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/*
* UCW Library -- Universal Sorter: Governing Routines
*
* (c) 2007 Martin Mares <mj@ucw.cz>
*
* This software may be freely distributed and used according to the terms
* of the GNU Lesser General Public License.
*/
#include <ucw/lib.h>
#include <ucw/fastbuf.h>
#include <ucw/mempool.h>
#include <ucw/stkstring.h>
#include <ucw/time.h>
#include <ucw/sorter/common.h>
#include <string.h>
#include <sys/time.h>
#include <time.h>
#define F_BSIZE(b) stk_fsize(sbuck_size(b))
static void
sorter_start_timer(struct sort_context *ctx)
{
init_timer(&ctx->start_time);
}
static void
sorter_stop_timer(struct sort_context *ctx, uint *account_to)
{
ctx->last_pass_time = get_timer(&ctx->start_time);
*account_to += ctx->last_pass_time;
}
static uint
sorter_speed(struct sort_context *ctx, u64 size)
{
if (!size)
return 0;
if (!ctx->last_pass_time)
return 0;
return (uint)((double)size / (1<<20) * 1000 / ctx->last_pass_time);
}
static int
sorter_presort(struct sort_context *ctx, struct sort_bucket *in, struct sort_bucket *out, struct sort_bucket *out_only)
{
sorter_alloc_buf(ctx);
if (in->flags & SBF_CUSTOM_PRESORT)
{
/*
* The trick with automatic joining, which we use for the normal presorter,
* is not necessary with the custom presorter, because the custom presorter
* is never called in the middle of the sorted data.
*/
struct fastbuf *f = sbuck_write(out);
out->runs++;
return ctx->custom_presort(f, ctx->big_buf, ctx->big_buf_size);
}
return ctx->internal_sort(ctx, in, out, out_only);
}
static struct sort_bucket *
sbuck_join_to(struct sort_bucket *b, ucw_off_t *sizep)
{
*sizep = 0; // Not needed, just to silence false warnings in some compilers about uninitialized sizep (it's OK for NULL result)
if (sorter_debug & SORT_DEBUG_NO_JOIN)
return NULL;
struct sort_bucket *out = (struct sort_bucket *) b->n.prev; // Such bucket is guaranteed to exist
if (!(out->flags & SBF_FINAL))
return NULL;
ASSERT(out->runs == 1);
*sizep = sbuck_size(out);
return out;
}
static ucw_off_t
sbuck_ins_or_join(struct sort_bucket *b, cnode *list_pos, struct sort_bucket *join, ucw_off_t join_size)
{
if (join && join->runs >= 2)
{
if (b)
sbuck_drop(b);
ASSERT(join->runs == 2);
join->runs--;
return sbuck_size(join) - join_size;
}
else if (b)
{
clist_insert_after(&b->n, list_pos);
return sbuck_size(b);
}
else
return 0;
}
static void
sorter_join(struct sort_bucket *b)
{
struct sort_bucket *join = (struct sort_bucket *) b->n.prev;
ASSERT(join->flags & SBF_FINAL);
ASSERT(b->runs == 1);
if (!sbuck_has_file(join))
{
// The final bucket doesn't have any file associated yet, so replace
// it with the new bucket.
