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Re: Terrific Dead Lock
From: |
Ludovic Courtès |
Subject: |
Re: Terrific Dead Lock |
Date: |
Fri, 14 Mar 2008 11:24:17 +0100 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) |
Hi,
address@hidden (Ludovic Courtès) writes:
> Two possibilities to fix it:
>
> 1. Copy `srcprop.[ch]' and `eval.c' bits from HEAD to 1.8. After all,
> it's probably solid enough (I use almost only HEAD). See [0] for
> an overview of the initial patch. It doesn't break the public API
> nor the ABI, but it (re)moves stuff from the `srcprop.h'.
>
> 2. Remove the critical section from 1.8 and synchronize accesses to
> `srcprops_freelist' with a private mutex, assuming that's a correct
> fix.
The second approach is actually wrong: we'd need to acquire a mutex in
`srcprops_free ()' to synchronize accesses to `srcprops_freelist', but
we can't do it since `srcprops_free ()' is called during GC---which is
why there was a critical section in the first place I suppose.
Thus the first approach seems unavoidable. Attached is the exact patch.
It removes non-public macros and data types from `srcprop.h', which is
acceptable IMO.
OK to apply?
Thanks,
Ludovic.
Index: libguile/eval.c
===================================================================
RCS file: /sources/guile/guile/guile-core/libguile/eval.c,v
retrieving revision 1.405.2.13
diff -u -r1.405.2.13 eval.c
--- libguile/eval.c 10 Mar 2008 22:13:33 -0000 1.405.2.13
+++ libguile/eval.c 13 Mar 2008 22:42:30 -0000
@@ -3039,7 +3039,7 @@
do { \
SCM_SET_ARGSREADY (debug);\
if (scm_check_apply_p && SCM_TRAPS_P)\
- if (SCM_APPLY_FRAME_P || (SCM_TRACE_P && PROCTRACEP (proc)))\
+ if (SCM_APPLY_FRAME_P || (SCM_TRACE_P && SCM_PROCTRACEP (proc)))\
{\
SCM tmp, tail = scm_from_bool(SCM_TRACED_FRAME_P (debug)); \
SCM_SET_TRACED_FRAME (debug); \
Index: libguile/srcprop.c
===================================================================
RCS file: /sources/guile/guile/guile-core/libguile/srcprop.c,v
retrieving revision 1.73.2.1
diff -u -r1.73.2.1 srcprop.c
--- libguile/srcprop.c 12 Feb 2006 13:42:51 -0000 1.73.2.1
+++ libguile/srcprop.c 13 Mar 2008 22:42:30 -0000
@@ -37,7 +37,7 @@
/* {Source Properties}
*
* Properties of source list expressions.
- * Five of these have special meaning and optimized storage:
+ * Five of these have special meaning:
*
* filename string The name of the source file.
* copy list A copy of the list expression.
@@ -55,29 +55,47 @@
SCM_GLOBAL_SYMBOL (scm_sym_column, "column");
SCM_GLOBAL_SYMBOL (scm_sym_breakpoint, "breakpoint");
-scm_t_bits scm_tc16_srcprops;
-static scm_t_srcprops_chunk *srcprops_chunklist = 0;
-static scm_t_srcprops *srcprops_freelist = 0;
+/*
+ * Source properties are stored as double cells with the
+ * following layout:
+
+ * car = tag
+ * cbr = pos
+ * ccr = copy
+ * cdr = plist
+ */
+
+#define SRCPROPSP(p) (SCM_SMOB_PREDICATE (scm_tc16_srcprops, (p)))
+#define SRCPROPBRK(p) (SCM_SMOB_FLAGS (p) & SCM_SOURCE_PROPERTY_FLAG_BREAK)
+#define SRCPROPPOS(p) (SCM_CELL_WORD(p,1))
+#define SRCPROPLINE(p) (SRCPROPPOS(p) >> 12)
+#define SRCPROPCOL(p) (SRCPROPPOS(p) & 0x0fffL)
+#define SRCPROPCOPY(p) (SCM_CELL_OBJECT(p,2))
+#define SRCPROPPLIST(p) (SCM_CELL_OBJECT_3(p))
+#define SETSRCPROPBRK(p) \
+ (SCM_SET_SMOB_FLAGS ((p), \
+ SCM_SMOB_FLAGS (p) | SCM_SOURCE_PROPERTY_FLAG_BREAK))
+#define CLEARSRCPROPBRK(p) \
+ (SCM_SET_SMOB_FLAGS ((p), \
+ SCM_SMOB_FLAGS (p) & ~SCM_SOURCE_PROPERTY_FLAG_BREAK))
+#define SRCPROPMAKPOS(l, c) (((l) << 12) + (c))
+#define SETSRCPROPPOS(p, l, c) (SCM_SET_CELL_WORD(p,1, SRCPROPMAKPOS (l, c)))
+#define SETSRCPROPLINE(p, l) SETSRCPROPPOS (p, l, SRCPROPCOL (p))
+#define SETSRCPROPCOL(p, c) SETSRCPROPPOS (p, SRCPROPLINE (p), c)
+
+
+
+scm_t_bits scm_tc16_srcprops;
+
static SCM
srcprops_mark (SCM obj)
{
- scm_gc_mark (SRCPROPFNAME (obj));
scm_gc_mark (SRCPROPCOPY (obj));
return SRCPROPPLIST (obj);
}
-
-static size_t
-srcprops_free (SCM obj)
-{
- *((scm_t_srcprops **) SCM_SMOB_DATA (obj)) = srcprops_freelist;
- srcprops_freelist = (scm_t_srcprops *) SCM_SMOB_DATA (obj);
- return 0; /* srcprops_chunks are not freed until leaving guile */
-}
-
-
static int
srcprops_print (SCM obj, SCM port, scm_print_state *pstate)
{
@@ -99,38 +117,45 @@
}
+/*
+ * We remember the last file name settings, so we can share that plist
+ * entry. This works because scm_set_source_property_x does not use
+ * assoc-set! for modifying the plist.
