git: 89d5cbb82294 - main - libnv: optimize nvlist size calculation
Mariusz Zaborski
oshogbo at FreeBSD.org
Fri Jun 11 15:51:52 UTC 2021
The branch main has been updated by oshogbo:
URL: https://cgit.FreeBSD.org/src/commit/?id=89d5cbb82294c8624e66f920d50353057ccab14b
commit 89d5cbb82294c8624e66f920d50353057ccab14b
Author: Mariusz Zaborski <oshogbo at FreeBSD.org>
AuthorDate: 2021-06-11 15:35:36 +0000
Commit: Mariusz Zaborski <oshogbo at FreeBSD.org>
CommitDate: 2021-06-11 15:51:29 +0000
libnv: optimize nvlist size calculation
If we had a multiple nvlist, during nvlist_pack, we calculated the size
of every nvlist separately. For example, if we had a nvlist with three
nodes each containing another (A contains B, and B contains C), we first
calculated the size of nvlist A (which contains B, C), then we calculate
the size of B (which contains C, notice that we already did the
calculation of B, when we calculate A), and finally C. This means that
this calculation was O(N!). This was done because each time we pack
nvlist, we have to put its size in the header
(the separate header for A, B, and C).
To not break the ABI and to reduce the complexity of nvlist_size,
instead of calculating the nvlist size when requested,
we track the size of each nvlist.
Reported by: pjd, kp
Tested by: kp
---
sys/contrib/libnv/nvlist.c | 124 +++++++++++++++++++--------------------------
1 file changed, 53 insertions(+), 71 deletions(-)
diff --git a/sys/contrib/libnv/nvlist.c b/sys/contrib/libnv/nvlist.c
index 311325d822ce..31ab62abeb67 100644
--- a/sys/contrib/libnv/nvlist.c
+++ b/sys/contrib/libnv/nvlist.c
@@ -99,6 +99,7 @@ struct nvlist {
int nvl_magic;
int nvl_error;
int nvl_flags;
+ size_t nvl_datasize;
nvpair_t *nvl_parent;
nvpair_t *nvl_array_next;
struct nvl_head nvl_head;
@@ -139,6 +140,7 @@ nvlist_create(int flags)
nvl->nvl_flags = flags;
nvl->nvl_parent = NULL;
nvl->nvl_array_next = NULL;
+ nvl->nvl_datasize = sizeof(struct nvlist_header);
TAILQ_INIT(&nvl->nvl_head);
nvl->nvl_magic = NVLIST_MAGIC;
@@ -247,6 +249,51 @@ nvlist_set_array_next(nvlist_t *nvl, nvpair_t *ele)
nvl->nvl_array_next = ele;
}
+static void
+nvlist_update_size(nvlist_t *nvl, nvpair_t *new, ssize_t mul)
+{
+ ssize_t size;
+ size_t nitems;
+ const nvlist_t *nvlistnew;
+ const nvlist_t * const *nvlarray;
+ nvlist_t *parent;
+ unsigned int ii;
+
+ NVLIST_ASSERT(nvl);
+ NVPAIR_ASSERT(new);
+ PJDLOG_ASSERT(mul == 1 || mul == -1);
+
+ size = nvpair_header_size();
+ size += strlen(nvpair_name(new)) + 1;
+
+ if (nvpair_type(new) == NV_TYPE_NVLIST) {
+ nvlistnew = nvpair_get_nvlist(new);
+ size += nvlistnew->nvl_datasize;
+ size += nvpair_header_size() + 1;
+ } else if (nvpair_type(new) == NV_TYPE_NVLIST_ARRAY) {
+ nvlarray = nvpair_get_nvlist_array(new, &nitems);
+ PJDLOG_ASSERT(nitems > 0);
+
+ size += (nvpair_header_size() + 1) * nitems;
+ for (ii = 0; ii < nitems; ii++) {
+ PJDLOG_ASSERT(nvlarray[ii]->nvl_error == 0);
+ size += nvlarray[ii]->nvl_datasize;
+ }
+ } else {
+ size += nvpair_size(new);
+ }
+
+ size *= mul;
+
