/**
* Delete key from database.
*/
void
dbmw_delete(dbmw_t *dw, gconstpointer key)
{
struct cached *entry;
dbmw_check(dw);
g_assert(key);
dw->w_access++;
entry = map_lookup(dw->values, key);
if (entry) {
if (entry->dirty)
dw->w_hits++;
if (!entry->absent) {
dw->count_needs_sync = TRUE; /* Deferred delete */
fill_entry(dw, entry, NULL, 0);
entry->absent = TRUE;
}
hash_list_moveto_tail(dw->keys, key);
} else {
dw->ioerr = FALSE;
dbmap_remove(dw->dm, key);
if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
g_warning("DBMW \"%s\" I/O error whilst deleting key: %s",
dw->name, dbmap_strerror(dw->dm));
}
/*
* If the maximum value length of the DB is 0, then it is used as a
* "search table" only, meaning there will be no read to get values,
* only existence checks.
*
* Therefore, it makes sense to cache that the key is no longer valid.
* Otherwise, possibly pushing a value out of the cache to record
* a deletion is not worth it.
*/
if (0 == dw->value_size) {
WALLOC0(entry);
entry->absent = TRUE;
(void) allocate_entry(dw, key, entry);
}
}
}
/**
* Is key present in the database?
*/
gboolean
dbmw_exists(dbmw_t *dw, gconstpointer key)
{
struct cached *entry;
gboolean ret;
dbmw_check(dw);
g_assert(key);
dw->r_access++;
entry = map_lookup(dw->values, key);
if (entry) {
dw->r_hits++;
return !entry->absent;
}
dw->ioerr = FALSE;
ret = dbmap_contains(dw->dm, key);
if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
g_warning("DBMW \"%s\" I/O error whilst checking key existence: %s",
dw->name, dbmap_strerror(dw->dm));
return FALSE;
}
/*
* If the maximum value length of the DB is 0, then it is used as a
* "search table" only, meaning there will be no read to get values,
* only existence checks.
*
* Therefore, it makes sense to cache existence checks. A data read
* will also correctly return a null item from the cache.
*/
if (0 == dw->value_size) {
WALLOC0(entry);
entry->absent = !ret;
(void) allocate_entry(dw, key, entry);
}
return ret;
}
/**
* Read value from database file, returning a pointer to the allocated
* deserialized data. These data can be modified freely and stored back,
* but their lifetime will not exceed that of the next call to a dbmw
* operation on the same descriptor.
*
* User code does not need to bother with freeing the allocated data, this
* is managed directly by the DBM wrapper.
*
* @param dw the DBM wrapper
* @param key the key (constant-width, determined at open time)
* @param lenptr if non-NULL, writes length of (deserialized) value
*
* @return pointer to value, or NULL if it was either not found or the
* deserialization failed.
*/
G_GNUC_HOT gpointer
dbmw_read(dbmw_t *dw, gconstpointer key, size_t *lenptr)
{
struct cached *entry;
dbmap_datum_t dval;
dbmw_check(dw);
g_assert(key);
dw->r_access++;
entry = map_lookup(dw->values, key);
if (entry) {
dw->r_hits++;
if (lenptr)
*lenptr = entry->len;
return entry->data;
}
/*
* Not cached, must read from DB.
*/
dw->ioerr = FALSE;
dval = dbmap_lookup(dw->dm, key);
if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
g_warning("DBMW \"%s\" I/O error whilst reading entry: %s",
dw->name, dbmap_strerror(dw->dm));
return NULL;
} else if (NULL == dval.data)
return NULL; /* Not found in DB */
/*
* Value was found, allocate a cache entry object for it.
*/
WALLOC0(entry);
/*
* Deserialize data if needed.
*/
if (dw->unpack) {
/*
* Allocate cache entry arena to hold the deserialized version.
*/
entry->data = walloc(dw->value_size);
entry->len = dw->value_size;
bstr_reset(dw->bs, dval.data, dval.len, BSTR_F_ERROR);
if (!dbmw_deserialize(dw, dw->bs, entry->data, dw->value_size)) {
g_carp("DBMW \"%s\" deserialization error in %s(): %s",
dw->name,
stacktrace_routine_name(func_to_pointer(dw->unpack), FALSE),
bstr_error(dw->bs));
/* Not calling value free routine on deserialization failures */
wfree(entry->data, dw->value_size);
WFREE(entry);
return NULL;
}
if (lenptr)
*lenptr = dw->value_size;
} else {
g_assert(dw->value_size >= dval.len);
if (dval.len) {
entry->len = dval.len;
entry->data = wcopy(dval.data, dval.len);
} else {
entry->data = NULL;
entry->len = 0;
}
if (lenptr)
*lenptr = dval.len;
}
g_assert((entry->len != 0) == (entry->data != NULL));
/*
* Insert into cache.
