Yet another swap-out.

[libucw.git] / lib / sorter / govern.c

diff --git a/lib/sorter/govern.c b/lib/sorter/govern.c
index 52d90e96dc7aacd8c7167d5acbb850678e0562c4..524b0c905d739734ebe0aab372d67ebf1d336fd6 100644 (file)
--- a/lib/sorter/govern.c
+++ b/lib/sorter/govern.c
@@ -177,6 +177,92 @@ sorter_twoway(struct sort_context *ctx, struct sort_bucket *b)
   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;
+  struct sort_bucket *join = sbuck_join_to(b);
+
+  clist_init(&parts);
+  ASSERT(!(sorter_debug & SORT_DEBUG_NO_PRESORT));
+  // FIXME: What if the parts will be too small?
+  SORT_XTRACE(3, "%s", ((b->flags & SBF_CUSTOM_PRESORT) ? "Custom presorting" : "Presorting"));
+  uns cont;
+  uns part_cnt = 0;
+  u64 total_size = 0;
+  sorter_start_timer(ctx);
+  do
+    {
+      struct sort_bucket *p = sbuck_new(ctx);
+      clist_add_tail(&parts, &p->n);
+      cont = sorter_presort(ctx, b, p, (!part_cnt && join) ? join : p);
+      part_cnt++;
+      total_size += sbuck_size(p);
+      sbuck_swap_out(p);
+    }
+  while (cont);
+  sorter_stop_timer(ctx, &ctx->total_pre_time);
+
+  // FIXME: This is way too similar to the two-way case.
+  if (part_cnt == 1)
+    {
+      struct sort_bucket *p = clist_head(&parts);
+      SORT_XTRACE(((b->flags & SBF_SOURCE) ? 1 : 2), "Sorted in memory");
+      if (join)
+       {
+         ASSERT(join->runs == 2);
+         join->runs--;
+         sbuck_drop(p);
+       }
+      else
+       clist_insert_after(&p->n, list_pos);
+      sbuck_drop(b);
+      return;
+    }
+
+  SORT_TRACE("Multi-way presorting pass (%d parts, %s, %dMB/s)", part_cnt, stk_fsize(total_size), sorter_speed(ctx, total_size));
+  sbuck_drop(b);
+
+  uns max_ways = 16;
+  struct sort_bucket *ways[max_ways+1];
+  SORT_XTRACE(2, "Starting up to %d-way merge", max_ways);
+  for (;;)
+    {
+      uns 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;
+      out = sbuck_new(ctx);            // FIXME: No joining so far
+      sorter_start_timer(ctx);
+      ctx->multiway_merge(ctx, ways, out);
+      sorter_stop_timer(ctx, &ctx->total_ext_time);
+
+      for (uns i=0; i<n; i++)
+       sbuck_drop(ways[i]);
+
+      if (clist_empty(&parts))
+       {
+         clist_insert_after(&out->n, list_pos);
+         SORT_TRACE("Multi-way merge completed (%s, %dMB/s)", F_BSIZE(out), sorter_speed(ctx, sbuck_size(out)));
+         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 uns
 sorter_radix_bits(struct sort_context *ctx, struct sort_bucket *b)
 {
@@ -251,7 +337,7 @@ sorter_run(struct sort_context *ctx)
   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", F_BSIZE(bin));
+  SORT_XTRACE(2, "Input size: %s, %d hash bits", F_BSIZE(bin), bin->hash_bits);
 
   // Create bucket for the output
   struct sort_bucket *bout = sbuck_new(ctx);
@@ -271,6 +357,8 @@ sorter_run(struct sort_context *ctx)
        sbuck_drop(b);
       else if (b->runs == 1)
        sorter_join(b);
+      else if (ctx->multiway_merge && !(sorter_debug & (SORT_DEBUG_NO_MULTIWAY | SORT_DEBUG_NO_PRESORT)))      // FIXME: Just kidding...
+       sorter_multiway(ctx, b);
       else if (bits = sorter_radix_bits(ctx, b))
        sorter_radix(ctx, b, bits);
       else