[btr] Add more documentation.

[paraslash.git] / buffer_tree.c

diff --git a/buffer_tree.c b/buffer_tree.c
index 57f1398eeeb441662805b7b36b8c95adde986b78..6dc3c41b2b9deb6787c1e6414e0f43ce394355af 100644 (file)
--- a/buffer_tree.c
+++ b/buffer_tree.c
@@ -100,6 +100,10 @@ size_t btr_pool_unused(struct btr_pool *btrp)
        return btr_pool_size(btrp) - btr_pool_filled(btrp);
 }
 
+/*
+ * Return maximal size available for one read. This is
+ * smaller than the value returned by btr_pool_unused().
+ */
 size_t btr_pool_available(struct btr_pool *btrp)
 {
        if (!btrp->whead)
@@ -122,7 +126,6 @@ void btr_pool_allocate(struct btr_pool *btrp, size_t size)
 
        if (size == 0)
                return;
-       //PARA_CRIT_LOG("filled: %zu, alloc %zu\n", btr_pool_filled(btrp), size);
        assert(size <= btr_pool_available(btrp));
        end = btrp->whead + size;
        assert(end <= btrp->area_end);
@@ -132,18 +135,16 @@ void btr_pool_allocate(struct btr_pool *btrp, size_t size)
                end = btrp->area_start;
        }
        if (end == btrp->rhead) {
-               PARA_DEBUG_LOG("btrp buffer full\n");
+               PARA_DEBUG_LOG("%s btrp buffer full\n", btrp->name);
                end = NULL; /* buffer full */
        }
        btrp->whead = end;
-       //PARA_CRIT_LOG("filled: %zu\n", btr_pool_filled(btrp));
 }
 
 static void btr_pool_deallocate(struct btr_pool *btrp, size_t size)
 {
        char *end = btrp->rhead + size;
 
-       //PARA_CRIT_LOG("filled: %zu, dealloc %zu\n", btr_pool_filled(btrp), size);
        if (size == 0)
                return;
        assert(end <= btrp->area_end);
@@ -155,7 +156,6 @@ static void btr_pool_deallocate(struct btr_pool *btrp, size_t size)
        btrp->rhead = end;
        if (btrp->rhead == btrp->whead)
                btrp->rhead = btrp->whead = btrp->area_start;
-       //PARA_CRIT_LOG("filled: %zu\n", btr_pool_filled(btrp));
 }
 
 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
@@ -168,14 +168,6 @@ static void btr_pool_deallocate(struct btr_pool *btrp, size_t size)
 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
        list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
 
-/*
-       (parent, child):
-       (NULL, NULL): new, isolated node.
-       (NULL, c): new node becomes root, c must be old root
-       (p, NULL): new leaf node
-       (p, c): new internal node, ch must be child of p
-
-*/
 struct btr_node *btr_new_node(struct btr_node_description *bnd)
 {
        struct btr_node *btrn = para_malloc(sizeof(*btrn));
@@ -186,14 +178,31 @@ struct btr_node *btr_new_node(struct btr_node_description *bnd)
        btrn->context = bnd->context;
        btrn->start.tv_sec = 0;
        btrn->start.tv_usec = 0;
-       if (bnd->parent)
-               list_add_tail(&btrn->node, &bnd->parent->children);
        INIT_LIST_HEAD(&btrn->children);
        INIT_LIST_HEAD(&btrn->input_queue);
-       if (bnd->parent)
-               PARA_INFO_LOG("added %s as child of %s\n", bnd->name, bnd->parent->name);
-       else
-               PARA_INFO_LOG("added %s as btr root\n", bnd->name);
+       if (!bnd->child) {
+               if (bnd->parent) {
+                       list_add_tail(&btrn->node, &bnd->parent->children);
+                       PARA_INFO_LOG("new leaf node: %s (child of %s)\n",
+                               bnd->name, bnd->parent->name);
+               } else
+                       PARA_INFO_LOG("added %s as btr root\n", bnd->name);
+               goto out;
+       }
+       if (!bnd->parent) {
+               assert(!bnd->child->parent);
+               PARA_INFO_LOG("new root: %s (was %s)\n",
+                       bnd->name, bnd->child->name);
+               btrn->parent = NULL;
+               list_add_tail(&bnd->child->node, &btrn->children);
+               /* link it in */
+               bnd->child->parent = btrn;
+               goto out;
+       }
+       PARA_EMERG_LOG("inserting internal nodes not yet supported.\n");
+       exit(EXIT_FAILURE);
+       assert(bnd->child->parent == bnd->parent);
+out:
        return btrn;
 }
 
@@ -235,7 +244,6 @@ static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
 {
        struct btr_buffer *btrb = br->btrb;
 
-       //PARA_CRIT_LOG("dropping buffer reference %p\n", br);
        list_del(&br->node);
        free(br);
        btrb->refcount--;
@@ -390,15 +398,8 @@ size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
                }
                if (!br->btrb->pool)
                        break;
-               if (result + rv != buf) {
-                       PARA_DEBUG_LOG("%s: pool merge impossible: %p != %p\n",
-                               btrn->name, result + rv, buf);
+               if (result + rv != buf)
                        break;
-               }
-//             PARA_CRIT_LOG("%s: inplace merge (%zu, %zu)->%zu\n", btrn->name,
-//                     rv, sz, rv + sz);
-//             PARA_CRIT_LOG("%s: inplace merge %p (%zu)\n", btrn->name,
-//                     result, sz);
                rv += sz;
        }
        if (bufp)
@@ -416,7 +417,6 @@ void btr_consume(struct btr_node *btrn, size_t numbytes)
        br = get_first_input_br(btrn);
        assert(br);
 
-       //PARA_CRIT_LOG("wrap count: %zu\n", br->wrap_count);
        if (br->wrap_count == 0) {
                /*
                 * No wrap buffer. Drop buffer references whose buffer
@@ -790,8 +790,7 @@ int btr_node_status(struct btr_node *btrn, size_t min_iqs,
 {
        size_t iqs;
 
-       if (!btrn)
-               return 0;
+       assert(btrn);
        if (type != BTR_NT_LEAF) {
                if (btr_no_children(btrn))
                        return -E_BTR_NO_CHILD;