Changeset d68e4d5 in mainline for uspace/lib/libblock/libblock.c

Timestamp:

2009-07-04T13:04:13Z (15 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

7114d83

Parents:

2a77841d

Message:

Make the libblock cache behave more like a cache and fix some bugs
present in the previously unused code paths.

File:

• uspace/lib/libblock/libblock.c (modified) (15 diffs)

uspace/lib/libblock/libblock.c

@@ -64 +64 @@
         size_t block_size;              /**< Block size. */
         unsigned block_count;           /**< Total number of blocks. */
+        unsigned blocks_cached;         /**< Number of cached blocks. */
         hash_table_t block_hash;
         link_t free_head;
@@ -73 +74 @@
         dev_handle_t dev_handle;
         int dev_phone;
+        fibril_mutex_t com_area_lock;
         void *com_area;
         size_t com_size;
@@ -113 +115 @@
         devcon->dev_handle = dev_handle;
         devcon->dev_phone = dev_phone;
+        fibril_mutex_initialize(&devcon->com_area_lock);
         devcon->com_area = com_area;
         devcon->com_size = com_size;
@@ -212 +215 @@
                 return ENOMEM;
         
+        fibril_mutex_lock(&devcon->com_area_lock);
         rc = read_block(devcon, 0, size);
         if (rc != EOK) {
+                fibril_mutex_unlock(&devcon->com_area_lock);
                 free(bb_buf);
                 return rc;
         }
-
         memcpy(bb_buf, devcon->com_area, size);
+        fibril_mutex_unlock(&devcon->com_area_lock);
 
         devcon->bb_buf = bb_buf;
@@ -272 +277 @@
         cache->block_size = size;
         cache->block_count = blocks;
+        cache->blocks_cached = 0;
         cache->mode = mode;
 
@@ -284 +290 @@
 }
 
+#define CACHE_LO_WATERMARK      10      
+#define CACHE_HI_WATERMARK      20      
 static bool cache_can_grow(cache_t *cache)
 {
+        if (cache->blocks_cached < CACHE_LO_WATERMARK)
+                return true;
+        if (!list_empty(&cache->free_head))
+                return false;
         return true;
 }
@@ -316 +328 @@
         link_t *l;
         unsigned long key = boff;
+        bn_t oboff;
         
         devcon = devcon_search(dev_handle);
@@ -356 +369 @@
                                 goto recycle;
                         }
+                        cache->blocks_cached++;
                 } else {
                         /*
@@ -365 +379 @@
                         l = cache->free_head.next;
                         list_remove(l);
-                        b = hash_table_get_instance(l, block_t, hash_link);
+                        b = list_get_instance(l, block_t, free_link);
                         sync = b->dirty;
+                        oboff = b->boff;
                         temp_key = b->boff;
                         hash_table_remove(&cache->block_hash, &temp_key, 1);
@@ -390 +405 @@
                          * the device before we can read in the new contents.
                          */
-                        abort();        /* TODO: block_write() */
+                        fibril_mutex_lock(&devcon->com_area_lock);
+                        memcpy(devcon->com_area, b->data, b->size);
+                        rc = write_block(devcon, oboff, cache->block_size);
+                        assert(rc == EOK);
+                        fibril_mutex_unlock(&devcon->com_area_lock);
                 }
                 if (!(flags & BLOCK_FLAGS_NOREAD)) {
@@ -397 +416 @@
                          * the new contents from the device.
                          */
+                        fibril_mutex_lock(&devcon->com_area_lock);
                         rc = read_block(devcon, b->boff, cache->block_size);
                         assert(rc == EOK);
                         memcpy(b->data, devcon->com_area, cache->block_size);
+                        fibril_mutex_unlock(&devcon->com_area_lock);
                 }
 
@@ -427 +448 @@
         if (!--block->refcnt) {
                 /*
-                 * Last reference to the block was dropped, put the block on the
-                 * free list.
+                 * Last reference to the block was dropped. Either free the
+                 * block or put it on the free list.
+                 */
+                if (cache->blocks_cached > CACHE_HI_WATERMARK) {
+                        /*
+                         * Currently there are too many cached blocks.
+                         */
+                        if (block->dirty) {
+                                fibril_mutex_lock(&devcon->com_area_lock);
+                                memcpy(devcon->com_area, block->data,
+                                    block->size);
+                                rc = write_block(devcon, block->boff,
+                                    block->size);
+                                assert(rc == EOK);
+                                fibril_mutex_unlock(&devcon->com_area_lock);
+                        }
+                        /*
+                         * Take the block out of the cache and free it.
+                         */
+                        unsigned long key = block->boff;
+                        hash_table_remove(&cache->block_hash, &key, 1);
+                        free(block);
+                        free(block->data);
+                        cache->blocks_cached--;
+                        fibril_mutex_unlock(&cache->lock);
+                        return;
+                }
+                /*
+                 * Put the block on the free list.
                  */
                 list_append(&block->free_link, &cache->free_head);
                 if (cache->mode != CACHE_MODE_WB && block->dirty) {
+                        fibril_mutex_lock(&devcon->com_area_lock);
                         memcpy(devcon->com_area, block->data, block->size);
                         rc = write_block(devcon, block->boff, block->size);
                         assert(rc == EOK);
+                        fibril_mutex_unlock(&devcon->com_area_lock);
 
                         block->dirty = false;
@@ -465 +515 @@
         assert(devcon);
         
+        fibril_mutex_lock(&devcon->com_area_lock);
         while (left > 0) {
                 size_t rd;
@@ -490 +541 @@
 
                         rc = read_block(devcon, *pos / block_size, block_size);
-                        if (rc != EOK)
+                        if (rc != EOK) {
+                                fibril_mutex_unlock(&devcon->com_area_lock);
                                 return rc;
+                        }
                         
                         *bufpos = 0;
@@ -497 +550 @@
                 }
         }
+        fibril_mutex_unlock(&devcon->com_area_lock);
         
         return EOK;