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std: ArenaAllocator tries to resize before allocating

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Closes #5116
This commit is contained in:
LemonBoy 2020-09-25 00:21:57 +02:00
parent bd89bd6fdb
commit bd9003ed5b
2 changed files with 22 additions and 6 deletions
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7
lib/std/heap.zig
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@ -919,6 +919,13 @@ pub fn testAllocator(base_allocator: *mem.Allocator) !void {
const zero_bit_ptr = try allocator.create(u0);
zero_bit_ptr.* = 0;
allocator.destroy(zero_bit_ptr);
const oversize = try allocator.allocAdvanced(u32, null, 5, .at_least);
testing.expect(oversize.len >= 5);
for (oversize) |*item| {
item.* = 0xDEADBEEF;
}
allocator.free(oversize);
}
pub fn testAllocatorAligned(base_allocator: *mem.Allocator, comptime alignment: u29) !void {

21
lib/std/heap/arena_allocator.zig
View File

@ -75,13 +75,22 @@ pub const ArenaAllocator = struct {
const adjusted_addr = mem.alignForward(addr, ptr_align);
const adjusted_index = self.state.end_index + (adjusted_addr - addr);
const new_end_index = adjusted_index + n;
if (new_end_index > cur_buf.len) {
cur_node = try self.createNode(cur_buf.len, n + ptr_align);
continue;
if (new_end_index <= cur_buf.len) {
const result = cur_buf[adjusted_index..new_end_index];
self.state.end_index = new_end_index;
return result;
}
const result = cur_buf[adjusted_index..new_end_index];
self.state.end_index = new_end_index;
return result;
const bigger_buf_size = @sizeOf(BufNode) + new_end_index;
// Try to grow the buffer in-place
cur_node.data = self.child_allocator.resize(cur_node.data, bigger_buf_size) catch |err| switch (err) {
error.OutOfMemory => {
// Allocate a new node if that's not possible
cur_node = try self.createNode(cur_buf.len, n + ptr_align);
continue;
},
};
}
}