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netsurf/content/fs_backing_store.c
Daniel Silverstone 14286b381b
fs_backing_store: Remove cache on failure to init 
If we fail to init the control file for reasons other than it
not being found, we blow away the cache in its entirety and then
try again.  We warn if the removal fails, but carry on regardless
since right now the worst that'll happen is that we'll end up
with more on disk than we know about in the cache.

Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>
2020-02-24 21:01:58 +00:00

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/*
* Copyright 2014 Vincent Sanders <vince@netsurf-browser.org>
*
* This file is part of NetSurf, http://www.netsurf-browser.org/
*
* NetSurf is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* NetSurf is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* \file
* Low-level resource cache persistent storage implementation.
*
* file based backing store.
*
* \todo Consider improving eviction sorting to include objects size
* and remaining lifetime and other cost metrics.
*
* \todo Implement mmap retrieval where supported.
*
* \todo Implement static retrieval for metadata objects as their heap
* lifetime is typically very short, though this may be obsoleted
* by a small object storage strategy.
*
*/
#include <unistd.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <errno.h>
#include <time.h>
#include <stdlib.h>
#include <nsutils/unistd.h>
#include "netsurf/inttypes.h"
#include "utils/filepath.h"
#include "utils/file.h"
#include "utils/nsurl.h"
#include "utils/log.h"
#include "utils/messages.h"
#include "utils/hashmap.h"
#include "desktop/gui_internal.h"
#include "netsurf/misc.h"
#include "content/backing_store.h"
/** Default number of bits of the ident to use in index hash */
#define DEFAULT_IDENT_SIZE 20
/** Default number of bits to use for an entry index. */
#define DEFAULT_ENTRY_SIZE 16
/** Backing store file format version */
#define CONTROL_VERSION 202
/** Number of milliseconds after a update before control data maintenance is performed */
#define CONTROL_MAINT_TIME 10000
/** Filename of serialised entries */
#define ENTRIES_FNAME "entries"
/** Filename of block file index */
#define BLOCKS_FNAME "blocks"
/** log2 block data address length (64k) */
#define BLOCK_ADDR_LEN 16
/** log2 number of entries per block file(1024) */
#define BLOCK_ENTRY_COUNT 10
/** log2 number of data block files */
#define BLOCK_FILE_COUNT (BLOCK_ADDR_LEN - BLOCK_ENTRY_COUNT)
/** log2 size of data blocks (8k) */
#define BLOCK_DATA_SIZE 13
/** log2 size of metadata blocks (8k) */
#define BLOCK_META_SIZE 13
/** length in bytes of a block files use map */
#define BLOCK_USE_MAP_SIZE (1 << (BLOCK_ENTRY_COUNT - 3))
/**
* The type used to store index values referring to store entries. Care
* must be taken with this type as it is used to build address to
* entry mapping so changing the size will have large impacts on
* memory usage.
*/
typedef uint16_t entry_index_t;
/**
* The type used as a binary identifier for each entry derived from
* the URL. A larger identifier will have fewer collisions but
* requires proportionately more storage.
*/
typedef uint32_t entry_ident_t;
/**
* The type used to store block file index values. If this is changed
* it will affect the entry storage/alignment and BLOCK_ADDR_LEN must
* also be updated.
*/
typedef uint16_t block_index_t;
/**
* Entry element index values.
*/
enum store_entry_elem_idx {
ENTRY_ELEM_DATA = 0, /**< entry element is data */
ENTRY_ELEM_META = 1, /**< entry element is metadata */
ENTRY_ELEM_COUNT = 2, /**< count of elements on an entry */
};
/**
* flags that indicate what additional information is contained within
* an entry element.
*/
enum store_entry_elem_flags {
/** store not managing any allocation on entry */
ENTRY_ELEM_FLAG_NONE = 0,
/** entry data allocation is on heap */
ENTRY_ELEM_FLAG_HEAP = 0x1,
/** entry data allocation is mmaped */
ENTRY_ELEM_FLAG_MMAP = 0x2,
/** entry data allocation is in small object pool */
ENTRY_ELEM_FLAG_SMALL = 0x4,
};
enum store_entry_flags {
/** entry is normal */
ENTRY_FLAGS_NONE = 0,
/** entry has been invalidated but something still holding a reference */
ENTRY_FLAGS_INVALID = 1,
};
/**
* Backing store entry element.
*
* An element keeps data about:
* - the current memory allocation
* - the number of outstanding references to the memory
* - the size of the element data
* - flags controlling how the memory and element are handled
*
* @note Order is important to avoid excessive structure packing overhead.
*/
struct store_entry_element {
uint8_t* data; /**< data allocated */
uint32_t size; /**< size of entry element on disc */
block_index_t block; /**< small object data block */
uint8_t ref; /**< element data reference count */
uint8_t flags; /**< entry flags */
};
/**
* Backing store object index entry.
*
* An entry in the backing store contains two elements for the actual
* data and the metadata. The two elements are treated identically for
* storage lifetime but as a collective whole for expiration and
* indexing.
*
* @note Order is important to avoid excessive structure packing overhead.
*/
struct store_entry {
nsurl *url; /**< The URL for this entry */
int64_t last_used; /**< UNIX time the entry was last used */
uint16_t use_count; /**< number of times this entry has been accessed */
uint8_t flags; /**< entry flags */
/** Entry element (data or meta) specific information */
struct store_entry_element elem[ENTRY_ELEM_COUNT];
};
/**
* Small block file.
*/
struct block_file {
/** file descriptor of the block file */
int fd;
/** map of used and unused entries within the block file */
uint8_t use_map[BLOCK_USE_MAP_SIZE];
};
/**
* log2 of block size.
*/
static const unsigned int log2_block_size[ENTRY_ELEM_COUNT] = {
BLOCK_DATA_SIZE, /**< Data block size */
BLOCK_META_SIZE /**< Metadata block size */
};
/**
* Parameters controlling the backing store.
*/
struct store_state {
/* store config */
char *path; /**< The path to the backing store */
size_t limit; /**< The backing store upper bound target size */
size_t hysteresis; /**< The hysteresis around the target size */
/**
* The cache object hash
*/
hashmap_t *entries;
/** flag indicating if the entries have been made persistent
* since they were last changed.
*/
bool entries_dirty;
/** small block indexes */
struct block_file blocks[ENTRY_ELEM_COUNT][BLOCK_FILE_COUNT];
/** flag indicating if the block file use maps have been made
* persistent since they were last changed.
*/
bool blocks_dirty;
/** flag indicating if a block file has been opened for update
* since maintenance was previously done.
*/
bool blocks_opened;
/* stats */
uint64_t total_alloc; /**< total size of all allocated storage. */
size_t hit_count; /**< number of cache hits */
uint64_t hit_size; /**< size of storage served */
size_t miss_count; /**< number of cache misses */
};
/**
* Global storage state.
*
* @todo Investigate if there is a way to have a context rather than
* use a global.
