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https://gitlab.nic.cz/labs/bird.git
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Rewrote fib functions to make them insert/delete/asynchronous-walk safe.
This is implemented in a way similar to lib/slists.h, but it took some more effort to make rehashing not disturb the readers. We do it by just taking _highest_ k bits of ipa_hash as our hash value and sorting each box by whole ipa_hash(). Consult FIB_ITERATE_* macros in nest/route.h. Implemented fib_check() debugging function and also rewrote the rehashing algorithm to use better thresholds and not to waste time by rehashing forth and back.
This commit is contained in:
Martin Mares
parent
a6f250f5c6
commit
3ab001b974
46
nest/route.h
46
nest/route.h
@ -17,21 +17,31 @@ struct proto;
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/*
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* Generic data structure for storing network prefixes. Also used
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* for the master routing table. Currently implemented as a hash
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* for the master routing table. Currently implemented as a hash
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* table.
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*
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* Available operations:
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* - insertion of new entry
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* - deletion of entry
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* - searching for entry by network prefix
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* - asynchronous retrieval of fib contents
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*/
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struct fib_node {
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ip_addr prefix; /* In host order */
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struct fib_node *next; /* Next in hash chain */
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struct fib_iterator *readers; /* List of readers of this node */
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byte pxlen;
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byte flags; /* User-defined */
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byte x0, x1; /* User-defined */
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struct fib_node *next; /* Next in hash chain */
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ip_addr prefix; /* In host order */
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};
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struct fib_iterator { /* See lib/slists.h for an explanation */
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struct fib_iterator *prev, *next; /* Must be synced with struct fib_node! */
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struct fib_node *node; /* Or NULL if freshly merged */
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byte efef; /* 0xff to distinguish between iterator and node */
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byte pad[3];
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unsigned int hash;
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};
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struct fib {
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@ -39,17 +49,23 @@ struct fib {
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slab *fib_slab; /* Slab holding all fib nodes */
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struct fib_node **hash_table; /* Node hash table */
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unsigned int hash_size; /* Number of hash table entries (a power of two) */
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unsigned int hash_mask; /* hash_size - 1 */
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unsigned int hash_order; /* Binary logarithm of hash_size */
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unsigned int hash_shift; /* 16 - hash_log */
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unsigned int entries; /* Number of entries */
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unsigned int entries_min, entries_max;/* Entry count limits (else start rehashing) */
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void (*init)(struct fib_node *); /* Constructor */
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};
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void fib_init(struct fib *, pool *, unsigned node_size, unsigned hash_size, void (*init)(struct fib_node *));
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void fib_init(struct fib *, pool *, unsigned node_size, unsigned hash_order, void (*init)(struct fib_node *));
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void *fib_find(struct fib *, ip_addr *, int); /* Find or return NULL if doesn't exist */
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void *fib_get(struct fib *, ip_addr *, int); /* Find or create new if nonexistent */
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void fib_delete(struct fib *, void *); /* Remove fib entry */
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void fib_free(struct fib *); /* Destroy the fib */
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void fib_check(struct fib *); /* Consistency check for debugging */
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void fit_init(struct fib_iterator *, struct fib *); /* Internal functions, don't call */
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struct fib_node *fit_get(struct fib *, struct fib_iterator *);
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void fit_put(struct fib_iterator *, struct fib_node *);
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#define FIB_WALK(fib, z) do { \
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struct fib_node *z, **ff = (fib)->hash_table; \
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@ -59,6 +75,24 @@ void fib_free(struct fib *); /* Destroy the fib */
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#define FIB_WALK_END } while (0)
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#define FIB_ITERATE_INIT(it, fib) fit_init(it, fib)
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#define FIB_ITERATE_START(fib, it, z) do { \
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struct fib_node *z = fit_get(fib, it); \
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unsigned int count = (fib)->hash_size; \
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unsigned int hpos = (it)->hash; \
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for(;;) { \
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again: if (!z) { \
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if (++hpos >= count) \
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break; \
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z = (fib)->hash_table[hpos]; \
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goto again; \
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}
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#define FIB_ITERATE_END z = z->next; } } while(0)
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#define FIB_ITERATE_PUT(it, z) fit_put(it, z)
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/*
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* Master Routing Tables. Generally speaking, each of them is a list
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* of FIB (one per TOS) with each entry pointing to a list of route entries
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@ -76,7 +110,7 @@ typedef struct rtable {
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} rtable;
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typedef struct network {
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struct fib_node n; /* FIB flags,x0 reserved for kernel syncer */
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struct fib_node n; /* FIB flags reserved for kernel syncer */
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struct rte *routes; /* Available routes for this network */
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} net;
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339
nest/rt-fib.c
339
nest/rt-fib.c
@ -13,24 +13,30 @@
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#include "nest/bird.h"
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#include "nest/route.h"
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#define HASH_DEF_SIZE 1024
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#define HASH_HI_MARK *16