+ nvl->nvl_datasize += size;
+
+ parent = nvl;
+ while ((parent = __DECONST(nvlist_t *,
+ nvlist_get_parent(parent, NULL))) != NULL) {
+ parent->nvl_datasize += size;
+ }
+}
+
nvpair_t *
nvlist_get_array_next_nvpair(nvlist_t *nvl)
{
@@ -640,78 +687,8 @@ nvlist_fdump(const nvlist_t *nvl, FILE *fp)
size_t
nvlist_size(const nvlist_t *nvl)
{
- const nvlist_t *tmpnvl;
- const nvlist_t * const *nvlarray;
- const nvpair_t *nvp, *tmpnvp;
- void *cookie;
- size_t size, nitems;
- unsigned int ii;
-
- NVLIST_ASSERT(nvl);
- PJDLOG_ASSERT(nvl->nvl_error == 0);
- size = sizeof(struct nvlist_header);
- nvp = nvlist_first_nvpair(nvl);
- while (nvp != NULL) {
- size += nvpair_header_size();
- size += strlen(nvpair_name(nvp)) + 1;
- if (nvpair_type(nvp) == NV_TYPE_NVLIST) {
- size += sizeof(struct nvlist_header);
- size += nvpair_header_size() + 1;
- tmpnvl = nvpair_get_nvlist(nvp);
- PJDLOG_ASSERT(tmpnvl->nvl_error == 0);
- tmpnvp = nvlist_first_nvpair(tmpnvl);
- if (tmpnvp != NULL) {
- nvl = tmpnvl;
- nvp = tmpnvp;
- continue;
- }
- } else if (nvpair_type(nvp) == NV_TYPE_NVLIST_ARRAY) {
- nvlarray = nvpair_get_nvlist_array(nvp, &nitems);
- PJDLOG_ASSERT(nitems > 0);
-
- size += (nvpair_header_size() + 1) * nitems;
- size += sizeof(struct nvlist_header) * nitems;
-
- tmpnvl = NULL;
- tmpnvp = NULL;
- for (ii = 0; ii < nitems; ii++) {
- PJDLOG_ASSERT(nvlarray[ii]->nvl_error == 0);
- tmpnvp = nvlist_first_nvpair(nvlarray[ii]);
- if (tmpnvp != NULL) {
- tmpnvl = nvlarray[ii];
- break;
- }
- }
- if (tmpnvp != NULL) {
- nvp = tmpnvp;
- nvl = tmpnvl;
- continue;
- }
-
- } else {
- size += nvpair_size(nvp);
- }
-
- while ((nvp = nvlist_next_nvpair(nvl, nvp)) == NULL) {
- do {
- cookie = NULL;
- nvl = nvlist_get_pararr(nvl, &cookie);
- if (nvl == NULL)
- goto out;
- if (nvlist_in_array(nvl) && cookie == NULL) {
- nvp = nvlist_first_nvpair(nvl);
- } else {
- nvp = cookie;
- }
- } while (nvp == NULL);
- if (nvlist_in_array(nvl) && cookie == NULL)
- break;
- }
- }
-
-out:
- return (size);
+ return (nvl->nvl_datasize);
}
#ifndef _KERNEL
@@ -1483,6 +1460,7 @@ nvlist_add_nvpair(nvlist_t *nvl, const nvpair_t *nvp)
}
nvpair_insert(&nvl->nvl_head, newnvp, nvl);
+ nvlist_update_size(nvl, newnvp, 1);
}
void
@@ -1631,10 +1609,12 @@ nvlist_append_##type##_array(nvlist_t *nvl, const char *name, vtype value)\
nvlist_add_##type##_array(nvl, name, &value, 1); \
return; \
} \
+ nvlist_update_size(nvl, nvp, -1); \
if (nvpair_append_##type##_array(nvp, value) == -1) { \
nvl->nvl_error = ERRNO_OR_DEFAULT(ENOMEM); \
ERRNO_SET(nvl->nvl_error); \
} \
+ nvlist_update_size(nvl, nvp, 1); \
}
NVLIST_APPEND_ARRAY(const bool, bool, BOOL)
@@ -1669,6 +1649,7 @@ nvlist_move_nvpair(nvlist_t *nvl, nvpair_t *nvp)
}
nvpair_insert(&nvl->nvl_head, nvp, nvl);
+ nvlist_update_size(nvl, nvp, 1);
return (true);
}
@@ -2020,6 +2001,7 @@ nvlist_remove_nvpair(nvlist_t *nvl, nvpair_t *nvp)
PJDLOG_ASSERT(nvpair_nvlist(nvp) == nvl);
nvpair_remove(&nvl->nvl_head, nvp, nvl);
+ nvlist_update_size(nvl, nvp, -1);
}
void
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