* cont.c: support callcc which everyone love.

  incomplete. please give me bug reports.
* common.mk, inits.c, thread.c: ditto.
* yarvcore.c: export thread_mark().
* yarvcore.h: disable value cache option.
* eval_intern.h: set th_get_ruby_level_cfp to inline.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@12380 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 302 insertions, 0 deletions

diff --git a/cont.c b/cont.c
new file mode 100644
index 0000000000..099cdde070
--- /dev/null
+++ b/cont.c
@@ -0,0 +1,302 @@
+/**********************************************************************
+
+  cont.c - 
+
+  $Author$
+  $Date$
+  created at: Thu May 23 09:03:43 2007
+
+  Copyright (C) 2007 Koichi Sasada
+
+**********************************************************************/
+
+#include "ruby.h"
+#include "yarvcore.h"
+#include "gc.h"
+#include "eval_intern.h"
+
+typedef struct rb_continuation_struct {
+    rb_thread_t saved_thread;
+    rb_jmpbuf_t jmpbuf;
+    VALUE retval;
+    VALUE *vm_stack;
+    VALUE *machine_stack;
+    VALUE *machine_stack_src;
+    int machine_stack_size;
+} rb_continuation_t;
+
+#define GetContPtr(obj, ptr)  \
+  Data_Get_Struct(obj, rb_continuation_t, ptr)
+
+NOINLINE(static VALUE cont_capture(volatile int *stat));
+
+void rb_thread_mark(rb_thread_t *th);
+
+static void
+cont_mark(void *ptr)
+{
+    MARK_REPORT_ENTER("cont");
+    if (ptr) {
+	rb_continuation_t *cont = ptr;
+	rb_gc_mark(cont->retval);
+	rb_thread_mark(&cont->saved_thread);
+
+	if (cont->vm_stack) {
+	    rb_gc_mark_locations(cont->vm_stack,
+				 cont->vm_stack + cont->saved_thread.stack_size);
+	}
+	
+	if (cont->machine_stack) {
+	    rb_gc_mark_locations(cont->machine_stack,
+				 cont->machine_stack + cont->machine_stack_size);
+	}
+    }
+    MARK_REPORT_LEAVE("cont");
+}
+
+static void
+cont_free(void *ptr)
+{
+    FREE_REPORT_ENTER("cont");
+    if (ptr) {
+	rb_continuation_t *cont = ptr;
+	FREE_UNLESS_NULL(cont->machine_stack);
+	FREE_UNLESS_NULL(cont->vm_stack);
+	ruby_xfree(ptr);
+    }
+    FREE_REPORT_LEAVE("cont");
+}
+
+static VALUE
+cont_capture(volatile int *stat)
+{
+    rb_continuation_t *cont;
+    VALUE contval;
+    rb_thread_t *th = GET_THREAD(), *sth;
+    int size;
+
+    contval = Data_Make_Struct(rb_cCont, rb_continuation_t,
+			       cont_mark, cont_free, cont);
+
+    /* save context */
+    cont->saved_thread = *th;
+    sth = &cont->saved_thread;
+    sth->stack = 0; /* clear to skip GC marking */
+    cont->vm_stack = ALLOC_N(VALUE, sth->stack_size);
+    MEMCPY(cont->vm_stack, th->stack, VALUE, sth->stack_size);
+
+    rb_gc_set_stack_end(&th->machine_stack_end);
+    if (th->machine_stack_start > th->machine_stack_end) {
+	size = cont->machine_stack_size = th->machine_stack_start - th->machine_stack_end;
+	cont->machine_stack_src = th->machine_stack_end;
+    }
+    else {
+	size = cont->machine_stack_size = th->machine_stack_end - th->machine_stack_start;
+	cont->machine_stack_src = th->machine_stack_start;
+    }
+
+    cont->machine_stack = ALLOC_N(VALUE, size);
+    MEMCPY(cont->machine_stack, cont->machine_stack_src, VALUE, size);
+
+    if (ruby_setjmp(cont->jmpbuf)) {
+	VALUE retval;
+
+	retval = cont->retval;
+	cont->retval = Qnil;
+	*stat = 1;
+	return retval;
+    }
+    else {
+	*stat = 0;
+	return contval;
+    }
+}
+
+static void
+cont_restore_context_1(rb_continuation_t *cont)
+{
+    rb_thread_t *th = GET_THREAD(), *sth = &cont->saved_thread;
+
+    /* restore thread context */
+    MEMCPY(th->stack, cont->vm_stack, VALUE, sth->stack_size);
+
+    th->cfp = sth->cfp;
+    th->safe_level = sth->safe_level;
+    th->raised_flag = sth->raised_flag;
+    th->state = sth->state;
+    th->status = sth->status;
+    th->tag = sth->tag;
+
+    /* restore machine stack */
+    MEMCPY(cont->machine_stack_src, cont->machine_stack,
+	   VALUE, cont->machine_stack_size);
+
+    ruby_longjmp(cont->jmpbuf, 1);
+}
+
+NORETURN(NOINLINE(static void restore_context_0(rb_continuation_t *, VALUE *)));
+
+static void
+cont_restore_context_0(rb_continuation_t *cont, VALUE *addr_in_prev_frame)
+{
+#define STACK_PAD_SIZE 1024
+    VALUE space[STACK_PAD_SIZE];
+
+#if STACK_GROW_DIRECTION < 0 /* downward */
+    if (addr_in_prev_frame > cont->machine_stack_src) {
+	cont_restore_context_0(cont, &space[0]);
+    }
+#elif STACK_GROW_DIRECTION > 0 /* upward */
+    if (addr_in_prev_frame < cont->machine_stack_src + cont->machine_stack_size) {
+	cont_restore_context_0(cont, &space[STACK_PAD_SIZE-1]);
+    }
+#else
+    if (addr_in_prev_frame > &space[0]) {
+	/* Stack grows downward */
+	if (addr_in_prev_frame > cont->saved_thread.machine_stack_src) {
+	    cont_restore_context_0(cont, &space[0]);
+	}
+    }
+    else {
+	/* Stack grows upward */
+	if (addr_in_prev_frame < cont->machine_stack_src + cont->machine_stack_size) {
+	    cont_restore_context_0(cont, &space[STACK_PAD_SIZE-1]);
+	}
+    }
+#endif
+    cont_restore_context_1(cont);
+}
+
+/*
+ *  Document-class: Continuation
+ *
+ *  Continuation objects are generated by
+ *  <code>Kernel#callcc</code>. They hold a return address and execution
+ *  context, allowing a nonlocal return to the end of the
+ *  <code>callcc</code> block from anywhere within a program.