*/
(void) allocate_entry(dw, key, entry);
return entry->data;
}
/**
* Write back cached value to disk.
* @return TRUE on success
*/
static gboolean
write_back(dbmw_t *dw, gconstpointer key, struct cached *value)
{
dbmap_datum_t dval;
gboolean ok;
g_assert(value->dirty);
if (value->absent) {
/* Key not present, value is null item */
dval.data = NULL;
dval.len = 0;
} else {
/*
* Serialize value into our reused message block if a
* serialization routine was provided.
*/
if (dw->pack) {
pmsg_reset(dw->mb);
(*dw->pack)(dw->mb, value->data);
dval.data = pmsg_start(dw->mb);
dval.len = pmsg_size(dw->mb);
/*
* We allocated the message block one byte larger than the
* maximum size, in order to detect unexpected serialization
* overflows.
*/
if (dval.len > dw->value_data_size) {
/* Don't g_carp() as this is asynchronous wrt data change */
g_warning("DBMW \"%s\" serialization overflow in %s() "
"whilst %s dirty entry",
dw->name,
stacktrace_routine_name(func_to_pointer(dw->pack), FALSE),
value->absent ? "deleting" : "flushing");
return FALSE;
}
} else {
dval.data = value->data;
dval.len = value->len;
}
}
/*
* If cached entry is absent, delete the key.
* Otherwise store the serialized value.
*
* Dirty bit is cleared on success.
*/
if (common_dbg > 4)
g_debug("DBMW \"%s\" %s dirty value (%lu byte%s)",
dw->name, value->absent ? "deleting" : "flushing",
(unsigned long) dval.len, 1 == dval.len ? "" : "s");
dw->ioerr = FALSE;
ok = value->absent ?
dbmap_remove(dw->dm, key) : dbmap_insert(dw->dm, key, dval);
if (ok) {
value->dirty = FALSE;
} else if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
g_warning("DBMW \"%s\" I/O error whilst %s dirty entry: %s",
dw->name, value->absent ? "deleting" : "flushing",
dbmap_strerror(dw->dm));
} else {
g_warning("DBMW \"%s\" error whilst %s dirty entry: %s",
dw->name, value->absent ? "deleting" : "flushing",
dbmap_strerror(dw->dm));
}
return ok;
}
/**
* Read value from database file, returning a pointer to the allocated
* deserialized data. These data can be modified freely and stored back,
* but their lifetime will not exceed that of the next call to a dbmw
* operation on the same descriptor.
*
* User code does not need to bother with freeing the allocated data, this
* is managed directly by the DBM wrapper.
*
* @param dw the DBM wrapper
* @param key the key (constant-width, determined at open time)
* @param lenptr if non-NULL, writes length of (deserialized) value
*
* @return pointer to value, or NULL if it was either not found or the
* deserialization failed.
*/
G_GNUC_HOT void *
dbmw_read(dbmw_t *dw, const void *key, size_t *lenptr)
{
struct cached *entry;
dbmap_datum_t dval;
dbmw_check(dw);
g_assert(key);
dw->r_access++;
entry = map_lookup(dw->values, key);
if (entry) {
if (dbg_ds_debugging(dw->dbg, 5, DBG_DSF_CACHING | DBG_DSF_ACCESS)) {
dbg_ds_log(dw->dbg, dw, "%s: read cache hit on %s key=%s%s",
G_STRFUNC, entry->dirty ? "dirty" : "clean",
dbg_ds_keystr(dw->dbg, key, (size_t) -1),
entry->absent ? " (absent)" : "");
}
dw->r_hits++;
if (lenptr)
*lenptr = entry->len;
return entry->data;
}
/*
* Not cached, must read from DB.
