pager history buffer: add config option, keep buffer on resize

kitty/config_data.py

@@ -323,6 +323,13 @@ def scrollback_lines(x):
     return x
 
 
+def size_mb(x):
+    x = int(x)
+    if x < 0 or x > 2 ** 12 - 1:
+        raise ValueError('Size {} is in MB (positive & <4GB)'.format(x))
+    return x
+
+
 o('scrollback_lines', 2000, option_type=scrollback_lines, long_text=_('''
 Number of lines of history to keep in memory for scrolling back. Memory is allocated
 on demand. Negative numbers are (effectively) infinite scrollback. Note that using
@@ -336,6 +343,13 @@ use can handle ANSI escape sequences for colors and text formatting.
 INPUT_LINE_NUMBER in the command line above will be replaced by an integer
 representing which line should be at the top of the screen.'''))
 
+o('scrollback_pager_history_size', 10, option_type=size_mb, long_text=_('''
+Separate scrollback history size, used only for pager, in MB.
+This separate buffer is not available for interactive scrolling but will be
+prepended to the pager program when viewing scrollback.
+The current implementation stores one character in 4 bytes, so approximatively
+2500 lines per megabyte at 100 chars per line'''))
+
 o('wheel_scroll_multiplier', 5.0, long_text=_('''
 Modify the amount scrolled by the mouse wheel. Note this is only used for low
 precision scrolling devices, not for high precision scrolling on platforms such

kitty/data-types.h

@@ -185,7 +185,7 @@ typedef struct {
 
     index_type xnum, ynum, num_segments;
     HistoryBufSegment *segments;
-    PagerHistoryBuf pagerhist;
+    PagerHistoryBuf *pagerhist;
     Line *line;
     index_type start_of_data, count;
 } HistoryBuf;
@@ -262,7 +262,7 @@ const char* base64_decode(const uint32_t *src, size_t src_sz, uint8_t *dest, siz
 Line* alloc_line();
 Cursor* alloc_cursor();
 LineBuf* alloc_linebuf(unsigned int, unsigned int);
-HistoryBuf* alloc_historybuf(unsigned int, unsigned int);
+HistoryBuf* alloc_historybuf(unsigned int, unsigned int, unsigned int);
 ColorProfile* alloc_color_profile();
 PyObject* create_256_color_table();
 PyObject* parse_bytes_dump(PyObject UNUSED *, PyObject *);

kitty/history.c

@@ -54,12 +54,24 @@ attrptr(HistoryBuf *self, index_type y) {
     seg_ptr(line_attrs, 1);
 }
 
+static inline PagerHistoryBuf*
+alloc_pagerhist(unsigned int pagerhist_sz) {
+    PagerHistoryBuf *ph;
+    if (!pagerhist_sz) return NULL;
+    pagerhist_sz *= 1024*1024;
+    ph = PyMem_Calloc(1, sizeof(PagerHistoryBuf));
+    ph->bufsize = pagerhist_sz / sizeof(Py_UCS4);
+    ph->buffer = PyMem_RawMalloc(pagerhist_sz);
+    if (!ph->buffer) { PyMem_Free(ph); return NULL; }
+    return ph;
+}
+
 static PyObject *
 new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
     HistoryBuf *self;
-    unsigned int xnum = 1, ynum = 1;
+    unsigned int xnum = 1, ynum = 1, pagerhist_sz = 0;
 
-    if (!PyArg_ParseTuple(args, "II", &ynum, &xnum)) return NULL;
+    if (!PyArg_ParseTuple(args, "II|I", &ynum, &xnum, &pagerhist_sz)) return NULL;
 
     if (xnum == 0 || ynum == 0) {
         PyErr_SetString(PyExc_ValueError, "Cannot create an empty history buffer");
@@ -74,10 +86,7 @@ new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
         add_segment(self);
         self->line = alloc_line();
         self->line->xnum = xnum;
-        self->pagerhist.start = self->pagerhist.end = self->pagerhist.bufend = 0;
+        self->pagerhist = alloc_pagerhist(pagerhist_sz);
-        self->pagerhist.buffer = PyMem_RawMalloc(1024*1024*10);
-        self->pagerhist.bufsize = 1024*1024*10 / sizeof(Py_UCS4);
-        // abort if allocation failed?
     }
 
     return (PyObject*)self;
@@ -92,7 +101,8 @@ dealloc(HistoryBuf* self) {
         PyMem_Free(self->segments[i].line_attrs);
     }
     PyMem_Free(self->segments);
-    PyMem_Free(self->pagerhist.buffer);
+    if (self->pagerhist) PyMem_Free(self->pagerhist->buffer);
+    PyMem_Free(self->pagerhist);
     Py_TYPE(self)->tp_free((PyObject*)self);
 }
 
