reftable: add a heap-based priority queue for reftable records
This is needed to create a merged view multiple reftables Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Han-Wen Nienhuys committed
Oct 7, 2021 at 20:25 UTC
3b34f636df9e6c32c2e9b819cd5ad907497c62b7
6 files changed
+224
Makefile
+2
@@ -2462,6 +2462,7 @@ REFTABLE_OBJS += reftable/block.o
2462
REFTABLE_OBJS += reftable/blocksource.o
2463
REFTABLE_OBJS += reftable/iter.o
2464
REFTABLE_OBJS += reftable/publicbasics.o
2465
+REFTABLE_OBJS += reftable/pq.o
2466
REFTABLE_OBJS += reftable/reader.o
2467
REFTABLE_OBJS += reftable/record.o
2468
REFTABLE_OBJS += reftable/refname.o
@@ -2472,6 +2473,7 @@ REFTABLE_OBJS += reftable/writer.o
2473
2474
REFTABLE_TEST_OBJS += reftable/basics_test.o
2475
REFTABLE_TEST_OBJS += reftable/block_test.o
2476
+REFTABLE_TEST_OBJS += reftable/pq_test.o
2477
REFTABLE_TEST_OBJS += reftable/record_test.o
2478
REFTABLE_TEST_OBJS += reftable/readwrite_test.o
2479
REFTABLE_TEST_OBJS += reftable/test_framework.o
reftable/pq.c
new
+105
@@ -0,0 +1,105 @@
1
+/*
2
+Copyright 2020 Google LLC
3
+
4
+Use of this source code is governed by a BSD-style
5
+license that can be found in the LICENSE file or at
6
+https://developers.google.com/open-source/licenses/bsd
7
+*/
8
+
9
+#include "pq.h"
10
+
11
+#include "reftable-record.h"
12
+#include "system.h"
13
+#include "basics.h"
14
+
15
+int pq_less(struct pq_entry *a, struct pq_entry *b)
16
+{
17
+ struct strbuf ak = STRBUF_INIT;
18
+ struct strbuf bk = STRBUF_INIT;
19
+ int cmp = 0;
20
+ reftable_record_key(&a->rec, &ak);
21
+ reftable_record_key(&b->rec, &bk);
22
+
23
+ cmp = strbuf_cmp(&ak, &bk);
24
+
25
+ strbuf_release(&ak);
26
+ strbuf_release(&bk);
27
+
28
+ if (cmp == 0)
29
+ return a->index > b->index;
30
+
31
+ return cmp < 0;
32
+}
33
+
34
+struct pq_entry merged_iter_pqueue_top(struct merged_iter_pqueue pq)
35
+{
36
+ return pq.heap[0];
37
+}
38
+
39
+int merged_iter_pqueue_is_empty(struct merged_iter_pqueue pq)
40
+{
41
+ return pq.len == 0;
42
+}
43
+
44
+struct pq_entry merged_iter_pqueue_remove(struct merged_iter_pqueue *pq)
45
+{
46
+ int i = 0;
47
+ struct pq_entry e = pq->heap[0];
48
+ pq->heap[0] = pq->heap[pq->len - 1];
49
+ pq->len--;
50
+
51
+ i = 0;
52
+ while (i < pq->len) {
53
+ int min = i;
54
+ int j = 2 * i + 1;
55
+ int k = 2 * i + 2;
56
+ if (j < pq->len && pq_less(&pq->heap[j], &pq->heap[i])) {
57
+ min = j;
58
+ }
59
+ if (k < pq->len && pq_less(&pq->heap[k], &pq->heap[min])) {
60
+ min = k;
61
+ }
62
+
63
+ if (min == i) {
64
+ break;
65
+ }
66
+
67
+ SWAP(pq->heap[i], pq->heap[min]);
68
+ i = min;
69
+ }
70
+
71
+ return e;
72
+}
73
+
74
+void merged_iter_pqueue_add(struct merged_iter_pqueue *pq, struct pq_entry e)
75
+{
76
+ int i = 0;
77
+ if (pq->len == pq->cap) {
78
+ pq->cap = 2 * pq->cap + 1;
79
+ pq->heap = reftable_realloc(pq->heap,
80
+ pq->cap * sizeof(struct pq_entry));
81
+ }
82
+
83
+ pq->heap[pq->len++] = e;
84
+ i = pq->len - 1;
85
+ while (i > 0) {
86
+ int j = (i - 1) / 2;
87
+ if (pq_less(&pq->heap[j], &pq->heap[i])) {
88
+ break;
89
+ }
90
+
91
+ SWAP(pq->heap[j], pq->heap[i]);
92
+
93
+ i = j;
94
+ }
95
+}
96
+
97
+void merged_iter_pqueue_release(struct merged_iter_pqueue *pq)
98
+{
99
+ int i = 0;
100
+ for (i = 0; i < pq->len; i++) {
101
+ reftable_record_destroy(&pq->heap[i].rec);
102
+ }
103
+ FREE_AND_NULL(pq->heap);
104
+ pq->len = pq->cap = 0;
105
+}
reftable/pq.h
new
+33
@@ -0,0 +1,33 @@
1
+/*
2
+Copyright 2020 Google LLC
3
+
4
+Use of this source code is governed by a BSD-style
5
+license that can be found in the LICENSE file or at
