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

1 files 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