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-rw-r--r--src/util/disk_cache.c712
1 files changed, 712 insertions, 0 deletions
diff --git a/src/util/disk_cache.c b/src/util/disk_cache.c
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+++ b/src/util/disk_cache.c
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+/*
+ * 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
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-09 16:09:40 +0000