/* * Copyright (c) 2015 Cisco and/or its affiliates. * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include <vppinfra/fheap.h> /* Fibonacci heaps. */ always_inline fheap_node_t * fheap_get_node (fheap_t * f, u32 i) { return i != ~0 ? vec_elt_at_index (f->nodes, i) : 0; } always_inline fheap_node_t * fheap_get_root (fheap_t * f) { return fheap_get_node (f, f->min_root); } static void fheap_validate (fheap_t * f) { fheap_node_t *n, *m; uword ni, si; if (!CLIB_DEBUG || !f->enable_validate) return; vec_foreach_index (ni, f->nodes) { n = vec_elt_at_index (f->nodes, ni); if (!n->is_valid) continue; /* Min root must have minimal key. */ m = vec_elt_at_index (f->nodes, f->min_root); ASSERT (n->key >= m->key); /* Min root must have no parent. */ if (ni == f->min_root) ASSERT (n->parent == ~0); /* Check sibling linkages. */ if (n->next_sibling == ~0) ASSERT (n->prev_sibling == ~0); else if (n->prev_sibling == ~0) ASSERT (n->next_sibling == ~0); else { fheap_node_t *prev, *next; u32 si = n->next_sibling, si_start = si; do { m = vec_elt_at_index (f->nodes, si); prev = vec_elt_at_index (f->nodes, m->prev_sibling); next = vec_elt_at_index (f->nodes, m->next_sibling); ASSERT (prev->next_sibling == si); ASSERT (next->prev_sibling == si); si = m->next_sibling; } while (si != si_start); } /* Loop through all siblings. */ { u32 n_siblings = 0; foreach_fheap_node_sibling (f, si, n->next_sibling, ( { m = vec_elt_at_index (f->nodes, si); /* All siblings must have same parent. */ ASSERT (m->parent == n-> parent); n_siblings += 1;} )); /* Either parent is non-empty or there are siblings present. */ if (n->parent == ~0 && ni != f->min_root) ASSERT (n_siblings > 0); } /* Loop through all children. */ { u32 found_first_child = n->first_child == ~0; u32 n_children = 0; foreach_fheap_node_sibling (f, si, n->first_child, ( { m = vec_elt_at_index (f->nodes, si); /* Children must have larger keys than their parent. */ ASSERT (m->key >= n->key); if (!found_first_child) found_first_child = si == n->first_child; n_children += 1;} )); /* Check that first child is present on list. */ ASSERT (found_first_child); /* Make sure rank is correct. */ ASSERT (n->rank == n_children); } } /* Increment serial number for each successful validate. Failure can be used as condition for gdb breakpoints. */ f->validate_serial++; } always_inline void fheap_node_add_sibling (fheap_t * f, u32 ni, u32 ni_to_add) { fheap_node_t *n = vec_elt_at_index (f->nodes, ni); fheap_node_t *n_to_add = vec_elt_at_index (f->nodes, ni_to_add); fheap_node_t *n_next = fheap_get_node (f, n->next_sibling); fheap_node_t *parent; /* Empty list? */ if (n->next_sibling == ~0) { ASSERT (n->prev_sibling == ~0); n->next_sibling = n->prev_sibling = ni_to_add; n_to_add->next_sibling = n_to_add->prev_sibling = ni; } else { /* Add node after existing node. */ n_to_add->prev_sibling = ni; n_to_add->next_sibling = n->next_sibling; n->next_sibling = ni_to_add; n_next->prev_sibling = ni_to_add; } n_to_add->parent = n->parent; parent = fheap_get_node (f, n->parent); if (parent) parent->rank += 1; } void fheap_add (fheap_t * f, u32 ni, u32 key) { fheap_node_t *r, *n; u32 ri; n = vec_elt_at_index (f->nodes, ni); memset (n, 0, sizeof (n[0])); n->parent = n->first_child = n->next_sibling = n->prev_sibling = ~0; n->key = key; r = fheap_get_root (f); ri = f->min_root; if (!r) { /* No root? Add node as new root. */ f->min_root = ni; } else { /* Add node as sibling of current root. */ fheap_node_add_sibling (f, ri, ni); /* New node may become new root. */ if (r->key > n->key) f->min_root = ni; } fheap_validate (f); } always_inline u32 fheap_node_remove_internal (fheap_t * f, u32 ni, u32 invalidate) { fheap_node_t *n = vec_elt_at_index (f->nodes, ni); u32 prev_ni = n->prev_sibling; u32 next_ni = n->next_sibling; u32 list_has_single_element = prev_ni == ni; fheap_node_t *prev = fheap_get_node (f, prev_ni); fheap_node_t *next = fheap_get_node (f, next_ni); fheap_node_t *p = fheap_get_node (f, n->parent); if (p) { ASSERT (p->rank > 0); p->rank -= 1; p->first_child = list_has_single_element ? ~0 : next_ni; } if (prev) { ASSERT (prev->next_sibling == ni); prev->next_sibling = next_ni; } if (next) { ASSERT (next->prev_sibling == ni); next->prev_sibling = prev_ni; } n->prev_sibling = n->next_sibling = ni; n->parent = ~0; n->is_valid = invalidate == 0; return list_has_single_element ? ~0 : next_ni; } always_inline u32 fheap_node_remove (fheap_t * f, u32 ni) { return fheap_node_remove_internal (f, ni, /* invalidate */ 0); } always_inline u32 fheap_node_remove_and_invalidate (fheap_t * f, u32 ni) { return fheap_node_remove_internal (f, ni, /* invalidate */ 1); } static void fheap_link_root (fheap_t * f, u32 ni) { fheap_node_t *n = vec_elt_at_index (f->nodes, ni); fheap_node_t *r, *lo, *hi; u32 ri, lo_i, hi_i, k; while (1) { k = n->rank; vec_validate_init_empty (f->root_list_by_rank, k, ~0); ri = f->root_list_by_rank[k]; r = fheap_get_node (f, ri); if (!r) { f->root_list_by_rank[k] = ni; return; } f->root_list_by_rank[k] = ~0; /* Sort n/r into lo/hi by their keys. */ lo = r, lo_i = ri; hi = n, hi_i = ni; if (hi->key < lo->key) { u32 ti; fheap_node_t *tn; ti = lo_i, tn = lo; lo = hi, lo_i = hi_i; hi = tn, hi_i = ti; } /* Remove larger key. */ fheap_node_remove (f, hi_i); /* Add larger key as child of smaller one. */ if (lo->first_child == ~0) { hi->parent = lo_i; lo->first_child = hi_i; lo->rank = 1; } else fheap_node_add_sibling (f, lo->first_child, hi_i); /* Following Fredman & Trajan: "When making a root node X a child of another node in a linking step, we unmark X". */ hi->is_marked = 0; ni = lo_i; n = lo; } } u32 fheap_del_min (fheap_t * f, u32 * min_key) { fheap_node_t *r = fheap_get_root (f); u32 to_delete_min_ri = f->min_root; u32 ri, ni; /* Empty heap? */ if (!r) return ~0; /* Root's children become siblings. Call this step a; see below. */ if (r->first_child != ~0) { u32 ci, cni, rni; fheap_node_t *c, *cn, *rn; /* Splice child & root circular lists together. */ ci = r->first_child; c = vec_elt_at_index (f->nodes, ci); cni = c->next_sibling; rni = r->next_sibling; cn = vec_elt_at_index (f->nodes, cni); rn = vec_elt_at_index (f->nodes, rni); r->next_sibling = cni; c->next_sibling = rni; cn->prev_sibling = to_delete_min_ri; rn->prev_sibling = ci; } /* Remove min root. */ ri = fheap_node_remove_and_invalidate (f, to_delete_min_ri); /* Find new min root from among siblings including the ones we've just added. */ f->min_root = ~0; if (ri != ~0) { u32 ri_last, ri_next, i, min_ds; r = fheap_get_node (f, ri); ri_last = r->prev_sibling; while (1) { /* Step a above can put children (with r->parent != ~0) on root list. */ r->parent = ~0; ri_next = r->next_sibling; fheap_link_root (f, ri); if (ri == ri_last) break; ri = ri_next; r = fheap_get_node (f, ri); } min_ds = ~0; vec_foreach_index (i, f->root_list_by_rank) { ni = f->root_list_by_rank[i]; if (ni == ~0) continue; f->root_list_by_rank[i] = ~0; r = fheap_get_node (f, ni); if (r->key < min_ds) { f->min_root = ni; min_ds = r->key; ASSERT (r->parent == ~0); } } } /* Return deleted min root. */ r = vec_elt_at_index (f->nodes, to_delete_min_ri); if (min_key) *min_key = r->key; fheap_validate (f); return to_delete_min_ri; } static void fheap_mark_parent (fheap_t * f, u32 pi) { fheap_node_t *p = vec_elt_at_index (f->nodes, pi); /* Parent is a root: do nothing. */ if (p->parent == ~0) return; /* If not marked, mark it. */ if (!p->is_marked) { p->is_marked = 1; return; } /* Its a previously marked, non-root parent. Cut edge to its parent and add to root list. */ fheap_node_remove (f, pi); fheap_node_add_sibling (f, f->min_root, pi); /* Unmark it since its now a root node. */ p->is_marked = 0; /* "Cascading cuts": check parent. */ if (p->parent != ~0) fheap_mark_parent (f, p->parent); } /* Set key to new smaller value. */ void fheap_decrease_key (fheap_t * f, u32 ni, u32 new_key) { fheap_node_t *n = vec_elt_at_index (f->nodes, ni); fheap_node_t *r = fheap_get_root (f); n->key = new_key; if (n->parent != ~0) { fheap_mark_parent (f, n->parent); /* Remove node and add to root list. */ fheap_node_remove (f, ni); fheap_node_add_sibling (f, f->min_root, ni); } if (n->key < r->key) f->min_root = ni; fheap_validate (f); } void fheap_del (fheap_t * f, u32 ni) { fheap_node_t *n; n = vec_elt_at_index (f->nodes, ni); if (n->parent == ~0) { ASSERT (ni == f->min_root); fheap_del_min (f, 0); } else { u32 ci; fheap_mark_parent (f, n->parent); /* Add children to root list. */ foreach_fheap_node_sibling (f, ci, n->first_child, ( { fheap_node_remove (f, ci); fheap_node_add_sibling (f, f->min_root, ci);} )); fheap_node_remove_and_invalidate (f, ni); } fheap_validate (f); } /* * fd.io coding-style-patch-verification: ON * * Local Variables: * eval: (c-set-style "gnu") * End: */