/*
* Copyright © 2014 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#ifdef ENABLE_SHADER_CACHE
#include <ctype.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/file.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <unistd.h>
#include <fcntl.h>
#include <pwd.h>
#include <errno.h>
#include <dirent.h>
#include "util/u_atomic.h"
#include "util/mesa-sha1.h"
#include "util/ralloc.h"
#include "main/errors.h"
#include "disk_cache.h"
/* Number of bits to mask off from a cache key to get an index. */
#define CACHE_INDEX_KEY_BITS 16
/* Mask for computing an index from a key. */
#define CACHE_INDEX_KEY_MASK ((1 << CACHE_INDEX_KEY_BITS) - 1)
/* The number of keys that can be stored in the index. */
#define CACHE_INDEX_MAX_KEYS (1 << CACHE_INDEX_KEY_BITS)
struct disk_cache {
/* The path to the cache directory. */
char *path;
/* A pointer to the mmapped index file within the cache directory. */
uint8_t *index_mmap;
size_t index_mmap_size;
/* Pointer to total size of all objects in cache (within index_mmap) */
uint64_t *size;
/* Pointer to stored keys, (within index_mmap). */
uint8_t *stored_keys;
/* Maximum size of all cached objects (in bytes). */
uint64_t max_size;
};
/* Create a directory named 'path' if it does not already exist.
*
* Returns: 0 if path already exists as a directory or if created.
* -1 in all other cases.
*/
static int
mkdir_if_needed(char *path)
{
struct stat sb;
/* If the path exists already, then our work is done if it's a
* directory, but it's an error if it is not.
*/
if (stat(path, &sb) == 0) {
if (S_ISDIR(sb.st_mode)) {
return 0;
} else {
fprintf(stderr, "Cannot use %s for shader cache (not a directory)"
"---disabling.\n", path);
return -1;
}
}
int ret = mkdir(path, 0755);
if (ret == 0 || (ret == -1 && errno == EEXIST))
return 0;
fprintf(stderr, "Failed to create %s for shader cache (%s)---disabling.\n",
path, strerror(errno));
return -1;
}
/* Concatenate an existing path and a new name to form a new path. If the new
* path does not exist as a directory, create it then return the resulting
* name of the new path (ralloc'ed off of 'ctx').
*
* Returns NULL on any error, such as:
*
* <path> does not exist or is not a directory
* <path>/<name> exists but is not a directory
* <path>/<name> cannot be created as a directory
*/
static char *
concatenate_and_mkdir(void *ctx, char *path, char *name)
{
char *new_path;
struct stat sb;
if (stat(path, &sb) != 0 || ! S_ISDIR(sb.st_mode))
return NULL;
new_path = ralloc_asprintf(ctx, "%s/%s", path, name);
if (mkdir_if_needed(new_path) == 0)
return new_path;
else
return NULL;
}
struct disk_cache *
disk_cache_create(void)
{
void *local;
struct disk_cache *cache = NULL;
char *path, *max_size_str;
uint64_t max_size;
int fd = -1;
struct stat sb;
size_t size;
/* A ralloc context for transient data during this invocation. */
local = ralloc_context(NULL);
if (local == NULL)
goto fail;
/* At user request, disable shader cache entirely. */
if (getenv("MESA_GLSL_CACHE_DISABLE"))
goto fail;
/* Determine path for cache based on the first defined name as follows:
*
* $MESA_GLSL_CACHE_DIR
* $XDG_CACHE_HOME/mesa
* <pwd.pw_dir>/.cache/mesa
*/
path = getenv("MESA_GLSL_CACHE_DIR");
if (path && mkdir_if_needed(path) == -1) {
goto fail;
}
if (path == NULL) {
char *xdg_cache_home = getenv("XDG_CACHE_HOME");
if (xdg_cache_home) {
if (mkdir_if_needed(xdg_cache_home) == -1)
goto fail;
path = concatenate_and_mkdir(local, xdg_cache_home, "mesa");
if (path == NULL)
goto fail;
}
}
if (path == NULL) {
char *buf;
size_t buf_size;
struct passwd pwd, *result;
buf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
if (buf_size == -1)
buf_size = 512;
/* Loop until buf_size is large enough to query the directory */
