1/* -*- mode: C; c-basic-offset: 3; -*- */
2/*
3  This file is part of drd, a thread error detector.
4
5  Copyright (C) 2006-2010 Bart Van Assche <bvanassche@acm.org>.
6
7  This program is free software; you can redistribute it and/or
8  modify it under the terms of the GNU General Public License as
9  published by the Free Software Foundation; either version 2 of the
10  License, or (at your option) any later version.
11
12  This program is distributed in the hope that it will be useful, but
13  WITHOUT ANY WARRANTY; without even the implied warranty of
14  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  General Public License for more details.
16
17  You should have received a copy of the GNU General Public License
18  along with this program; if not, write to the Free Software
19  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
20  02111-1307, USA.
21
22  The GNU General Public License is contained in the file COPYING.
23*/
24
25/*
26 * Block allocator for second-level bitmap nodes. Each node consists of
27 * an OSetGen node and a struct bitmap2. The code below allocates
28 * NODES_PER_CHUNK nodes at a time.
29 */
30
31
32#include "drd_basics.h"           /* DRD_() */
33#include "drd_bitmap.h"           /* struct bitmap2 */
34#include "pub_drd_bitmap.h"
35#include "pub_tool_basics.h"      /* Addr, SizeT */
36#include "pub_tool_libcassert.h"  /* tl_assert() */
37#include "pub_tool_libcbase.h"    /* VG_ROUNDUP() */
38#include "pub_tool_libcprint.h"   /* VG_(message)() */
39#include "pub_tool_mallocfree.h"  /* VG_(malloc), VG_(free) */
40
41
42#define NODES_PER_CHUNCK 512
43
44
45/* Local type definitions. */
46
47struct block_allocator_chunk {
48   struct block_allocator_chunk* next;
49   struct block_allocator_chunk* prev;
50   int   nallocated;
51   void* data;
52   void* data_end;
53   void* first_free;
54};
55
56
57/* Local variables. */
58
59static SizeT s_bm2_node_size;
60static struct block_allocator_chunk* s_first;
61
62
63/* Function definitions. */
64
65/**
66 * Allocate a new chunk and insert it at the start of the doubly-linked list
67 * s_first.
68 */
69static struct block_allocator_chunk* allocate_new_chunk(void)
70{
71   struct block_allocator_chunk* p;
72   int i;
73
74   tl_assert(s_bm2_node_size > 0);
75
76   p = VG_(malloc)("drd.bitmap.bac",
77                   sizeof(*p) + NODES_PER_CHUNCK * s_bm2_node_size);
78   tl_assert(p);
79   p->next = s_first;
80   if (s_first)
81      p->next->prev = p;
82   s_first = p;
83   p->prev = 0;
84   p->nallocated = 0;
85   p->data = (char*)p + sizeof(*p);
86   tl_assert(p->data);
87   p->data_end = (char*)(p->data) + NODES_PER_CHUNCK * s_bm2_node_size;
88   p->first_free = p->data;
89   for (i = 0; i < NODES_PER_CHUNCK - 1; i++)
90   {
91      *(void**)((char*)(p->data) + i * s_bm2_node_size)
92         = (char*)(p->data) + (i + 1) * s_bm2_node_size;
93   }
94   tl_assert(i == NODES_PER_CHUNCK - 1);
95   *(void**)((char*)(p->data) + i * s_bm2_node_size) = NULL;
96
97   return p;
98}
99
100/** Free a chunk and remove it from the list of chunks. */
101static void free_chunk(struct block_allocator_chunk* const p)
102{
103   tl_assert(p);
104   tl_assert(p->nallocated == 0);
105
106   if (p == s_first)
107      s_first = p->next;
108   else if (p->prev)
109      p->prev->next = p->next;
110   if (p->next)
111      p->next->prev = p->prev;
112   VG_(free)(p);
113}
114
115/** Allocate a node. */
116void* DRD_(bm2_alloc_node)(HChar* const ec, const SizeT szB)
117{
118   /*
119    * If szB < sizeof(struct bitmap2) then this function has been called to
120    * allocate an AVL tree root node. Otherwise it has been called to allocate
121    * an AVL tree branch or leaf node.
122    */
123   if (szB < sizeof(struct bitmap2))
124      return VG_(malloc)(ec, szB);
125
126   while (True)
127   {
128      struct block_allocator_chunk* p;
129
130      if (s_bm2_node_size == 0)
131         s_bm2_node_size = szB;
132      else
133         tl_assert(s_bm2_node_size == szB);
134
135      for (p = s_first; p; p = p->next)
136      {
137         if (p->first_free)
138         {
139            void* result;
140
141            p->nallocated++;
142            result = p->first_free;
143            p->first_free = *(void**)(p->first_free);
144            return result;
145         }
146      }
147
148      allocate_new_chunk();
149   }
150}
151
152/** Free a node. */
153void  DRD_(bm2_free_node)(void* const bm2)
154{
155   struct block_allocator_chunk* p;
156
157   tl_assert(s_bm2_node_size > 0);
158   tl_assert(bm2);
159
160   for (p = s_first; p; p = p->next)
161   {
162      if (p->data <= bm2 && bm2 < p->data_end)
163      {
164	 /* Free the memory that was allocated for a non-root AVL tree node. */
165         tl_assert(((char*)bm2 - (char*)(p->data)) % s_bm2_node_size == 0);
166         *(void**)bm2 = p->first_free;
167         p->first_free = bm2;
168         tl_assert(p->nallocated >= 1);
169         if (--(p->nallocated) == 0)
170            free_chunk(p);
171         return;
172      }
173   }
174
175   /* Free the memory that was allocated for an AVL tree root node. */
176   VG_(free)(bm2);
177}
178