place-kill
+         place-wait
+         place-dead-evt
+         place-sleep
+
+         place-channel
+         place-channel? 
+         place-channel-get
+         place-channel-put
+         place-message-allowed?
+
+         place-pumper-threads
+         place-shared?
+         unsafe-add-post-custodian-shutdown)
+
+;; ----------------------------------------
+
+(struct place ([result #:mutable]
+               custodian
+               [post-shutdown #:mutable]
+               pumper-threads))
+
+(define-place-local current-place #f)
+
+(define place-prompt-tag (make-continuation-prompt-tag 'place))
+
+(define (dynamic-place path sym in out err)
+  (define c (make-custodian))
+  (define new-place (place #f                   ; result
+                           c
+                           '()                  ; post-shutdown
+                           (make-vector 3 #f))) ; pumper-threads
+  (define orig-plumber (make-plumber))
+  (define (default-exit v)
+    (plumber-flush-all orig-plumber)
+    (unsafe-abort-current-continuation/no-wind
+     place-prompt-tag
+     (if (byte? v) v 0)))
+  (host:fork-place
+   (lambda ()
+     (define finish (host:start-place path sym in out err))
+     (call-in-main-thread
+      (lambda ()
+        (define result
+          (call-with-continuation-prompt
+           (lambda ()
+             (set! current-place new-place)
+             (current-custodian c)
+             (current-plumber orig-plumber)
+             (exit-handler default-exit)
+             (finish
+              (lambda (in-th out-th err-th)
+                (vector-set! (place-pumper-threads place) 0 in-th)
+                (vector-set! (place-pumper-threads place) 1 out-th)
+                (vector-set! (place-pumper-threads place) 2 err-th)))
+             (default-exit 0))
+           place-prompt-tag
+           (lambda (v) v)))
+        (set-place-result! new-place result)))))
+  new-place)
+
+(define/who (place-break p [kind #f])
+  (check who place? p)
+  (unless (or (not kind) (eq? kind 'hangup) (eq? kind 'terminate))
+    (raise-argument-error who "(or/c #f 'hangup 'terminate)" kind))
+  (void))
+
+(define/who (place-kill p)
+  (check who place? p)
+  (void))
+
+(define/who (place-wait p)
+  (check who place? p)
+  (sync never-evt))
+
+(define/who (place-dead-evt p)
+  (check who place? p)
+  never-evt)
+
+(define/who (place-sleep msecs)
+  (void))
+
+;; ----------------------------------------
+
+(struct pchannel ()
+  #:reflection-name 'place-channel)
+
+(define (place-channel? v)
+  (pchannel? v))
+
+(define (place-channel)
+  (values (pchannel)
+          (pchannel)))
+
+(define (place-channel-get pch)
+  (sync never-evt))
+
+(define (place-channel-put pch v)
+  (void))
+
+(define (place-message-allowed? v)
+  #t)
+
+;; ----------------------------------------
+
+(define (place-shared? v)
+  #f)
+
+(define (unsafe-add-post-custodian-shutdown proc)
+  (atomically
+   (set-place-post-shutdown! current-place
+                             (cons proc
+                                   (place-post-shutdown current-place)))))
diff --git a/racket/src/thread/sandman.rkt b/racket/src/thread/sandman.rkt
index c56b77aec2..790137c717 100644
--- a/racket/src/thread/sandman.rkt
+++ b/racket/src/thread/sandman.rkt
@@ -1,5 +1,5 @@
 #lang racket/base
-(require racket/private/place-local
+(require "place-local.rkt"
          "check.rkt"
          "tree.rkt"
          "internal-error.rkt"
diff --git a/racket/src/thread/schedule.rkt b/racket/src/thread/schedule.rkt
index 487ce99a23..2657248219 100644
--- a/racket/src/thread/schedule.rkt
+++ b/racket/src/thread/schedule.rkt
@@ -1,7 +1,7 @@
 #lang racket/base
-(require racket/private/place-local
+(require "place-local.rkt"
          "atomic.rkt"
-         "engine.rkt"
+         "host.rkt"
          "internal-error.rkt"
          "sandman.rkt"
          "parameter.rkt"
diff --git a/racket/src/thread/thread-group.rkt b/racket/src/thread/thread-group.rkt
index de361e9c98..d3f192dfb2 100644
--- a/racket/src/thread/thread-group.rkt
+++ b/racket/src/thread/thread-group.rkt
@@ -1,5 +1,5 @@
 #lang racket/base
-(require racket/private/place-local
+(require "place-local.rkt"
          "check.rkt"
          "internal-error.rkt"
          "atomic.rkt")
diff --git a/racket/src/thread/thread.rkt b/racket/src/thread/thread.rkt
index 47b5016d55..ac785f5a91 100644
--- a/racket/src/thread/thread.rkt
+++ b/racket/src/thread/thread.rkt
@@ -1,9 +1,9 @@
 #lang racket/base
-(require racket/private/place-local
-         "../common/queue.rkt"
+(require "../common/queue.rkt"
+         "place-local.rkt"
          "check.rkt"
          "internal-error.rkt"
-         "engine.rkt"
+         "host.rkt"
          "sandman.rkt"
          "parameter.rkt"
          "evt.rkt"
diff --git a/racket/src/thread/time.rkt b/racket/src/thread/time.rkt
index 9cd6aa2ef7..e065be936b 100644
--- a/racket/src/thread/time.rkt
+++ b/racket/src/thread/time.rkt
@@ -1,14 +1,14 @@
 #lang racket/base
 (require "check.rkt"
          (submod "thread.rkt" scheduling)
-         (prefix-in engine: "engine.rkt"))
+         (prefix-in host: "host.rkt"))
 
 (provide current-process-milliseconds
          set-get-subprocesses-time!)
 
 (define/who (current-process-milliseconds [scope #f])
   (cond
-    [(not scope) (engine:current-process-milliseconds)]
+    [(not scope) (host:current-process-milliseconds)]
     [(thread? scope) (thread-cpu-time scope)]
     [(eq? scope 'subprocesses) (get-subprocesses-time)]
     [else
diff --git a/racket/src/thread/will-executor.rkt b/racket/src/thread/will-executor.rkt
index 68163ac6a0..94ed2a8629 100644
--- a/racket/src/thread/will-executor.rkt
+++ b/racket/src/thread/will-executor.rkt
@@ -1,7 +1,7 @@
 #lang racket/base
 (require "check.rkt"
          "atomic.rkt"
-         "engine.rkt"
+         "host.rkt"
          "evt.rkt"
          "sync.rkt"
          "semaphore.rkt")