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netsurf/content/fs_backing_store.c
Vincent Sanders ea9a2ff01d Fix up some doxygen errors
2015-04-03 00:28:22 +01:00

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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 retrival for metadata objects as their heap
* lifetime is typically very short, though this may be obsoleted
* by a small object storage stratagy.
*
* \todo make backing store have a more efficient small object storage.
*
*/
#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 "utils/filepath.h"
#include "utils/file.h"
#include "utils/nsurl.h"
#include "utils/log.h"
#include "utils/utils.h"
#include "utils/messages.h"
#include "desktop/gui_internal.h"
#include "desktop/gui_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 130
/** Number of milliseconds after a update before control data maintinance is performed */
#define CONTROL_MAINT_TIME 10000
/** Get address from ident */
#define BS_ADDRESS(ident, state) ((ident) & ((1 << state->ident_bits) - 1))
/** Lookup store entry index from ident */
#define BS_ENTRY_INDEX(ident, state) state->addrmap[(ident) & ((1 << state->ident_bits) - 1)]
/** Get store entry from ident. */
#define BS_ENTRY(ident, state) state->entries[state->addrmap[(ident) & ((1 << state->ident_bits) - 1)]]
/** 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(4k) */
#define BLOCK_ENTRY_COUNT 12
/** 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 (1k) */
#define BLOCK_META_SIZE 10
/** 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 refering 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 {
int64_t last_used; /**< unix time the entry was last used */
entry_ident_t ident; /**< entry identifier */
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 */
unsigned int ident_bits; /**< log2 number of bits to use for address. */
/* cache entry management */
struct store_entry *entries; /**< store entries. */
unsigned int entry_bits; /**< log2 number of bits in entry index. */
unsigned int last_entry; /**< index of last usable entry. */
/** flag indicating if the entries have been made persistant
* since they were last changed.
*/
bool entries_dirty;
/** URL identifier to entry index mapping.
*
* This is an open coded index on the entries url field and
* provides a computationaly inexpensive way to go from the
* url to an entry.
*/
entry_index_t *addrmap;
/* small block managemet */
struct block_file blocks[ENTRY_ELEM_COUNT][BLOCK_FILE_COUNT];
/** flag indicating if the block file use maps have been made
* persistant since they were last changed.
*/
bool blocks_dirty;
/* 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;
/**
* Remove a backing store entry from the entry table.
*
* This finds the store entry associated with the given key and
* removes it from the table. The removed entry is returned but is
* only valid until the next set_store_entry call.
*
* @param[in] state The store state to use.
* @param[in, out] bse Pointer to the entry to be removed.
* @return NSERROR_OK and \a bse updated on succes or NSERROR_NOT_FOUND
* if no entry coresponds to the url.
*/
static nserror
remove_store_entry(struct store_state *state, struct store_entry **bse)
{
entry_index_t sei; /* store entry index */
/* sei is index to entry to be removed, we swap it to the end
* of the table so there are no gaps and the returned entry is
* held in storage with reasonable lifetime.
*/
sei = BS_ENTRY_INDEX((*bse)->ident, state);
/* remove entry from map */
BS_ENTRY_INDEX((*bse)->ident, state) = 0;
/* global allocation accounting */
state->total_alloc -= state->entries[sei].elem[ENTRY_ELEM_DATA].size;
state->total_alloc -= state->entries[sei].elem[ENTRY_ELEM_META].size;
state->last_entry--;
if (sei == state->last_entry) {
/* the removed entry was the last one, how convenient */
*bse = &state->entries[sei];
} else {
/* need to swap entries */
struct store_entry tent;
tent = state->entries[sei];
state->entries[sei] = state->entries[state->last_entry];
state->entries[state->last_entry] = tent;
/* update map for moved entry */
BS_ENTRY_INDEX(state->entries[sei].ident, state) = sei;
*bse = &state->entries[state->last_entry];
}
return NSERROR_OK;
}
/**
* 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 sucess 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, bse->ident, elem_idx);
if (fname == NULL) {
return NSERROR_NOMEM;
}
unlink(fname);
free(fname);
}
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 sucess 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.
*/
LOG(("invalidating entry with referenced allocation"));
return NSERROR_OK;
}
LOG(("Removing entry for %p", bse));
/* remove the entry from the index */
ret = remove_store_entry(state, &bse);
if (ret != NSERROR_OK) {
return ret;
}
ret = invalidate_element(state, bse, ENTRY_ELEM_META);
if (ret != NSERROR_OK) {
LOG(("Error invalidating metadata element"));
}
ret = invalidate_element(state, bse, ENTRY_ELEM_DATA);
if (ret != NSERROR_OK) {
LOG(("Error invalidating data element"));
}
return NSERROR_OK;
}
/**
* Quick sort comparison.
