/*
This file is part of drd, a thread error detector.
Copyright (C) 2006-2012 Bart Van Assche <bvanassche@acm.org>.
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., 59 Temple Place, Suite 330, Boston, MA
02111-1307, USA.
The GNU General Public License is contained in the file COPYING.
*/
#include "drd_vc.h"
#include "pub_tool_basics.h" // Addr, SizeT
#include "pub_tool_libcassert.h" // tl_assert()
#include "pub_tool_libcbase.h" // VG_(memcpy)
#include "pub_tool_libcprint.h" // VG_(printf)
#include "pub_tool_mallocfree.h" // VG_(malloc), VG_(free)
/* Local function declarations. */
static
void DRD_(vc_reserve)(VectorClock* const vc, const unsigned new_capacity);
/* Function definitions. */
/**
* Initialize the memory 'vc' points at as a vector clock with size 'size'.
* If the pointer 'vcelem' is not null, it is assumed to be an array with
* 'size' elements and it becomes the initial value of the vector clock.
*/
void DRD_(vc_init)(VectorClock* const vc,
const VCElem* const vcelem,
const unsigned size)
{
tl_assert(vc);
vc->size = 0;
vc->capacity = 0;
vc->vc = 0;
DRD_(vc_reserve)(vc, size);
tl_assert(size == 0 || vc->vc != 0);
if (vcelem)
{
VG_(memcpy)(vc->vc, vcelem, size * sizeof(vcelem[0]));
vc->size = size;
}
}
/** Reset vc to the empty vector clock. */
void DRD_(vc_cleanup)(VectorClock* const vc)
{
DRD_(vc_reserve)(vc, 0);
}
/** Copy constructor -- initializes *new. */
void DRD_(vc_copy)(VectorClock* const new, const VectorClock* const rhs)
{
DRD_(vc_init)(new, rhs->vc, rhs->size);
}
/** Assignment operator -- *lhs is already a valid vector clock. */
void DRD_(vc_assign)(VectorClock* const lhs, const VectorClock* const rhs)
{
DRD_(vc_cleanup)(lhs);
DRD_(vc_copy)(lhs, rhs);
}
/** Increment the clock of thread 'tid' in vector clock 'vc'. */
void DRD_(vc_increment)(VectorClock* const vc, DrdThreadId const tid)
{
unsigned i;
for (i = 0; i < vc->size; i++)
{
if (vc->vc[i].threadid == tid)
{
typeof(vc->vc[i].count) const oldcount = vc->vc[i].count;
vc->vc[i].count++;
// Check for integer overflow.
tl_assert(oldcount < vc->vc[i].count);
return;
}
}
/*
* The specified thread ID does not yet exist in the vector clock
* -- insert it.
*/
{
const VCElem vcelem = { tid, 1 };
VectorClock vc2;
DRD_(vc_init)(&vc2, &vcelem, 1);
DRD_(vc_combine)(vc, &vc2);
DRD_(vc_cleanup)(&vc2);
}
}
/**
* @return True if vector clocks vc1 and vc2 are ordered, and false otherwise.
* Order is as imposed by thread synchronization actions ("happens before").
*/
Bool DRD_(vc_ordered)(const VectorClock* const vc1,
const VectorClock* const vc2)
{
return DRD_(vc_lte)(vc1, vc2) || DRD_(vc_lte)(vc2, vc1);
}
/** Compute elementwise minimum. */
void DRD_(vc_min)(VectorClock* const result, const VectorClock* const rhs)
{
unsigned i;
unsigned j;
tl_assert(result);
tl_assert(rhs);
DRD_(vc_check)(result);
/* Next, combine both vector clocks into one. */
i = 0;
for (j = 0; j < rhs->size; j++)
{
while (i < result->size && result->vc[i].threadid < rhs->vc[j].threadid)
{
/* Thread ID is missing in second vector clock. Clear the count. */
result->vc[i].count = 0;
i++;
}
if (i >= result->size)
{
break;
}
if (result->vc[i].threadid <= rhs->vc[j].threadid)
{
/* The thread ID is present in both vector clocks. Compute the */
/* minimum of vc[i].count and vc[j].count. */
tl_assert(result->vc[i].threadid == rhs->vc[j].threadid);
if (rhs->vc[j].count < result->vc[i].count)
{
result->vc[i].count = rhs->vc[j].count;
}
}
}
DRD_(vc_check)(result);
}
/**
* Compute elementwise maximum.
*/
void DRD_(vc_combine)(VectorClock* const result, const VectorClock* const rhs)
{
unsigned i;
unsigned j;
unsigned shared;
unsigned new_size;
tl_assert(result);
tl_assert(rhs);
// First count the number of shared thread id's.
j = 0;
shared = 0;
for (i = 0; i < result->size; i++)
{
while (j < rhs->size && rhs->vc[j].threadid < result->vc[i].threadid)
j++;
if (j >= rhs->size)
break;
if (result->vc[i].threadid == rhs->vc[j].threadid)
shared++;
}
DRD_(vc_check)(result);
new_size = result->size + rhs->size - shared;
if (new_size > result->capacity)
DRD_(vc_reserve)(result, new_size);
DRD_(vc_check)(result);
// Next, combine both vector clocks into one.
