[Mesa-dev] [PATCH V3] util/disk_cache: support caches for multiple architectures

[Timothy Arceri]

Previously we were deleting the entire cache if a user switched
between 32 and 64 bit applications.

V2: make the check more generic, it should now work with any
platform we are likely to support.

V3: Use suggestion from Emil to make even more generic/fix issue
with __ILP32__ not being declared on gcc for regular 32-bit builds.
---
 src/util/disk_cache.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/src/util/disk_cache.c b/src/util/disk_cache.c
index 3abdec4..7543b0d 100644
--- a/src/util/disk_cache.c
+++ b/src/util/disk_cache.c
@@ -67,20 +67,37 @@ struct disk_cache {
    /* 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;
 };
 
+static const char *
+get_arch_bitness_str(void)
+{
+    if (sizeof(void *) == 4)
+#ifdef __ILP32__
+        return "ilp-32";
+#else
+        return "32";
+#endif
+    if (sizeof(void *) == 8)
+        return "64";
+
+    /* paranoia check which will be dropped by the optimiser */
+    assert(!"unknown_arch");
+    return "unknown_arch";
+}
+
 /* 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;
 
@@ -170,20 +187,29 @@ remove_old_cache_directories(void *mem_ctx, char *path, const char *timestamp)
 }
 
 static char *
 create_mesa_cache_dir(void *mem_ctx, char *path, const char *timestamp,
                       const char *gpu_name)
 {
    char *new_path = concatenate_and_mkdir(mem_ctx, path, "mesa");
    if (new_path == NULL)
       return NULL;
 
+   /* Create a parent architecture directory so that we don't remove cache
+    * files for other architectures. In theory we could share the cache
+    * between architectures but we have no way of knowing if they were created
+    * by a compatible Mesa version.
+    */
+   new_path = concatenate_and_mkdir(mem_ctx, new_path, get_arch_bitness_str());
+   if (new_path == NULL)
+      return NULL;
+
    /* Remove cache directories for old Mesa versions */
    remove_old_cache_directories(mem_ctx, new_path, timestamp);
 
    new_path = concatenate_and_mkdir(mem_ctx, new_path, timestamp);
    if (new_path == NULL)
       return NULL;
 
    new_path = concatenate_and_mkdir(mem_ctx, new_path, gpu_name);
    if (new_path == NULL)
       return NULL;
-- 
2.9.3