r3057: - moved the idtree.c code into lib/

- converted the tid handling to use a idtree instead of bitmaps
(This used to be commit 4220914179d10132057216650b65ed7f7679717e)

1 files changed, 360 insertions, 0 deletions

diff --git a/source4/lib/idtree.c b/source4/lib/idtree.c
new file mode 100644
index 0000000000..80f7df97a0
--- /dev/null
+++ b/source4/lib/idtree.c
@@ -0,0 +1,360 @@
+/* 
+   Unix SMB/CIFS implementation.
+
+   very efficient functions to manage mapping a id (such as a fnum) to
+   a pointer. This is used for fnum and search id allocation.
+
+   Copyright (C) Andrew Tridgell 2004
+
+   This code is derived from lib/idr.c in the 2.6 Linux kernel, which was 
+   written by Jim Houston jim.houston@ccur.com, and is
+   Copyright (C) 2002 by Concurrent Computer Corporation
+    
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+/*
+  see the section marked "public interface" below for documentation
+*/
+
+#include "includes.h"
+
+#define IDR_BITS 5
+#define IDR_FULL 0xfffffffful
+#define TOP_LEVEL_FULL (IDR_FULL >> 30)
+#define IDR_SIZE (1 << IDR_BITS)
+#define IDR_MASK ((1 << IDR_BITS)-1)
+#define MAX_ID_SHIFT (sizeof(int)*8 - 1)
+#define MAX_ID_BIT (1U << MAX_ID_SHIFT)
+#define MAX_ID_MASK (MAX_ID_BIT - 1)
+#define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS
+#define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL
+
+#define set_bit(bit, v) (v) |= (1<<(bit))
+#define clear_bit(bit, v) (v) &= ~(1<<(bit))
+				   
+struct idr_layer {
+	uint32_t		 bitmap;
+	struct idr_layer	*ary[IDR_SIZE];
+	int			 count;
+};
+
+struct idr {
+	struct idr_layer *top;
+	struct idr_layer *id_free;
+	int		  layers;
+	int		  id_free_cnt;
+};
+
+static struct idr_layer *alloc_layer(struct idr *idp)
+{
+	struct idr_layer *p;
+
+	if (!(p = idp->id_free))
+		return NULL;
+	idp->id_free = p->ary[0];
+	idp->id_free_cnt--;
+	p->ary[0] = NULL;
+	return p;
+}
+
+static int find_next_bit(uint32_t bm, int maxid, int n)
+{
+	while (n<maxid && ((bm & (1<<n)) == 0)) n++;
+	return n;
+}
+
+static void free_layer(struct idr *idp, struct idr_layer *p)
+{
+	p->ary[0] = idp->id_free;
+	idp->id_free = p;
+	idp->id_free_cnt++;
+}
+
+static int idr_pre_get(struct idr *idp)
+{
+	while (idp->id_free_cnt < IDR_FREE_MAX) {
+		struct idr_layer *new = talloc_zero_p(idp, struct idr_layer);
+		if(new == NULL)
+			return (0);
+		free_layer(idp, new);
+	}
+	return 1;
+}
+
+static int sub_alloc(struct idr *idp, void *ptr, int *starting_id)
+{
+	int n, m, sh;
+	struct idr_layer *p, *new;
+	struct idr_layer *pa[MAX_LEVEL];
+	int l, id;
+	uint32_t bm;
+
+	id = *starting_id;
+	p = idp->top;
+	l = idp->layers;
+	pa[l--] = NULL;
+	while (1) {
+		/*
+		 * We run around this while until we reach the leaf node...
+		 */
+		n = (id >> (IDR_BITS*l)) & IDR_MASK;
+		bm = ~p->bitmap;
+		m = find_next_bit(bm, IDR_SIZE, n);
+		if (m == IDR_SIZE) {
+			/* no space available go back to previous layer. */
+			l++;
+			id = (id | ((1 << (IDR_BITS*l))-1)) + 1;
+			if (!(p = pa[l])) {
+				*starting_id = id;
+				return -2;
+			}
+			continue;
+		}
+		if (m != n) {
+			sh = IDR_BITS*l;
+			id = ((id >> sh) ^ n ^ m) << sh;
+		}
+		if ((id >= MAX_ID_BIT) || (id < 0))
+			return -1;
+		if (l == 0)
+			break;
+		/*
+		 * Create the layer below if it is missing.
+		 */
+		if (!p->ary[m]) {
+			if (!(new = alloc_layer(idp)))
+				return -1;
+			p->ary[m] = new;
+			p->count++;
+		}
+		pa[l--] = p;
+		p = p->ary[m];
+	}
+	/*
+	 * We have reached the leaf node, plant the
+	 * users pointer and return the raw id.
+	 */
+	p->ary[m] = (struct idr_layer *)ptr;
+	set_bit(m, p->bitmap);
+	p->count++;
+	/*
+	 * If this layer is full mark the bit in the layer above
+	 * to show that this part of the radix tree is full.
+	 * This may complete the layer above and require walking
+	 * up the radix tree.
+	 */
+	n = id;
+	while (p->bitmap == IDR_FULL) {
+		if (!(p = pa[++l]))
+			break;
+		n = n >> IDR_BITS;
+		set_bit((n & IDR_MASK), p->bitmap);
+	}
+	return(id);
+}
+
+static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
+{
+	struct idr_layer *p, *new;
+	int layers, v, id;
+
+	idr_pre_get(idp);
+	
+	id = starting_id;
+build_up:
+	p = idp->top;
