/*
* tuplestore_begin_xxx
*
* Initialize for a tuple store operation.
*/
static Tuplestorestate *
tuplestore_begin_common(int eflags, bool interXact, int maxKBytes)
{
Tuplestorestate *state;
state = (Tuplestorestate *) palloc0(sizeof(Tuplestorestate));
state->status = TSS_INMEM;
state->eflags = eflags;
state->interXact = interXact;
state->availMem = maxKBytes * 1024L;
state->availMemMin = state->availMem;
state->allowedMem = state->availMem;
state->myfile = NULL;
state->context = CurrentMemoryContext;
state->resowner = CurrentResourceOwner;
state->memtupcount = 0;
state->memtupsize = 1024; /* initial guess */
state->memtuples = (void **) palloc(state->memtupsize * sizeof(void *));
state->pos.eof_reached = false;
state->pos.current = 0;
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
state->eof_reached = false;
state->current = 0;
return state;
}
/*
* tuplestore_begin_xxx
*
* Initialize for a tuple store operation.
*/
static Tuplestorestate *
tuplestore_begin_common(int eflags, bool interXact, int maxKBytes)
{
Tuplestorestate *state;
state = (Tuplestorestate *) palloc0(sizeof(Tuplestorestate));
state->status = TSS_INMEM;
state->eflags = eflags;
state->interXact = interXact;
state->truncated = false;
state->availMem = maxKBytes * 1024L;
state->myfile = NULL;
state->context = CurrentMemoryContext;
state->resowner = CurrentResourceOwner;
state->memtupcount = 0;
state->memtupsize = 1024; /* initial guess */
state->memtuples = (void **) palloc(state->memtupsize * sizeof(void *));
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
state->activeptr = 0;
state->readptrcount = 1;
state->readptrsize = 8; /* arbitrary */
state->readptrs = (TSReadPointer *)
palloc(state->readptrsize * sizeof(TSReadPointer));
state->readptrs[0].eflags = eflags;
state->readptrs[0].eof_reached = false;
state->readptrs[0].current = 0;
return state;
}
static void *
copytup_heap(Tuplestorestate *state, void *tup)
{
MinimalTuple tuple;
tuple = minimal_tuple_from_heap_tuple((HeapTuple) tup);
USEMEM(state, GetMemoryChunkSpace(tuple));
return (void *) tuple;
}
static void *
readtup_heap(Tuplestorestate *state, unsigned int len)
{
void *tup = NULL;
uint32 tuplen = 0;
if (is_len_memtuplen(len))
{
tuplen = memtuple_size_from_uint32(len);
}
else
{
/* len is HeapTuple.t_len. The record size includes rest of the HeapTuple fields */
tuplen = len + HEAPTUPLESIZE;
}
tup = (void *) palloc(tuplen);
USEMEM(state, GetMemoryChunkSpace(tup));
if(is_len_memtuplen(len))
{
/* read in the tuple proper */
memtuple_set_mtlen((MemTuple) tup, len);
if (BufFileRead(state->myfile, (void *) ((char *) tup + sizeof(uint32)),
tuplen - sizeof(uint32))
!= (size_t) (tuplen - sizeof(uint32)))
{
insist_log(false, "unexpected end of data");
}
}
else
{
HeapTuple htup = (HeapTuple) tup;
htup->t_len = tuplen - HEAPTUPLESIZE;
if (BufFileRead(state->myfile, (void *) ((char *) tup + sizeof(uint32)),
tuplen - sizeof(uint32))
!= (size_t) (tuplen - sizeof(uint32)))
{
insist_log(false, "unexpected end of data");
}
htup->t_data = (HeapTupleHeader ) ((char *) tup + HEAPTUPLESIZE);
}
if (state->backward) /* need trailing length word? */
{
if (BufFileRead(state->myfile, (void *) &tuplen,
sizeof(tuplen)) != sizeof(tuplen))
{
insist_log(false, "unexpected end of data");
}
}
return (void *) tup;
}
/*
* Similar to tuplestore_puttuple(), but work from values + nulls arrays.
* This avoids an extra tuple-construction operation.