*/
static int compar(const void *va, const void *vb)
{
const struct store_entry *a = &BS_ENTRY(*(entry_ident_t *)va, storestate);
const struct store_entry *b = &BS_ENTRY(*(entry_ident_t *)vb, storestate);
/* consider the allocation flags - if an entry has an
* allocation it is considered more valuble 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;
}
/**
* 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)
{
entry_ident_t *elist; /* sorted list of entry identifiers */
unsigned int ent;
unsigned int ent_count;
size_t removed; /* size of removed entries */
nserror ret = NSERROR_OK;
/* check if the cache has exceeded configured limit */
if ((state->total_alloc < state->limit) &&
(state->last_entry < (1U << state->entry_bits))) {
/* cache within limits */
return NSERROR_OK;
}
LOG(("Evicting entries to reduce %d by %d",
state->total_alloc, state->hysteresis));
/* allocate storage for the list */
elist = malloc(sizeof(entry_ident_t) * state->last_entry);
if (elist == NULL) {
return NSERROR_NOMEM;
}
/* sort the list avoiding entry 0 which is the empty sentinel */
for (ent = 1; ent < state->last_entry; ent++) {
elist[ent - 1] = state->entries[ent].ident;
}
ent_count = ent - 1; /* important to keep this as the entry count will change when entries are removed */
qsort(elist, ent_count, sizeof(entry_ident_t), compar);
/* evict entries in listed order */
removed = 0;
for (ent = 0; ent < ent_count; ent++) {
struct store_entry *bse;
bse = &BS_ENTRY(elist[ent], state);
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(elist);
LOG(("removed %d in %d entries", removed, ent));
return ret;
}
/**
* Write filesystem entries to file.
*
* Serialise entry index out to storage.
*
* @param state The backing store state to serialise.
* @return NSERROR_OK on sucess or error code on faliure.
*/
static nserror write_entries(struct store_state *state)
{
int fd;
char *tname = NULL; /* temporary file name for atomic replace */
char *fname = NULL; /* target filename */
size_t entries_size;
size_t written;
nserror ret;
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;
}
fd = open(tname, O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
if (fd == -1) {
free(tname);
return NSERROR_SAVE_FAILED;
}
entries_size = state->last_entry * sizeof(struct store_entry);
written = (size_t)write(fd, state->entries, entries_size);
close(fd);
/* check all data was written */
if (written != entries_size) {
unlink(tname);
free(tname);
return NSERROR_SAVE_FAILED;
}
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;
}
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 sucess or error code on faliure.
*/
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) {
LOG(("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;
}
/**
* maintinance 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_maintinance(void *s)
{
struct store_state *state = s;
write_entries(state);
write_blocks(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)
{
entry_ident_t ident;
unsigned int sei; /* store entry index */
LOG(("url:%s", nsurl_access(url)));
/* use the url hash as the entry identifier */
ident = nsurl_hash(url);
sei = BS_ENTRY_INDEX(ident, state);
if (sei == 0) {
LOG(("Failed to find ident 0x%x in index", ident));
return NSERROR_NOT_FOUND;
}
if (state->entries[sei].ident != ident) {
/* entry ident did not match */
LOG(("ident did not match entry"));
return NSERROR_NOT_FOUND;
}
*bse = &state->entries[sei];
state->entries[sei].last_used = time(NULL);
state->entries[sei].use_count++;
state->entries_dirty = true;
guit->browser->schedule(CONTROL_MAINT_TIME, control_maintinance, 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 coresponds 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)
{
entry_ident_t ident;
entry_index_t sei; /* store entry index */
struct store_entry *se;
nserror ret;
struct store_entry_element *elem;
LOG(("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;
}
/* use the url hash as the entry identifier */
ident = nsurl_hash(url);
/* get the entry index from the ident */
sei = BS_ENTRY_INDEX(ident, state);
if (sei == 0) {
/* allocating the next available entry */
sei = state->last_entry;
state->last_entry++;
BS_ENTRY_INDEX(ident, state) = sei;
/* the entry */
se = &state->entries[sei];
/* clear the new entry */
memset(se, 0, sizeof(struct store_entry));
} else {
/* index found existing entry */
/* the entry */
se = &state->entries[sei];
if (se->ident != ident) {
/** @todo Is there a better heuristic than
* first come, first served? Should we check
* to see if the old entry is in use and if
* not prefer the newly stored entry instead?
*/
LOG(("Entry index collision trying to replace %x with %x",
se->ident, ident));
return NSERROR_PERMISSION;
}
}
/* 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.
