feat: add union-find-delete data structure

src/utils/ufd.c

@@ -0,0 +1,61 @@
+#include "ufd.h"
+#include "stdlib.h"
+#include <sys/queue.h>
+
+struct ufd_t ufd__make_set(struct context_entry_t* thread)
+{
+    struct ufd_children_t children = TAILQ_HEAD_INITIALIZER(children);
+
+    return (struct ufd_t) {
+        .thread = thread,
+        .parent = NULL,
+        .repr = NULL,
+        .children = children,
+    };
+}
+
+
+void ufd__init(struct ufd_t* ufd, struct context_entry_t* thread)
+{
+    TAILQ_INIT(&ufd->children);
+    ufd->thread = thread;
+    ufd->repr = NULL,
+    ufd->parent = NULL;
+}
+
+
+void ufd__join(struct ufd_t* th1, struct ufd_t* th2)
+{
+    struct ufd_t* a = ufd__find(th1);
+    struct ufd_t* b = ufd__find(th2);
+
+    if (a != b)
+    {
+        a->parent = b;
+        a->repr = b;
+    }
+}
+
+
+struct ufd_t* ufd__find(struct ufd_t* th)
+{
+    if (th->parent == NULL)
+        return th;
+
+    // If parent is null, repr can't be null
+    if (th->repr->parent == NULL)
+        return th->repr;
+
+    struct ufd_t* nrepr = ufd__find(th->repr);
+    th->repr = nrepr;
+    return nrepr;
+}
+
+
+void ufd__delete(struct ufd_t* th)
+{
+    struct ufd_t* child;
+    TAILQ_FOREACH(child, &th->children, link) {
+        child->parent = NULL;
+    }
+}

src/utils/ufd.h

@@ -0,0 +1,35 @@
+#ifndef _UNION_FIND_H_
+#define _UNION_FIND_H_
+#include <sys/queue.h>
+
+TAILQ_HEAD(ufd_children_t, ufd_t);
+
+// union find delete data structure
+struct ufd_t {
+    struct ufd_t* parent;
+    struct ufd_t* repr;
+    struct context_entry_t* thread;
+    struct ufd_children_t children;
+    TAILQ_ENTRY(ufd_t) link;
+};
+
+
+struct ufd_t ufd__make_set(struct context_entry_t* thread);
+
+void ufd__init(struct ufd_t* ufd, struct context_entry_t* thread);
+
+/*
+ * Join th1 set to th2 set
+ */
+void ufd__join(struct ufd_t* th1, struct ufd_t* th2);
+
+/*
+ * Find th's representent
+ */
+struct ufd_t* ufd__find(struct ufd_t* th);
+
+/*
+ * Deletes th from its set
+ */
+void ufd__delete(struct ufd_t* th);
+#endif  // _UNION_FIND_H_