1/*
2  This file is part of drd, a thread error detector.
3
4  Copyright (C) 2006-2013 Bart Van Assche <bvanassche@acm.org>.
5
6  This program is free software; you can redistribute it and/or
7  modify it under the terms of the GNU General Public License as
8  published by the Free Software Foundation; either version 2 of the
9  License, or (at your option) any later version.
10
11  This program is distributed in the hope that it will be useful, but
12  WITHOUT ANY WARRANTY; without even the implied warranty of
13  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  General Public License for more details.
15
16  You should have received a copy of the GNU General Public License
17  along with this program; if not, write to the Free Software
18  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19  02111-1307, USA.
20
21  The GNU General Public License is contained in the file COPYING.
22*/
23
24
25#include "drd_error.h"
26#include "drd_segment.h"
27#include "drd_thread.h"
28#include "pub_tool_basics.h"      // Addr, SizeT
29#include "pub_tool_libcassert.h"  // tl_assert()
30#include "pub_tool_libcbase.h"    // VG_(strlen)()
31#include "pub_tool_libcprint.h"   // VG_(printf)()
32#include "pub_tool_machine.h"     // VG_(get_SP)()
33#include "pub_tool_mallocfree.h"  // VG_(malloc)(), VG_(free)()
34#include "pub_tool_threadstate.h" // VG_INVALID_THREADID
35
36
37/* Global variables. */
38
39Segment* DRD_(g_sg_list);
40
41
42/* Local variables. */
43
44static ULong s_segment_merge_count;
45static ULong s_segments_created_count;
46static ULong s_segments_alive_count;
47static ULong s_max_segments_alive_count;
48static Bool s_trace_segment;
49
50
51/* Function definitions. */
52
53/**
54 * Initialize the memory 'sg' points at.
55 *
56 * @note The creator and created thread ID's may be equal.
57 * @note This function copies the vector clock of thread 'creator', a technique
58 *   also known as clock snooping. This will only work reliably if the thread
59 *   that called pthread_create() waits until the created thread has copied
60 *   the vector clock.
61 */
62static void sg_init(Segment* const sg,
63                    const DrdThreadId creator,
64                    const DrdThreadId created)
65{
66   Segment* creator_sg;
67   ThreadId vg_created = DRD_(DrdThreadIdToVgThreadId)(created);
68
69   tl_assert(sg);
70   tl_assert(creator == DRD_INVALID_THREADID
71             || DRD_(IsValidDrdThreadId)(creator));
72
73   creator_sg = (creator != DRD_INVALID_THREADID
74                 ? DRD_(thread_get_segment)(creator) : 0);
75
76   sg->g_next = NULL;
77   sg->g_prev = NULL;
78   sg->thr_next = NULL;
79   sg->thr_prev = NULL;
80   sg->tid = created;
81   sg->refcnt = 1;
82
83   if (vg_created != VG_INVALID_THREADID && VG_(get_SP)(vg_created) != 0)
84      sg->stacktrace = VG_(record_ExeContext)(vg_created, 0);
85   else
86      sg->stacktrace = 0;
87
88   if (creator_sg)
89      DRD_(vc_copy)(&sg->vc, &creator_sg->vc);
90   else
91      DRD_(vc_init)(&sg->vc, 0, 0);
92   DRD_(vc_increment)(&sg->vc, created);
93   DRD_(bm_init)(&sg->bm);
94
95   if (s_trace_segment)
96   {
97      HChar* vc;
98
99      vc = DRD_(vc_aprint)(&sg->vc);
100      VG_(message)(Vg_DebugMsg, "New segment for thread %d with vc %s\n",
101                   created, vc);
102      VG_(free)(vc);
103   }
104}
105
106/** Deallocate the memory that was allocated by sg_init(). */
107static void DRD_(sg_cleanup)(Segment* const sg)
108{
109   tl_assert(sg);
110   tl_assert(sg->refcnt == 0);
111
112   DRD_(vc_cleanup)(&sg->vc);
113   DRD_(bm_cleanup)(&sg->bm);
114}
115
116/** Allocate and initialize a new segment. */
117Segment* DRD_(sg_new)(const DrdThreadId creator, const DrdThreadId created)