*/
void
tuplestore_putvalues(Tuplestorestate *state, TupleDesc tdesc,
Datum *values, bool *isnull)
{
MinimalTuple tuple;
MemoryContext oldcxt = MemoryContextSwitchTo(state->context);
tuple = heap_form_minimal_tuple(tdesc, values, isnull);
USEMEM(state, GetMemoryChunkSpace(tuple));
tuplestore_puttuple_common(state, (void *) tuple);
MemoryContextSwitchTo(oldcxt);
}
/*
* Accept one tuple and append it to the tuplestore.
*
* Note that the input tuple is always copied; the caller need not save it.
*
* If the active read pointer is currently "at EOF", it remains so (the read
* pointer implicitly advances along with the write pointer); otherwise the
* read pointer is unchanged. Non-active read pointers do not move, which
* means they are certain to not be "at EOF" immediately after puttuple.
* This curious-seeming behavior is for the convenience of nodeMaterial.c and
* nodeCtescan.c, which would otherwise need to do extra pointer repositioning
* steps.
*
* tuplestore_puttupleslot() is a convenience routine to collect data from
* a TupleTableSlot without an extra copy operation.
*/
void
tuplestore_puttupleslot(Tuplestorestate *state,
TupleTableSlot *slot)
{
MinimalTuple tuple;
/*
* Form a MinimalTuple in working memory
*/
tuple = ExecCopySlotMinimalTuple(slot);
USEMEM(state, GetMemoryChunkSpace(tuple));
tuplestore_puttuple_common(state, (void *) tuple);
}
/*
* Accept one tuple and append it to the tuplestore.
*
* Note that the input tuple is always copied; the caller need not save it.
*
* If the read status is currently "AT EOF" then it remains so (the read
* pointer advances along with the write pointer); otherwise the read
* pointer is unchanged. This is for the convenience of nodeMaterial.c.
*
* tuplestore_puttupleslot() is a convenience routine to collect data from
* a TupleTableSlot without an extra copy operation.
*/
void
tuplestore_puttupleslot_pos(Tuplestorestate *state, TuplestorePos *pos,
TupleTableSlot *slot)
{
MemTuple tuple;
MemoryContext oldcxt = MemoryContextSwitchTo(state->context);
/*
* Form a MinimalTuple in working memory
*/
tuple = ExecCopySlotMemTuple(slot);
USEMEM(state, GetMemoryChunkSpace(tuple));
tuplestore_puttuple_common(state, pos, (void *) tuple);
MemoryContextSwitchTo(oldcxt);
}
/*
* tuplestore_begin_xxx
*
* Initialize for a tuple store operation.
*/
static Tuplestorestate *
tuplestore_begin_common(int eflags, bool interXact, int maxKBytes)
{
Tuplestorestate *state;
state = (Tuplestorestate *) palloc0(sizeof(Tuplestorestate));
state->status = TSS_INMEM;
state->eflags = eflags;
state->interXact = interXact;
state->truncated = false;
state->allowedMem = maxKBytes * 1024L;
state->availMem = state->allowedMem;
state->myfile = NULL;
state->context = CurrentMemoryContext;
state->resowner = CurrentResourceOwner;
state->memtupdeleted = 0;
state->memtupcount = 0;
state->tuples = 0;
/*
* Initial size of array must be more than ALLOCSET_SEPARATE_THRESHOLD;
* see comments in grow_memtuples().
*/
state->memtupsize = Max(16384 / sizeof(void *),
ALLOCSET_SEPARATE_THRESHOLD / sizeof(void *) + 1);
state->growmemtuples = true;
state->memtuples = (void **) palloc(state->memtupsize * sizeof(void *));
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
state->activeptr = 0;
state->readptrcount = 1;
state->readptrsize = 8; /* arbitrary */
state->readptrs = (TSReadPointer *)
palloc(state->readptrsize * sizeof(TSReadPointer));
state->readptrs[0].eflags = eflags;
state->readptrs[0].eof_reached = false;
state->readptrs[0].current = 0;
return state;
}
static void *
readtup_heap(Tuplestorestate *state, unsigned int len)
{
unsigned int tupbodylen = len - sizeof(int);
unsigned int tuplen = tupbodylen + MINIMAL_TUPLE_DATA_OFFSET;
MinimalTuple tuple = (MinimalTuple) palloc(tuplen);
char *tupbody = (char *) tuple + MINIMAL_TUPLE_DATA_OFFSET;
USEMEM(state, GetMemoryChunkSpace(tuple));
/* read in the tuple proper */
tuple->t_len = tuplen;
if (BufFileRead(state->myfile, (void *) tupbody,
tupbodylen) != (size_t) tupbodylen)
elog(ERROR, "unexpected end of data");
if (state->backward) /* need trailing length word? */
if (BufFileRead(state->myfile, (void *) &tuplen,
sizeof(tuplen)) != sizeof(tuplen))
elog(ERROR, "unexpected end of data");
return (void *) tuple;
}
/*
* Similar to tuplestore_puttuple(), but work from values + nulls arrays.