*/
dw->ioerr = FALSE;
dval = dbmap_lookup(dw->dm, key);
if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
s_warning_once_per(LOG_PERIOD_SECOND,
"DBMW \"%s\" I/O error whilst reading entry: %s",
dw->name, dbmap_strerror(dw->dm));
return NULL;
} else if (NULL == dval.data)
return NULL; /* Not found in DB */
/*
* Value was found, allocate a cache entry object for it.
*/
WALLOC0(entry);
/*
* Deserialize data if needed.
*/
if (dw->unpack) {
/*
* Allocate cache entry arena to hold the deserialized version.
*/
entry->data = walloc(dw->value_size);
entry->len = dw->value_size;
bstr_reset(dw->bs, dval.data, dval.len, BSTR_F_ERROR);
if (!dbmw_deserialize(dw, dw->bs, entry->data, dw->value_size)) {
s_critical("DBMW \"%s\" deserialization error in %s(): %s",
dw->name, stacktrace_function_name(dw->unpack),
bstr_error(dw->bs));
/* Not calling value free routine on deserialization failures */
wfree(entry->data, dw->value_size);
WFREE(entry);
return NULL;
}
if (lenptr)
*lenptr = dw->value_size;
} else {
g_assert(dw->value_size >= dval.len);
if (dval.len) {
entry->len = dval.len;
entry->data = wcopy(dval.data, dval.len);
} else {
entry->data = NULL;
entry->len = 0;
}
if (lenptr)
*lenptr = dval.len;
}
g_assert((entry->len != 0) == (entry->data != NULL));
/*
* Insert into cache.
*/
(void) allocate_entry(dw, key, entry);
if (dbg_ds_debugging(dw->dbg, 4, DBG_DSF_CACHING)) {
dbg_ds_log(dw->dbg, dw, "%s: cached %s key=%s%s",
G_STRFUNC, entry->dirty ? "dirty" : "clean",
dbg_ds_keystr(dw->dbg, key, (size_t) -1),
entry->absent ? " (absent)" : "");
}
return entry->data;
}
/**
* Write back cached value to disk.
* @return TRUE on success
*/
static bool
write_back(dbmw_t *dw, const void *key, struct cached *value)
{
dbmap_datum_t dval;
bool ok;
g_assert(value->dirty);
if (value->absent) {
/* Key not present, value is null item */
dval.data = NULL;
dval.len = 0;
} else {
/*
* Serialize value into our reused message block if a
* serialization routine was provided.
*/
if (dw->pack) {
pmsg_reset(dw->mb);
(*dw->pack)(dw->mb, value->data);
dval.data = pmsg_start(dw->mb);
dval.len = pmsg_size(dw->mb);
/*
* We allocated the message block one byte larger than the
* maximum size, in order to detect unexpected serialization
* overflows.
*/
if (dval.len > dw->value_data_size) {
/* Don't s_carp() as this is asynchronous wrt data change */
s_critical("DBMW \"%s\" serialization overflow in %s() "
"whilst flushing dirty entry",
dw->name, stacktrace_function_name(dw->pack));
return FALSE;
}
} else {
dval.data = value->data;
dval.len = value->len;
}
}
/*
* If cached entry is absent, delete the key.
* Otherwise store the serialized value.
*
* Dirty bit is cleared on success.
*/
if (
dbg_ds_debugging(dw->dbg, 1,
DBG_DSF_CACHING | DBG_DSF_UPDATE | DBG_DSF_INSERT | DBG_DSF_DELETE)
) {
dbg_ds_log(dw->dbg, dw, "%s: %s dirty value (%zu byte%s) key=%s",
G_STRFUNC, value->absent ? "deleting" : "flushing",
dval.len, plural(dval.len),
dbg_ds_keystr(dw->dbg, key, (size_t) -1));
}
dw->ioerr = FALSE;
ok = value->absent ?
dbmap_remove(dw->dm, key) : dbmap_insert(dw->dm, key, dval);
if (ok) {
value->dirty = FALSE;
} else if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
s_warning("DBMW \"%s\" I/O error whilst %s dirty entry: %s",
dw->name, value->absent ? "deleting" : "flushing",
dbmap_strerror(dw->dm));
} else {
s_warning("DBMW \"%s\" error whilst %s dirty entry: %s",
dw->name, value->absent ? "deleting" : "flushing",
dbmap_strerror(dw->dm));
}
return ok;
}
/**
* Delete key from database.