*/
struct store_state *storestate;
/* Entries hashmap parameters
*
* Our hashmap has nsurl keys and store_entry values
*/
static bool
entries_hashmap_key_eq(void *key1, void *key2)
{
return nsurl_compare((nsurl *)key1, (nsurl *)key2, NSURL_COMPLETE);
}
static void *
entries_hashmap_value_alloc(void *key)
{
struct store_entry *ent = calloc(1, sizeof(struct store_entry));
if (ent != NULL) {
ent->url = nsurl_ref(key);
}
return ent;
}
static void
entries_hashmap_value_destroy(void *value)
{
struct store_entry *ent = value;
/** \todo Do we need to do any disk cleanup here? if so, meep! */
nsurl_unref(ent->url);
free(ent);
}
static hashmap_parameters_t entries_hashmap_parameters = {
.key_clone = (hashmap_key_clone_t)nsurl_ref,
.key_destroy = (hashmap_key_destroy_t)nsurl_unref,
.key_hash = (hashmap_key_hash_t)nsurl_hash,
.key_eq = entries_hashmap_key_eq,
.value_alloc = entries_hashmap_value_alloc,
.value_destroy = entries_hashmap_value_destroy,
};
/**
* Generate a filename for an object.
*
* this generates the filename for an object on disc. It is necessary
* for this to generate a filename which conforms to the limitations
* of all the filesystems the cache can be placed upon.
*
* From http://en.wikipedia.org/wiki/Comparison_of_file_systems#Limits
* the relevant subset is:
* - path elements no longer than 8 characters
* - acceptable characters are A-Z, 0-9
* - short total path lengths (255 or less)
* - no more than 77 entries per directory (6bits worth)
*
* The short total path lengths mean the encoding must represent as
* much data as possible in the least number of characters.
*
* To achieve all these goals we use RFC4648 base32 encoding which
* packs 5bits into each character of the filename. To represent a 32
* bit ident this requires a total path length of between 17 and 22
* bytes (including directory separators) BA/BB/BC/BD/BE/ABCDEFG
*
* @note Version 1.00 of the cache implementation used base64 to
* encode this, however that did not meet the requirement for only
* using uppercase characters.
*
* @note Versions prior to 1.30 only packed 5 bits per directory level
* A/B/C/D/E/F/ABCDEFG which only required 19 characters to represent
* but resulted in requiring an extra level of directory which is less
* desirable than the three extra characters using six bits.
*
* @param state The store state to use.
* @param ident The identifier to use.
* @param elem_idx The element index.
* @return The filename string or NULL on allocation error.
*/
static char *
store_fname(struct store_state *state,
entry_ident_t ident,
int elem_idx)
{
char *fname = NULL;
uint8_t b32u_i[8]; /* base32 encoded ident */
const uint8_t *b32u_d[6]; /* base32 ident as separate components */
/* directories used to separate elements */
const char *base_dir_table[] = {
"d", "m", "dblk", "mblk"
};
/* RFC4648 base32 encoding table (six bits) */
const uint8_t encoding_table[64][3] = {
{ 'A', 0, 0 }, { 'B', 0, 0 }, /* 0 */
{ 'C', 0, 0 }, { 'D', 0, 0 }, /* 2 */
{ 'E', 0, 0 }, { 'F', 0, 0 }, /* 4 */
{ 'G', 0, 0 }, { 'H', 0, 0 }, /* 6 */
{ 'I', 0, 0 }, { 'J', 0, 0 }, /* 8 */
{ 'K', 0, 0 }, { 'L', 0, 0 }, /* 10 */
{ 'M', 0, 0 }, { 'N', 0, 0 }, /* 12 */
{ 'O', 0, 0 }, { 'P', 0, 0 }, /* 14 */
{ 'Q', 0, 0 }, { 'R', 0, 0 }, /* 16 */
{ 'S', 0, 0 }, { 'T', 0, 0 }, /* 18 */
{ 'U', 0, 0 }, { 'V', 0, 0 }, /* 20 */
{ 'W', 0, 0 }, { 'X', 0, 0 }, /* 22 */
{ 'Y', 0, 0 }, { 'Z', 0, 0 }, /* 24 */
{ '2', 0, 0 }, { '3', 0, 0 }, /* 26 */
{ '4', 0, 0 }, { '5', 0, 0 }, /* 28 */
{ '6', 0, 0 }, { '7', 0, 0 }, /* 30 */
{ 'B', 'A', 0 }, { 'B', 'B', 0 }, /* 32 */
{ 'B', 'C', 0 }, { 'B', 'D', 0 }, /* 34 */
{ 'B', 'E', 0 }, { 'B', 'F', 0 }, /* 36 */
{ 'B', 'G', 0 }, { 'B', 'H', 0 }, /* 38 */
{ 'B', 'I', 0 }, { 'B', 'J', 0 }, /* 40 */
{ 'B', 'K', 0 }, { 'B', 'L', 0 }, /* 42 */
{ 'B', 'M', 0 }, { 'B', 'N', 0 }, /* 44 */
{ 'B', 'O', 0 }, { 'B', 'P', 0 }, /* 46 */
{ 'B', 'Q', 0 }, { 'B', 'R', 0 }, /* 48 */
{ 'B', 'S', 0 }, { 'B', 'T', 0 }, /* 50 */
{ 'B', 'U', 0 }, { 'B', 'V', 0 }, /* 52 */
{ 'B', 'W', 0 }, { 'B', 'X', 0 }, /* 54 */
{ 'B', 'Y', 0 }, { 'B', 'Z', 0 }, /* 56 */
{ 'B', '2', 0 }, { 'B', '3', 0 }, /* 58 */
{ 'B', '4', 0 }, { 'B', '5', 0 }, /* 60 */
{ 'B', '6', 0 }, { 'B', '7', 0 } /* 62 */
};
/* base32 encode ident */
b32u_i[0] = encoding_table[(ident ) & 0x1f][0];
b32u_i[1] = encoding_table[(ident >> 5) & 0x1f][0];
b32u_i[2] = encoding_table[(ident >> 10) & 0x1f][0];
b32u_i[3] = encoding_table[(ident >> 15) & 0x1f][0];
b32u_i[4] = encoding_table[(ident >> 20) & 0x1f][0];
b32u_i[5] = encoding_table[(ident >> 25) & 0x1f][0];
b32u_i[6] = encoding_table[(ident >> 30) & 0x1f][0];
b32u_i[7] = 0; /* null terminate ident string */
/* base32 encode directory separators */
b32u_d[0] = (uint8_t*)base_dir_table[elem_idx];
b32u_d[1] = &encoding_table[(ident ) & 0x3f][0];
b32u_d[2] = &encoding_table[(ident >> 6) & 0x3f][0];
b32u_d[3] = &encoding_table[(ident >> 12) & 0x3f][0];
b32u_d[4] = &encoding_table[(ident >> 18) & 0x3f][0];
b32u_d[5] = &encoding_table[(ident >> 24) & 0x3f][0];
switch (elem_idx) {
case ENTRY_ELEM_DATA:
case ENTRY_ELEM_META:
netsurf_mkpath(&fname, NULL, 8,
state->path, b32u_d[0], b32u_d[1], b32u_d[2],
b32u_d[3], b32u_d[4], b32u_d[5], b32u_i);
break;
case (ENTRY_ELEM_COUNT + ENTRY_ELEM_META):
case (ENTRY_ELEM_COUNT + ENTRY_ELEM_DATA):
netsurf_mkpath(&fname, NULL, 3,
state->path, b32u_d[0], b32u_d[1]);
break;
default:
assert("bad element index" == NULL);
break;
}
return fname;
}
/**
* invalidate an element of an entry
*
* @param state The store state to use.
* @param bse The entry to invalidate.