* This avoids an extra tuple-construction operation.
*/
void
tuplestore_putvalues(Tuplestorestate *state, TupleDesc tdesc,
Datum *values, bool *isnull)
{
MemoryContext oldcxt = MemoryContextSwitchTo(state->context);
if (!state->mt_bind)
{
state->mt_bind = create_memtuple_binding(tdesc);
Assert(state->mt_bind);
}
MemTuple tuple = memtuple_form_to(state->mt_bind, values, isnull, NULL, NULL, false);
USEMEM(state, GetMemoryChunkSpace(tuple));
tuplestore_puttuple_common(state, (void *) tuple);
MemoryContextSwitchTo(oldcxt);
}
static void *
readtup_heap(Tuplestorestate *state, unsigned int len)
{
unsigned int tupbodylen = len - sizeof(int);
unsigned int tuplen = tupbodylen + MINIMAL_TUPLE_DATA_OFFSET;
MinimalTuple tuple = (MinimalTuple) palloc(tuplen);
char *tupbody = (char *) tuple + MINIMAL_TUPLE_DATA_OFFSET;
USEMEM(state, GetMemoryChunkSpace(tuple));
/* read in the tuple proper */
tuple->t_len = tuplen;
if (BufFileRead(state->myfile, (void *) tupbody,
tupbodylen) != (size_t) tupbodylen)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from tuplestore temporary file: %m")));
if (state->backward) /* need trailing length word? */
if (BufFileRead(state->myfile, (void *) &tuplen,
sizeof(tuplen)) != sizeof(tuplen))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from tuplestore temporary file: %m")));
return (void *) tuple;
}
/*
* Grow the memtuples[] array, if possible within our memory constraint. We
* must not exceed INT_MAX tuples in memory or the caller-provided memory
* limit. Return TRUE if we were able to enlarge the array, FALSE if not.
*
* Normally, at each increment we double the size of the array. When doing
* that would exceed a limit, we attempt one last, smaller increase (and then
* clear the growmemtuples flag so we don't try any more). That allows us to
* use memory as fully as permitted; sticking to the pure doubling rule could
* result in almost half going unused. Because availMem moves around with
* tuple addition/removal, we need some rule to prevent making repeated small
* increases in memtupsize, which would just be useless thrashing. The
* growmemtuples flag accomplishes that and also prevents useless
* recalculations in this function.
*/
static bool
grow_memtuples(Tuplestorestate *state)
{
int newmemtupsize;
int memtupsize = state->memtupsize;
int64 memNowUsed = state->allowedMem - state->availMem;
/* Forget it if we've already maxed out memtuples, per comment above */
if (!state->growmemtuples)
return false;
/* Select new value of memtupsize */
if (memNowUsed <= state->availMem)
{
/*
* We've used no more than half of allowedMem; double our usage,
* clamping at INT_MAX tuples.
*/
if (memtupsize < INT_MAX / 2)
newmemtupsize = memtupsize * 2;
else
{
newmemtupsize = INT_MAX;
state->growmemtuples = false;
}
}
else
{
/*
* This will be the last increment of memtupsize. Abandon doubling
* strategy and instead increase as much as we safely can.
*
* To stay within allowedMem, we can't increase memtupsize by more
* than availMem / sizeof(void *) elements. In practice, we want to
* increase it by considerably less, because we need to leave some
* space for the tuples to which the new array slots will refer. We
* assume the new tuples will be about the same size as the tuples
* we've already seen, and thus we can extrapolate from the space
* consumption so far to estimate an appropriate new size for the
* memtuples array. The optimal value might be higher or lower than
* this estimate, but it's hard to know that in advance. We again
* clamp at INT_MAX tuples.
*
* This calculation is safe against enlarging the array so much that
* LACKMEM becomes true, because the memory currently used includes
* the present array; thus, there would be enough allowedMem for the
* new array elements even if no other memory were currently used.
