Revert "util/mesa-db: Further simplify mesa_db_compact"

This reverts commit 92893309bcc0c1a9ab9eab844a896d99cbc4b4e2.

Need to revert this as well for the next revert.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32078>

1 files changed, 36 insertions, 22 deletions

diff --git a/src/util/mesa_cache_db.c b/src/util/mesa_cache_db.c
index 4372051c839..4ee926f94be 100644
--- a/src/util/mesa_cache_db.c
+++ b/src/util/mesa_cache_db.c
@@ -605,7 +605,7 @@ mesa_db_compact(struct mesa_cache_db *db, int64_t blob_size,
    FILE *compacted_cache = NULL, *compacted_index = NULL;
    struct mesa_index_db_file_entry *index_entry;
    struct sort_entry *entries;
-   bool success = false;
+   bool success = false, compact = false;
    void *buffer = NULL;
    unsigned int i = 0;
 
@@ -665,38 +665,52 @@ mesa_db_compact(struct mesa_cache_db *db, int64_t blob_size,
        !mesa_db_write_header(&db->index, 0, false))
       goto cleanup;
 
-   /* Skip non-evicted entries at the start of the files */
-   for (i = 0; i < num_entries; i++) {
-      if (entries[i].evicted)
-         break;
-   }
-
    /* Sync the file pointers */
-   if (!mesa_db_seek(compacted_cache, entries[i].index_entry->cache_db_file_offset) ||
-       !mesa_db_seek(compacted_index, ftell(db->index.file) +
-                     i * sizeof(struct mesa_index_db_file_entry)))
+   if (!mesa_db_seek(compacted_cache, ftell(db->cache.file)) ||
+       !mesa_db_seek(compacted_index, ftell(db->index.file)))
       goto cleanup;
 
    /* Do the compaction */
-   for (; i < num_entries; i++) {
+   for (i = 0; i < num_entries; i++) {
       struct mesa_index_db_file_entry *index_entry = entries[i].index_entry;
 
-      if (entries[i].evicted)
-         continue;
-
       blob_size = blob_file_size(index_entry->size);
 
-      /* Compact the cache file */
-      if (!mesa_db_seek(db->cache.file, index_entry->cache_db_file_offset) ||
-          !mesa_db_read_data(db->cache.file, buffer, blob_size) ||
-          !mesa_db_cache_entry_valid(buffer) ||
-          !mesa_db_write_data(compacted_cache, buffer, blob_size))
+      /* Sanity-check the cache-read offset */
+      if (ftell(db->cache.file) != index_entry->cache_db_file_offset)
          goto cleanup;
 
-      index_entry->cache_db_file_offset = ftell(compacted_cache) - blob_size;
+      if (entries[i].evicted) {
+         /* Jump over the evicted entry */
+         if (!mesa_db_seek_cur(db->cache.file, blob_size))
+            goto cleanup;
 
-      if (!mesa_db_write(compacted_index, index_entry))
-         goto cleanup;
+         compact = true;
+         continue;
+      }
+
+      if (compact) {
+         /* Compact the cache file */
+         if (!mesa_db_read_data(db->cache.file,   buffer, blob_size) ||
+             !mesa_db_cache_entry_valid(buffer) ||
+             !mesa_db_write_data(compacted_cache, buffer, blob_size))
+            goto cleanup;
+
+         index_entry->cache_db_file_offset = ftell(compacted_cache) - blob_size;
+
+         if (!mesa_db_write(compacted_index, index_entry))
+            goto cleanup;
+      } else {
+         /* Sanity-check the cache-write offset */
+         if (ftell(compacted_cache) != index_entry->cache_db_file_offset)
+            goto cleanup;
+
+         /* Jump over the unchanged entry */
+         if (!mesa_db_seek_cur(compacted_index, sizeof(*index_entry)) ||
+             !mesa_db_seek_cur(db->cache.file,  blob_size) ||
+             !mesa_db_seek_cur(compacted_cache, blob_size))
+            goto cleanup;
+      }
    }
 
    fflush(compacted_cache);