mail-index-alloc-cache.c revision 04dff721d2a63566a4dbe1c856f8218b6550aa3e
/* Copyright (c) 2010 Dovecot authors, see the included COPYING file */
#include "lib.h"
#include "ioloop.h"
#include "module-context.h"
#include "eacces-error.h"
#include "mail-index-private.h"
#include "mail-index-alloc-cache.h"
#define MAIL_INDEX_ALLOC_CACHE_CONTEXT(obj) \
MODULE_CONTEXT(obj, mail_index_alloc_cache_index_module)
/* How many seconds to keep index opened for reuse after it's been closed */
#define INDEX_CACHE_TIMEOUT 10
/* How many closed indexes to keep */
#define INDEX_CACHE_MAX 3
struct mail_index_alloc_cache_list {
union mail_index_module_context module_ctx;
struct mail_index_alloc_cache_list *next;
struct mail_index *index;
char *mailbox_path;
int refcount;
dev_t index_dir_dev;
ino_t index_dir_ino;
time_t destroy_time;
};
static MODULE_CONTEXT_DEFINE_INIT(mail_index_alloc_cache_index_module,
&mail_index_module_register);
static struct mail_index_alloc_cache_list *indexes = NULL;
static struct timeout *to_index = NULL;
static struct mail_index_alloc_cache_list *
mail_index_alloc_cache_add(struct mail_index *index,
const char *mailbox_path, struct stat *st)
{
struct mail_index_alloc_cache_list *list;
list = i_new(struct mail_index_alloc_cache_list, 1);
list->refcount = 1;
list->index = index;
list->mailbox_path = i_strdup(mailbox_path);
list->index_dir_dev = st->st_dev;
list->index_dir_ino = st->st_ino;
list->next = indexes;
indexes = list;
MODULE_CONTEXT_SET(index, mail_index_alloc_cache_index_module, list);
return list;
}
static void
mail_index_alloc_cache_list_free(struct mail_index_alloc_cache_list *list)
{
mail_index_free(&list->index);
i_free(list->mailbox_path);
i_free(list);
}
struct mail_index *
mail_index_alloc_cache_get(const char *mailbox_path,
const char *index_dir, const char *prefix)
{
struct mail_index_alloc_cache_list **indexp, *rec, *match;
struct stat st, st2;
unsigned int destroy_count;
/* compare index_dir inodes so we don't break even with symlinks.
if index_dir doesn't exist yet or if using in-memory indexes, just
compare mailbox paths */
memset(&st, 0, sizeof(st));
if (index_dir == NULL) {
/* in-memory indexes */
} else if (stat(index_dir, &st) < 0) {
if (errno == ENOENT) {
/* it'll be created later */
} else if (errno == EACCES) {
i_error("%s", eacces_error_get("stat", index_dir));
} else {
i_error("stat(%s) failed: %m", index_dir);
}
}
destroy_count = 0; match = NULL;
for (indexp = &indexes; *indexp != NULL;) {
rec = *indexp;
if (match != NULL) {
/* already found the index. we're just going through
the rest of them to drop 0 refcounts */
} else if (rec->refcount == 0 && rec->index->open_count == 0) {
/* index is already closed. don't even try to
reuse it. */
} else if (index_dir != NULL && rec->index_dir_ino != 0) {
if (st.st_ino == rec->index_dir_ino &&
CMP_DEV_T(st.st_dev, rec->index_dir_dev)) {
/* make sure the directory still exists.
it might have been renamed and we're trying
to access it via its new path now. */
if (stat(rec->index->dir, &st2) < 0 ||
st2.st_ino != st.st_ino ||
!CMP_DEV_T(st2.st_dev, st.st_dev))
rec->destroy_time = 0;
else
match = rec;
}
} else {
if (strcmp(mailbox_path, rec->mailbox_path) == 0)
match = rec;
}
if (rec->refcount == 0 && rec != match) {
if (rec->destroy_time <= ioloop_time ||
destroy_count >= INDEX_CACHE_MAX) {
*indexp = rec->next;
mail_index_alloc_cache_list_free(rec);
continue;
} else {
destroy_count++;
}
}
indexp = &(*indexp)->next;
}
if (match == NULL) {
struct mail_index *index = mail_index_alloc(index_dir, prefix);
match = mail_index_alloc_cache_add(index, mailbox_path, &st);
} else {
match->refcount++;
}
i_assert(match->index != NULL);
return match->index;
}
static void destroy_unrefed(bool all)
{
struct mail_index_alloc_cache_list **list, *rec;
for (list = &indexes; *list != NULL;) {
rec = *list;
if (rec->refcount == 0 &&
(all || rec->destroy_time <= ioloop_time)) {
*list = rec->next;
mail_index_alloc_cache_list_free(rec);
} else {
list = &(*list)->next;
}
}
if (indexes == NULL && to_index != NULL)
timeout_remove(&to_index);
}
static void index_removal_timeout(void *context ATTR_UNUSED)
{
destroy_unrefed(FALSE);
}
void mail_index_alloc_cache_unref(struct mail_index **_index)
{
struct mail_index *index = *_index;
struct mail_index_alloc_cache_list *list, **listp;
*_index = NULL;
list = NULL;
for (listp = &indexes; *listp != NULL; listp = &(*listp)->next) {
if ((*listp)->index == index) {
list = *listp;
break;
}
}
i_assert(list != NULL);
i_assert(list->refcount > 0);
list->refcount--;
list->destroy_time = ioloop_time + INDEX_CACHE_TIMEOUT;
if (list->refcount == 0 && index->open_count == 0) {
/* index was already closed. don't even try to cache it. */
*listp = list->next;
mail_index_alloc_cache_list_free(list);
} else if (to_index == NULL) {
to_index = timeout_add(INDEX_CACHE_TIMEOUT*1000/2,
index_removal_timeout, NULL);
}
}
void mail_index_alloc_cache_destroy_unrefed(void)
{
destroy_unrefed(TRUE);
}
void mail_index_alloc_cache_index_opened(struct mail_index *index)
{
struct mail_index_alloc_cache_list *list =
MAIL_INDEX_ALLOC_CACHE_CONTEXT(index);
struct stat st;
if (list != NULL && list->index_dir_ino == 0 &&
!MAIL_INDEX_IS_IN_MEMORY(index)) {
/* newly created index directory. update its stat. */
if (stat(index->dir, &st) == 0) {
list->index_dir_ino = st.st_ino;
list->index_dir_dev = st.st_dev;
}
}
}