while (1) {
buf = ralloc_size(local, buf_size);
getpwuid_r(getuid(), &pwd, buf, buf_size, &result);
if (result)
break;
if (errno == ERANGE) {
ralloc_free(buf);
buf = NULL;
buf_size *= 2;
} else {
goto fail;
}
}
path = concatenate_and_mkdir(local, pwd.pw_dir, ".cache");
if (path == NULL)
goto fail;
path = concatenate_and_mkdir(local, path, "mesa");
if (path == NULL)
goto fail;
}
cache = ralloc(NULL, struct disk_cache);
if (cache == NULL)
goto fail;
cache->path = ralloc_strdup(cache, path);
if (cache->path == NULL)
goto fail;
path = ralloc_asprintf(local, "%s/index", cache->path);
if (path == NULL)
goto fail;
fd = open(path, O_RDWR | O_CREAT | O_CLOEXEC, 0644);
if (fd == -1)
goto fail;
if (fstat(fd, &sb) == -1)
goto fail;
/* Force the index file to be the expected size. */
size = sizeof(*cache->size) + CACHE_INDEX_MAX_KEYS * CACHE_KEY_SIZE;
if (sb.st_size != size) {
if (ftruncate(fd, size) == -1)
goto fail;
}
/* We map this shared so that other processes see updates that we
* make.
*
* Note: We do use atomic addition to ensure that multiple
* processes don't scramble the cache size recorded in the
* index. But we don't use any locking to prevent multiple
* processes from updating the same entry simultaneously. The idea
* is that if either result lands entirely in the index, then
* that's equivalent to a well-ordered write followed by an
* eviction and a write. On the other hand, if the simultaneous
* writes result in a corrupt entry, that's not really any
* different than both entries being evicted, (since within the
* guarantees of the cryptographic hash, a corrupt entry is
* unlikely to ever match a real cache key).
*/
cache->index_mmap = mmap(NULL, size, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0);
if (cache->index_mmap == MAP_FAILED)
goto fail;
cache->index_mmap_size = size;
close(fd);
cache->size = (uint64_t *) cache->index_mmap;
cache->stored_keys = cache->index_mmap + sizeof(uint64_t);
max_size = 0;
max_size_str = getenv("MESA_GLSL_CACHE_MAX_SIZE");
if (max_size_str) {
char *end;
max_size = strtoul(max_size_str, &end, 10);
if (end == max_size_str) {
max_size = 0;
} else {
while (*end && isspace(*end))
end++;
switch (*end) {
case 'K':
case 'k':
max_size *= 1024;
break;
case 'M':
case 'm':
max_size *= 1024*1024;
break;
case '\0':
case 'G':
case 'g':
default:
max_size *= 1024*1024*1024;
break;
}
}
}
/* Default to 1GB for maximum cache size. */
if (max_size == 0)
max_size = 1024*1024*1024;
cache->max_size = max_size;
ralloc_free(local);
return cache;
fail:
if (fd != -1)
close(fd);
if (cache)
ralloc_free(cache);
ralloc_free(local);
return NULL;
}
void
disk_cache_destroy(struct disk_cache *cache)
{
munmap(cache->index_mmap, cache->index_mmap_size);
ralloc_free(cache);
}
/* Return a filename within the cache's directory corresponding to 'key'. The
* returned filename is ralloced with 'cache' as the parent context.
*
* Returns NULL if out of memory.
*/
static char *
get_cache_file(struct disk_cache *cache, cache_key key)
{
char buf[41];
_mesa_sha1_format(buf, key);
return ralloc_asprintf(cache, "%s/%c%c/%s",
cache->path, buf[0], buf[1], buf + 2);
}
/* Create the directory that will be needed for the cache file for \key.
*
* Obviously, the implementation here must closely match
* _get_cache_file above.
*/
static void
make_cache_file_directory(struct disk_cache *cache, cache_key key)
{
char *dir;
char buf[41];
_mesa_sha1_format(buf, key);
dir = ralloc_asprintf(cache, "%s/%c%c", cache->path, buf[0], buf[1]);
mkdir_if_needed(dir);
ralloc_free(dir);
}
/* Given a directory path and predicate function, count all entries in
* that directory for which the predicate returns true. Then choose a
* random entry from among those counted.