+ *  Continuations are somewhat analogous to a structured version of C's
+ *  <code>setjmp/longjmp</code> (although they contain more state, so
+ *  you might consider them closer to threads).
+ *     
+ *  For instance:
+ *     
+ *     arr = [ "Freddie", "Herbie", "Ron", "Max", "Ringo" ]
+ *     callcc{|$cc|}
+ *     puts(message = arr.shift)
+ *     $cc.call unless message =~ /Max/
+ *     
+ *  <em>produces:</em>
+ *     
+ *     Freddie
+ *     Herbie
+ *     Ron
+ *     Max
+ *     
+ *  This (somewhat contrived) example allows the inner loop to abandon
+ *  processing early:
+ *     
+ *     callcc {|cont|
+ *       for i in 0..4
+ *         print "\n#{i}: "
+ *         for j in i*5...(i+1)*5
+ *           cont.call() if j == 17
+ *           printf "%3d", j
+ *         end
+ *       end
+ *     }
+ *     print "\n"
+ *     
+ *  <em>produces:</em>
+ *     
+ *     0:   0  1  2  3  4
+ *     1:   5  6  7  8  9
+ *     2:  10 11 12 13 14
+ *     3:  15 16
+ */
+
+VALUE rb_cCont;
+
+/*
+ *  call-seq:
+ *     callcc {|cont| block }   =>  obj
+ *  
+ *  Generates a <code>Continuation</code> object, which it passes to the
+ *  associated block. Performing a <em>cont</em><code>.call</code> will
+ *  cause the <code>callcc</code> to return (as will falling through the
+ *  end of the block). The value returned by the <code>callcc</code> is
+ *  the value of the block, or the value passed to
+ *  <em>cont</em><code>.call</code>. See class <code>Continuation</code>
+ *  for more details. Also see <code>Kernel::throw</code> for
+ *  an alternative mechanism for unwinding a call stack.
+ */
+
+static VALUE
+rb_callcc(VALUE self)
+{
+    volatile int called;
+    volatile VALUE val = cont_capture(&called);
+
+    if (called) {
+	return val;
+    }
+    else {
+	return rb_yield(val);
+    }
+}
+
+/*
+ *  call-seq:
+ *     cont.call(args, ...)
+ *     cont[args, ...]
+ *  
+ *  Invokes the continuation. The program continues from the end of the
+ *  <code>callcc</code> block. If no arguments are given, the original
+ *  <code>callcc</code> returns <code>nil</code>. If one argument is
+ *  given, <code>callcc</code> returns it. Otherwise, an array
+ *  containing <i>args</i> is returned.
+ *     
+ *     callcc {|cont|  cont.call }           #=> nil
+ *     callcc {|cont|  cont.call 1 }         #=> 1
+ *     callcc {|cont|  cont.call 1, 2, 3 }   #=> [1, 2, 3]
+ */
+
+static VALUE
+rb_cont_call(int argc, VALUE *argv, VALUE contval)
+{
+    rb_continuation_t *cont;
+    rb_thread_t *th = GET_THREAD();
+    GetContPtr(contval, cont);
+
+    if (cont->saved_thread.value != th->value) {
+	rb_raise(rb_eRuntimeError, "continuation called across threads");
+    }
+    /* TODO: check "continuation called across trap" */
+    printf("--> %p\n", cont);
+
+    switch(argc) {
+      case 0:
+	cont->retval = Qnil;
+	break;
+      case 1:
+	cont->retval = argv[0];
+	break;
+      default:
+	cont->retval = rb_ary_new4(argc, argv);
+	break;
+    }
+
+    cont_restore_context_0(cont, (VALUE *)&cont);
+    return Qnil; /* unreachable */
+}
+
+void
+Init_Cont(void)
+{
+    rb_cCont = rb_define_class("Continuation", rb_cObject);
+    rb_undef_alloc_func(rb_cCont);
+    rb_undef_method(CLASS_OF(rb_cCont), "new");
+    rb_define_method(rb_cCont, "call", rb_cont_call, -1);
+    rb_define_method(rb_cCont, "[]", rb_cont_call, -1);
+    rb_define_global_function("callcc", rb_callcc, 0);
+}
+