#ifdef FRONTEND
#include "common/logging.h"
#endif
+#include "common/hashfn.h"
#include "lib/binaryheap.h"
+/*
+ * Define parameters for hash table code generation. The interface is *also*
+ * declared in binaryheap.h (to generate the types, which are externally
+ * visible).
+ */
+#define SH_PREFIX bh_nodeidx
+#define SH_ELEMENT_TYPE bh_nodeidx_entry
+#define SH_KEY_TYPE bh_node_type
+#define SH_KEY key
+#define SH_HASH_KEY(tb, key) \
+ hash_bytes((const unsigned char *) &key, sizeof(bh_node_type))
+#define SH_EQUAL(tb, a, b) (memcmp(&a, &b, sizeof(bh_node_type)) == 0)
+#define SH_SCOPE extern
+#ifdef FRONTEND
+#define SH_RAW_ALLOCATOR pg_malloc0
+#endif
+#define SH_STORE_HASH
+#define SH_GET_HASH(tb, a) a->hash
+#define SH_DEFINE
+#include "lib/simplehash.h"
+
static void sift_down(binaryheap *heap, int node_off);
static void sift_up(binaryheap *heap, int node_off);
* of nodes, and with the heap property defined by the given comparator
* function, which will be invoked with the additional argument specified by
* 'arg'.
+ *
+ * If 'indexed' is true, we create a hash table to track each node's
+ * index in the heap, enabling to perform some operations such as
+ * binaryheap_remove_node_ptr() etc.
*/
binaryheap *
-binaryheap_allocate(int num_nodes, binaryheap_comparator compare, void *arg)
+binaryheap_allocate(int num_nodes, binaryheap_comparator compare,
+ bool indexed, void *arg)
{
binaryheap *heap;
heap->bh_size = 0;
heap->bh_has_heap_property = true;
heap->bh_nodes = (bh_node_type *) palloc(sizeof(bh_node_type) * num_nodes);
+ heap->bh_nodeidx = NULL;
+
+ if (indexed)
+ {
+#ifdef FRONTEND
+ heap->bh_nodeidx = bh_nodeidx_create(num_nodes, NULL);
+#else
+ heap->bh_nodeidx = bh_nodeidx_create(CurrentMemoryContext, num_nodes,
+ NULL);
+#endif
+ }
return heap;
}
{
heap->bh_size = 0;
heap->bh_has_heap_property = true;
+
+ if (binaryheap_indexed(heap))
+ bh_nodeidx_reset(heap->bh_nodeidx);
}
/*
void
binaryheap_free(binaryheap *heap)
{
+ if (binaryheap_indexed(heap))
+ bh_nodeidx_destroy(heap->bh_nodeidx);
+
pfree(heap->bh_nodes);
pfree(heap);
}
sizeof(bh_node_type) * heap->bh_space);
}
+/*
+ * Set the given node at the 'index' and track it if required.
+ *
+ * Return true if the node's index is already tracked.
+ */
+static bool
+set_node(binaryheap *heap, bh_node_type node, int index)
+{
+ bool found = false;
+
+ /* Set the node to the nodes array */
+ heap->bh_nodes[index] = node;
+
+ if (binaryheap_indexed(heap))
+ {
+ bh_nodeidx_entry *ent;
+
+ /* Keep track of the node index */
+ ent = bh_nodeidx_insert(heap->bh_nodeidx, node, &found);
+ ent->index = index;
+ }
+
+ return found;
+}
+
+/*
+ * Remove the node's index from the hash table if the heap is indexed.
+ */
+static inline void
+delete_nodeidx(binaryheap *heap, bh_node_type node)
+{
+ if (binaryheap_indexed(heap))
+ bh_nodeidx_delete(heap->bh_nodeidx, node);
+}
+
+/*
+ * Replace the existing node at 'idx' with the given 'new_node'. Also
+ * update their positions accordingly. Note that we assume the new_node's
+ * position is already tracked if enabled, i.e. the new_node is already
+ * present in the heap.
