Implement fetching of cloud log items via range requests.

[bluesky.git] / bluesky / util.c

diff --git a/bluesky/util.c b/bluesky/util.c
index f899420..e7514fc 100644 (file)
--- a/bluesky/util.c
+++ b/bluesky/util.c
@@ -75,14 +75,14 @@ BlueSkyRCStr *bluesky_string_new_from_gstring(GString *s)
 }
 
 /* Create a new BlueSkyRCStr from a memory-mapped buffer. */
-BlueSkyRCStr *bluesky_string_new_from_mmap(BlueSkyMmap *mmap,
+BlueSkyRCStr *bluesky_string_new_from_mmap(BlueSkyCacheFile *mmap,
                                            int offset, gsize len)
 {
-    g_assert(offset + len < mmap->len);
+    g_assert(offset + len <= mmap->len);
 
     BlueSkyRCStr *string = g_new(BlueSkyRCStr, 1);
     string->mmap = mmap;
-    g_atomic_int_inc(&mmap->refcount);
+    g_atomic_int_inc(&mmap->mapcount);
     string->data = (char *)mmap->addr + offset;
     string->len = len;
     g_atomic_int_set(&string->refcount, 1);
@@ -219,3 +219,96 @@ BlueSkyInode *bluesky_list_tail(GList *head)
     else
         return (BlueSkyInode *)head->prev->data;
 }
+
+/**** Range sets. ****/
+
+/* These are a data structure which can track a set of discontiguous integer
+ * ranges--such as the partitioning of the inode number space or the bytes in a
+ * log file into objects.  This current prototype implementation just tracks
+ * the starting offset with a hash table and doesn't track the length, but
+ * should be extended later to track properly. */
+
+struct BlueSkyRangeset {
+    GSequence *seq;
+};
+
+static gint compare64(gconstpointer a, gconstpointer b, gpointer user_data)
+{
+    uint64_t x = *(uint64_t *)a;
+    uint64_t y = *(uint64_t *)b;
+
+    if (x < y)
+        return -1;
+    else if (x > y)
+        return 1;
+    else
+        return 0;
+}
+
+BlueSkyRangeset *bluesky_rangeset_new()
+{
+    BlueSkyRangeset *rangeset = g_new(BlueSkyRangeset, 1);
+    rangeset->seq = g_sequence_new(g_free);
+    return rangeset;
+}
+
+void bluesky_rangeset_free(BlueSkyRangeset *rangeset)
+{
+    g_sequence_free(rangeset->seq);
+    g_free(rangeset);
+}
+
+gboolean bluesky_rangeset_insert(BlueSkyRangeset *rangeset,
+                                 uint64_t start, uint64_t length,
+                                 gpointer data)
+{
+    GSequenceIter *i;
+    i = g_sequence_search(rangeset->seq, &start, compare64, NULL);
+    i = g_sequence_iter_prev(i);
+
+    /* TODO: Checks that no other item overlaps. */
+
+    BlueSkyRangesetItem *item = g_new(BlueSkyRangesetItem, 1);
+    item->start = start;
+    item->length = length;
+    item->data = data;
+    g_sequence_insert_sorted(rangeset->seq, item, compare64, NULL);
+
+    return TRUE;
+}
+
+const BlueSkyRangesetItem *bluesky_rangeset_lookup(BlueSkyRangeset *rangeset,
+                                                   uint64_t offset)
+{
+    GSequenceIter *i;
+    i = g_sequence_search(rangeset->seq, &offset, compare64, NULL);
+    i = g_sequence_iter_prev(i);
+    if (g_sequence_iter_is_end(i))
+        return NULL;
+
+    BlueSkyRangesetItem *item = (BlueSkyRangesetItem *)g_sequence_get(i);
+    if (offset >= item->start && offset < item->start + item->length)
+        return item;
+    else
+        return NULL;
+}
+
+/* Look up the first rangeset item starting at or following the given address.
+ * Can be used to iterate through a rangeset. */
+const BlueSkyRangesetItem *bluesky_rangeset_lookup_next(BlueSkyRangeset *rangeset, uint64_t offset)
+{
+    GSequenceIter *i;
+    i = g_sequence_search(rangeset->seq, &offset, compare64, NULL);
+    i = g_sequence_iter_prev(i);
+    if (g_sequence_iter_is_end(i))
+        return NULL;
+    BlueSkyRangesetItem *item = (BlueSkyRangesetItem *)g_sequence_get(i);
+    if (item->start < offset) {
+        i = g_sequence_iter_next(i);
+        if (g_sequence_iter_is_end(i))
+            item = NULL;
+        else
+            item = (BlueSkyRangesetItem *)g_sequence_get(i);
+    }
+    return item;
+}