*/
LOG(("attempt to overwrite entry with in use data"));
return NSERROR_PERMISSION;
}
/* set the common entry data */
se->ident = ident;
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 elemnt 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 maintinance scheduled. */
state->entries_dirty = true;
guit->browser->schedule(CONTROL_MAINT_TIME, control_maintinance, 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) {
LOG(("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) {
LOG(("file path \"%s\" could not be created", fname));
free(fname);
return -1;
}
}
LOG(("opening %s", fname));
fd = open(fname, openflags, S_IRUSR | S_IWUSR);
free(fname);
return fd;
}
/**
* Construct address ident to filesystem entry map
*
* To allow a filesystem entry to be found from it's identifier we
* construct an mapping index. This is a hash map from the entries URL
* (its unique key) to filesystem entry.
*
* As the entire entry list must be iterated over to construct the map
* we also compute the total storage in use.
*
* @param state The backing store global state.
* @return NSERROR_OK on sucess or NSERROR_NOMEM if the map storage
* could not be allocated.
*/
static nserror
build_entrymap(struct store_state *state)
{
unsigned int eloop;
LOG(("Allocating %d bytes for max of %d buckets",
(1 << state->ident_bits) * sizeof(entry_index_t),
1 << state->ident_bits));
state->addrmap = calloc(1 << state->ident_bits, sizeof(entry_index_t));
if (state->addrmap == NULL) {
return NSERROR_NOMEM;
}
state->total_alloc = 0;
for (eloop = 1; eloop < state->last_entry; eloop++) {
/*
LOG(("entry:%d ident:0x%08x used:%d",
eloop,
BS_ADDRESS(state->entries[eloop].ident, state),
state->entries[eloop].use_count));
*/
/* update the address map to point at the entry */
BS_ENTRY_INDEX(state->entries[eloop].ident, state) = eloop;
/* account for the storage space */
state->total_alloc += state->entries[eloop].elem[ENTRY_ELEM_DATA].size;
state->total_alloc += state->entries[eloop].elem[ENTRY_ELEM_META].size;
/* ensure entry does not have any allocation state */
state->entries[eloop].elem[ENTRY_ELEM_DATA].flags &= ~(ENTRY_ELEM_FLAG_HEAP | ENTRY_ELEM_FLAG_MMAP);
state->entries[eloop].elem[ENTRY_ELEM_META].flags &= ~(ENTRY_ELEM_FLAG_HEAP | ENTRY_ELEM_FLAG_MMAP);
}
return NSERROR_OK;
}
/**
* Unlink entries file
*
* @param state The backing store state.
* @return NSERROR_OK on sucess or error code on faliure.
*/
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 sucess or error code on faliure.
*/
static nserror
read_entries(struct store_state *state)
{
int fd;
ssize_t rd;
size_t entries_size;
char *fname = NULL;
nserror ret;
ret = netsurf_mkpath(&fname, NULL, 2, state->path, ENTRIES_FNAME);
if (ret != NSERROR_OK) {
return ret;
}
entries_size = (1 << state->entry_bits) * sizeof(struct store_entry);
LOG(("Allocating %d bytes for max of %d entries of %d length elements %d length",
entries_size, 1 << state->entry_bits,
sizeof(struct store_entry),
sizeof(struct store_entry_element)));
state->entries = calloc(1, entries_size);
if (state->entries == NULL) {
free(fname);
return NSERROR_NOMEM;
}
fd = open(fname, O_RDWR);
free(fname);
if (fd != -1) {
rd = read(fd, state->entries, entries_size);
close(fd);
if (rd > 0) {
state->last_entry = rd / sizeof(struct store_entry);
LOG(("Read %d entries", state->last_entry));
}
} else {
/* could rebuild entries from fs */
state->last_entry = 1;
}
return NSERROR_OK;
}
/**
* Read block file usage bitmaps.
*
* @param state The backing store state to put the loaded entries in.
* @return NSERROR_OK on sucess or error code on faliure.
*/
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;
}
LOG(("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) {
LOG(("reading block file %d use index on file number %d failed", elem_idx, bfidx));
goto rd_err;
}
}
}
rd_err:
close(fd);
} else {
LOG(("Initialising block use map to defaults"));
/* ensure block 0 (invalid sentinal) 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 sucess or error code on faliure.
*/
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 sucess or error code on faliure.
*/
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;
}
LOG(("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);
fprintf(fcontrol, "%u%c", state->entry_bits, 0);
fprintf(fcontrol, "%u%c", state->ident_bits, 0);
fprintf(fcontrol, "%u%c", state->last_entry, 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 sucess or error code on faliure.