+ */
+static void
+replace_node(binaryheap *heap, int index, bh_node_type new_node)
+{
+ bool found PG_USED_FOR_ASSERTS_ONLY;
+
+ /* Quick return if not necessary to move */
+ if (heap->bh_nodes[index] == new_node)
+ return;
+
+ /* Remove the overwritten node's index */
+ delete_nodeidx(heap, heap->bh_nodes[index]);
+
+ /*
+ * Replace it with the given new node. This node's position must also be
+ * tracked as we assume to replace the node with the existing node.
+ */
+ found = set_node(heap, new_node, index);
+ Assert(!binaryheap_indexed(heap) || found);
+}
+
/*
* binaryheap_add_unordered
*
enlarge_node_array(heap);
heap->bh_has_heap_property = false;
- heap->bh_nodes[heap->bh_size] = d;
+ set_node(heap, d, heap->bh_size);
heap->bh_size++;
}
if (heap->bh_size >= heap->bh_space)
enlarge_node_array(heap);
- heap->bh_nodes[heap->bh_size] = d;
+ set_node(heap, d, heap->bh_size);
heap->bh_size++;
sift_up(heap, heap->bh_size - 1);
}
if (heap->bh_size == 1)
{
heap->bh_size--;
+ delete_nodeidx(heap, result);
+
return result;
}
* Remove the last node, placing it in the vacated root entry, and sift
* the new root node down to its correct position.
*/
- heap->bh_nodes[0] = heap->bh_nodes[--heap->bh_size];
+ replace_node(heap, 0, heap->bh_nodes[--heap->bh_size]);
sift_down(heap, 0);
return result;
heap->bh_arg);
/* remove the last node, placing it in the vacated entry */
- heap->bh_nodes[n] = heap->bh_nodes[heap->bh_size];
+ replace_node(heap, n, heap->bh_nodes[heap->bh_size]);
/* sift as needed to preserve the heap property */
if (cmp > 0)
sift_down(heap, n);
}
+/*
+ * binaryheap_remove_node_ptr
+ *
+ * Similar to binaryheap_remove_node() but removes the given node. The caller
+ * must ensure that the given node is in the heap. O(log n) worst case.
+ *
+ * This function can be used only if the heap is indexed.
+ */
+void
+binaryheap_remove_node_ptr(binaryheap *heap, bh_node_type d)
+{
+ bh_nodeidx_entry *ent;
+
+ Assert(!binaryheap_empty(heap) && heap->bh_has_heap_property);
+ Assert(binaryheap_indexed(heap));
+
+ ent = bh_nodeidx_lookup(heap->bh_nodeidx, d);
+ Assert(ent);
+
+ binaryheap_remove_node(heap, ent->index);
+}
+
+/*
+ * Workhorse for binaryheap_update_up and binaryheap_update_down.
+ */
+static void
+resift_node(binaryheap *heap, bh_node_type node, bool sift_dir_up)
+{
+ bh_nodeidx_entry *ent;
+
+ Assert(!binaryheap_empty(heap) && heap->bh_has_heap_property);
+ Assert(binaryheap_indexed(heap));
+
+ ent = bh_nodeidx_lookup(heap->bh_nodeidx, node);
+ Assert(ent);
+ Assert(ent->index >= 0 && ent->index < heap->bh_size);
+
+ if (sift_dir_up)
+ sift_up(heap, ent->index);
+ else
+ sift_down(heap, ent->index);
+}
+
+/*
+ * binaryheap_update_up
+ *
+ * Sift the given node up after the node's key is updated. The caller must
+ * ensure that the given node is in the heap. O(log n) worst case.
+ *
+ * This function can be used only if the heap is indexed.
+ */
+void
+binaryheap_update_up(binaryheap *heap, bh_node_type d)
+{
+ resift_node(heap, d, true);
+}
+
+/*
+ * binaryheap_update_down
+ *
+ * Sift the given node down after the node's key is updated. The caller must
+ * ensure that the given node is in the heap. O(log n) worst case.