*
* We do the arithmetic in float8, because otherwise the product of
* memtupsize and allowedMem could overflow. Any inaccuracy in the
* result should be insignificant; but even if we computed a
* completely insane result, the checks below will prevent anything
* really bad from happening.
*/
double grow_ratio;
grow_ratio = (double) state->allowedMem / (double) memNowUsed;
if (memtupsize * grow_ratio < INT_MAX)
newmemtupsize = (int) (memtupsize * grow_ratio);
else
newmemtupsize = INT_MAX;
/* We won't make any further enlargement attempts */
state->growmemtuples = false;
}
/* Must enlarge array by at least one element, else report failure */
if (newmemtupsize <= memtupsize)
goto noalloc;
/*
* On a 32-bit machine, allowedMem could exceed MaxAllocHugeSize. Clamp
* to ensure our request won't be rejected. Note that we can easily
* exhaust address space before facing this outcome. (This is presently
* impossible due to guc.c's MAX_KILOBYTES limitation on work_mem, but
* don't rely on that at this distance.)
*/
if ((Size) newmemtupsize >= MaxAllocHugeSize / sizeof(void *))
{
newmemtupsize = (int) (MaxAllocHugeSize / sizeof(void *));
state->growmemtuples = false; /* can't grow any more */
}
/*
* We need to be sure that we do not cause LACKMEM to become true, else
* the space management algorithm will go nuts. The code above should
* never generate a dangerous request, but to be safe, check explicitly
* that the array growth fits within availMem. (We could still cause
* LACKMEM if the memory chunk overhead associated with the memtuples
* array were to increase. That shouldn't happen because we chose the
* initial array size large enough to ensure that palloc will be treating
* both old and new arrays as separate chunks. But we'll check LACKMEM
* explicitly below just in case.)
*/
if (state->availMem < (int64) ((newmemtupsize - memtupsize) * sizeof(void *)))
goto noalloc;
/* OK, do it */
FREEMEM(state, GetMemoryChunkSpace(state->memtuples));
state->memtupsize = newmemtupsize;
state->memtuples = (void **)
repalloc_huge(state->memtuples,
state->memtupsize * sizeof(void *));
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
if (LACKMEM(state))
elog(ERROR, "unexpected out-of-memory situation in tuplestore");
return true;
noalloc:
/* If for any reason we didn't realloc, shut off future attempts */
state->growmemtuples = false;
return false;
}
static void
tuplestore_puttuple_common(Tuplestorestate *state, void *tuple)
{
TSReadPointer *readptr;
int i;
ResourceOwner oldowner;
switch (state->status)
{
case TSS_INMEM:
/*
* Update read pointers as needed; see API spec above.
*/
readptr = state->readptrs;
for (i = 0; i < state->readptrcount; readptr++, i++)
{
if (readptr->eof_reached && i != state->activeptr)
{
readptr->eof_reached = false;
readptr->current = state->memtupcount;
}
}
/*
* Grow the array as needed. Note that we try to grow the array
* when there is still one free slot remaining --- if we fail,
* there'll still be room to store the incoming tuple, and then
* we'll switch to tape-based operation.
*/
if (state->memtupcount >= state->memtupsize - 1)
{
/*
* See grow_memtuples() in tuplesort.c for the rationale
* behind these two tests.
*/
if (state->availMem > (long) (state->memtupsize * sizeof(void *)) &&
(Size) (state->memtupsize * 2) < MaxAllocSize / sizeof(void *))
{
FREEMEM(state, GetMemoryChunkSpace(state->memtuples));
state->memtupsize *= 2;
state->memtuples = (void **)
repalloc(state->memtuples,
state->memtupsize * sizeof(void *));
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
}
}
/* Stash the tuple in the in-memory array */
state->memtuples[state->memtupcount++] = tuple;
/*
* Done if we still fit in available memory and have array slots.
*/
if (state->memtupcount < state->memtupsize && !LACKMEM(state))
return;
/*
* Nope; time to switch to tape-based operation. Make sure that
* the temp file(s) are created in suitable temp tablespaces.
*/
PrepareTempTablespaces();
/* associate the file with the store's resource owner */
oldowner = CurrentResourceOwner;
CurrentResourceOwner = state->resowner;
state->myfile = BufFileCreateTemp(state->interXact);
CurrentResourceOwner = oldowner;
/*
* Freeze the decision about whether trailing length words will be
* used. We can't change this choice once data is on tape, even
* though callers might drop the requirement.