+	layers = idp->layers;
+	if (!p) {
+		if (!(p = alloc_layer(idp)))
+			return -1;
+		layers = 1;
+	}
+	/*
+	 * Add a new layer to the top of the tree if the requested
+	 * id is larger than the currently allocated space.
+	 */
+	while ((layers < MAX_LEVEL) && (id >= (1 << (layers*IDR_BITS)))) {
+		layers++;
+		if (!p->count)
+			continue;
+		if (!(new = alloc_layer(idp))) {
+			/*
+			 * The allocation failed.  If we built part of
+			 * the structure tear it down.
+			 */
+			for (new = p; p && p != idp->top; new = p) {
+				p = p->ary[0];
+				new->ary[0] = NULL;
+				new->bitmap = new->count = 0;
+				free_layer(idp, new);
+			}
+			return -1;
+		}
+		new->ary[0] = p;
+		new->count = 1;
+		if (p->bitmap == IDR_FULL)
+			set_bit(0, new->bitmap);
+		p = new;
+	}
+	idp->top = p;
+	idp->layers = layers;
+	v = sub_alloc(idp, ptr, &id);
+	if (v == -2)
+		goto build_up;
+	return(v);
+}
+
+static void sub_remove(struct idr *idp, int shift, int id)
+{
+	struct idr_layer *p = idp->top;
+	struct idr_layer **pa[MAX_LEVEL];
+	struct idr_layer ***paa = &pa[0];
+
+	*paa = NULL;
+	*++paa = &idp->top;
+
+	while ((shift > 0) && p) {
+		int n = (id >> shift) & IDR_MASK;
+		clear_bit(n, p->bitmap);
+		*++paa = &p->ary[n];
+		p = p->ary[n];
+		shift -= IDR_BITS;
+	}
+	if (p != NULL) {
+		int n = id & IDR_MASK;
+		clear_bit(n, p->bitmap);
+		p->ary[n] = NULL;
+		while(*paa && ! --((**paa)->count)){
+			free_layer(idp, **paa);
+			**paa-- = NULL;
+		}
+		if ( ! *paa )
+			idp->layers = 0;
+	}
+}
+
+static void *_idr_find(struct idr *idp, int id)
+{
+	int n;
+	struct idr_layer *p;
+
+	n = idp->layers * IDR_BITS;
+	p = idp->top;
+	/*
+	 * This tests to see if bits outside the current tree are
+	 * present.  If so, tain't one of ours!
+	 */
+	if ((id & ~(~0 << MAX_ID_SHIFT)) >> (n + IDR_BITS))
+	     return NULL;
+
+	/* Mask off upper bits we don't use for the search. */
+	id &= MAX_ID_MASK;
+
+	while (n > 0 && p) {
+		n -= IDR_BITS;
+		p = p->ary[(id >> n) & IDR_MASK];
+	}
+	return((void *)p);
+}
+
+static void _idr_remove(struct idr *idp, int id)
+{
+	struct idr_layer *p;
+
+	if (_idr_find(idp, id) == NULL) {
+		DEBUG(0,("WARNING: attempt to remove non-existant id %d in idtree\n",
+			 id));
+		return;
+	}
+
+	/* Mask off upper bits we don't use for the search. */
+	id &= MAX_ID_MASK;
+
+	sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
+	if ( idp->top && idp->top->count == 1 && 
+	     (idp->layers > 1) &&
+	     idp->top->ary[0]) {
+		/* We can drop a layer */
+		p = idp->top->ary[0];
+		idp->top->bitmap = idp->top->count = 0;
+		free_layer(idp, idp->top);
+		idp->top = p;
+		--idp->layers;
+	}
+	while (idp->id_free_cnt >= IDR_FREE_MAX) {
+		p = alloc_layer(idp);
+		talloc_free(p);
+		return;
+	}
+}
+
+/************************************************************************
+  this is the public interface
+**************************************************************************/
+
+/*
+  initialise a idr tree. The context return value must be passed to
+  all subsequent idr calls. To destroy the idr tree use talloc_free()
+  on this context
+ */
+void *idr_init(TALLOC_CTX *mem_ctx)
+{
+	return talloc_zero_p(mem_ctx, struct idr);
+}
+
+/*
+  allocate the next available id, and assign 'ptr' into its slot.
+  you can retrieve later this pointer using idr_find()
+*/
+int idr_get_new(void *idp, void *ptr, int limit)
+{
+	int ret = idr_get_new_above_int((struct idr *)idp, ptr, 0);
+	if (ret >= limit) {
+		idr_remove(idp, ret);
+		return -1;
+	}
+	return ret;
+}
+
+/* 
+   allocate a new id, giving the first available value greater than or
+   equal to the given starting id
+*/
+int idr_get_new_above(void *idp, void *ptr, int starting_id, int limit)
+{
+	int ret = idr_get_new_above_int((struct idr *)idp, ptr, starting_id);
+	if (ret >= limit) {
+		idr_remove(idp, ret);
+		return -1;
+	}
+	return ret;
+}
+
+/*
+  find a pointer value previously set with idr_get_new given an id
+*/
+void *idr_find(void *idp, int id)
+{
+	return _idr_find((struct idr *)idp, id);
+}
+
+/*
+  remove an id from the idr tree
+*/
+void idr_remove(void *idp, int id)
+{
+	return _idr_remove((struct idr *)idp, id);
+}