* @param elem_idx The element index to invalidate.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror
invalidate_element(struct store_state *state,
struct store_entry *bse,
int elem_idx)
{
if (bse->elem[elem_idx].block != 0) {
block_index_t bf;
block_index_t bi;
/* block file block resides in */
bf = (bse->elem[elem_idx].block >> BLOCK_ENTRY_COUNT) &
((1 << BLOCK_FILE_COUNT) - 1);
/* block index in file */
bi = bse->elem[elem_idx].block & ((1U << BLOCK_ENTRY_COUNT) -1);
/* clear bit in use map */
state->blocks[elem_idx][bf].use_map[bi >> 3] &= ~(1U << (bi & 7));
} else {
char *fname;
/* unlink the file from disc */
fname = store_fname(state, nsurl_hash(bse->url), elem_idx);
if (fname == NULL) {
return NSERROR_NOMEM;
}
unlink(fname);
free(fname);
}
state->total_alloc -= bse->elem[elem_idx].size;
return NSERROR_OK;
}
/**
* Remove the entry and files associated with an identifier.
*
* @param state The store state to use.
* @param bse The entry to invalidate.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror
invalidate_entry(struct store_state *state, struct store_entry *bse)
{
nserror ret;
/* mark entry as invalid */
bse->flags |= ENTRY_FLAGS_INVALID;
/* check if the entry has storage already allocated */
if (((bse->elem[ENTRY_ELEM_DATA].flags &
(ENTRY_ELEM_FLAG_HEAP | ENTRY_ELEM_FLAG_MMAP)) != 0) ||
((bse->elem[ENTRY_ELEM_META].flags &
(ENTRY_ELEM_FLAG_HEAP | ENTRY_ELEM_FLAG_MMAP)) != 0)) {
/*
* This entry cannot be immediately removed as it has
* associated allocation so wait for allocation release.
*/
NSLOG(netsurf, DEBUG,
"invalidating entry with referenced allocation");
return NSERROR_OK;
}
NSLOG(netsurf, VERBOSE, "Removing entry for %s", nsurl_access(bse->url));
ret = invalidate_element(state, bse, ENTRY_ELEM_META);
if (ret != NSERROR_OK) {
NSLOG(netsurf, ERROR, "Error invalidating metadata element");
}
ret = invalidate_element(state, bse, ENTRY_ELEM_DATA);
if (ret != NSERROR_OK) {
NSLOG(netsurf, ERROR, "Error invalidating data element");
}
/* As our final act we remove bse from the cache */
hashmap_remove(state->entries, bse->url);
/* From now, bse is invalid memory */
return NSERROR_OK;
}
/**
* Quick sort comparison.
*/
static int compar(const void *va, const void *vb)
{
const struct store_entry *a = *(const struct store_entry **)va;
const struct store_entry *b = *(const struct store_entry **)vb;
/* consider the allocation flags - if an entry has an
* allocation it is considered more valuable as it cannot be
* freed.
*/
if ((a->elem[ENTRY_ELEM_DATA].flags == ENTRY_ELEM_FLAG_NONE) &&
(b->elem[ENTRY_ELEM_DATA].flags != ENTRY_ELEM_FLAG_NONE)) {
return -1;
} else if ((a->elem[ENTRY_ELEM_DATA].flags != ENTRY_ELEM_FLAG_NONE) &&
(b->elem[ENTRY_ELEM_DATA].flags == ENTRY_ELEM_FLAG_NONE)) {
return 1;
}
if ((a->elem[ENTRY_ELEM_META].flags == ENTRY_ELEM_FLAG_NONE) &&
(b->elem[ENTRY_ELEM_META].flags != ENTRY_ELEM_FLAG_NONE)) {
return -1;
} else if ((a->elem[ENTRY_ELEM_META].flags != ENTRY_ELEM_FLAG_NONE) &&
(b->elem[ENTRY_ELEM_META].flags == ENTRY_ELEM_FLAG_NONE)) {
return 1;
}
if (a->use_count < b->use_count) {
return -1;
} else if (a->use_count > b->use_count) {
return 1;
}
/* use count is the same - now consider last use time */
if (a->last_used < b->last_used) {
return -1;
} else if (a->last_used > b->last_used) {
return 1;
}
/* they are the same */
return 0;
}
typedef struct {
struct store_entry **elist;
size_t ent_count;
} eviction_state_t;
/**
* Iterator for gathering entries to compute eviction order
*/
static bool
entry_eviction_iterator_cb(void *key, void *value, void *ctx)
{
eviction_state_t *estate = ctx;
struct store_entry *ent = value;
estate->elist[estate->ent_count++] = ent;
return false;
}
/**
* Evict entries from backing store as per configuration.
*
* Entries are evicted to ensure the cache remains within the
* configured limits on size and number of entries.
*
* The approach is to check if the cache limits have been exceeded and
* if so build and sort list of entries to evict. The list is sorted
* by use count and then by age, so oldest object with least number of uses
* get evicted first.
*
* @param state The store state to use.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror store_evict(struct store_state *state)
{
size_t ent = 0;
size_t removed = 0; /* size of removed entries */
nserror ret = NSERROR_OK;
size_t old_count;
eviction_state_t estate;
/* check if the cache has exceeded configured limit */
if (state->total_alloc < state->limit) {
/* cache within limits */
return NSERROR_OK;
}
NSLOG(netsurf, INFO,
"Evicting entries to reduce %"PRIu64" by %"PRIsizet,
state->total_alloc,
state->hysteresis);
/* allocate storage for the list */
old_count = hashmap_count(state->entries);
estate.ent_count = 0;
estate.elist = malloc(sizeof(struct state_entry*) * old_count);
if (estate.elist == NULL) {
return NSERROR_NOMEM;
}
if (hashmap_iterate(state->entries, entry_eviction_iterator_cb, &estate)) {
NSLOG(netsurf, WARNING, "Unexpected termination of eviction iterator");
free(estate.elist);
return NSERROR_UNKNOWN;
}
if (old_count != estate.ent_count) {
NSLOG(netsurf, WARNING, "Incorrect entry count after eviction iterator");
free(estate.elist);
return NSERROR_UNKNOWN;
}
qsort(estate.elist, estate.ent_count, sizeof(struct state_entry*), compar);
/* evict entries in listed order */
removed = 0;
for (ent = 0; ent < estate.ent_count; ent++) {
struct store_entry *bse = estate.elist[ent];
removed += bse->elem[ENTRY_ELEM_DATA].size;
removed += bse->elem[ENTRY_ELEM_META].size;
ret = invalidate_entry(state, bse);
if (ret != NSERROR_OK) {
break;
}
if (removed > state->hysteresis) {
break;
}
}
free(estate.elist);
NSLOG(netsurf, INFO,
"removed %"PRIsizet" in %"PRIsizet" entries, %"PRIu64" remaining in %"PRIsizet" entries",
removed, ent, state->total_alloc, old_count - ent);
return ret;
}
/**
* Write a single store entry to disk
*
* To serialise a single store entry for now we write out a 32bit int
* which is the length of the url, then that many bytes of the url.
* Then we write out the full store entry struct as-is, which includes
* a useless nsurl pointer.
