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/* fifo_string_cache.c
* A string cache, possibly with a bounded size, using FIFO order to control
* the size.
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include <stdio.h>
#include "fifo_string_cache.h"
void
fifo_string_cache_init(fifo_string_cache_t *fcache, guint max_entries, GDestroyNotify string_free_func)
{
fcache->set = g_hash_table_new_full(g_str_hash, g_str_equal, string_free_func, NULL);
fcache->head = NULL;
fcache->tail = NULL;
fcache->max_entries = max_entries;
}
void
fifo_string_cache_free(fifo_string_cache_t *fcache)
{
if (fcache->set != NULL) {
g_hash_table_destroy(fcache->set);
fcache->set = NULL;
}
if (fcache->head != NULL) {
g_slist_free(fcache->head);
fcache->head = NULL;
fcache->tail = NULL;
}
}
gboolean
fifo_string_cache_contains(fifo_string_cache_t *fcache, const gchar *entry)
{
return g_hash_table_contains(fcache->set, entry);
}
gboolean
fifo_string_cache_insert(fifo_string_cache_t *fcache, const gchar *entry)
{
GSList *prev_head;
GSList *new_start_of_tail;
// In GLIB 2.40, g_hash_table_insert() returns a bool that gives us what we
// need (did the entry exist already?). But, if we're not using that
// version, we need to first check if the entry exists. So we just check
// the hash all the time, regardless of GLIB version.
gboolean exists;
exists = g_hash_table_contains(fcache->set, entry);
if (exists) {
return TRUE;
}
// Shall we remove one item?
if (fcache->max_entries > 0) {
if (g_hash_table_size(fcache->set) == fcache->max_entries) {
g_hash_table_remove(fcache->set, fcache->head->data);
prev_head = fcache->head;
fcache->head = fcache->head->next;
g_slist_free_1(prev_head);
// If max_entries is 1, the head was also the tail. Reset the tail.
if (fcache->tail == prev_head) {
fcache->tail = NULL;
}
// Now the size of the hash table is max_entries
}
}
g_hash_table_insert(fcache->set, (gpointer) entry, /*value=*/NULL);
// Do we need to constrain the number of entries?
if (fcache->max_entries > 0) {
// Keep track of the new entry at the end of the queue
new_start_of_tail = g_slist_append(fcache->tail, (gpointer) entry);
// Set the new tail
if (fcache->tail == NULL) {
fcache->tail = new_start_of_tail;
// This is the first entry, so head is NULL too. Set it.
fcache->head = new_start_of_tail;
} else {
fcache->tail = new_start_of_tail->next;
}
}
return FALSE;
}
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