i = 0;
for (j = 0; j < rhs->size; j++)
{
/* First of all, skip those clocks in result->vc[] for which there */
/* is no corresponding clock in rhs->vc[]. */
while (i < result->size && result->vc[i].threadid < rhs->vc[j].threadid)
{
i++;
}
/* If the end of *result is met, append rhs->vc[j] to *result. */
if (i >= result->size)
{
result->size++;
result->vc[i] = rhs->vc[j];
}
/* If clock rhs->vc[j] is not in *result, insert it. */
else if (result->vc[i].threadid > rhs->vc[j].threadid)
{
unsigned k;
for (k = result->size; k > i; k--)
{
result->vc[k] = result->vc[k - 1];
}
result->size++;
result->vc[i] = rhs->vc[j];
}
/* Otherwise, both *result and *rhs have a clock for thread */
/* result->vc[i].threadid == rhs->vc[j].threadid. Compute the maximum. */
else
{
tl_assert(result->vc[i].threadid == rhs->vc[j].threadid);
if (rhs->vc[j].count > result->vc[i].count)
{
result->vc[i].count = rhs->vc[j].count;
}
}
}
DRD_(vc_check)(result);
tl_assert(result->size == new_size);
}
/** Print the contents of vector clock 'vc'. */
void DRD_(vc_print)(const VectorClock* const vc)
{
char* str;
if ((str = DRD_(vc_aprint)(vc)) != NULL)
{
VG_(printf)("%s", str);
VG_(free)(str);
}
}
/**
* Print the contents of vector clock 'vc' to a newly allocated string.
* The caller must call VG_(free)() on the return value of this function.
*/
char* DRD_(vc_aprint)(const VectorClock* const vc)
{
unsigned i;
unsigned reserved;
unsigned size;
char* str = 0;
tl_assert(vc);
reserved = 64;
size = 0;
str = VG_(realloc)("drd.vc.aprint.1", str, reserved);
if (! str)
return str;
size += VG_(snprintf)(str, reserved, "[");
for (i = 0; i < vc->size; i++)
{
tl_assert(vc->vc);
if (VG_(strlen)(str) + 32 > reserved)
{
reserved *= 2;
str = VG_(realloc)("drd.vc.aprint.2", str, reserved);
if (! str)
return str;
}
size += VG_(snprintf)(str + size, reserved - size,
"%s %d: %d", i > 0 ? "," : "",
vc->vc[i].threadid, vc->vc[i].count);
}
size += VG_(snprintf)(str + size, reserved - size, " ]");
return str;
}
/**
* Invariant test.
*
* The function below tests whether the following two conditions are
* satisfied:
* - size <= capacity.
* - Vector clock elements are stored in thread ID order.
*
* If one of these conditions is not met, an assertion failure is triggered.
*/
void DRD_(vc_check)(const VectorClock* const vc)
{
unsigned i;
tl_assert(vc->size <= vc->capacity);
for (i = 1; i < vc->size; i++)
{
tl_assert(vc->vc[i-1].threadid < vc->vc[i].threadid);
}
}
/**
* Change the size of the memory block pointed at by vc->vc.
* Changes capacity, but does not change size. If the size of the memory
* block is increased, the newly allocated memory is not initialized.
*/
static
void DRD_(vc_reserve)(VectorClock* const vc, const unsigned new_capacity)
{
tl_assert(vc);
tl_assert(vc->capacity > VC_PREALLOCATED
|| vc->vc == 0
|| vc->vc == vc->preallocated);
if (new_capacity > vc->capacity)
{
if (vc->vc && vc->capacity > VC_PREALLOCATED)
{
tl_assert(vc->vc
&& vc->vc != vc->preallocated
&& vc->capacity > VC_PREALLOCATED);
vc->vc = VG_(realloc)("drd.vc.vr.1",
vc->vc, new_capacity * sizeof(vc->vc[0]));
}
else if (vc->vc && new_capacity > VC_PREALLOCATED)
{
tl_assert((vc->vc == 0 || vc->vc == vc->preallocated)
&& new_capacity > VC_PREALLOCATED
&& vc->capacity <= VC_PREALLOCATED);
vc->vc = VG_(malloc)("drd.vc.vr.2",
new_capacity * sizeof(vc->vc[0]));
VG_(memcpy)(vc->vc, vc->preallocated,
vc->capacity * sizeof(vc->vc[0]));
}
else if (vc->vc)
{
tl_assert(vc->vc == vc->preallocated
&& new_capacity <= VC_PREALLOCATED
&& vc->capacity <= VC_PREALLOCATED);
}
else if (new_capacity > VC_PREALLOCATED)
{
tl_assert(vc->vc == 0
&& new_capacity > VC_PREALLOCATED
&& vc->capacity == 0);
vc->vc = VG_(malloc)("drd.vc.vr.3",
new_capacity * sizeof(vc->vc[0]));
}
else
{
tl_assert(vc->vc == 0
&& new_capacity <= VC_PREALLOCATED
&& vc->capacity == 0);
vc->vc = vc->preallocated;
}
vc->capacity = new_capacity;
}
else if (new_capacity == 0 && vc->vc)
{
if (vc->capacity > VC_PREALLOCATED)
VG_(free)(vc->vc);
vc->vc = 0;
vc->capacity = 0;
}
tl_assert(new_capacity == 0 || vc->vc != 0);
tl_assert(vc->capacity > VC_PREALLOCATED
|| vc->vc == 0
|| vc->vc == vc->preallocated);
}