From c056df223ee830067daa297aa4d6224eb67b310f Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 16 Jul 2024 07:43:50 +0530
Subject: [PATCH] Nicer way to prevent defrag

---
 kitty/disk-cache.c      | 8 ++++++--
 kitty_tests/graphics.py | 7 ++++---
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/kitty/disk-cache.c b/kitty/disk-cache.c
index 456aca1cf..5cb213b98 100644
--- a/kitty/disk-cache.c
+++ b/kitty/disk-cache.c
@@ -77,6 +77,7 @@ typedef struct {
     char *cache_dir;
     int cache_file_fd;
     Py_ssize_t small_hole_threshold;
+    unsigned int defrag_factor;
     pthread_mutex_t lock;
     pthread_t write_thread;
     bool thread_started, lock_inited, loop_data_inited, shutting_down, fully_initialized;
@@ -96,6 +97,7 @@ new_diskcache_object(PyTypeObject *type, PyObject UNUSED *args, PyObject UNUSED
     if (self) {
         self->cache_file_fd = -1;
         self->small_hole_threshold = 512;
+        self->defrag_factor = 2;
     }
     return (PyObject*) self;
 }
@@ -304,7 +306,7 @@ find_hole_to_use(DiskCache *self, const off_t required_sz) {
 static inline bool
 needs_defrag(DiskCache *self) {
     off_t size_on_disk = size_of_cache_file(self);
-    return self->total_size && size_on_disk > 0 && (size_t)size_on_disk > self->total_size * 2;
+    return self->total_size && size_on_disk > 0 && (size_t)size_on_disk > self->total_size * self->defrag_factor;
 }
 
 static void
@@ -453,7 +455,8 @@ write_loop(void *data) {
             continue;
         } else if (!count) {
             mutex(lock);
-            if (self->cache_file_fd > -1) {
+            count = vt_size(&self->map);
+            if (!count && self->cache_file_fd > -1) {
                 if (ftruncate(self->cache_file_fd, 0) == 0) lseek(self->cache_file_fd, 0, SEEK_END);
             }
             mutex(unlock);
@@ -916,6 +919,7 @@ static PyMethodDef methods[] = {
 static PyMemberDef members[] = {
     {"total_size", T_ULONGLONG, offsetof(DiskCache, total_size), READONLY, "total_size"},
     {"small_hole_threshold", T_PYSSIZET, offsetof(DiskCache, small_hole_threshold), 0, "small_hole_threshold"},
+    {"defrag_factor", T_UINT, offsetof(DiskCache, defrag_factor), 0, "defrag_factor"},
     {NULL},
 };
 
diff --git a/kitty_tests/graphics.py b/kitty_tests/graphics.py
index 77ec1fe56..b2e797794 100644
--- a/kitty_tests/graphics.py
+++ b/kitty_tests/graphics.py
@@ -233,11 +233,12 @@ class TestGraphics(BaseTest):
             for key, val in data.items():
                 self.ae(dc.get(key_as_bytes(key)), val)
 
-        def reset(small_hole_threshold=0):
+        def reset(small_hole_threshold=0, defrag_factor=2):
             nonlocal dc, data, s
             s = self.create_screen()
             dc = s.grman.disk_cache
             dc.small_hole_threshold = small_hole_threshold
+            dc.defrag_factor = defrag_factor
             data = {}
 
         holes_to_create = 2, 4, 6, 8
@@ -342,8 +343,8 @@ class TestGraphics(BaseTest):
         self.ae(sz, dc.size_on_disk())
 
         # test hole coalescing
-        reset()
-        for i in range(1, 8):
+        reset(defrag_factor=20)
+        for i in range(1, 6):
             self.assertIsNone(add(i, str(i)*i))
             dc.wait_for_write()
         remove(2)