*/
static nserror
write_entry(struct store_entry *ent, int fd)
{
uint32_t len = strlen(nsurl_access(ent->url));
if (write(fd, &len, sizeof(len)) != sizeof(len))
return NSERROR_SAVE_FAILED;
if (write(fd, nsurl_access(ent->url), len) != (ssize_t)len)
return NSERROR_SAVE_FAILED;
if (write(fd, ent, sizeof(*ent)) != sizeof(*ent))
return NSERROR_SAVE_FAILED;
return NSERROR_OK;
}
typedef struct {
int fd;
size_t written;
} write_entry_iteration_state;
/**
* Callback for iterating the entries hashmap
*/
static bool
write_entry_iterator(void *key, void *value, void *ctx)
{
/* We ignore the key */
struct store_entry *ent = value;
write_entry_iteration_state *state = ctx;
state->written++;
/* We stop early if we fail to write this entry */
return write_entry(ent, state->fd) != NSERROR_OK;
}
/**
* Write filesystem entries to file.
*
* Serialise entry index out to storage.
*
* @param state The backing store state to serialise.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror write_entries(struct store_state *state)
{
char *tname = NULL; /* temporary file name for atomic replace */
char *fname = NULL; /* target filename */
write_entry_iteration_state weistate;
nserror ret;
memset(&weistate, 0, sizeof(weistate));
if (state->entries_dirty == false) {
/* entries have not been updated since last write */
return NSERROR_OK;
}
ret = netsurf_mkpath(&tname, NULL, 2, state->path, "t"ENTRIES_FNAME);
if (ret != NSERROR_OK) {
return ret;
}
weistate.fd = open(tname, O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
if (weistate.fd == -1) {
free(tname);
return NSERROR_SAVE_FAILED;
}
if (hashmap_iterate(state->entries, write_entry_iterator, &weistate)) {
/* The iteration ended early, so we failed */
close(weistate.fd);
unlink(tname);
free(tname);
return NSERROR_SAVE_FAILED;
}
close(weistate.fd);
ret = netsurf_mkpath(&fname, NULL, 2, state->path, ENTRIES_FNAME);
if (ret != NSERROR_OK) {
unlink(tname);
free(tname);
return ret;
}
/* remove() call is to handle non-POSIX rename() implementations */
(void)remove(fname);
if (rename(tname, fname) != 0) {
unlink(tname);
free(tname);
free(fname);
return NSERROR_SAVE_FAILED;
}
NSLOG(netsurf, INFO, "Wrote out %"PRIsizet" entries", weistate.written);
return NSERROR_OK;
}
/**
* Write block file use map to file.
*
* Serialise block file use map out to storage.
*
* \param state The backing store state to serialise.
* \return NSERROR_OK on success or error code on failure.
*/
static nserror write_blocks(struct store_state *state)
{
int fd;
char *tname = NULL; /* temporary file name for atomic replace */
char *fname = NULL; /* target filename */
size_t blocks_size;
size_t written = 0;
size_t wr;
nserror ret;
int bfidx; /* block file index */
int elem_idx;
if (state->blocks_dirty == false) {
/* blocks use maps have not been updated since last write */
return NSERROR_OK;
}
ret = netsurf_mkpath(&tname, NULL, 2, state->path, "t"BLOCKS_FNAME);
if (ret != NSERROR_OK) {
return ret;
}
fd = open(tname, O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
if (fd == -1) {
free(tname);
return NSERROR_SAVE_FAILED;
}
blocks_size = (BLOCK_FILE_COUNT * ENTRY_ELEM_COUNT) * BLOCK_USE_MAP_SIZE;
for (elem_idx = 0; elem_idx < ENTRY_ELEM_COUNT; elem_idx++) {
for (bfidx = 0; bfidx < BLOCK_FILE_COUNT; bfidx++) {
wr = write(fd,
&state->blocks[elem_idx][bfidx].use_map[0],
BLOCK_USE_MAP_SIZE);
if (wr != BLOCK_USE_MAP_SIZE) {
NSLOG(netsurf, DEBUG,
"writing block file %d use index on file number %d failed",
elem_idx,
bfidx);
goto wr_err;
}
written += wr;
}
}
wr_err:
close(fd);
/* check all data was written */
if (written != blocks_size) {
unlink(tname);
free(tname);
return NSERROR_SAVE_FAILED;
}
ret = netsurf_mkpath(&fname, NULL, 2, state->path, BLOCKS_FNAME);
if (ret != NSERROR_OK) {
unlink(tname);
free(tname);
return ret;
}
/* remove() call is to handle non-POSIX rename() implementations */
(void)remove(fname);
if (rename(tname, fname) != 0) {
unlink(tname);
free(tname);
free(fname);
return NSERROR_SAVE_FAILED;
}
return NSERROR_OK;
}
/**
* Ensures block files are of the correct extent
*
* block files have their extent set to their maximum size to ensure
* subsequent reads and writes do not need to extend the file and are
* therefore faster.
*
* \param state The backing store state to set block extent for.
* \return NSERROR_OK on success or error code on failure.
*/
static nserror set_block_extents(struct store_state *state)
{
int bfidx; /* block file index */
int elem_idx;
int ftr;
if (state->blocks_opened == false) {
/* no blocks have been opened since last write */
return NSERROR_OK;
}
NSLOG(netsurf, DEBUG, "Starting");
for (elem_idx = 0; elem_idx < ENTRY_ELEM_COUNT; elem_idx++) {
for (bfidx = 0; bfidx < BLOCK_FILE_COUNT; bfidx++) {
if (state->blocks[elem_idx][bfidx].fd != -1) {
/* ensure block file is correct extent */
ftr = ftruncate(state->blocks[elem_idx][bfidx].fd, 1U << (log2_block_size[elem_idx] + BLOCK_ENTRY_COUNT));
if (ftr == -1) {
NSLOG(netsurf, ERROR,
"Truncate failed errno:%d",
errno);
}
}
}
}
NSLOG(netsurf, DEBUG, "Complete");
state->blocks_opened = false;
return NSERROR_OK;
}
/**
* maintenance of control structures.
*
* callback scheduled when control data has been update. Currently
* this is for when the entries table is dirty and requires
* serialising.
*
* \param s store state to maintain.
*/
static void control_maintenance(void *s)
{
struct store_state *state = s;
write_entries(state);
write_blocks(state);
set_block_extents(state);
}
/**
* Lookup a backing store entry in the entry table from a url.
*
* This finds the store entry associated with the given
* key. Additionally if an entry is found it updates the usage data
* about the entry.
*
* @param state The store state to use.
* @param url The value used as the unique key to search entries for.
* @param bse Pointer used to return value.
* @return NSERROR_OK and bse updated on success or NSERROR_NOT_FOUND
* if no entry corresponds to the url.
*/
static nserror
get_store_entry(struct store_state *state, nsurl *url, struct store_entry **bse)
{
struct store_entry *ent;
ent = hashmap_lookup(state->entries, url);
if (ent == NULL) {
return NSERROR_NOT_FOUND;
}
*bse = ent;
ent->last_used = time(NULL);
ent->use_count++;
state->entries_dirty = true;
guit->misc->schedule(CONTROL_MAINT_TIME, control_maintenance, state);
return NSERROR_OK;
}
/**
* Find next available small block.