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#define HASH_LO_MARK *0
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#define HASH_LO_MIN 128
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#define HASH_HI_RESIZE *16
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#define HASH_LO_RESIZE *0
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#define HASH_DEF_ORDER 10
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#define HASH_HI_MARK *4
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#define HASH_HI_STEP 2
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#define HASH_HI_MAX 16 /* Must be at most 16 */
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#define HASH_LO_MARK /5
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#define HASH_LO_STEP 2
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#define HASH_LO_MIN 10
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static void
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fib_ht_alloc(struct fib *f)
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{
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f->hash_mask = f->hash_size - 1;
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f->entries_max = f->hash_size HASH_HI_MARK;
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f->entries_min = f->hash_size HASH_LO_MARK;
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if (f->entries_min < HASH_LO_MIN)
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f->hash_size = 1 << f->hash_order;
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f->hash_shift = 16 - f->hash_order;
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if (f->hash_order > HASH_HI_MAX - HASH_HI_STEP)
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f->entries_max = ~0;
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else
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f->entries_max = f->hash_size HASH_HI_MARK;
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if (f->hash_order < HASH_LO_MIN + HASH_LO_STEP)
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f->entries_min = 0;
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DBG("Allocating FIB: %d entries, %d low, %d high\n", f->hash_size, f->entries_min, f->entries_max);
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else
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f->entries_min = f->hash_size HASH_LO_MARK;
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DBG("Allocating FIB hash of order %d: %d entries, %d low, %d high\n",
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f->hash_order, f->hash_size, f->entries_min, f->entries_max);
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f->hash_table = mb_alloc(f->fib_pool, f->hash_size * sizeof(struct fib_node *));
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bzero(f->hash_table, f->hash_size * sizeof(struct fib_node *));
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}
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static inline void
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@ -42,46 +48,64 @@ fib_ht_free(struct fib_node **h)
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static inline unsigned
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fib_hash(struct fib *f, ip_addr *a)
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{
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return ipa_hash(*a) & f->hash_mask;
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return ipa_hash(*a) >> f->hash_shift;
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}
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void
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fib_init(struct fib *f, pool *p, unsigned node_size, unsigned hash_size, void (*init)(struct fib_node *))
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fib_init(struct fib *f, pool *p, unsigned node_size, unsigned hash_order, void (*init)(struct fib_node *))
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{
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if (!hash_size)
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hash_size = HASH_DEF_SIZE;
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if (!hash_order)
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hash_order = HASH_DEF_ORDER;
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f->fib_pool = p;
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f->fib_slab = sl_new(p, node_size);
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f->hash_size = hash_size;
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f->hash_order = hash_order;
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fib_ht_alloc(f);
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bzero(f->hash_table, f->hash_size * sizeof(struct fib_node *));
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f->entries = 0;
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f->entries_min = 0;
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f->init = init;
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}
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static void
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fib_rehash(struct fib *f, unsigned new)
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fib_rehash(struct fib *f, int step)
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{
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unsigned old;
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unsigned old, new, oldn, newn, ni, nh;
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struct fib_node **n, *e, *x, **t, **m, **h;
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old = f->hash_size;
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old = f->hash_order;
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oldn = f->hash_size;
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new = old + step;
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m = h = f->hash_table;
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DBG("Re-hashing FIB from %d to %d\n", old, new);
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f->hash_size = new;
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DBG("Re-hashing FIB from order %d to %d\n", old, new);
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f->hash_order = new;
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fib_ht_alloc(f);
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n = f->hash_table;
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t = n = f->hash_table;
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newn = f->hash_size;
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ni = 0;
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while (old--)
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{
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x = *h++;
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while (e = x)
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{
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x = e->next;
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t = n + fib_hash(f, &e->prefix);
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e->next = *t;
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nh = fib_hash(f, &e->prefix);
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while (nh > ni)
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{
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*t = NULL;
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ni++;
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t = ++n;
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}
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*t = e;
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t = &e->next;
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}
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}
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while (ni < newn)
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{
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*t = NULL;
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ni++;
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t = ++n;
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}
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fib_ht_free(m);
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}
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@ -98,8 +122,9 @@ fib_find(struct fib *f, ip_addr *a, int len)
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void *
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fib_get(struct fib *f, ip_addr *a, int len)
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{