+ *
+ * This variable contains a protected cons, whose cdr is the cached
+ * plist
+ */
+static SCM scm_last_plist_filename;
+
SCM
scm_make_srcprops (long line, int col, SCM filename, SCM copy, SCM plist)
{
- register scm_t_srcprops *ptr;
- SCM_CRITICAL_SECTION_START;
- if ((ptr = srcprops_freelist) != NULL)
- srcprops_freelist = *(scm_t_srcprops **)ptr;
- else
+ if (!SCM_UNBNDP (filename))
{
- size_t i;
- scm_t_srcprops_chunk *mem;
- size_t n = sizeof (scm_t_srcprops_chunk)
- + sizeof (scm_t_srcprops) * (SRCPROPS_CHUNKSIZE - 1);
- SCM_SYSCALL (mem = (scm_t_srcprops_chunk *) scm_malloc (n));
- if (mem == NULL)
- scm_memory_error ("srcprops");
- scm_gc_register_collectable_memory (mem, n, "srcprops");
-
- mem->next = srcprops_chunklist;
- srcprops_chunklist = mem;
- ptr = &mem->srcprops[0];
- for (i = 1; i < SRCPROPS_CHUNKSIZE - 1; ++i)
- *(scm_t_srcprops **)&ptr[i] = &ptr[i + 1];
- *(scm_t_srcprops **)&ptr[SRCPROPS_CHUNKSIZE - 1] = 0;
- srcprops_freelist = (scm_t_srcprops *) &ptr[1];
+ SCM old_plist = plist;
+
+ /*
+ have to extract the acons, and operate on that, for
+ thread safety.
+ */
+ SCM last_acons = SCM_CDR (scm_last_plist_filename);
+ if (old_plist == SCM_EOL
+ && SCM_CDAR (last_acons) == filename)
+ {
+ plist = last_acons;
+ }
+ else
+ {
+ plist = scm_acons (scm_sym_filename, filename, plist);
+ if (old_plist == SCM_EOL)
+ SCM_SETCDR (scm_last_plist_filename, plist);
+ }
}
- ptr->pos = SRCPROPMAKPOS (line, col);
- ptr->fname = filename;
- ptr->copy = copy;
- ptr->plist = plist;
- SCM_CRITICAL_SECTION_END;
- SCM_RETURN_NEWSMOB (scm_tc16_srcprops, ptr);
+
+ SCM_RETURN_NEWSMOB3 (scm_tc16_srcprops,
+ SRCPROPMAKPOS (line, col),
+ copy,
+ plist);
}
@@ -140,8 +165,6 @@
SCM plist = SRCPROPPLIST (obj);
if (!SCM_UNBNDP (SRCPROPCOPY (obj)))
plist = scm_acons (scm_sym_copy, SRCPROPCOPY (obj), plist);
- if (!SCM_UNBNDP (SRCPROPFNAME (obj)))
- plist = scm_acons (scm_sym_filename, SRCPROPFNAME (obj), plist);
plist = scm_acons (scm_sym_column, scm_from_int (SRCPROPCOL (obj)), plist);
plist = scm_acons (scm_sym_line, scm_from_int (SRCPROPLINE (obj)), plist);
plist = scm_acons (scm_sym_breakpoint, scm_from_bool (SRCPROPBRK (obj)),
plist);
@@ -206,7 +229,6 @@
if (scm_is_eq (scm_sym_breakpoint, key)) p = scm_from_bool (SRCPROPBRK
(p));
else if (scm_is_eq (scm_sym_line, key)) p = scm_from_int (SRCPROPLINE
(p));
else if (scm_is_eq (scm_sym_column, key)) p = scm_from_int (SRCPROPCOL
(p));
- else if (scm_is_eq (scm_sym_filename, key)) p = SRCPROPFNAME (p);
else if (scm_is_eq (scm_sym_copy, key)) p = SRCPROPCOPY (p);
else
{
@@ -277,13 +299,6 @@
scm_make_srcprops (0, scm_to_int (datum),
SCM_UNDEFINED, SCM_UNDEFINED, p));
}
- else if (scm_is_eq (scm_sym_filename, key))
- {
- if (SRCPROPSP (p))
- SRCPROPFNAME (p) = datum;
- else
- SCM_WHASHSET (scm_source_whash, h, scm_make_srcprops (0, 0, datum,
SCM_UNDEFINED, p));
- }
else if (scm_is_eq (scm_sym_copy, key))
{
if (SRCPROPSP (p))
@@ -308,29 +323,18 @@
{