*
* Returns: A malloc'ed string for the path to the chosen file, (or
* NULL on any error). The caller should free the string when
* finished.
*/
static char *
choose_random_file_matching(const char *dir_path,
bool (*predicate)(struct dirent *,
const char *dir_path))
{
DIR *dir;
struct dirent *entry;
unsigned int count, victim;
char *filename;
dir = opendir(dir_path);
if (dir == NULL)
return NULL;
count = 0;
while (1) {
entry = readdir(dir);
if (entry == NULL)
break;
if (!predicate(entry, dir_path))
continue;
count++;
}
if (count == 0) {
closedir(dir);
return NULL;
}
victim = rand() % count;
rewinddir(dir);
count = 0;
while (1) {
entry = readdir(dir);
if (entry == NULL)
break;
if (!predicate(entry, dir_path))
continue;
if (count == victim)
break;
count++;
}
if (entry == NULL) {
closedir(dir);
return NULL;
}
if (asprintf(&filename, "%s/%s", dir_path, entry->d_name) < 0)
filename = NULL;
closedir(dir);
return filename;
}
/* Is entry a regular file, and not having a name with a trailing
* ".tmp"
*/
static bool
is_regular_non_tmp_file(struct dirent *entry, const char *path)
{
char *filename;
if (asprintf(&filename, "%s/%s", path, entry->d_name) == -1)
return false;
struct stat sb;
int res = stat(filename, &sb);
free(filename);
if (res == -1 || !S_ISREG(sb.st_mode))
return false;
size_t len = strlen (entry->d_name);
if (len >= 4 && strcmp(&entry->d_name[len-4], ".tmp") == 0)
return false;
return true;
}
/* Returns the size of the deleted file, (or 0 on any error). */
static size_t
unlink_random_file_from_directory(const char *path)
{
struct stat sb;
char *filename;
filename = choose_random_file_matching(path, is_regular_non_tmp_file);
if (filename == NULL)
return 0;
if (stat(filename, &sb) == -1) {
free (filename);
return 0;
}
unlink(filename);
free (filename);
return sb.st_size;
}
/* Is entry a directory with a two-character name, (and not the
* special name of "..")
*/
static bool
is_two_character_sub_directory(struct dirent *entry, const char *path)
{
char *subdir;
if (asprintf(&subdir, "%s/%s", path, entry->d_name) == -1)
return false;
struct stat sb;
int res = stat(subdir, &sb);
free(subdir);
if (res == -1 || !S_ISDIR(sb.st_mode))
return false;
if (strlen(entry->d_name) != 2)
return false;
if (strcmp(entry->d_name, "..") == 0)
return false;
return true;
}
static void
evict_random_item(struct disk_cache *cache)
{
const char hex[] = "0123456789abcde";
char *dir_path;
int a, b;
size_t size;
/* With a reasonably-sized, full cache, (and with keys generated
* from a cryptographic hash), we can choose two random hex digits
* and reasonably expect the directory to exist with a file in it.
*/
a = rand() % 16;
b = rand() % 16;
if (asprintf(&dir_path, "%s/%c%c", cache->path, hex[a], hex[b]) < 0)
return;
size = unlink_random_file_from_directory(dir_path);
free(dir_path);
if (size) {
p_atomic_add(cache->size, - size);
return;
}
/* In the case where the random choice of directory didn't find
* something, we choose randomly from the existing directories.
*
* Really, the only reason this code exists is to allow the unit
* tests to work, (which use an artificially-small cache to be able
* to force a single cached item to be evicted).
*/
dir_path = choose_random_file_matching(cache->path,
is_two_character_sub_directory);
if (dir_path == NULL)
return;
size = unlink_random_file_from_directory(dir_path);
free(dir_path);
if (size)
p_atomic_add(cache->size, - size);
}
void
disk_cache_put(struct disk_cache *cache,
cache_key key,
const void *data,
size_t size)
{
int fd = -1, fd_final = -1, err, ret;
size_t len;
char *filename = NULL, *filename_tmp = NULL;
const char *p = data;
filename = get_cache_file(cache, key);
if (filename == NULL)
goto done;
/* Write to a temporary file to allow for an atomic rename to the
* final destination filename, (to prevent any readers from seeing
* a partially written file).
