diff options
Diffstat (limited to 'src/util/disk_cache.c')
| -rw-r--r-- | src/util/disk_cache.c | 712 |
1 files changed, 712 insertions, 0 deletions
diff --git a/src/util/disk_cache.c b/src/util/disk_cache.c new file mode 100644 index 00000000000..79242aa3c1e --- /dev/null +++ b/src/util/disk_cache.c @@ -0,0 +1,712 @@ +/* + * 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 program_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 program_cache * +cache_create(void) +{ + void *local; + struct program_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 program_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 +cache_destroy(struct program_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 program_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 program_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 *)) +{ + 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)) + 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)) + 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) +{ + size_t len; + + if (entry->d_type != DT_REG) + return false; + + 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) +{ + if (entry->d_type != DT_DIR) + 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 program_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 +cache_put(struct program_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); + + /* This close finally releases the flock, (now that the final dile + * has been renamed into place and the size has been added). + */ + close(fd); + fd = -1; + + done: + if (filename_tmp) + ralloc_free(filename_tmp); + if (filename) + ralloc_free(filename); + if (fd != -1) + close(fd); +} + +void * +cache_get(struct program_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 +cache_put_key(struct program_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 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 cache_put_key, then that's just an extra cache miss and an + * extra recompile. + */ +bool +cache_has_key(struct program_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 |