118{
119   Segment* sg;
120
121   s_segments_created_count++;
122   s_segments_alive_count++;
123   if (s_max_segments_alive_count < s_segments_alive_count)
124      s_max_segments_alive_count = s_segments_alive_count;
125
126   sg = VG_(malloc)("drd.segment.sn.1", sizeof(*sg));
127   sg_init(sg, creator, created);
128   if (DRD_(g_sg_list)) {
129      DRD_(g_sg_list)->g_prev = sg;
130      sg->g_next = DRD_(g_sg_list);
131   }
132   DRD_(g_sg_list) = sg;
133   return sg;
134}
135
136static void DRD_(sg_delete)(Segment* const sg)
137{
138   if (DRD_(sg_get_trace)())
139   {
140      HChar* vc;
141
142      vc = DRD_(vc_aprint)(&sg->vc);
143      VG_(message)(Vg_DebugMsg, "Discarding the segment with vector clock %s\n",
144                   vc);
145      VG_(free)(vc);
146   }
147
148   s_segments_alive_count--;
149
150   tl_assert(sg);
151   if (sg->g_next)
152      sg->g_next->g_prev = sg->g_prev;
153   if (sg->g_prev)
154      sg->g_prev->g_next = sg->g_next;
155   else
156      DRD_(g_sg_list) = sg->g_next;
157   DRD_(sg_cleanup)(sg);
158   VG_(free)(sg);
159}
160
161/** Increment the reference count of the specified segment. */
162Segment* DRD_(sg_get)(Segment* const sg)
163{
164   tl_assert(sg);
165
166   sg->refcnt++;
167   return sg;
168}
169
170/**
171 * Decrement the reference count of the specified segment and deallocate the
172 * segment if the reference count became zero.
173 */
174void DRD_(sg_put)(Segment* const sg)
175{
176   if (sg == 0)
177      return;
178
179   if (s_trace_segment)
180   {
181      HChar* vc;
182
183      vc = DRD_(vc_aprint)(&sg->vc);
184      VG_(message)(Vg_DebugMsg,
185                   "Decrementing segment reference count %d -> %d with vc %s\n",
186                   sg->refcnt, sg->refcnt - 1, vc);
187      VG_(free)(vc);
188   }
189
190   tl_assert(sg->refcnt >= 1);
191
192   if (--sg->refcnt == 0)
193   {
194      DRD_(sg_delete)(sg);
195   }
196}
197
198/** Merge sg1 and sg2 into sg1. */
199void DRD_(sg_merge)(Segment* const sg1, Segment* const sg2)
200{
201   tl_assert(sg1);
202   tl_assert(sg1->refcnt == 1);
203   tl_assert(sg2);
204   tl_assert(sg2->refcnt == 1);
205
206   if (s_trace_segment)
207   {
208      HChar *vc1, *vc2;
209
210      vc1 = DRD_(vc_aprint)(&sg1->vc);
211      vc2 = DRD_(vc_aprint)(&sg2->vc);
212
213      VG_(message)(Vg_DebugMsg,
214		   "Merging segments with vector clocks %s and %s\n", vc1, vc2);
215      VG_(free)(vc1);
216      VG_(free)(vc2);
217   }
218
219   s_segment_merge_count++;
220
221   // Keep sg1->stacktrace.
222   // Keep sg1->vc.
223   // Merge sg2->bm into sg1->bm.
224   DRD_(bm_merge2)(&sg1->bm, &sg2->bm);
225}
226
227/** Print the vector clock and the bitmap of the specified segment. */
228void DRD_(sg_print)(Segment* const sg)
229{
230   tl_assert(sg);
231   VG_(printf)("vc: ");
232   DRD_(vc_print)(&sg->vc);
233   VG_(printf)("\n");
234   DRD_(bm_print)(&sg->bm);
235}
236
237/** Query whether segment tracing has been enabled. */
238Bool DRD_(sg_get_trace)(void)
239{
240   return s_trace_segment;
241}
242
243/** Enable or disable segment tracing. */
244void DRD_(sg_set_trace)(Bool const trace_segment)
245{
246   tl_assert(trace_segment == False || trace_segment == True);
247   s_trace_segment = trace_segment;
248}
249
250ULong DRD_(sg_get_segments_created_count)(void)
251{
252   return s_segments_created_count;
253}
254
255ULong DRD_(sg_get_segments_alive_count)(void)
256{
257   return s_segments_alive_count;
258}
259
260ULong DRD_(sg_get_max_segments_alive_count)(void)
261{
262   return s_max_segments_alive_count;
263}
264
265ULong DRD_(sg_get_segment_merge_count)(void)
266{
267   return s_segment_merge_count;
268}
269