*/
static block_index_t alloc_block(struct store_state *state, int elem_idx)
{
int bf;
int idx;
int bit;
uint8_t *map;
for (bf = 0; bf < BLOCK_FILE_COUNT; bf++) {
map = &state->blocks[elem_idx][bf].use_map[0];
for (idx = 0; idx < BLOCK_USE_MAP_SIZE; idx++) {
if (*(map + idx) != 0xff) {
/* located an unused block */
for (bit = 0; bit < 8;bit++) {
if (((*(map + idx)) & (1U << bit)) == 0) {
/* mark block as used */
*(map + idx) |= 1U << bit;
state->blocks_dirty = true;
return (((bf * BLOCK_USE_MAP_SIZE) + idx) * 8) + bit;
}
}
}
}
}
return 0;
}
/**
* Set a backing store entry in the entry table from a url.
*
* This creates a backing store entry in the entry table for a url.
*
* @param state The store state to use.
* @param url The value used as the unique key to search entries for.
* @param elem_idx The index of the entry element to use.
* @param data The data to store
* @param datalen The length of data in \a data
* @param bse Pointer used to return value.
* @return NSERROR_OK and \a bse updated on success or NSERROR_NOT_FOUND
* if no entry corresponds to the url.
*/
static nserror
set_store_entry(struct store_state *state,
nsurl *url,
int elem_idx,
uint8_t *data,
const size_t datalen,
struct store_entry **bse)
{
struct store_entry *se;
nserror ret;
struct store_entry_element *elem;
NSLOG(netsurf, DEBUG, "url:%s", nsurl_access(url));
/* evict entries as required and ensure there is at least one
* new entry available.
*/
ret = store_evict(state);
if (ret != NSERROR_OK) {
return ret;
}
se = hashmap_lookup(state->entries, url);
if (se == NULL) {
se = hashmap_insert(state->entries, url);
}
if (se == NULL) {
return NSERROR_NOMEM;
}
/* the entry element */
elem = &se->elem[elem_idx];
/* check if the element has storage already allocated */
if ((elem->flags & (ENTRY_ELEM_FLAG_HEAP | ENTRY_ELEM_FLAG_MMAP)) != 0) {
/* this entry cannot be removed as it has associated
* allocation.
*/
NSLOG(netsurf, ERROR,
"attempt to overwrite entry with in use data");
return NSERROR_PERMISSION;
}
/* set the common entry data */
se->use_count = 1;
se->last_used = time(NULL);
/* store the data in the element */
elem->flags |= ENTRY_ELEM_FLAG_HEAP;
elem->data = data;
elem->ref = 1;
/* account for size of entry element */
state->total_alloc -= elem->size;
elem->size = datalen;
state->total_alloc += elem->size;
/* if the element will fit in a small block attempt to allocate one */
if (elem->size <= (1U << log2_block_size[elem_idx])) {
elem->block = alloc_block(state, elem_idx);
}
/* ensure control maintenance scheduled. */
state->entries_dirty = true;
guit->misc->schedule(CONTROL_MAINT_TIME, control_maintenance, state);
*bse = se;
return NSERROR_OK;
}
/**
* Open a file using a store ident.
*
* @param state The store state to use.
* @param ident The identifier to open file for.
* @param elem_idx The element within the store entry to open. The
* value should be be one of the values in the
* store_entry_elem_idx enum. Additionally it may have
* ENTRY_ELEM_COUNT added to it to indicate block file
* names.
* @param openflags The flags used with the open call.
* @return An fd from the open call or -1 on error.
*/
static int
store_open(struct store_state *state,
entry_ident_t ident,
int elem_idx,
int openflags)
{
char *fname;
nserror ret;
int fd;
fname = store_fname(state, ident, elem_idx);
if (fname == NULL) {
NSLOG(netsurf, ERROR, "filename error");
return -1;
}
/* ensure all path elements to file exist if creating file */
if (openflags & O_CREAT) {
ret = netsurf_mkdir_all(fname);
if (ret != NSERROR_OK) {
NSLOG(netsurf, WARNING,
"file path \"%s\" could not be created", fname);
free(fname);
return -1;
}
}
NSLOG(netsurf, DEBUG, "opening %s", fname);
fd = open(fname, openflags, S_IRUSR | S_IWUSR);
free(fname);
return fd;
}
/**
* Unlink entries file
*
* @param state The backing store state.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror
unlink_entries(struct store_state *state)
{
char *fname = NULL;
nserror ret;
ret = netsurf_mkpath(&fname, NULL, 2, state->path, ENTRIES_FNAME);
if (ret != NSERROR_OK) {
return ret;
}
unlink(fname);
free(fname);
return NSERROR_OK;
}
/**
* Read description entries into memory.
*
* @param state The backing store state to put the loaded entries in.
* @return NSERROR_OK on success or error code on faliure.
*/
static nserror
read_entries(struct store_state *state)
{
char *fname = NULL;
char *url;
nsurl *nsurl;
nserror ret;
size_t read_entries = 0;
struct store_entry *ent;
int fd;
ret = netsurf_mkpath(&fname, NULL, 2, state->path, ENTRIES_FNAME);
if (ret != NSERROR_OK) {
return ret;
}
state->entries = hashmap_create(&entries_hashmap_parameters);
if (state->entries == NULL) {
free(fname);
return NSERROR_NOMEM;
}
fd = open(fname, O_RDWR);
if (fd != -1) {
uint32_t urllen;
while (read(fd, &urllen, sizeof(urllen)) == sizeof(urllen)) {
url = calloc(1, urllen+1);
if (url == NULL) {
close(fd);
free(fname);
return NSERROR_NOMEM;
}
if (read(fd, url, urllen) != (ssize_t)urllen) {
free(url);
close(fd);
free(fname);
return NSERROR_INIT_FAILED;
}
ret = nsurl_create(url, &nsurl);
if (ret != NSERROR_OK) {
free(url);
close(fd);
free(fname);
return ret;
}
free(url);
/* We have to be careful here about nsurl refs */
ent = hashmap_insert(state->entries, nsurl);
if (ent == NULL) {
nsurl_unref(nsurl);
close(fd);
free(fname);
return NSERROR_NOMEM;
}
/* At this point, ent actually owns a ref of nsurl */
if (read(fd, ent, sizeof(*ent)) != sizeof(*ent)) {
/* The read failed, so reset the ptr */
ent->url = nsurl; /* It already had a ref */
nsurl_unref(nsurl);
close(fd);
free(fname);
return NSERROR_INIT_FAILED;
}
ent->url = nsurl; /* It already owns a ref */
nsurl_unref(nsurl);
NSLOG(netsurf, DEBUG, "Successfully read entry for %s", nsurl_access(ent->url));
read_entries++;
/* Note the size allocation */
state->total_alloc += ent->elem[ENTRY_ELEM_DATA].size;
state->total_alloc += ent->elem[ENTRY_ELEM_META].size;
/* And ensure we don't pretend to have this in memory yet */
ent->elem[ENTRY_ELEM_DATA].flags &= ~(ENTRY_ELEM_FLAG_HEAP | ENTRY_ELEM_FLAG_MMAP);
ent->elem[ENTRY_ELEM_META].flags &= ~(ENTRY_ELEM_FLAG_HEAP | ENTRY_ELEM_FLAG_MMAP);
}
close(fd);
}
NSLOG(netsurf, INFO, "Read %"PRIsizet" entries from cache", read_entries);
free(fname);
return NSERROR_OK;
}
/**
* Read block file usage bitmaps.