@@ -139,8 +149,8 @@ historybuf_clear(HistoryBuf *self) {
 
 static inline void
 pagerhist_push(HistoryBuf *self) {
-    PagerHistoryBuf *ph = &self->pagerhist;
+    PagerHistoryBuf *ph = self->pagerhist;
-    if (!ph->buffer) return;
+    if (!ph) return;
     Line l = {.xnum=self->xnum};
     init_line(self, self->start_of_data, &l);
     if (ph->start != ph->end && !l.continued) {
@@ -241,10 +251,10 @@ get_line(HistoryBuf *self, index_type y, Line *l) { init_line(self, index_of(sel
 
 static PyObject *
 pagerhist_as_text(HistoryBuf *self, PyObject *callback) {
-    PagerHistoryBuf *ph = &self->pagerhist;
+    PagerHistoryBuf *ph = self->pagerhist;
     PyObject *ret = NULL, *t = NULL;
     Py_UCS4 *buf = NULL;
-    if (!ph->buffer) Py_RETURN_NONE;
+    if (!ph) Py_RETURN_NONE;
 
     index_type num = (ph->bufend ? ph->bufend : ph->end) - ph->start;
     buf = ph->buffer + ph->start;
@@ -340,8 +350,8 @@ PyTypeObject HistoryBuf_Type = {
 
 INIT_TYPE(HistoryBuf)
 
-HistoryBuf *alloc_historybuf(unsigned int lines, unsigned int columns) {
+HistoryBuf *alloc_historybuf(unsigned int lines, unsigned int columns, unsigned int pagerhist_sz) {
-    return (HistoryBuf*)new(&HistoryBuf_Type, Py_BuildValue("II", lines, columns), NULL);
+    return (HistoryBuf*)new(&HistoryBuf_Type, Py_BuildValue("III", lines, columns, pagerhist_sz), NULL);
 }
 // }}}
 

kitty/screen.c

@@ -107,7 +107,7 @@ new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
         self->color_profile = alloc_color_profile();
         self->main_linebuf = alloc_linebuf(lines, columns); self->alt_linebuf = alloc_linebuf(lines, columns);
         self->linebuf = self->main_linebuf;
-        self->historybuf = alloc_historybuf(MAX(scrollback, lines), columns);
+        self->historybuf = alloc_historybuf(MAX(scrollback, lines), columns, OPT(scrollback_pager_history_size));
         self->main_grman = grman_alloc();
         self->alt_grman = grman_alloc();
         self->grman = self->main_grman;
@@ -165,8 +165,9 @@ screen_dirty_sprite_positions(Screen *self) {
 
 static inline HistoryBuf*
 realloc_hb(HistoryBuf *old, unsigned int lines, unsigned int columns) {
-    HistoryBuf *ans = alloc_historybuf(lines, columns);
+    HistoryBuf *ans = alloc_historybuf(lines, columns, 0);
     if (ans == NULL) { PyErr_NoMemory(); return NULL; }
+    ans->pagerhist = old->pagerhist; old->pagerhist = NULL;
     historybuf_rewrap(old, ans);
     return ans;
 }

kitty/state.c

@@ -367,6 +367,7 @@ PYWRAP1(set_options) {
     S(dynamic_background_opacity, PyObject_IsTrue);
     S(inactive_text_alpha, PyFloat_AsDouble);
     S(window_padding_width, PyFloat_AsDouble);
+    S(scrollback_pager_history_size, PyLong_AsLong);
     S(cursor_shape, PyLong_AsLong);
     S(url_style, PyLong_AsUnsignedLong);
     S(tab_bar_edge, PyLong_AsLong);

kitty/state.h

@@ -19,6 +19,7 @@ typedef struct {
     unsigned int open_url_modifiers;
     unsigned int rectangle_select_modifiers;
     unsigned int url_style;
+    unsigned int scrollback_pager_history_size;
     char_type select_by_word_characters[256]; size_t select_by_word_characters_count;
     color_type url_color, background, active_border_color, inactive_border_color, bell_border_color;
     double repaint_delay, input_delay;