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struct fib_node **ee = f->hash_table + fib_hash(f, a);
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struct fib_node *e = *ee;
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unsigned int h = ipa_hash(*a);
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struct fib_node **ee = f->hash_table + (h >> f->hash_shift);
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struct fib_node *g, *e = *ee;
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while (e && (e->pxlen != len || !ipa_equal(*a, e->prefix)))
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e = e->next;
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@ -112,28 +137,80 @@ fib_get(struct fib *f, ip_addr *a, int len)
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e = sl_alloc(f->fib_slab);
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e->prefix = *a;
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e->pxlen = len;
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while ((g = *ee) && ipa_hash(g->prefix) < h)
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ee = &g->next;
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e->next = *ee;
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*ee = e;
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e->readers = NULL;
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f->init(e);
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if (f->entries++ > f->entries_max)
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fib_rehash(f, f->hash_size HASH_HI_RESIZE);
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fib_rehash(f, HASH_HI_STEP);
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return e;
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}
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static inline void
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fib_merge_readers(struct fib_iterator *i, struct fib_node *to)
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{
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if (to)
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{
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struct fib_iterator *j = to->readers;
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if (!j)
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{
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/* Fast path */
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to->readers = i;
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i->prev = (struct fib_iterator *) to;
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fixup:
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while (i && i->node)
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{
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i->node = NULL;
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i = i->next;
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}
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return;
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}
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/* Really merging */
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while (j->next)
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j = j->next;
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j->next = i;
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i->prev = j;
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goto fixup;
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}
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else /* No more nodes */
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while (i)
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{
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i->prev = NULL;
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i = i->next;
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}
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}
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void
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fib_delete(struct fib *f, void *E)
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{
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struct fib_node *e = E;
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struct fib_node **ee = f->hash_table + fib_hash(f, &e->prefix);
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unsigned int h = fib_hash(f, &e->prefix);
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struct fib_node **ee = f->hash_table + h;
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struct fib_iterator *it;
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while (*ee)
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{
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if (*ee == e)
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{
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*ee = e->next;
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if (it = e->readers)
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{
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struct fib_node *l = e->next;
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while (!l)
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{
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h++;
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if (h >= f->hash_size)
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break;
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else
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l = f->hash_table[h];
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}
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fib_merge_readers(it, l);
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}
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sl_free(f->fib_slab, e);
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if (f->entries-- < f->entries_min)
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fib_rehash(f, f->hash_size HASH_LO_RESIZE);
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fib_rehash(f, -HASH_LO_STEP);
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return;
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}
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ee = &((*ee)->next);
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@ -147,3 +224,205 @@ fib_free(struct fib *f)
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fib_ht_free(f->hash_table);
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rfree(f->fib_slab);
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}
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void
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fit_init(struct fib_iterator *i, struct fib *f)
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{
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unsigned h;
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struct fib_node *n;
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i->efef = 0xff;
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for(h=0; h<f->hash_size; h++)
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if (n = f->hash_table[h])
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{
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i->prev = (struct fib_iterator *) n;
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if (i->next = n->readers)
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i->next->prev = i;
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n->readers = i;
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i->node = n;
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return;
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}
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/* The fib is empty, nothing to do */
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i->prev = i->next = NULL;
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i->node = NULL;
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}
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struct fib_node *
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fit_get(struct fib *f, struct fib_iterator *i)
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{
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struct fib_node *n;
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struct fib_iterator *j, *k;
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if (!i->prev)
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{
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/* We are at the end */
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i->hash = f->hash_size;
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return NULL;