*/
state->backward = (state->eflags & EXEC_FLAG_BACKWARD) != 0;
state->status = TSS_WRITEFILE;
dumptuples(state);
break;
case TSS_WRITEFILE:
/*
* Update read pointers as needed; see API spec above. Note:
* BufFileTell is quite cheap, so not worth trying to avoid
* multiple calls.
*/
readptr = state->readptrs;
for (i = 0; i < state->readptrcount; readptr++, i++)
{
if (readptr->eof_reached && i != state->activeptr)
{
readptr->eof_reached = false;
BufFileTell(state->myfile,
&readptr->file,
&readptr->offset);
}
}
WRITETUP(state, tuple);
break;
case TSS_READFILE:
/*
* Switch from reading to writing.
*/
if (!state->readptrs[state->activeptr].eof_reached)
BufFileTell(state->myfile,
&state->readptrs[state->activeptr].file,
&state->readptrs[state->activeptr].offset);
if (BufFileSeek(state->myfile,
state->writepos_file, state->writepos_offset,
SEEK_SET) != 0)
elog(ERROR, "tuplestore seek to EOF failed");
state->status = TSS_WRITEFILE;
/*
* Update read pointers as needed; see API spec above.
*/
readptr = state->readptrs;
for (i = 0; i < state->readptrcount; readptr++, i++)
{
if (readptr->eof_reached && i != state->activeptr)
{
readptr->eof_reached = false;
readptr->file = state->writepos_file;
readptr->offset = state->writepos_offset;
}
}
WRITETUP(state, tuple);
break;
default:
elog(ERROR, "invalid tuplestore state");
break;
}
}
static void
tuplestore_puttuple_common(Tuplestorestate *state, TuplestorePos *pos, void *tuple)
{
ResourceOwner oldowner;
switch (state->status)
{
case TSS_INMEM:
/*
* Grow the array as needed. Note that we try to grow the array
* when there is still one free slot remaining --- if we fail,
* there'll still be room to store the incoming tuple, and then
* we'll switch to tape-based operation.
*/
if (state->memtupcount >= state->memtupsize - 1)
{
/*
* See grow_memtuples() in tuplesort.c for the rationale
* behind these two tests.
*/
if (state->availMem > (long) (state->memtupsize * sizeof(void *)) &&
(Size) (state->memtupsize * 2) < MaxAllocSize / sizeof(void *))
{
FREEMEM(state, GetMemoryChunkSpace(state->memtuples));
state->memtupsize *= 2;
state->memtuples = (void **)
repalloc(state->memtuples,
state->memtupsize * sizeof(void *));
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
}
}
/* Stash the tuple in the in-memory array */
state->memtuples[state->memtupcount++] = tuple;
/* If eof_reached, keep read position in sync */
if (pos->eof_reached)
pos->current = state->memtupcount;
/*
* Done if we still fit in available memory and have array slots.
*/
if (state->memtupcount < state->memtupsize && !LACKMEM(state))
return;
/*
* Nope; time to switch to tape-based operation. Make sure that
* the temp file(s) are created in suitable temp tablespaces.
*/
PrepareTempTablespaces();
/* associate the file with the store's resource owner */
oldowner = CurrentResourceOwner;
CurrentResourceOwner = state->resowner;
{
char tmpprefix[50];
snprintf(tmpprefix, 50, "slice%d_tuplestore", currentSliceId);
state->myfile = BufFileCreateTemp(tmpprefix, state->interXact);
}
CurrentResourceOwner = oldowner;
state->status = TSS_WRITEFILE;
dumptuples(state, pos);
break;
case TSS_WRITEFILE:
WRITETUP(state, pos, tuple);
break;
case TSS_READFILE:
/*
* Switch from reading to writing.
*/
if (!pos->eof_reached)
BufFileTell(state->myfile,
&pos->readpos_offset);
if (BufFileSeek(state->myfile,
pos->writepos_offset,
SEEK_SET) != 0)
elog(ERROR, "seek to EOF failed");
state->status = TSS_WRITEFILE;
WRITETUP(state, pos, tuple);
break;
default:
elog(ERROR, "invalid tuplestore state");
break;
}
}