SORT_XTRACE(3, "Replaced final bucket");
b->flags |= SBF_FINAL;
sbuck_drop(join);
}
else
{
SORT_TRACE("Copying to output file: %s", F_BSIZE(b));
struct fastbuf *src = sbuck_read(b);
struct fastbuf *dest = sbuck_write(join);
bbcopy(src, dest, ~0U);
sbuck_drop(b);
}
}
static void
sorter_twoway(struct sort_context *ctx, struct sort_bucket *b)
{
struct sort_bucket *ins[3] = { NULL }, *outs[3] = { NULL };
cnode *list_pos = b->n.prev;
ucw_off_t join_size;
struct sort_bucket *join = sbuck_join_to(b, &join_size);
if (!(sorter_debug & SORT_DEBUG_NO_PRESORT) || (b->flags & SBF_CUSTOM_PRESORT))
{
SORT_XTRACE(3, "%s", ((b->flags & SBF_CUSTOM_PRESORT) ? "Custom presorting" : "Presorting"));
sorter_start_timer(ctx);
ins[0] = sbuck_new(ctx);
if (!sorter_presort(ctx, b, ins[0], join ? : ins[0]))
{
sorter_stop_timer(ctx, &ctx->total_pre_time);
ucw_off_t size = sbuck_ins_or_join(ins[0], list_pos, join, join_size);
SORT_XTRACE(((b->flags & SBF_SOURCE) ? 1 : 3), "Sorted in memory (%s, %dMB/s)", stk_fsize(size), sorter_speed(ctx, size));
sbuck_drop(b);
return;
}
ins[1] = sbuck_new(ctx);
int i = 1;
while (sorter_presort(ctx, b, ins[i], ins[i]))
i = 1-i;
sbuck_drop(b);
sorter_stop_timer(ctx, &ctx->total_pre_time);
SORT_TRACE("Presorting pass (%d+%d runs, %s+%s, %dMB/s)",
ins[0]->runs, ins[1]->runs,
F_BSIZE(ins[0]), F_BSIZE(ins[1]),
sorter_speed(ctx, sbuck_size(ins[0]) + sbuck_size(ins[1])));
}
else
{
SORT_XTRACE(2, "Presorting disabled");
ins[0] = b;
}
SORT_XTRACE(3, "Main sorting");
uint pass = 0;
do {
++pass;
sorter_start_timer(ctx);
if (ins[0]->runs <= 1 && ins[1]->runs <= 1 && join)
{
// This is guaranteed to produce a single run, so join if possible
outs[0] = join;
outs[1] = NULL;
ctx->twoway_merge(ctx, ins, outs);
ucw_off_t size = sbuck_ins_or_join(NULL, NULL, join, join_size);
sorter_stop_timer(ctx, &ctx->total_ext_time);
SORT_TRACE("Mergesort pass %d (final run, %s, %dMB/s)", pass, stk_fsize(size), sorter_speed(ctx, size));
sbuck_drop(ins[0]);
sbuck_drop(ins[1]);
return;
}
outs[0] = sbuck_new(ctx);
outs[1] = sbuck_new(ctx);
outs[2] = NULL;
ctx->twoway_merge(ctx, ins, outs);
sorter_stop_timer(ctx, &ctx->total_ext_time);
SORT_TRACE("Mergesort pass %d (%d+%d runs, %s+%s, %dMB/s)", pass,
outs[0]->runs, outs[1]->runs,
F_BSIZE(outs[0]), F_BSIZE(outs[1]),
sorter_speed(ctx, sbuck_size(outs[0]) + sbuck_size(outs[1])));
sbuck_drop(ins[0]);
sbuck_drop(ins[1]);
memcpy(ins, outs, 3*sizeof(struct sort_bucket *));
} while (sbuck_have(ins[1]));
sbuck_drop(ins[1]);
clist_insert_after(&ins[0]->n, list_pos);
}
static void
sorter_multiway(struct sort_context *ctx, struct sort_bucket *b)
{
clist parts;
cnode *list_pos = b->n.prev;
ucw_off_t join_size;
struct sort_bucket *join = sbuck_join_to(b, &join_size);
uint trace_level = (b->flags & SBF_SOURCE) ? 1 : 3;
clist_init(&parts);
ASSERT(!(sorter_debug & SORT_DEBUG_NO_PRESORT));
SORT_XTRACE(3, "%s", ((b->flags & SBF_CUSTOM_PRESORT) ? "Custom presorting" : "Presorting"));
uint cont;
uint part_cnt = 0;
u64 total_size = 0;
sorter_start_timer(ctx);
do
{
