Commit 137e23ea authored by Richard M. Stallman's avatar Richard M. Stallman

(truncate_undo_list): Return void.

Take just one argument, the buffer.
Make it current, and inhibit recursive GC.
Access and update the undo list directly; return void.
Refer to the undo...limit variables directly.
Test undo_outer_limit only after counting the whole current command.
When it's exceeded, call the function in undo-outer-limit-function.
(undo_limit, undo_strong_limit, undo_outer_limit): Moved from alloc.c.
(Vundo_outer_limit_function): New variable.
(syms_of_undo): Define undo-limit, undo-strong-limit
and undo-outer-limit here, and undo-outer-limit-function.
Doc fixes.
parent 3c7e66a8
......@@ -24,6 +24,16 @@ Boston, MA 02111-1307, USA. */
#include "buffer.h"
#include "commands.h"
/* Limits controlling how much undo information to keep. */
EMACS_INT undo_limit;
EMACS_INT undo_strong_limit;
EMACS_INT undo_outer_limit;
/* Function to call when undo_outer_limit is exceeded. */
Lisp_Object Vundo_outer_limit_function;
/* Last buffer for which undo information was recorded. */
Lisp_Object last_undo_buffer;
......@@ -291,31 +301,35 @@ but another undo command will undo to the previous boundary. */)
}
/* At garbage collection time, make an undo list shorter at the end,
returning the truncated list.
MINSIZE, MAXSIZE and LIMITSIZE are the limits on size allowed,
as described below.
In practice, these are the values of undo-limit,
undo-strong-limit, and undo-outer-limit. */
Lisp_Object
truncate_undo_list (list, minsize, maxsize, limitsize)
Lisp_Object list;
int minsize, maxsize, limitsize;
returning the truncated list. How this is done depends on the
variables undo-limit, undo-strong-limit and undo-outer-limit.
In some cases this works by calling undo-outer-limit-function. */
void
truncate_undo_list (b)
struct buffer *b;
{
Lisp_Object list;
Lisp_Object prev, next, last_boundary;
int size_so_far = 0;
/* Make sure that calling undo-outer-limit-function
won't cause another GC. */
int count = inhibit_garbage_collection ();
/* Make the buffer current to get its local values of variables such
as undo_limit. Also so that Vundo_outer_limit_function can
tell which buffer to operate on. */
record_unwind_protect (set_buffer_if_live, Fcurrent_buffer ());
set_buffer_internal (b);
list = b->undo_list;
prev = Qnil;
next = list;
last_boundary = Qnil;
/* Always preserve at least the most recent undo record
unless it is really horribly big.
If the first element is an undo boundary, skip past it.
Skip, skip, skip the undo, skip, skip, skip the undo,
Skip, skip, skip the undo, skip to the undo bound'ry.
(Get it? "Skip to my Loo?") */
/* If the first element is an undo boundary, skip past it. */
if (CONSP (next) && NILP (XCAR (next)))
{
/* Add in the space occupied by this element and its chain link. */
......@@ -326,6 +340,12 @@ truncate_undo_list (list, minsize, maxsize, limitsize)
next = XCDR (next);
}
/* Always preserve at least the most recent undo record
unless it is really horribly big.
