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//
// Copyright 2016 Garrett D'Amore <garrett@damore.org>
//
// This software is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt). A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//
#include "core/nng_impl.h"
#include <string.h>
int
nni_idhash_init(nni_idhash *h)
{
h->ih_entries = nni_alloc(8 * sizeof (nni_idhash_entry));
if (h->ih_entries == NULL) {
return (NNG_ENOMEM);
}
(void) memset(h->ih_entries, 0, (8 * sizeof (nni_idhash_entry)));
h->ih_count = 0;
h->ih_cap = 8;
h->ih_maxcount = 5;
h->ih_mincount = 0; // never shrink below this
return (0);
}
void
nni_idhash_fini(nni_idhash *h)
{
nni_free(h->ih_entries, h->ih_cap * sizeof (nni_idhash_entry));
}
// Inspired by Python dict implementation. This probe will visit every
// cell. We always hash consecutively assigned IDs.
#define NNI_IDHASH_NEXTPROBE(h, j) \
((((j) * 5) + 1) & ~(h->ih_cap))
int
nni_idhash_find(nni_idhash *h, uint32_t id, void **valp)
{
uint32_t index = id & (h->ih_cap - 1);
for (;;) {
if (h->ih_entries[index].ihe_val == NULL) {
return (NNG_ENOENT);
}
if (h->ih_entries[index].ihe_key == id) {
*valp = h->ih_entries[index].ihe_val;
return (0);
}
index = NNI_IDHASH_NEXTPROBE(h, index);
}
}
static int
nni_hash_resize(nni_idhash *h)
{
uint32_t newsize;
uint32_t oldsize;
nni_idhash_entry *newents;
nni_idhash_entry *oldents;
if ((h->ih_count < h->ih_maxcount) && (h->ih_count >= h->ih_mincount)) {
// No resize needed.
return (0);
}
oldsize = h->ih_cap;
newsize = h->ih_cap;
newsize = 8;
while (newsize < (h->ih_count * 2)) {
newsize *= 2;
}
oldents = h->ih_entries;
newents = nni_alloc(sizeof (nni_idhash_entry) * newsize);
if (newents == NULL) {
return (NNG_ENOMEM);
}
h->ih_entries = newents;
h->ih_cap = newsize;
if (newsize > 8) {
h->ih_mincount = newsize / 8;
h->ih_maxcount = newsize * 2 / 3;
} else {
h->ih_mincount = 0;
h->ih_maxcount = 5;
}
for (int i = 0; i < oldsize; i++) {
uint32_t index;
if (oldents[i].ihe_val == NULL) {
continue;
}
index = oldents[i].ihe_key & (newsize - 1);
for (;;) {
if (newents[index].ihe_val == NULL) {
newents[index].ihe_val = oldents[i].ihe_val;
newents[index].ihe_key = oldents[i].ihe_key;
break;
}
index = NNI_IDHASH_NEXTPROBE(h, index);
}
}
nni_free(oldents, sizeof (nni_idhash_entry) * oldsize);
return (0);
}
int
nni_hash_remove(nni_idhash *h, uint32_t id)
{
uint32_t index = id & (h->ih_cap - 1);
for (;;) {
if (h->ih_entries[index].ihe_val == NULL) {
return (NNG_ENOENT);
}
if (h->ih_entries[index].ihe_key == id) {
h->ih_entries[index].ihe_val = NULL;
h->ih_entries[index].ihe_key = 0;
h->ih_count--;
break;
}
index = NNI_IDHASH_NEXTPROBE(h, index);
}
// Shrink -- but it's ok if we can't.
(void) nni_hash_resize(h);
return (0);
}
int
nni_hash_insert(nni_idhash *h, uint32_t id, void *val)
{
uint32_t index;
// Try to resize. If we can't, but we still have room, go ahead
// and store it.
if ((nni_hash_resize(h) != 0) && (h->ih_count >= (h->ih_cap - 1))) {
return (NNG_ENOMEM);
}
index = id & (h->ih_cap - 1);
for (;;) {
if (h->ih_entries[index].ihe_val == NULL) {
h->ih_entries[index].ihe_key = id;
h->ih_entries[index].ihe_val = val;
h->ih_count++;
return (0);
}
index = NNI_IDHASH_NEXTPROBE(h, index);
}
}
int
nni_idhash_count(nni_idhash *h, uint32_t *countp)
{
*countp = h->ih_count;
return (0);
}
int
nni_idhash_walk(nni_idhash *h, nni_idhash_walkfn fn, void *arg)
{
int i, rv;
for (i = 0; i < h->ih_cap; i++) {
nni_idhash_entry *ent = &h->ih_entries[i];
if (ent->ihe_val == NULL) {
continue;
}
rv = fn(arg, ent->ihe_key, ent->ihe_val);
if (rv != 0) {
return (rv);
}
}
return (0);
}
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