struct sort_bucket *p = sbuck_new(ctx);
cont = sorter_presort(ctx, b, p, (!part_cnt && join) ? join : p);
if (sbuck_have(p))
{
part_cnt++;
clist_add_tail(&parts, &p->n);
total_size += sbuck_size(p);
sbuck_swap_out(p);
}
else
sbuck_drop(p);
}
while (cont);
sorter_stop_timer(ctx, &ctx->total_pre_time);
sorter_free_buf(ctx);
sbuck_drop(b);
if (part_cnt <= 1)
{
ucw_off_t size = sbuck_ins_or_join(clist_head(&parts), list_pos, (part_cnt ? NULL : join), join_size);
SORT_XTRACE(trace_level, "Sorted in memory (%s, %dMB/s)", stk_fsize(size), sorter_speed(ctx, size));
return;
}
SORT_TRACE("Multi-way presorting pass (%d parts, %s, %dMB/s)", part_cnt, stk_fsize(total_size), sorter_speed(ctx, total_size));
uint max_ways = 1 << sorter_max_multiway_bits;
struct sort_bucket *ways[max_ways+1];
SORT_XTRACE(3, "Starting up to %d-way merge", max_ways);
for (;;)
{
uint n = 0;
struct sort_bucket *p;
while (n < max_ways && (p = clist_head(&parts)))
{
clist_remove(&p->n);
ways[n++] = p;
}
ways[n] = NULL;
ASSERT(n > 1);
struct sort_bucket *out;
if (clist_empty(&parts) && join)
out = join;
else
out = sbuck_new(ctx);
sorter_start_timer(ctx);
ctx->multiway_merge(ctx, ways, out);
sorter_stop_timer(ctx, &ctx->total_ext_time);
for (uint i=0; i<n; i++)
sbuck_drop(ways[i]);
if (clist_empty(&parts))
{
ucw_off_t size = sbuck_ins_or_join((join ? NULL : out), list_pos, join, join_size);
SORT_TRACE("Multi-way merge completed (%d ways, %s, %dMB/s)", n, stk_fsize(size), sorter_speed(ctx, size));
return;
}
else
{
sbuck_swap_out(out);
clist_add_tail(&parts, &out->n);
SORT_TRACE("Multi-way merge pass (%d ways, %s, %dMB/s)", n, F_BSIZE(out), sorter_speed(ctx, sbuck_size(out)));
}
}
}
static void
sorter_radix(struct sort_context *ctx, struct sort_bucket *b, uint bits)
{
// Add more bits if requested and allowed.
bits = MIN(bits + sorter_add_radix_bits, sorter_max_radix_bits);
uint nbuck = 1 << bits;
SORT_XTRACE(3, "Running radix split on %s with hash %d bits of %d (expecting %s buckets)",
F_BSIZE(b), bits, b->hash_bits, stk_fsize(sbuck_size(b) / nbuck));
sorter_free_buf(ctx);
sorter_start_timer(ctx);
struct sort_bucket **outs = alloca(nbuck * sizeof(struct sort_bucket *));
for (uint i=nbuck; i--; )
{
outs[i] = sbuck_new(ctx);
outs[i]->hash_bits = b->hash_bits - bits;
clist_insert_after(&outs[i]->n, &b->n);
}
ctx->radix_split(ctx, b, outs, b->hash_bits - bits, bits);
u64 min = ~(u64)0, max = 0, sum = 0;
for (uint i=0; i<nbuck; i++)
{
u64 s = sbuck_size(outs[i]);
min = MIN(min, s);
max = MAX(max, s);
sum += s;
if (nbuck > 4)
sbuck_swap_out(outs[i]);
}
sorter_stop_timer(ctx, &ctx->total_ext_time);
SORT_TRACE("Radix split (%d buckets, %s min, %s max, %s avg, %dMB/s)", nbuck,
stk_fsize(min), stk_fsize(max), stk_fsize(sum / nbuck), sorter_speed(ctx, sum));
sbuck_drop(b);
}
static void
sorter_decide(struct sort_context *ctx, struct sort_bucket *b)
{
// Drop empty buckets
if (!sbuck_have(b))
{
SORT_XTRACE(4, "Dropping empty bucket");
sbuck_drop(b);
return;
}
// How many bits of bucket size we have to reduce before it fits in the RAM?
