From 7015edb0705e8d6badde2769de78d470cb8f4627 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Wed, 2 Dec 2009 20:00:32 +0000
Subject: [PATCH] fix corner case of futures where the initial procedure needs
 too deep a Scheme stack

svn: r17165
---
 src/mzscheme/src/future.c | 14 ++++++++++++--
 src/mzscheme/src/future.h |  1 +
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/mzscheme/src/future.c b/src/mzscheme/src/future.c
index fccd214156..bdf43c12d3 100644
--- a/src/mzscheme/src/future.c
+++ b/src/mzscheme/src/future.c
@@ -163,6 +163,7 @@ static void init_future_thread(struct Scheme_Future_State *fs, int i);
 
 #define THREAD_POOL_SIZE 12
 #define INITIAL_C_STACK_SIZE 500000
+#define FUTURE_RUNSTACK_SIZE 1000
 
 typedef struct Scheme_Future_State {
   struct Scheme_Future_Thread_State *pool_threads[THREAD_POOL_SIZE];
@@ -397,7 +398,7 @@ static void init_future_thread(Scheme_Future_State *fs, int i)
 
   {
     Scheme_Object **rs_start, **rs;
-    long init_runstack_size = 1000;
+    long init_runstack_size = FUTURE_RUNSTACK_SIZE;
     rs_start = scheme_alloc_runstack(init_runstack_size);
     rs = rs_start XFORM_OK_PLUS init_runstack_size;
     params.runstack_start = rs_start;
@@ -565,6 +566,11 @@ Scheme_Object *future(int argc, Scheme_Object *argv[])
       scheme_on_demand_generate_lambda(nc, 0, NULL);
     }
 
+  if (ncd->max_let_depth > FUTURE_RUNSTACK_SIZE * sizeof(void*)) {
+    /* Can't even call it in a future thread */
+    ft->status = PENDING_OVERSIZE;
+  }
+
   ft->code = (void*)ncd->code;
 
   pthread_mutex_lock(&fs->future_mutex);
@@ -631,7 +637,11 @@ Scheme_Object *touch(int argc, Scheme_Object *argv[])
 #endif
 
   pthread_mutex_lock(&fs->future_mutex);
-  if (ft->status == PENDING) {
+  if ((ft->status == PENDING) || (ft->status == PENDING_OVERSIZE)) {
+    if (ft->status == PENDING_OVERSIZE) {
+      scheme_log(scheme_main_logger, SCHEME_LOG_DEBUG, 0,
+                 "future: oversize procedure deferred to runtime thread");
+    }
     ft->status = RUNNING;
     pthread_mutex_unlock(&fs->future_mutex);
 
diff --git a/src/mzscheme/src/future.h b/src/mzscheme/src/future.h
index a2c8eee44e..e1bad68ffe 100644
--- a/src/mzscheme/src/future.h
+++ b/src/mzscheme/src/future.h
@@ -34,6 +34,7 @@ typedef void* (*prim_pvoid_pvoid_pvoid_t)(void*, void*);
 #define RUNNING 1
 #define WAITING_FOR_PRIM 2
 #define FINISHED 3
+#define PENDING_OVERSIZE 4
 
 #define FSRC_OTHER 0
 #define FSRC_RATOR 1