Skip, skip, skip the undo, skip, skip, skip the undo,
Skip, skip, skip the undo, skip to the undo bound'ry. */
while (CONSP (next) && ! NILP (XCAR (next)))
{
Lisp_Object elt;
......@@ -341,35 +361,52 @@ truncate_undo_list (list, minsize, maxsize, limitsize)
+ SCHARS (XCAR (elt)));
}
/* If we reach LIMITSIZE before the first boundary,
we're heading for memory full, so truncate the list to nothing. */
if (size_so_far > limitsize)
return Qnil;
/* Advance to next element. */
prev = next;
next = XCDR (next);
}
/* If by the first boundary we have already passed undo_outer_limit,
we're heading for memory full, so offer to clear out the list. */
if (size_so_far > undo_outer_limit
&& !NILP (Vundo_outer_limit_function))
{
Lisp_Object temp = last_undo_buffer;
/* Normally the function this calls is undo-outer-limit-truncate. */
if (! NILP (call1 (Vundo_outer_limit_function,
make_number (size_so_far))))
{
/* The function is responsible for making
any desired changes in buffer-undo-list. */
unbind_to (count, Qnil);
return;
}
/* That function probably used the minibuffer, and if so, that
changed last_undo_buffer. Change it back so that we don't
force next change to make an undo boundary here. */
last_undo_buffer = temp;
}
if (CONSP (next))
last_boundary = prev;
/* Keep more if it fits. */
/* Keep additional undo data, if it fits in the limits. */
while (CONSP (next))
{
Lisp_Object elt;
elt = XCAR (next);
/* When we get to a boundary, decide whether to truncate
either before or after it. The lower threshold, MINSIZE,
either before or after it. The lower threshold, undo_limit,
tells us to truncate after it. If its size pushes past
the higher threshold MAXSIZE as well, we truncate before it. */
the higher threshold undo_strong_limit, we truncate before it. */
if (NILP (elt))
{
if (size_so_far > maxsize)
if (size_so_far > undo_strong_limit)
break;
last_boundary = prev;
if (size_so_far > minsize)
if (size_so_far > undo_limit)
break;
}
......@@ -390,16 +427,15 @@ truncate_undo_list (list, minsize, maxsize, limitsize)
/* If we scanned the whole list, it is short enough; don't change it. */
if (NILP (next))
return list;
;
/* Truncate at the boundary where we decided to truncate. */
if (!NILP (last_boundary))
{
XSETCDR (last_boundary, Qnil);
return list;
}
else if (!NILP (last_boundary))
XSETCDR (last_boundary, Qnil);
/* There's nothing we decided to keep, so clear it out. */
else
return Qnil;
b->undo_list = Qnil;
unbind_to (count, Qnil);
}
DEFUN ("primitive-undo", Fprimitive_undo, Sprimitive_undo, 2, 2, 0,
......@@ -563,6 +599,54 @@ syms_of_undo ()
defsubr (&Sprimitive_undo);
defsubr (&Sundo_boundary);
DEFVAR_INT ("undo-limit", &undo_limit,
doc: /* Keep no more undo information once it exceeds this size.
This limit is applied when garbage collection happens.
When a previous command increases the total undo list size past this
value, the earlier commands that came before it are forgotten.
The size is counted as the number of bytes occupied,
which includes both saved text and other data. */);
undo_limit = 20000;
DEFVAR_INT ("undo-strong-limit", &undo_strong_limit,
doc: /* Don't keep more than this much size of undo information.
This limit is applied when garbage collection happens.
When a previous command increases the total undo list size past this
value, that command and the earlier commands that came before it are forgotten.
However, the most recent buffer-modifying command's undo info
is never discarded for this reason.
The size is counted as the number of bytes occupied,
which includes both saved text and other data. */);
undo_strong_limit = 30000;
DEFVAR_INT ("undo-outer-limit", &undo_outer_limit,
doc: /* Outer limit on size of undo information for one command.
At garbage collection time, if the current command has produced
more than this much undo information, it asks you whether to delete
the information. This is a last-ditch limit to prevent memory overflow.
The size is counted as the number of bytes occupied,
which includes both saved text and other data.
In fact, this calls the function which is the value of
`undo-outer-limit-function' with one argument, the size.
The text above describes the behavior of the function
that variable usually specifies. */);
undo_outer_limit = 300000;
DEFVAR_LISP ("undo-outer-limit-function", &Vundo_outer_limit_function,
doc: /* Function to call when an undo list exceeds `undo-outer-limit'.
This function is called with one argument, the current undo list size
for the most recent command (since the last undo boundary).
If the function returns t, that means truncation has been fully handled.
If it returns nil, the other forms of truncation are done.
Garbage collection is inhibited around the call to this function,
so it must make sure not to do a lot of consing. */);
Vundo_outer_limit_function = Qnil;
}
/* arch-tag: d546ee01-4aed-4ffb-bb8b-eefaae50d38a
......
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