+ *
+ * This function can be used only if the heap is indexed.
+ */
+void
+binaryheap_update_down(binaryheap *heap, bh_node_type d)
+{
+ resift_node(heap, d, false);
+}
+
/*
* binaryheap_replace_first
*
{
Assert(!binaryheap_empty(heap) && heap->bh_has_heap_property);
- heap->bh_nodes[0] = d;
+ replace_node(heap, 0, d);
if (heap->bh_size > 1)
sift_down(heap, 0);
* Otherwise, swap the parent value with the hole, and go on to check
* the node's new parent.
*/
- heap->bh_nodes[node_off] = parent_val;
+ set_node(heap, parent_val, node_off);
node_off = parent_off;
}
/* Re-fill the hole */
- heap->bh_nodes[node_off] = node_val;
+ set_node(heap, node_val, node_off);
}
/*
* Otherwise, swap the hole with the child that violates the heap
* property; then go on to check its children.
*/
- heap->bh_nodes[node_off] = heap->bh_nodes[swap_off];
+ set_node(heap, heap->bh_nodes[swap_off], node_off);
node_off = swap_off;
}
/* Re-fill the hole */
- heap->bh_nodes[node_off] = node_val;
+ set_node(heap, node_val, node_off);
}
*/
typedef int (*binaryheap_comparator) (bh_node_type a, bh_node_type b, void *arg);
+/*
+ * Struct for a hash table element to store the node's index in the bh_nodes
+ * array.
+ */
+typedef struct bh_nodeidx_entry
+{
+ bh_node_type key;
+ int index; /* entry's index within the node array */
+ char status; /* hash status */
+ uint32 hash; /* hash values (cached) */
+} bh_nodeidx_entry;
+
+/* Define parameters necessary to generate the hash table interface. */
+#define SH_PREFIX bh_nodeidx
+#define SH_ELEMENT_TYPE bh_nodeidx_entry
+#define SH_KEY_TYPE bh_node_type
+#define SH_SCOPE extern
+#ifdef FRONTEND
+#define SH_RAW_ALLOCATOR pg_malloc0
+#endif
+#define SH_DECLARE
+#include "lib/simplehash.h"
+
/*
* binaryheap
*
binaryheap_comparator bh_compare;
void *bh_arg;
bh_node_type *bh_nodes;
+
+ /*
+ * If bh_nodeidx is not NULL, the bh_nodeidx is used to track of each
+ * node's index in bh_nodes. This enables the caller to perform
+ * binaryheap_remove_node_ptr(), binaryheap_update_up/down in O(log n).
+ */
+ bh_nodeidx_hash *bh_nodeidx;
} binaryheap;
extern binaryheap *binaryheap_allocate(int num_nodes,
binaryheap_comparator compare,
- void *arg);
+ bool indexed, void *arg);
extern void binaryheap_reset(binaryheap *heap);
extern void binaryheap_free(binaryheap *heap);
extern void binaryheap_add_unordered(binaryheap *heap, bh_node_type d);
extern bh_node_type binaryheap_first(binaryheap *heap);
extern bh_node_type binaryheap_remove_first(binaryheap *heap);
extern void binaryheap_remove_node(binaryheap *heap, int n);
+extern void binaryheap_remove_node_ptr(binaryheap *heap, bh_node_type d);
extern void binaryheap_replace_first(binaryheap *heap, bh_node_type d);
+extern void binaryheap_update_up(binaryheap *heap, bh_node_type d);
+extern void binaryheap_update_down(binaryheap *heap, bh_node_type d);
#define binaryheap_empty(h) ((h)->bh_size == 0)
#define binaryheap_size(h) ((h)->bh_size)
#define binaryheap_get_node(h, n) ((h)->bh_nodes[n])
+#define binaryheap_indexed(h) ((h)->bh_nodeidx != NULL)
#endif /* BINARYHEAP_H */
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