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05538c0264
netsurf/content/fs_backing_store.c
Vincent Sanders 05538c0264 Ensure small block cache files allocate their entire extent at open. 
It seems many filesystems are greatly more efficient if the block file
is allocated its entire extent once rather than trying to
continuously grown the file later.

The size of the block files is known at their creation time so this
change ensures they are grown to the full possible extent hence removing
future inefficient writes.
2015-04-30 13:49:25 +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.
*
*/
#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) {
LOG(("Open failed errno %d", errno));
return NSERROR_SAVE_FAILED;
}
/* ensure block file is correct length at open */
ftruncate(state->blocks[elem_idx][bf].fd,
1U << (log2_block_size[elem_idx] + BLOCK_ENTRY_COUNT));
}
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;
}
/* ensure block file is correct length at open */
ftruncate(state->blocks[elem_idx][bf].fd,
1U << (log2_block_size[elem_idx] + BLOCK_ENTRY_COUNT));
}
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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