// (this is insanely large if the input size is unknown, but it serves our purpose)
u64 insize = sbuck_size(b);
u64 mem = ctx->internal_estimate(ctx, b) * 0.8; // Magical factor accounting for various non-uniformities
uint bits = 0;
while ((insize >> bits) > mem)
bits++;
// Calculate the possibilities of radix splits
uint radix_bits;
if (!ctx->radix_split ||
(b->flags & SBF_CUSTOM_PRESORT) ||
(sorter_debug & SORT_DEBUG_NO_RADIX))
radix_bits = 0;
else
{
radix_bits = MIN(bits, b->hash_bits);
radix_bits = MIN(radix_bits, sorter_max_radix_bits);
if (radix_bits < sorter_min_radix_bits)
radix_bits = 0;
}
// The same for multi-way merges
uint multiway_bits;
if (!ctx->multiway_merge ||
(sorter_debug & SORT_DEBUG_NO_MULTIWAY) ||
(sorter_debug & SORT_DEBUG_NO_PRESORT))
multiway_bits = 0;
else
{
multiway_bits = MIN(bits, sorter_max_multiway_bits);
if (multiway_bits < sorter_min_multiway_bits)
multiway_bits = 0;
}
SORT_XTRACE(3, "Decisions: size=%s max=%s runs=%d bits=%d hash=%d -> radix=%d multi=%d",
stk_fsize(insize), stk_fsize(mem), b->runs, bits, b->hash_bits,
radix_bits, multiway_bits);
// If the input already consists of a single run, just join it
if (b->runs)
return sorter_join(b);
// If everything fits in memory, the 2-way strategy will sort it in memory
if (!bits)
return sorter_twoway(ctx, b);
// If we can reduce everything in one pass, do so and prefer radix splits
if (radix_bits == bits)
return sorter_radix(ctx, b, radix_bits);
if (multiway_bits == bits)
return sorter_multiway(ctx, b);
// Otherwise, reduce as much as possible and again prefer radix splits
if (radix_bits)
return sorter_radix(ctx, b, radix_bits);
if (multiway_bits)
return sorter_multiway(ctx, b);
// Fall back to 2-way strategy if nothing else applies
return sorter_twoway(ctx, b);
}
void
sorter_run(struct sort_context *ctx)
{
ctx->pool = mp_new(4096);
clist_init(&ctx->bucket_list);
sorter_prepare_buf(ctx);
asort_start_threads(0);
// Create bucket containing the source
struct sort_bucket *bin = sbuck_new(ctx);
bin->flags = SBF_SOURCE | SBF_OPEN_READ;
if (ctx->custom_presort)
bin->flags |= SBF_CUSTOM_PRESORT;
else
bin->fb = ctx->in_fb;
bin->ident = "in";
bin->size = ctx->in_size;
bin->hash_bits = ctx->hash_bits;
clist_add_tail(&ctx->bucket_list, &bin->n);
SORT_XTRACE(2, "Input size: %s, %d hash bits", F_BSIZE(bin), bin->hash_bits);
ctx->fb_params = (bin->size < sorter_small_input) ? &sorter_small_fb_params : &sorter_fb_params;
// Create bucket for the output
struct sort_bucket *bout = sbuck_new(ctx);
bout->flags = SBF_FINAL;
if (bout->fb = ctx->out_fb)
bout->flags |= SBF_OPEN_WRITE;
bout->ident = "out";
bout->runs = 1;
clist_add_head(&ctx->bucket_list, &bout->n);
// Repeatedly sort buckets
struct sort_bucket *b;
while (bout = clist_head(&ctx->bucket_list), b = clist_next(&ctx->bucket_list, &bout->n))
sorter_decide(ctx, b);
asort_stop_threads();
sorter_free_buf(ctx);
sbuck_write(bout); // Force empty bucket to a file
SORT_XTRACE(2, "Final size: %s", F_BSIZE(bout));
SORT_XTRACE(2, "Final timings: %.3fs external sorting, %.3fs presorting, %.3fs internal sorting",
ctx->total_ext_time/1000., ctx->total_pre_time/1000., ctx->total_int_time/1000.);
ctx->out_fb = sbuck_read(bout);
mp_delete(ctx->pool);
}