6
+https://developers.google.com/open-source/licenses/bsd
7
+*/
8
+
9
+#ifndef PQ_H
10
+#define PQ_H
11
+
12
+#include "record.h"
13
+
14
+struct pq_entry {
15
+ int index;
16
+ struct reftable_record rec;
17
+};
18
+
19
+struct merged_iter_pqueue {
20
+ struct pq_entry *heap;
21
+ size_t len;
22
+ size_t cap;
23
+};
24
+
25
+struct pq_entry merged_iter_pqueue_top(struct merged_iter_pqueue pq);
26
+int merged_iter_pqueue_is_empty(struct merged_iter_pqueue pq);
27
+void merged_iter_pqueue_check(struct merged_iter_pqueue pq);
28
+struct pq_entry merged_iter_pqueue_remove(struct merged_iter_pqueue *pq);
29
+void merged_iter_pqueue_add(struct merged_iter_pqueue *pq, struct pq_entry e);
30
+void merged_iter_pqueue_release(struct merged_iter_pqueue *pq);
31
+int pq_less(struct pq_entry *a, struct pq_entry *b);
32
+
33
+#endif
reftable/pq_test.c
new
+82
@@ -0,0 +1,82 @@
1
+/*
2
+Copyright 2020 Google LLC
3
+
4
+Use of this source code is governed by a BSD-style
5
+license that can be found in the LICENSE file or at
6
+https://developers.google.com/open-source/licenses/bsd
7
+*/
8
+
9
+#include "system.h"
10
+
11
+#include "basics.h"
12
+#include "constants.h"
13
+#include "pq.h"
14
+#include "record.h"
15
+#include "reftable-tests.h"
16
+#include "test_framework.h"
17
+
18
+void merged_iter_pqueue_check(struct merged_iter_pqueue pq)
19
+{
20
+ int i;
21
+ for (i = 1; i < pq.len; i++) {
22
+ int parent = (i - 1) / 2;
23
+
24
+ EXPECT(pq_less(&pq.heap[parent], &pq.heap[i]));
25
+ }
26
+}
27
+
28
+static void test_pq(void)
29
+{
30
+ char *names[54] = { NULL };
31
+ int N = ARRAY_SIZE(names) - 1;
32
+
33
+ struct merged_iter_pqueue pq = { NULL };
34
+ const char *last = NULL;
35
+
36
+ int i = 0;
37
+ for (i = 0; i < N; i++) {
38
+ char name[100];
39
+ snprintf(name, sizeof(name), "%02d", i);
40
+ names[i] = xstrdup(name);
41
+ }
42
+
43
+ i = 1;
44
+ do {
45
+ struct reftable_record rec =
46
+ reftable_new_record(BLOCK_TYPE_REF);
47
+ struct pq_entry e = { 0 };
48
+
49
+ reftable_record_as_ref(&rec)->refname = names[i];
50
+ e.rec = rec;
51
+ merged_iter_pqueue_add(&pq, e);
52
+ merged_iter_pqueue_check(pq);
53
+ i = (i * 7) % N;
54
+ } while (i != 1);
55
+
56
+ while (!merged_iter_pqueue_is_empty(pq)) {
57
+ struct pq_entry e = merged_iter_pqueue_remove(&pq);
58
+ struct reftable_ref_record *ref =
59
+ reftable_record_as_ref(&e.rec);
60
+
61
+ merged_iter_pqueue_check(pq);
62
+
63
+ if (last) {
64
+ EXPECT(strcmp(last, ref->refname) < 0);
65
+ }
66
+ last = ref->refname;
67
+ ref->refname = NULL;
68
+ reftable_free(ref);
69
+ }
70
+
71
+ for (i = 0; i < N; i++) {
72
+ reftable_free(names[i]);
73
+ }
74
+
75
+ merged_iter_pqueue_release(&pq);
76
+}
77
+
78
+int pq_test_main(int argc, const char *argv[])
79
+{
80
+ RUN_TEST(test_pq);
81
+ return 0;
82
+}
reftable/reftable-tests.h
+1
@@ -12,6 +12,7 @@ https://developers.google.com/open-source/licenses/bsd
12
int basics_test_main(int argc, const char **argv);
13
int block_test_main(int argc, const char **argv);
14
int merged_test_main(int argc, const char **argv);
15
+int pq_test_main(int argc, const char **argv);
16
int record_test_main(int argc, const char **argv);
17
int refname_test_main(int argc, const char **argv);
18
int readwrite_test_main(int argc, const char **argv);
t/helper/test-reftable.c
+1
@@ -5,6 +5,7 @@ int cmd__reftable(int argc, const char **argv)
5
{
6
basics_test_main(argc, argv);
7
block_test_main(argc, argv);
8
+ pq_test_main(argc, argv);
9
record_test_main(argc, argv);
10
readwrite_test_main(argc, argv);
11
tree_test_main(argc, argv);