drd/drd_segment.c

   1 /*
   2   This file is part of drd, a thread error detector.
   3
   4   Copyright (C) 2006-2017 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
  39 Segment* DRD_(g_sg_list);
  40
  41
  42 /* Local variables. */
  43
  44 static ULong s_segment_merge_count;
  45 static ULong s_segments_created_count;
  46 static ULong s_segments_alive_count;
  47 static ULong s_max_segments_alive_count;
  48 static 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  */
  62 static 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 %u with vc %s\n",
 101                    created, vc);
 102       VG_(free)(vc);
 103    }
 104 }
 105
 106 /** Deallocate the memory that was allocated by sg_init(). */
 107 static 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. */
 117 Segment* 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
 136 static 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. */
 162 Segment* 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  */
 174 void 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. */
 199 void 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. */
 228 void 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. */
 238 Bool DRD_(sg_get_trace)(void)
 239 {
 240    return s_trace_segment;
 241 }
 242
 243 /** Enable or disable segment tracing. */
 244 void 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
 250 ULong DRD_(sg_get_segments_created_count)(void)
 251 {
 252    return s_segments_created_count;
 253 }
 254
 255 ULong DRD_(sg_get_segments_alive_count)(void)
 256 {
 257    return s_segments_alive_count;
 258 }
 259
 260 ULong DRD_(sg_get_max_segments_alive_count)(void)
 261 {
 262    return s_max_segments_alive_count;
 263 }
 264
 265 ULong DRD_(sg_get_segment_merge_count)(void)
 266 {
 267    return s_segment_merge_count;
 268 }