*
* @param state The backing store state to put the loaded entries in.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror
read_blocks(struct store_state *state)
{
int bfidx; /* block file index */
int elem_idx;
int fd;
ssize_t rd;
char *fname = NULL;
nserror ret;
ret = netsurf_mkpath(&fname, NULL, 2, state->path, BLOCKS_FNAME);
if (ret != NSERROR_OK) {
return ret;
}
NSLOG(netsurf, INFO, "Initialising block use map from %s", fname);
fd = open(fname, O_RDWR);
free(fname);
if (fd != -1) {
/* initialise block file use array */
for (elem_idx = 0; elem_idx < ENTRY_ELEM_COUNT; elem_idx++) {
for (bfidx = 0; bfidx < BLOCK_FILE_COUNT; bfidx++) {
rd = read(fd,
&state->blocks[elem_idx][bfidx].use_map[0],
BLOCK_USE_MAP_SIZE);
if (rd <= 0) {
NSLOG(netsurf, ERROR,
"reading block file %d use index on file number %d failed",
elem_idx,
bfidx);
goto rd_err;
}
}
}
rd_err:
close(fd);
} else {
NSLOG(netsurf, INFO, "Initialising block use map to defaults");
/* ensure block 0 (invalid sentinel) is skipped */
state->blocks[ENTRY_ELEM_DATA][0].use_map[0] = 1;
state->blocks[ENTRY_ELEM_META][0].use_map[0] = 1;
}
/* initialise block file file descriptors */
for (bfidx = 0; bfidx < BLOCK_FILE_COUNT; bfidx++) {
state->blocks[ENTRY_ELEM_DATA][bfidx].fd = -1;
state->blocks[ENTRY_ELEM_META][bfidx].fd = -1;
}
return NSERROR_OK;
}
/**
* Write the cache tag file.
*
* @param state The cache state.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror
write_cache_tag(struct store_state *state)
{
FILE *fcachetag;
nserror ret;
char *fname = NULL;
ret = netsurf_mkpath(&fname, NULL, 2, state->path, "CACHEDIR.TAG");
if (ret != NSERROR_OK) {
return ret;
}
fcachetag = fopen(fname, "wb");
free(fname);
if (fcachetag == NULL) {
return NSERROR_NOT_FOUND;
}
fprintf(fcachetag,
"Signature: 8a477f597d28d172789f06886806bc55\n"
"# This file is a cache directory tag created by NetSurf.\n"
"# For information about cache directory tags, see:\n"
"# http://www.brynosaurus.com/cachedir/\n");
fclose(fcachetag);
return NSERROR_OK;
}
/**
* Write the control file for the current state.
*
* @param state The state to write to the control file.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror
write_control(struct store_state *state)
{
FILE *fcontrol;
nserror ret;
char *fname = NULL;
ret = netsurf_mkpath(&fname, NULL, 2, state->path, "control");
if (ret != NSERROR_OK) {
return ret;
}
NSLOG(netsurf, INFO, "writing control file \"%s\"", fname);
ret = netsurf_mkdir_all(fname);
if (ret != NSERROR_OK) {
free(fname);
return ret;
}
fcontrol = fopen(fname, "wb");
free(fname);
if (fcontrol == NULL) {
return NSERROR_NOT_FOUND;
}
fprintf(fcontrol, "%u%c", CONTROL_VERSION, 0);
fclose(fcontrol);
return NSERROR_OK;
}
/**
* Read and parse the control file.
*
* @param state The state to read from the control file.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror
read_control(struct store_state *state)
{
nserror ret;
FILE *fcontrol;
unsigned int ctrlversion;
char *fname = NULL;
ret = netsurf_mkpath(&fname, NULL, 2, state->path, "control");
if (ret != NSERROR_OK) {
return ret;
}
NSLOG(netsurf, INFO, "opening control file \"%s\"", fname);
fcontrol = fopen(fname, "rb");
free(fname);
if (fcontrol == NULL) {
/* unable to open control file */
if (errno == ENOENT) {
return NSERROR_NOT_FOUND;
} else {
return NSERROR_INIT_FAILED;
}
}
/* read control and setup new state */
/* first line is version */
if (fscanf(fcontrol, "%u", &ctrlversion) != 1) {
goto control_error;
}
if (ctrlversion != CONTROL_VERSION) {
goto control_error;
}
if (fgetc(fcontrol) != 0) {
goto control_error;
}
fclose(fcontrol);
return NSERROR_OK;
control_error: /* problem with the control file */
fclose(fcontrol);
return NSERROR_INIT_FAILED;
}
/* Functions exported in the backing store table */
/**
* Initialise the backing store.
*
* @param parameters to configure backing store.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror
initialise(const struct llcache_store_parameters *parameters)
{
struct store_state *newstate;
nserror ret;
/* check backing store is not already initialised */
if (storestate != NULL) {
return NSERROR_INIT_FAILED;
}
/* if we are not allowed any space simply give up on init */
if (parameters->limit == 0) {
return NSERROR_OK;
}
/* if the path to the cache directory is not set do not init */
if (parameters->path == NULL) {
return NSERROR_OK;
}
/* allocate new store state and set defaults */
newstate = calloc(1, sizeof(struct store_state));
if (newstate == NULL) {
return NSERROR_NOMEM;
}
newstate->path = strdup(parameters->path);
newstate->limit = parameters->limit;
newstate->hysteresis = parameters->hysteresis;
/* read store control and create new if required */
ret = read_control(newstate);
if (ret != NSERROR_OK) {
if (ret == NSERROR_NOT_FOUND) {
NSLOG(netsurf, INFO, "cache control file not found, making fresh");
} else {
NSLOG(netsurf, ERROR, "read control failed %s",
messages_get_errorcode(ret));
ret = netsurf_recursive_rm(newstate->path);
if (ret != NSERROR_OK) {
NSLOG(netsurf, WARNING, "Error `%s` while removing `%s`",
messages_get_errorcode(ret), newstate->path);
NSLOG(netsurf, WARNING, "Unable to clean up partial cache state.");
NSLOG(netsurf, WARNING, "Funky behaviour may ensue.");
} else {
NSLOG(netsurf, INFO, "Successfully removed old cache from `%s`",
newstate->path);
}
}
ret = write_control(newstate);
if (ret == NSERROR_OK) {
unlink_entries(newstate);
write_cache_tag(newstate);
}
}
if (ret != NSERROR_OK) {
/* that went well obviously */
free(newstate->path);
free(newstate);
return ret;
}
/* read filesystem entries */
ret = read_entries(newstate);
if (ret != NSERROR_OK) {
/* that went well obviously */
free(newstate->path);
free(newstate);
return ret;
}
/* read blocks */
ret = read_blocks(newstate);
if (ret != NSERROR_OK) {
/* oh dear */
hashmap_destroy(newstate->entries);
free(newstate->path);
free(newstate);
return ret;
}
storestate = newstate;
NSLOG(netsurf, INFO, "FS backing store init successful");
NSLOG(netsurf, INFO,
"path:%s limit:%"PRIsizet" hyst:%"PRIsizet,
newstate->path,
newstate->limit,
newstate->hysteresis);
NSLOG(netsurf, INFO, "Using %"PRIu64"/%"PRIsizet,
newstate->total_alloc, newstate->limit);
return NSERROR_OK;
}
/**
* Finalise the backing store.