*/
static nserror
read_control(struct store_state *state)
{
nserror ret;
FILE *fcontrol;
unsigned int ctrlversion;
unsigned int addrbits;
unsigned int entrybits;
char *fname = NULL;
ret = netsurf_mkpath(&fname, NULL, 2, state->path, "control");
if (ret != NSERROR_OK) {
return ret;
}
LOG(("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;
}
/* second line is log2 max number of entries */
if (fscanf(fcontrol, "%u", &entrybits) != 1) {
goto control_error;
}
if (fgetc(fcontrol) != 0) {
goto control_error;
}
/* second line is log2 size of address hash */
if (fscanf(fcontrol, "%u", &addrbits) != 1) {
goto control_error;
}
if (fgetc(fcontrol) != 0) {
goto control_error;
}
fclose(fcontrol);
state->entry_bits = entrybits;
state->ident_bits = addrbits;
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 faliure.
*/
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;
if (parameters->address_size == 0) {
newstate->ident_bits = DEFAULT_IDENT_SIZE;
} else {
newstate->ident_bits = parameters->address_size;
}
if (parameters->entry_size == 0) {
newstate->entry_bits = DEFAULT_ENTRY_SIZE;
} else {
newstate->entry_bits = parameters->entry_size;
}
/* read store control and create new if required */
ret = read_control(newstate);
if (ret != NSERROR_OK) {
LOG(("read control failed %s", messages_get_errorcode(ret)));
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;
}
/* ensure the maximum number of entries can be represented in
* the type available to store it.
*/
if (newstate->entry_bits > (8 * sizeof(entry_index_t))) {
newstate->entry_bits = (8 * sizeof(entry_index_t));
}
/* read filesystem entries */
ret = read_entries(newstate);
if (ret != NSERROR_OK) {
/* that went well obviously */
free(newstate->path);
free(newstate);
return ret;
}
/* build entry hash map */
ret = build_entrymap(newstate);
if (ret != NSERROR_OK) {
/* that obviously went well */
free(newstate->path);
free(newstate);
return ret;
}
ret = read_blocks(newstate);
if (ret != NSERROR_OK) {
/* oh dear */
free(newstate->path);
free(newstate);
return ret;
}
storestate = newstate;
LOG(("FS backing store init successful"));
LOG(("path:%s limit:%d hyst:%d addr:%d entries:%d",
newstate->path, newstate->limit, newstate->hysteresis,
newstate->ident_bits, newstate->entry_bits));
LOG(("Using %lld/%lld", 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 */
if (storestate != NULL) {
guit->browser->schedule(-1, control_maintinance, 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);
}
}
/* avoid division by zero */
if (storestate->miss_count == 0) {
storestate->miss_count = 1;
}
LOG(("hits:%d misses:%d hit ratio:%d returned:%d bytes",
storestate->hit_count, storestate->miss_count,
storestate->hit_count / storestate->miss_count,
storestate->hit_size));
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) {
return NSERROR_SAVE_FAILED;
}
offst = 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) {
LOG(("Write failed %d of %d bytes from %p at 0x%x block %d errno %d",
wr, bse->elem[elem_idx].size, bse->elem[elem_idx].data,
offst, bse->elem[elem_idx].block, errno));
return NSERROR_SAVE_FAILED;
}
LOG(("Wrote %d bytes from %p at 0x%x block %d",
wr, bse->elem[elem_idx].data,
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, bse->ident, elem_idx, O_CREAT | O_WRONLY);
if (fd < 0) {
perror("");
LOG(("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) {
LOG(("Write failed %d 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;
}
LOG(("Wrote %d 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 faliure.
*/
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) {
LOG(("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) {
LOG(("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) {
LOG(("Open failed errno %d", errno));
return NSERROR_SAVE_FAILED;
}
offst = 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) {
LOG(("Failed reading %d of %d bytes into %p from 0x%x block %d errno %d",
rd, bse->elem[elem_idx].size, bse->elem[elem_idx].data,
offst, bse->elem[elem_idx].block, errno));
return NSERROR_SAVE_FAILED;
}
LOG(("Read %d bytes into %p from 0x%x block %d",
rd, bse->elem[elem_idx].data,
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, bse->ident, elem_idx, O_RDONLY);
if (fd < 0) {
LOG(("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) {
LOG(("read error returned %d errno %d", rd, errno));
ret = NSERROR_NOT_FOUND;
break;
}
tot += rd;
}
close(fd);
LOG(("Read %d bytes into %p", tot, bse->elem[elem_idx].data));
return ret;
}
/**
* Retrive 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 faliure.
*/
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) {
LOG(("entry not found"));
storestate->miss_count++;
return ret;
}
storestate->hit_count++;
LOG(("retriving 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++;
LOG(("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) {
LOG(("Failed to create new heap allocation"));
return NSERROR_NOMEM;
}
LOG(("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 faliure.
*/
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) {
LOG(("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 faliure.
*/
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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