}
}
+static unsigned int dep_count;
static void add_dependency(void *ctx,
struct op *op[],
char *filename[],
pre->file = satisfies_file;
pre->op = satisfies_opnum;
list_add(&op[needs_file][needs_opnum].pre, &pre->list);
+
+ dep_count++;
}
#if TRAVERSALS_TAKE_TRANSACTION_LOCK
dep[i-1].file, dep[i-1].op->trav->end);
}
talloc_free(dep);
+ printf("Dep count after traverses: %u\n", dep_count);
}
#endif /* TRAVERSALS_TAKE_TRANSACTION_LOCK */
+static bool changes_db(const struct op *op)
+{
+ return gives(op, NULL) != NULL;
+}
+
+static void depend_on_previous(struct op *op[],
+ char *filename[],
+ unsigned int num,
+ struct key_user user[],
+ unsigned int i,
+ int prev)
+{
+ bool deps[num];
+ int j;
+
+ if (i == 0)
+ return;
+
+ if (prev == i - 1) {
+ /* Just depend on previous. */
+ add_dependency(NULL, op, filename,
+ user[i].file, user[i].op_num,
+ user[prev].file, user[prev].op_num);
+ return;
+ }
+
+ /* We have to wait for the readers. Find last one in *each* file. */
+ memset(deps, 0, sizeof(deps));
+ deps[user[i].file] = true;
+ for (j = i - 1; j > prev; j--) {
+ if (!deps[user[j].file]) {
+ add_dependency(NULL, op, filename,
+ user[i].file, user[i].op_num,
+ user[j].file, user[j].op_num);
+ deps[user[j].file] = true;
+ }
+ }
+}
+
static void derive_dependencies(char *filename[],
struct op *op[], unsigned int num_ops[],
unsigned int num)
{
struct keyinfo *hash;
- unsigned int i, j;
+ unsigned int h, i;
/* Create hash table for faster key lookup. */
hash = hash_ops(op, num_ops, num);
/* Now handle the hard cases: same serial number. */
sort_ops(hash, filename, op);
- /* We make the naive assumption that two ops on the same key
- * have to be ordered; it's overkill. */
- for (i = 0; i < total_keys * 2; i++) {
- for (j = 1; j < hash[i].num_users; j++) {
- add_dependency(hash, op, filename,
- hash[i].user[j].file,
- hash[i].user[j].op_num,
- hash[i].user[j-1].file,
- hash[i].user[j-1].op_num);
+ /* Create dependencies back to the last change, rather than
+ * creating false dependencies by naively making each one
+ * depend on the previous. This has two purposes: it makes
+ * later optimization simpler, and it also avoids deadlock with
+ * same sequence number ops inside traversals (if one
+ * traversal doesn't write anything, two ops can have the same
+ * sequence number yet we can create a traversal dependency
+ * the other way). */
+ for (h = 0; h < total_keys * 2; h++) {
+ int prev = -1;
+
+ if (hash[h].num_users < 2)
+ continue;
+
+ for (i = 0; i < hash[h].num_users; i++) {
+ if (changes_db(&op[hash[h].user[i].file]
+ [hash[h].user[i].op_num])) {
+ depend_on_previous(op, filename, num,
+ hash[h].user, i, prev);
+ prev = i;
+ } else if (prev >= 0)
+ add_dependency(hash, op, filename,
+ hash[h].user[i].file,
+ hash[h].user[i].op_num,
+ hash[h].user[prev].file,
+ hash[h].user[prev].op_num);
}
}
+ printf("Dep count after deriving: %u\n", dep_count);
#if TRAVERSALS_TAKE_TRANSACTION_LOCK
make_traverse_depends(filename, op, num_ops, num);