*
* \todo This will cause the backing store to leak any outstanding memory
* allocations. This will probably best be done by a global use count.
*
* @return NSERROR_OK on success.
*/
static nserror
finalise(void)
{
int bf; /* block file index */
unsigned int op_count;
if (storestate != NULL) {
guit->misc->schedule(-1, control_maintenance, storestate);
write_entries(storestate);
write_blocks(storestate);
/* ensure all block files are closed */
for (bf = 0; bf < BLOCK_FILE_COUNT; bf++) {
if (storestate->blocks[ENTRY_ELEM_DATA][bf].fd != -1) {
close(storestate->blocks[ENTRY_ELEM_DATA][bf].fd);
}
if (storestate->blocks[ENTRY_ELEM_META][bf].fd != -1) {
close(storestate->blocks[ENTRY_ELEM_META][bf].fd);
}
}
op_count = storestate->hit_count + storestate->miss_count;
/* avoid division by zero */
if (op_count > 0) {
NSLOG(netsurf, INFO,
"Cache total/hit/miss/fail (counts) %d/%"PRIsizet"/%"PRIsizet"/%d (100%%/%"PRIsizet"%%/%"PRIsizet"%%/%d%%)",
op_count,
storestate->hit_count,
storestate->miss_count,
0,
(storestate->hit_count * 100) / op_count,
(storestate->miss_count * 100) / op_count,
0);
}
hashmap_destroy(storestate->entries);
free(storestate->path);
free(storestate);
storestate = NULL;
}
return NSERROR_OK;
}
/**
* Write an element of an entry to backing storage in a small block file.
*
* \param state The backing store state to use.
* \param bse The entry to store
* \param elem_idx The element index within the entry.
* \return NSERROR_OK on success or error code.
*/
static nserror store_write_block(struct store_state *state,
struct store_entry *bse,
int elem_idx)
{
block_index_t bf = (bse->elem[elem_idx].block >> BLOCK_ENTRY_COUNT) &
((1 << BLOCK_FILE_COUNT) - 1); /* block file block resides in */
block_index_t bi = bse->elem[elem_idx].block & ((1U << BLOCK_ENTRY_COUNT) -1); /* block index in file */
ssize_t wr;
off_t offst;
/* ensure the block file fd is good */
if (state->blocks[elem_idx][bf].fd == -1) {
state->blocks[elem_idx][bf].fd = store_open(state, bf,
elem_idx + ENTRY_ELEM_COUNT, O_CREAT | O_RDWR);
if (state->blocks[elem_idx][bf].fd == -1) {
NSLOG(netsurf, ERROR, "Open failed errno %d", errno);
return NSERROR_SAVE_FAILED;
}
/* flag that a block file has been opened */
state->blocks_opened = true;
}
offst = (unsigned int)bi << log2_block_size[elem_idx];
wr = nsu_pwrite(state->blocks[elem_idx][bf].fd,
bse->elem[elem_idx].data,
bse->elem[elem_idx].size,
offst);
if (wr != (ssize_t)bse->elem[elem_idx].size) {
NSLOG(netsurf, ERROR,
"Write failed %"PRIssizet" of %d bytes from %p at 0x%jx block %d errno %d",
wr,
bse->elem[elem_idx].size,
bse->elem[elem_idx].data,
(uintmax_t)offst,
bse->elem[elem_idx].block,
errno);
return NSERROR_SAVE_FAILED;
}
NSLOG(netsurf, INFO,
"Wrote %"PRIssizet" bytes from %p at 0x%jx block %d", wr,
bse->elem[elem_idx].data, (uintmax_t)offst,
bse->elem[elem_idx].block);
return NSERROR_OK;
}
/**
* Write an element of an entry to backing storage as an individual file.
*
* \param state The backing store state to use.
* \param bse The entry to store
* \param elem_idx The element index within the entry.
* \return NSERROR_OK on success or error code.
*/
static nserror store_write_file(struct store_state *state,
struct store_entry *bse,
int elem_idx)
{
ssize_t wr;
int fd;
int err;
fd = store_open(state, nsurl_hash(bse->url), elem_idx, O_CREAT | O_WRONLY);
if (fd < 0) {
perror("");
NSLOG(netsurf, ERROR, "Open failed %d errno %d", fd, errno);
return NSERROR_SAVE_FAILED;
}
wr = write(fd, bse->elem[elem_idx].data, bse->elem[elem_idx].size);
err = errno; /* close can change errno */
close(fd);
if (wr != (ssize_t)bse->elem[elem_idx].size) {
NSLOG(netsurf, ERROR,
"Write failed %"PRIssizet" of %d bytes from %p errno %d",
wr,
bse->elem[elem_idx].size,
bse->elem[elem_idx].data,
err);
/** @todo Delete the file? */
return NSERROR_SAVE_FAILED;
}
NSLOG(netsurf, VERBOSE, "Wrote %"PRIssizet" bytes from %p", wr,
bse->elem[elem_idx].data);
return NSERROR_OK;
}
/**
* Place an object in the backing store.
*
* takes ownership of the heap block passed in.
*
* @param url The url is used as the unique primary key for the data.
* @param bsflags The flags to control how the object is stored.
* @param data The objects source data.
* @param datalen The length of the \a data.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror
store(nsurl *url,
enum backing_store_flags bsflags,
uint8_t *data,
const size_t datalen)
{
nserror ret;
struct store_entry *bse;
int elem_idx;
/* check backing store is initialised */
if (storestate == NULL) {
return NSERROR_INIT_FAILED;
}
/* calculate the entry element index */
if ((bsflags & BACKING_STORE_META) != 0) {
elem_idx = ENTRY_ELEM_META;
} else {
elem_idx = ENTRY_ELEM_DATA;
}
/* set the store entry up */
ret = set_store_entry(storestate, url, elem_idx, data, datalen, &bse);
if (ret != NSERROR_OK) {
NSLOG(netsurf, ERROR, "store entry setting failed");
return ret;
}
if (bse->elem[elem_idx].block != 0) {
/* small block storage */
ret = store_write_block(storestate, bse, elem_idx);
} else {
/* separate file in backing store */
ret = store_write_file(storestate, bse, elem_idx);
}
return ret;
}
/**
* release any allocation for an entry
*/
static nserror entry_release_alloc(struct store_entry_element *elem)
{
if ((elem->flags & ENTRY_ELEM_FLAG_HEAP) != 0) {
elem->ref--;
if (elem->ref == 0) {
NSLOG(netsurf, DEEPDEBUG, "freeing %p", elem->data);
free(elem->data);
elem->flags &= ~ENTRY_ELEM_FLAG_HEAP;
}
}
return NSERROR_OK;
}
/**
* Read an element of an entry from a small block file in the backing storage.
*
* \param state The backing store state to use.
* \param bse The entry to read.
* \param elem_idx The element index within the entry.
* \return NSERROR_OK on success or error code.
