1/* ----------------------------------------------------------------------------
2Copyright (c) 2019-2020 Microsoft Research, Daan Leijen
3This is free software; you can redistribute it and/or modify it under the
4terms of the MIT license. A copy of the license can be found in the file
5"LICENSE" at the root of this distribution.
6-----------------------------------------------------------------------------*/
7
8/* ----------------------------------------------------------------------------
9Concurrent bitmap that can set/reset sequences of bits atomically,
10represeted as an array of fields where each field is a machine word (`size_t`)
11
12There are two api's; the standard one cannot have sequences that cross
13between the bitmap fields (and a sequence must be <= MI_BITMAP_FIELD_BITS).
14(this is used in region allocation)
15
16The `_across` postfixed functions do allow sequences that can cross over
17between the fields. (This is used in arena allocation)
18---------------------------------------------------------------------------- */
19#pragma once
20#ifndef MI_BITMAP_H
21#define MI_BITMAP_H
22
23/* -----------------------------------------------------------
24 Bitmap definition
25----------------------------------------------------------- */
26
27#define MI_BITMAP_FIELD_BITS (8*MI_SIZE_SIZE)
28#define MI_BITMAP_FIELD_FULL (~((size_t)0)) // all bits set
29
30// An atomic bitmap of `size_t` fields
31typedef _Atomic(size_t) mi_bitmap_field_t;
32typedef mi_bitmap_field_t* mi_bitmap_t;
33
34// A bitmap index is the index of the bit in a bitmap.
35typedef size_t mi_bitmap_index_t;
36
37// Create a bit index.
38static inline mi_bitmap_index_t mi_bitmap_index_create(size_t idx, size_t bitidx) {
39 mi_assert_internal(bitidx < MI_BITMAP_FIELD_BITS);
40 return (idx*MI_BITMAP_FIELD_BITS) + bitidx;
41}
42
43// Create a bit index.
44static inline mi_bitmap_index_t mi_bitmap_index_create_from_bit(size_t full_bitidx) {
45 return mi_bitmap_index_create(full_bitidx / MI_BITMAP_FIELD_BITS, full_bitidx % MI_BITMAP_FIELD_BITS);
46}
47
48// Get the field index from a bit index.
49static inline size_t mi_bitmap_index_field(mi_bitmap_index_t bitmap_idx) {
50 return (bitmap_idx / MI_BITMAP_FIELD_BITS);
51}
52
53// Get the bit index in a bitmap field
54static inline size_t mi_bitmap_index_bit_in_field(mi_bitmap_index_t bitmap_idx) {
55 return (bitmap_idx % MI_BITMAP_FIELD_BITS);
56}
57
58// Get the full bit index
59static inline size_t mi_bitmap_index_bit(mi_bitmap_index_t bitmap_idx) {
60 return bitmap_idx;
61}
62
63/* -----------------------------------------------------------
64 Claim a bit sequence atomically
65----------------------------------------------------------- */
66
67// Try to atomically claim a sequence of `count` bits in a single
68// field at `idx` in `bitmap`. Returns `true` on success.
69bool _mi_bitmap_try_find_claim_field(mi_bitmap_t bitmap, size_t idx, const size_t count, mi_bitmap_index_t* bitmap_idx);
70
71// Starts at idx, and wraps around to search in all `bitmap_fields` fields.
72// For now, `count` can be at most MI_BITMAP_FIELD_BITS and will never cross fields.
73bool _mi_bitmap_try_find_from_claim(mi_bitmap_t bitmap, const size_t bitmap_fields, const size_t start_field_idx, const size_t count, mi_bitmap_index_t* bitmap_idx);
74
75// Like _mi_bitmap_try_find_from_claim but with an extra predicate that must be fullfilled
76typedef bool (mi_cdecl *mi_bitmap_pred_fun_t)(mi_bitmap_index_t bitmap_idx, void* pred_arg);
77bool _mi_bitmap_try_find_from_claim_pred(mi_bitmap_t bitmap, const size_t bitmap_fields, const size_t start_field_idx, const size_t count, mi_bitmap_pred_fun_t pred_fun, void* pred_arg, mi_bitmap_index_t* bitmap_idx);
78
79// Set `count` bits at `bitmap_idx` to 0 atomically
80// Returns `true` if all `count` bits were 1 previously.
81bool _mi_bitmap_unclaim(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx);
82
83// Set `count` bits at `bitmap_idx` to 1 atomically
84// Returns `true` if all `count` bits were 0 previously. `any_zero` is `true` if there was at least one zero bit.
85bool _mi_bitmap_claim(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx, bool* any_zero);
86
87bool _mi_bitmap_is_claimed(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx);
88bool _mi_bitmap_is_any_claimed(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx);
89
90
91//--------------------------------------------------------------------------
92// the `_across` functions work on bitmaps where sequences can cross over
93// between the fields. This is used in arena allocation
94//--------------------------------------------------------------------------
95
96// Find `count` bits of zeros and set them to 1 atomically; returns `true` on success.
97// Starts at idx, and wraps around to search in all `bitmap_fields` fields.
98bool _mi_bitmap_try_find_from_claim_across(mi_bitmap_t bitmap, const size_t bitmap_fields, const size_t start_field_idx, const size_t count, mi_bitmap_index_t* bitmap_idx);
99
100// Set `count` bits at `bitmap_idx` to 0 atomically
101// Returns `true` if all `count` bits were 1 previously.
102bool _mi_bitmap_unclaim_across(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx);
103
104// Set `count` bits at `bitmap_idx` to 1 atomically
105// Returns `true` if all `count` bits were 0 previously. `any_zero` is `true` if there was at least one zero bit.
106bool _mi_bitmap_claim_across(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx, bool* pany_zero);
107
108bool _mi_bitmap_is_claimed_across(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx);
109bool _mi_bitmap_is_any_claimed_across(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx);
110
111#endif
112