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}
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if (!(n = i->node))
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{
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/* No node info available, we are a victim of merging. Try harder. */
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j = i;
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while (j->efef == 0xff)
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j = j->prev;
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n = (struct fib_node *) j;
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}
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j = i->prev;
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if (k = i->next)
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k->prev = j;
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j->next = k;
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i->hash = fib_hash(f, &n->prefix);
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return n;
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}
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void
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fit_put(struct fib_iterator *i, struct fib_node *n)
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{
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struct fib_iterator *j;
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i->node = n;
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if (j = n->readers)
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j->prev = i;
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i->next = j;
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n->readers = i;
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i->prev = (struct fib_iterator *) n;
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}
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#ifdef DEBUGGING
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void
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fib_check(struct fib *f)
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{
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unsigned int i, ec, lo, nulls;
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ec = 0;
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for(i=0; i<f->hash_size; i++)
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{
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struct fib_node *n;
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lo = 0;
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for(n=f->hash_table[i]; n; n=n->next)
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{
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struct fib_iterator *j, *j0;
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unsigned int h0 = ipa_hash(n->prefix);
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if (h0 < lo)
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die("fib_check: discord in hash chains");
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lo = h0;
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if ((h0 >> f->hash_shift) != i)
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die("fib_check: mishashed %x->%x (order %d)", h0, i, f->hash_order);
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j0 = (struct fib_iterator *) n;
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nulls = 0;
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for(j=n->readers; j; j=j->next)
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{
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if (j->prev != j0)
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die("fib_check: iterator->prev mismatch");
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j0 = j;
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if (!j->node)
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nulls++;
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else if (nulls)
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die("fib_check: iterator nullified");
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else if (j->node != n)
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die("fib_check: iterator->node mismatch");
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}
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ec++;
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}
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}
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if (ec != f->entries)
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die("fib_check: invalid entry count (%d != %d)", ec, f->entries);
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}
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#endif
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#ifdef TEST
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#include "lib/resource.h"
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struct fib f;
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void dump(char *m)
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{
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unsigned int i;
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debug("%s ... order=%d, size=%d, entries=%d\n", m, f.hash_order, f.hash_size, f.hash_size);
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for(i=0; i<f.hash_size; i++)
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{
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struct fib_node *n;
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struct fib_iterator *j;
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for(n=f.hash_table[i]; n; n=n->next)
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{
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debug("%04x %04x %p %I/%2d", i, ipa_hash(n->prefix), n, n->prefix, n->pxlen);
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for(j=n->readers; j; j=j->next)
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debug(" %p[%p]", j, j->node);
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debug("\n");
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}
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}
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fib_check(&f);
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debug("-----\n");
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}
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void init(struct fib_node *n)
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{
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}
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int main(void)
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{
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struct fib_node *n;
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struct fib_iterator i, j;
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ip_addr a;
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int c;
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log_init_debug(NULL);
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resource_init();
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fib_init(&f, &root_pool, sizeof(struct fib_node), 4, init);
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dump("init");
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|
||||
a = ipa_from_u32(0x01020304); n = fib_get(&f, &a, 32);
|
||||
a = ipa_from_u32(0x02030405); n = fib_get(&f, &a, 32);
|
||||
a = ipa_from_u32(0x03040506); n = fib_get(&f, &a, 32);
|
||||
a = ipa_from_u32(0x00000000); n = fib_get(&f, &a, 32);
|
||||
a = ipa_from_u32(0x00000c01); n = fib_get(&f, &a, 32);
|
||||
a = ipa_from_u32(0xffffffff); n = fib_get(&f, &a, 32);
|
||||
dump("fill");
|
||||
|
||||
fit_init(&i, &f);
|
||||
dump("iter init");
|
||||
|
||||
fib_rehash(&f, 1);
|
||||
dump("rehash up");
|
||||
|
||||
fib_rehash(&f, -1);
|
||||
dump("rehash down");
|
||||
|
||||
next:
|
||||
c = 0;
|
||||
FIB_ITERATE_START(&f, &i, z)
|
||||
{
|
||||
if (c)
|
||||
{
|
||||
FIB_ITERATE_PUT(&i, z);
|
||||
dump("iter");
|
||||
goto next;
|
||||
}
|
||||
c = 1;
|
||||
debug("got %p\n", z);
|
||||
}
|
||||
FIB_ITERATE_END;
|
||||
dump("iter end");
|
||||
|
||||
fit_init(&i, &f);
|
||||
fit_init(&j, &f);
|
||||
dump("iter init 2");
|
||||
|
||||
n = fit_get(&f, &i);
|
||||
dump("iter step 2");
|
||||
|
||||
fit_put(&i, n->next);
|
||||
dump("iter step 3");
|
||||
|
||||
a = ipa_from_u32(0xffffffff); n = fib_get(&f, &a, 32);
|
||||
fib_delete(&f, n);
|
||||
dump("iter step 3");
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
#endif
|
||||
|
||||
Loading…
Reference in New Issue
Block a user