*/
filename_tmp = ralloc_asprintf(cache, "%s.tmp", filename);
if (filename_tmp == NULL)
goto done;
fd = open(filename_tmp, O_WRONLY | O_CLOEXEC | O_CREAT, 0644);
/* Make the two-character subdirectory within the cache as needed. */
if (fd == -1) {
if (errno != ENOENT)
goto done;
make_cache_file_directory(cache, key);
fd = open(filename_tmp, O_WRONLY | O_CLOEXEC | O_CREAT, 0644);
if (fd == -1)
goto done;
}
/* With the temporary file open, we take an exclusive flock on
* it. If the flock fails, then another process still has the file
* open with the flock held. So just let that file be responsible
* for writing the file.
*/
err = flock(fd, LOCK_EX | LOCK_NB);
if (err == -1)
goto done;
/* Now that we have the lock on the open temporary file, we can
* check to see if the destination file already exists. If so,
* another process won the race between when we saw that the file
* didn't exist and now. In this case, we don't do anything more,
* (to ensure the size accounting of the cache doesn't get off).
*/
fd_final = open(filename, O_RDONLY | O_CLOEXEC);
if (fd_final != -1)
goto done;
/* OK, we're now on the hook to write out a file that we know is
* not in the cache, and is also not being written out to the cache
* by some other process.
*
* Before we do that, if the cache is too large, evict something
* else first.
*/
if (*cache->size + size > cache->max_size)
evict_random_item(cache);
/* Now, finally, write out the contents to the temporary file, then
* rename them atomically to the destination filename, and also
* perform an atomic increment of the total cache size.
*/
for (len = 0; len < size; len += ret) {
ret = write(fd, p + len, size - len);
if (ret == -1) {
unlink(filename_tmp);
goto done;
}
}
rename(filename_tmp, filename);
p_atomic_add(cache->size, size);
done:
if (fd_final != -1)
close(fd_final);
/* This close finally releases the flock, (now that the final dile
* has been renamed into place and the size has been added).
*/
if (fd != -1)
close(fd);
if (filename_tmp)
ralloc_free(filename_tmp);
if (filename)
ralloc_free(filename);
}
void *
disk_cache_get(struct disk_cache *cache, cache_key key, size_t *size)
{
int fd = -1, ret, len;
struct stat sb;
char *filename = NULL;
uint8_t *data = NULL;
if (size)
*size = 0;
filename = get_cache_file(cache, key);
if (filename == NULL)
goto fail;
fd = open(filename, O_RDONLY | O_CLOEXEC);
if (fd == -1)
goto fail;
if (fstat(fd, &sb) == -1)
goto fail;
data = malloc(sb.st_size);
if (data == NULL)
goto fail;
for (len = 0; len < sb.st_size; len += ret) {
ret = read(fd, data + len, sb.st_size - len);
if (ret == -1)
goto fail;
}
ralloc_free(filename);
close(fd);
if (size)
*size = sb.st_size;
return data;
fail:
if (data)
free(data);
if (filename)
ralloc_free(filename);
if (fd != -1)
close(fd);
return NULL;
}
void
disk_cache_put_key(struct disk_cache *cache, cache_key key)
{
uint32_t *key_chunk = (uint32_t *) key;
int i = *key_chunk & CACHE_INDEX_KEY_MASK;
unsigned char *entry;
entry = &cache->stored_keys[i + CACHE_KEY_SIZE];
memcpy(entry, key, CACHE_KEY_SIZE);
}
/* This function lets us test whether a given key was previously
* stored in the cache with disk_cache_put_key(). The implement is
* efficient by not using syscalls or hitting the disk. It's not
* race-free, but the races are benign. If we race with someone else
* calling disk_cache_put_key, then that's just an extra cache miss and an
* extra recompile.
*/
bool
disk_cache_has_key(struct disk_cache *cache, cache_key key)
{
uint32_t *key_chunk = (uint32_t *) key;
int i = *key_chunk & CACHE_INDEX_KEY_MASK;
unsigned char *entry;
entry = &cache->stored_keys[i + CACHE_KEY_SIZE];
return memcmp(entry, key, CACHE_KEY_SIZE) == 0;
}
#endif /* ENABLE_SHADER_CACHE */