scm_tc16_srcprops = scm_make_smob_type ("srcprops", 0);
scm_set_smob_mark (scm_tc16_srcprops, srcprops_mark);
- scm_set_smob_free (scm_tc16_srcprops, srcprops_free);
scm_set_smob_print (scm_tc16_srcprops, srcprops_print);
scm_source_whash = scm_make_weak_key_hash_table (scm_from_int (2047));
scm_c_define ("source-whash", scm_source_whash);
+ scm_last_plist_filename
+ = scm_permanent_object (scm_cons (SCM_EOL,
+ scm_acons (SCM_EOL, SCM_EOL, SCM_EOL)));
+
#include "libguile/srcprop.x"
}
-void
-scm_finish_srcprop ()
-{
- register scm_t_srcprops_chunk *ptr = srcprops_chunklist, *next;
- size_t n= sizeof (scm_t_srcprops_chunk)
- + sizeof (scm_t_srcprops) * (SRCPROPS_CHUNKSIZE - 1);
- while (ptr)
- {
- next = ptr->next;
- scm_gc_unregister_collectable_memory (ptr, n, "srcprops");
- free ((char *) ptr);
- ptr = next;
- }
-}
/*
Local Variables:
Index: libguile/srcprop.h
===================================================================
RCS file: /sources/guile/guile/guile-core/libguile/srcprop.h,v
retrieving revision 1.36.2.1
diff -u -r1.36.2.1 srcprop.h
--- libguile/srcprop.h 12 Feb 2006 13:42:51 -0000 1.36.2.1
+++ libguile/srcprop.h 13 Mar 2008 22:42:30 -0000
@@ -49,46 +49,10 @@
/* {Source properties}
*/
-
-SCM_API scm_t_bits scm_tc16_srcprops;
-
-typedef struct scm_t_srcprops
-{
- unsigned long pos;
- SCM fname;
- SCM copy;
- SCM plist;
-} scm_t_srcprops;
-
-#define SRCPROPS_CHUNKSIZE 2047 /* Number of srcprops per chunk */
-typedef struct scm_t_srcprops_chunk
-{
- struct scm_t_srcprops_chunk *next;
- scm_t_srcprops srcprops[1];
-} scm_t_srcprops_chunk;
-
+#define SCM_PROCTRACEP(x) (scm_is_true (scm_procedure_property (x,
scm_sym_trace)))
#define SCM_SOURCE_PROPERTY_FLAG_BREAK 1
-#define SRCPROPSP(p) (SCM_SMOB_PREDICATE (scm_tc16_srcprops, (p)))
-#define SRCPROPBRK(p) (SCM_SMOB_FLAGS (p) & SCM_SOURCE_PROPERTY_FLAG_BREAK)
-#define SRCPROPPOS(p) ((scm_t_srcprops *) SCM_SMOB_DATA (p))->pos
-#define SRCPROPLINE(p) (SRCPROPPOS(p) >> 12)
-#define SRCPROPCOL(p) (SRCPROPPOS(p) & 0x0fffL)
-#define SRCPROPFNAME(p) ((scm_t_srcprops *) SCM_SMOB_DATA (p))->fname
-#define SRCPROPCOPY(p) ((scm_t_srcprops *) SCM_SMOB_DATA (p))->copy
-#define SRCPROPPLIST(p) ((scm_t_srcprops *) SCM_SMOB_DATA (p))->plist
-#define SETSRCPROPBRK(p) \
- (SCM_SET_SMOB_FLAGS ((p), \
- SCM_SMOB_FLAGS (p) | SCM_SOURCE_PROPERTY_FLAG_BREAK))
-#define CLEARSRCPROPBRK(p) \
- (SCM_SET_SMOB_FLAGS ((p), \
- SCM_SMOB_FLAGS (p) & ~SCM_SOURCE_PROPERTY_FLAG_BREAK))
-#define SRCPROPMAKPOS(l, c) (((l) << 12) + (c))
-#define SETSRCPROPPOS(p, l, c) (SRCPROPPOS (p) = SRCPROPMAKPOS (l, c))
-#define SETSRCPROPLINE(p, l) SETSRCPROPPOS (p, l, SRCPROPCOL (p))
-#define SETSRCPROPCOL(p, c) SETSRCPROPPOS (p, SRCPROPLINE (p), c)
-
-#define PROCTRACEP(x) (scm_is_true (scm_procedure_property (x, scm_sym_trace)))
+SCM_API scm_t_bits scm_tc16_srcprops;
SCM_API SCM scm_sym_filename;
SCM_API SCM scm_sym_copy;
- Terrific Dead Lock, Ludovic Courtès, 2008/03/13
- Re: Terrific Dead Lock,
Ludovic Courtès <=