*/
void
dbmw_delete(dbmw_t *dw, const void *key)
{
struct cached *entry;
dbmw_check(dw);
g_assert(key);
dw->w_access++;
entry = map_lookup(dw->values, key);
if (entry) {
if (dbg_ds_debugging(dw->dbg, 2, DBG_DSF_CACHING | DBG_DSF_DELETE)) {
dbg_ds_log(dw->dbg, dw, "%s: %s key=%s%s",
G_STRFUNC, entry->dirty ? "dirty" : "clean",
dbg_ds_keystr(dw->dbg, key, (size_t) -1),
entry->absent ? " (was absent)" : "");
}
if (entry->dirty)
dw->w_hits++;
if (!entry->absent) {
/*
* Entry was present but is now deleted.
*
* If it was clean, then it was flushed to the database and we now
* know that there is one less entry in the database than there is
* physically present in the map.
*
* If it was dirty, then we do not know whether it exists in the
* database or not, and therefore we cannot adjust the amount
* of cached entries down.
*/
if (entry->dirty)
dw->count_needs_sync = TRUE; /* Deferred delete */
else
dw->cached--; /* One less entry in database */
fill_entry(dw, entry, NULL, 0);
entry->absent = TRUE;
}
hash_list_moveto_tail(dw->keys, key);
} else {
if (dbg_ds_debugging(dw->dbg, 2, DBG_DSF_DELETE)) {
dbg_ds_log(dw->dbg, dw, "%s: removing key=%s",
G_STRFUNC, dbg_ds_keystr(dw->dbg, key, (size_t) -1));
}
dw->ioerr = FALSE;
dbmap_remove(dw->dm, key);
if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
s_warning("DBMW \"%s\" I/O error whilst deleting key: %s",
dw->name, dbmap_strerror(dw->dm));
}
/*
* If the maximum value length of the DB is 0, then it is used as a
* "search table" only, meaning there will be no read to get values,
* only existence checks.
*
* Therefore, it makes sense to cache that the key is no longer valid.
* Otherwise, possibly pushing a value out of the cache to record
* a deletion is not worth it.
*/
if (0 == dw->value_size) {
WALLOC0(entry);
entry->absent = TRUE;
(void) allocate_entry(dw, key, entry);
if (dbg_ds_debugging(dw->dbg, 2, DBG_DSF_CACHING)) {
dbg_ds_log(dw->dbg, dw, "%s: cached absent key=%s",
G_STRFUNC, dbg_ds_keystr(dw->dbg, key, (size_t) -1));
}
}
}
}
/**
* Is key present in the database?
*/
bool
dbmw_exists(dbmw_t *dw, const void *key)
{
struct cached *entry;
bool ret;
dbmw_check(dw);
g_assert(key);
dw->r_access++;
entry = map_lookup(dw->values, key);
if (entry) {
if (dbg_ds_debugging(dw->dbg, 5, DBG_DSF_CACHING | DBG_DSF_ACCESS)) {
dbg_ds_log(dw->dbg, dw, "%s: read cache hit on %s key=%s%s",
G_STRFUNC, entry->dirty ? "dirty" : "clean",
dbg_ds_keystr(dw->dbg, key, (size_t) -1),
entry->absent ? " (absent)" : "");
}
dw->r_hits++;
return !entry->absent;
}
dw->ioerr = FALSE;
ret = dbmap_contains(dw->dm, key);
if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
s_warning("DBMW \"%s\" I/O error whilst checking key existence: %s",
dw->name, dbmap_strerror(dw->dm));
return FALSE;
}
/*
* If the maximum value length of the DB is 0, then it is used as a
* "search table" only, meaning there will be no read to get values,
* only existence checks.
*
* Therefore, it makes sense to cache existence checks. A data read
* will also correctly return a null item from the cache.
*
* If the value length is not 0, we only cache negative lookups (i.e.
* the value was not found) because we did not get any value so it is
* possible to record an absent cache entry.
*/
if (0 == dw->value_size || !ret) {
WALLOC0(entry);
entry->absent = !ret;
(void) allocate_entry(dw, key, entry);
if (dbg_ds_debugging(dw->dbg, 2, DBG_DSF_CACHING)) {
dbg_ds_log(dw->dbg, dw, "%s: cached %s key=%s",
G_STRFUNC, entry->absent ? "absent" : "present",
dbg_ds_keystr(dw->dbg, key, (size_t) -1));
}
}
return ret;
}
