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Fix bug where Buffers were never freed

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The issue was that, when reiniting Buffers, the intrusive linkedlist
node was clobbered and we lost reference to it. That meant most of the
Buffers would be memory leaks. Now, we save the node during
reinitializion.
This commit is contained in:
Ben Buhse 2026-03-06 11:37:21 -06:00
commit 411f679491
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GPG key ID: 7916ACFCD38FD0B4
3 changed files with 14 additions and 5 deletions
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9
src/Buffer.zig
View file

@ -76,6 +76,15 @@ pub fn init(shm: *wl.Shm, width: u31, height: u31) !Buffer {
};
}
/// Re-initialize this buffer with new dimensions, preserving its position in
/// any intrusive linked list. Equivalent to deinit + init but keeps node intact.
pub fn reinit(buffer: *Buffer, shm: *wl.Shm, width: u31, height: u31) !void {
const saved_node = buffer.node;
buffer.deinit();
buffer.* = try Buffer.init(shm, width, height);
buffer.node = saved_node;
}
pub fn deinit(buffer: *Buffer) void {
_ = buffer.pixman_image.unref();
buffer.wl_buffer.destroy();

9
src/BufferPool.zig
View file

@ -37,7 +37,7 @@ pub fn deinit(buffer_pool: *BufferPool) void {
/// Get a buffer with the specified dimensions. If possible, an idle buffer is
/// reused, otherwise a new one is created.
pub fn nextBuffer(buffer_pool: *BufferPool, wl_shm: *wl.Shm, width: u31, height: u31) !*Buffer {
log.debug("looking for buffer with dimensions {}x{}, total existing buffers: {}", .{ width, height, buffer_pool.len });
log.debug("Looking for buffer with dimensions {}x{}, total existing buffers: {}", .{ width, height, buffer_pool.len });
defer {
// Clear up extra buffers
if (buffer_pool.len > max_buffer_multiplicity * buffer_pool.surface_count) {
@ -71,8 +71,7 @@ fn findSuitableBuffer(buffer_pool: *BufferPool, wl_shm: *wl.Shm, width: u31, hei
// No buffer has matching dimensions, however we do have an unbusy
// buffer which we can just re-init.
if (first_unbusy_buffer) |buffer| {
buffer.deinit();
buffer.* = try Buffer.init(wl_shm, width, height);
try buffer.reinit(wl_shm, width, height);
buffer.setListener();
return buffer;
}
@ -81,7 +80,7 @@ fn findSuitableBuffer(buffer_pool: *BufferPool, wl_shm: *wl.Shm, width: u31, hei
}
fn newBuffer(buffer_pool: *BufferPool, wl_shm: *wl.Shm, width: u31, height: u31) !*Buffer {
log.debug("creating new buffer {}x{}", .{ width, height });
log.debug("Creating new {}x{} buffer", .{ width, height });
const buffer = try utils.gpa.create(Buffer);
errdefer utils.gpa.destroy(buffer);
buffer.* = try Buffer.init(wl_shm, width, height);
@ -92,8 +91,8 @@ fn newBuffer(buffer_pool: *BufferPool, wl_shm: *wl.Shm, width: u31, height: u31)
}
fn cullBuffers(buffer_pool: *BufferPool) void {
log.debug("culling extra buffers", .{});
var overhead = buffer_pool.len - max_buffer_multiplicity * buffer_pool.surface_count;
log.debug("Culling extra buffers {d}->{d}", .{ buffer_pool.len, buffer_pool.surface_count });
var it = buffer_pool.buffers.first;
while (it) |node| {
if (overhead == 0) break;