*/
static nserror store_read_block(struct store_state *state,
struct store_entry *bse,
int elem_idx)
{
block_index_t bf = (bse->elem[elem_idx].block >> BLOCK_ENTRY_COUNT) &
((1 << BLOCK_FILE_COUNT) - 1); /* block file block resides in */
block_index_t bi = bse->elem[elem_idx].block & ((1 << BLOCK_ENTRY_COUNT) -1); /* block index in file */
ssize_t rd;
off_t offst;
/* ensure the block file fd is good */
if (state->blocks[elem_idx][bf].fd == -1) {
state->blocks[elem_idx][bf].fd = store_open(state, bf,
elem_idx + ENTRY_ELEM_COUNT, O_CREAT | O_RDWR);
if (state->blocks[elem_idx][bf].fd == -1) {
NSLOG(netsurf, ERROR, "Open failed errno %d", errno);
return NSERROR_SAVE_FAILED;
}
/* flag that a block file has been opened */
state->blocks_opened = true;
}
offst = (unsigned int)bi << log2_block_size[elem_idx];
rd = nsu_pread(state->blocks[elem_idx][bf].fd,
bse->elem[elem_idx].data,
bse->elem[elem_idx].size,
offst);
if (rd != (ssize_t)bse->elem[elem_idx].size) {
NSLOG(netsurf, ERROR,
"Failed reading %"PRIssizet" of %d bytes into %p from 0x%jx block %d errno %d",
rd,
bse->elem[elem_idx].size,
bse->elem[elem_idx].data,
(uintmax_t)offst,
bse->elem[elem_idx].block,
errno);
return NSERROR_SAVE_FAILED;
}
NSLOG(netsurf, DEEPDEBUG,
"Read %"PRIssizet" bytes into %p from 0x%jx block %d", rd,
bse->elem[elem_idx].data, (uintmax_t)offst,
bse->elem[elem_idx].block);
return NSERROR_OK;
}
/**
* Read an element of an entry from an individual file in the backing storage.
*
* \param state The backing store state to use.
* \param bse The entry to read.
* \param elem_idx The element index within the entry.
* \return NSERROR_OK on success or error code.
*/
static nserror store_read_file(struct store_state *state,
struct store_entry *bse,
int elem_idx)
{
int fd;
ssize_t rd; /* return from read */
int ret = NSERROR_OK;
size_t tot = 0; /* total size */
/* separate file in backing store */
fd = store_open(storestate, nsurl_hash(bse->url), elem_idx, O_RDONLY);
if (fd < 0) {
NSLOG(netsurf, ERROR, "Open failed %d errno %d", fd, errno);
/** @todo should this invalidate the entry? */
return NSERROR_NOT_FOUND;
}
while (tot < bse->elem[elem_idx].size) {
rd = read(fd,
bse->elem[elem_idx].data + tot,
bse->elem[elem_idx].size - tot);
if (rd <= 0) {
NSLOG(netsurf, ERROR,
"read error returned %"PRIssizet" errno %d",
rd,
errno);
ret = NSERROR_NOT_FOUND;
break;
}
tot += rd;
}
close(fd);
NSLOG(netsurf, DEEPDEBUG, "Read %"PRIsizet" bytes into %p", tot,
bse->elem[elem_idx].data);
return ret;
}
/**
* Retrieve an object from the backing store.
*
* @param[in] url The url is used as the unique primary key for the data.
* @param[in] bsflags The flags to control how the object is retrieved.
* @param[out] data_out The objects data.
* @param[out] datalen_out The length of the \a data retrieved.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror
fetch(nsurl *url,
enum backing_store_flags bsflags,
uint8_t **data_out,
size_t *datalen_out)
{
nserror ret;
struct store_entry *bse;
struct store_entry_element *elem;
int elem_idx;
/* check backing store is initialised */
if (storestate == NULL) {
return NSERROR_INIT_FAILED;
}
/* fetch store entry */
ret = get_store_entry(storestate, url, &bse);
if (ret != NSERROR_OK) {
NSLOG(netsurf, DEBUG, "Entry for %s not found", nsurl_access(url));
storestate->miss_count++;
return ret;
}
storestate->hit_count++;
NSLOG(netsurf, DEBUG, "retrieving cache data for url:%s",
nsurl_access(url));
/* calculate the entry element index */
if ((bsflags & BACKING_STORE_META) != 0) {
elem_idx = ENTRY_ELEM_META;
} else {
elem_idx = ENTRY_ELEM_DATA;
}
elem = &bse->elem[elem_idx];
/* if an allocation already exists return it */
if ((elem->flags & ENTRY_ELEM_FLAG_HEAP) != 0) {
/* use the existing allocation and bump the ref count. */
elem->ref++;
NSLOG(netsurf, DEEPDEBUG,
"Using existing entry (%p) allocation %p refs:%d", bse,
elem->data, elem->ref);
} else {
/* allocate from the heap */
elem->data = malloc(elem->size);
if (elem->data == NULL) {
NSLOG(netsurf, ERROR,
"Failed to create new heap allocation");
return NSERROR_NOMEM;
}
NSLOG(netsurf, DEEPDEBUG, "Created new heap allocation %p",
elem->data);
/* mark the entry as having a valid heap allocation */
elem->flags |= ENTRY_ELEM_FLAG_HEAP;
elem->ref = 1;
/* fill the new block */
if (elem->block != 0) {
ret = store_read_block(storestate, bse, elem_idx);
} else {
ret = store_read_file(storestate, bse, elem_idx);
}
}
/* free the allocation if there is a read error */
if (ret != NSERROR_OK) {
entry_release_alloc(elem);
} else {
/* update stats and setup return pointers */
storestate->hit_size += elem->size;
*data_out = elem->data;
*datalen_out = elem->size;
}
return ret;
}
/**
* release a previously fetched or stored memory object.
*
* @param[in] url The url is used as the unique primary key to invalidate.
* @param[in] bsflags The flags to control how the object data is released.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror release(nsurl *url, enum backing_store_flags bsflags)
{
nserror ret;
struct store_entry *bse;
struct store_entry_element *elem;
/* check backing store is initialised */
if (storestate == NULL) {
return NSERROR_INIT_FAILED;
}
ret = get_store_entry(storestate, url, &bse);
if (ret != NSERROR_OK) {
NSLOG(netsurf, WARNING, "entry not found");
return ret;
}
/* the entry element */
if ((bsflags & BACKING_STORE_META) != 0) {
elem = &bse->elem[ENTRY_ELEM_META];
} else {
elem = &bse->elem[ENTRY_ELEM_DATA];
}
ret = entry_release_alloc(elem);
/* if the entry has previously been invalidated but had
* allocation it must be invalidated fully now the allocation
* has been released.
*/
if ((ret == NSERROR_OK) &&
((bse->flags & ENTRY_FLAGS_INVALID) != 0)) {
ret = invalidate_entry(storestate, bse);
}
return ret;
}
/**
* Invalidate a source object from the backing store.
*
* The entry (if present in the backing store) must no longer
* be returned as a result to the fetch or meta operations.
*
* @param url The url is used as the unique primary key to invalidate.
* @return NSERROR_OK on success or error code on failure.
*/
static nserror
invalidate(nsurl *url)
{
nserror ret;
struct store_entry *bse;
/* check backing store is initialised */
if (storestate == NULL) {
return NSERROR_INIT_FAILED;
}
ret = get_store_entry(storestate, url, &bse);
if (ret != NSERROR_OK) {
return ret;
}
return invalidate_entry(storestate, bse);
}
static struct gui_llcache_table llcache_table = {
.initialise = initialise,
.finalise = finalise,
.store = store,
.fetch = fetch,
.invalidate = invalidate,
.release = release,
};
struct gui_llcache_table *filesystem_llcache_table = &llcache_table;
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