Factor out dot rendering.

Can't use redex's version because it needs the GUI.

collects/profile/contract-profile.rkt

@@ -4,8 +4,7 @@
          racket/contract
          (only-in racket/contract/private/guts contract-continuation-mark-key)
          "sampler.rkt" "utils.rkt"
-         ;; for grphviz rendering
-         redex/private/dot racket/system)
+         "contract-profiler/dot.rkt")
 
 (struct contract-profile
   (total-time n-samples n-contract-samples
@@ -130,7 +129,6 @@
 ;; boundary.
 ;; Typed modules are in green, untyped modules are in red.
 
-(define dot-exe (find-dot))
 (define module-graph-dot-file "tmp-contract-profile-module-graph.dot")
 
 (define (module-graph-view correlated)
@@ -195,10 +193,7 @@
                 (samples-time v)))
       (printf "}\n")))
   ;; render, if graphviz is installed
-  (when dot-exe
-    (system (format "~a -Tpdf -O ~a"
-                    (path->string dot-exe)
-                    module-graph-dot-file))))
+  (render-dot module-graph-dot-file))
 
 
 ;;---------------------------------------------------------------------------

collects/profile/contract-profiler/dot.rkt

@@ -0,0 +1,29 @@
+#lang racket/base
+
+;; Graphviz support
+;; inspired by redex/private/dot.rkt (can't use directly because it uses GUI)
+
+(require racket/system)
+
+(provide render-dot)
+
+;; these paths are explicitly checked (when find-executable-path
+;; fails) because starting drracket from the finder (or the dock)
+;; under mac os x generally does not get the path right.
+(define dot-paths
+  '("/usr/bin"
+    "/bin"
+    "/usr/local/bin"
+    "/opt/local/bin/"))
+
+(define dot.exe (if (eq? (system-type) 'windows) "dot.exe" "dot"))
+(define dot
+  (or (find-executable-path dot.exe)
+      (ormap (λ (x)
+               (define candidate (build-path x dot.exe))
+               (and (file-exists? candidate) candidate))
+             dot-paths)))
+
+(define (render-dot input-file)
+  (when dot
+    (system (format "~a -Tpdf -O ~a" (path->string dot) input-file))))