X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=lib%2Fprio_heap%2Fprio_heap.c;h=ae47ebb8e4ba8f0b378e9a31b71b56ba4e4c207f;hb=94a7d04ee6e0d9464422e3d680860d8a2464e6c1;hp=8945c2a019804f7d0afe9e126b8c4a1b4dcce79d;hpb=f3bc08c50e1b302bceea699027d889fd6d9af525;p=lttng-modules.git

diff --git a/lib/prio_heap/prio_heap.c b/lib/prio_heap/prio_heap.c
index 8945c2a0..ae47ebb8 100644
--- a/lib/prio_heap/prio_heap.c
+++ b/lib/prio_heap/prio_heap.c
@@ -1,23 +1,34 @@
 /*
- * LICENSING: this file is copied from the Linux kernel. We should therefore
- * assume a GPLv2 license for the code that comes from the Linux mainline.
- */
-
-/*
- * Static-sized priority heap containing pointers. Based on CLR, chapter 7.
+ * prio_heap.c
+ *
+ * Static-sized priority heap containing pointers. Based on CLRS,
+ * chapter 6.
+ *
+ * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
  */
 
 #include <linux/slab.h>
 #include <linux/prio_heap.h>
 
-int heap_init(struct ptr_heap *heap, size_t size, gfp_t gfp_mask,
-	      int (*gt)(void *, void *))
+int heap_init(struct ptr_heap *heap, size_t size,
+	       gfp_t gfpmask, int gt(void *a, void *b))
 {
-	heap->ptrs = kmalloc(size, gfp_mask);
+	WARN_ON_ONCE(size == 0);
+	heap->ptrs = kmalloc(size * sizeof(void *), gfpmask);
 	if (!heap->ptrs)
 		return -ENOMEM;
 	heap->size = 0;
-	heap->max = size / sizeof(void *);
+	heap->max = size;
 	heap->gt = gt;
 	return 0;
 }
@@ -29,24 +40,7 @@ void heap_free(struct ptr_heap *heap)
 
 static void heapify(struct ptr_heap *heap, int pos)
 {
-	void **ptrs = heap->ptrs;
-	void *p = ptrs[pos];
-
-	while (1) {
-		int left = 2 * pos + 1;
-		int right = 2 * pos + 2;
-		int largest = pos;
-		if (left < heap->size && heap->gt(ptrs[left], p))
-			largest = left;
-		if (right < heap->size && heap->gt(ptrs[right], ptrs[largest]))
-			largest = right;
-		if (largest == pos)
-			break;
-		/* Push p down the heap one level and bump one up */
-		ptrs[pos] = ptrs[largest];
-		ptrs[largest] = p;
-		pos = largest;
-	}
+	/* TODO */
 }
 
 void *heap_replace_max(struct ptr_heap *heap, void *p)
@@ -70,27 +64,29 @@ void *heap_replace_max(struct ptr_heap *heap, void *p)
 void *heap_insert(struct ptr_heap *heap, void *p)
 {
 	void **ptrs = heap->ptrs;
-	int pos;
+	void *tmp = NULL;
 
 	if (heap->size < heap->max) {
-		/* Heap insertion */
-		pos = heap->size++;
-		while (pos > 0 && heap->gt(p, ptrs[(pos-1)/2])) {
-			ptrs[pos] = ptrs[(pos-1)/2];
-			pos = (pos-1)/2;
-		}
-		ptrs[pos] = p;
+		/* Add the element to the end */
+		heap->ptrs[heap->size++] = p;
+		/* rebalance */
+		heapify(heap, 0);
 		return NULL;
 	}
 
-	/* The heap is full, so something will have to be dropped */
-
-	/* If the new pointer is greater than the current max, drop it */
-	if (heap->gt(p, ptrs[0]))
-		return p;
-
-	/* Replace the current max and heapify */
-	return heap_replace_max(heap, p);
+	/*
+	 * Full. We need to replace the largest (if we are
+	 * smaller or equal to this element).
+	 */
+	if (heap->gt(ptrs[0], p)) {
+		tmp = ptrs[0];
+		ptrs[0] = p;
+		/* rebalance */
+		heapify(heap, 0);
+	} else {
+		tmp = p;
+	}
+	return tmp;
 }
 
 void *heap_remove(struct ptr_heap *heap)