When rebuilding uidlist, read the existing one entirely into memory at the

beginning. This this is a lot faster than reading it with random access in
smaller pieces.

--HG--
branch : HEAD

diff --git a/src/plugins/fts-squat/squat-uidlist.c b/src/plugins/fts-squat/squat-uidlist.c
index fbfd59a594de214733b788463553b088a1670046..da1cbdb5e7258625dbe002d9a697584bd5201db2 100644 (file)
--- a/src/plugins/fts-squat/squat-uidlist.c
+++ b/src/plugins/fts-squat/squat-uidlist.c
@@ -8,12 +8,12 @@
 #include "read-full.h"
 #include "write-full.h"
 #include "ostream.h"
+#include "mmap-util.h"
 #include "squat-trie-private.h"
 #include "squat-uidlist.h"
 
 #include <stdio.h>
 #include <sys/stat.h>
-#include <sys/mman.h>
 
 #define UIDLIST_LIST_SIZE 31
 #define UIDLIST_BLOCK_LIST_COUNT 100
@@ -473,6 +473,40 @@ static int squat_uidlist_map(struct squat_uidlist *uidlist)
        return squat_uidlist_map_header(uidlist);
 }
 
+static int squat_uidlist_read_to_memory(struct squat_uidlist *uidlist)
+{
+       size_t i, page_size = mmap_get_page_size();
+       char x;
+
+       if (uidlist->file_cache != NULL) {
+               return uidlist_file_cache_read(uidlist, 0,
+                                              uidlist->hdr.used_file_size);
+       }
+       /* Tell the kernel we're going to use the uidlist data, so it loads
+          it into memory and keeps it there. */
+       (void)madvise(uidlist->mmap_base, uidlist->mmap_size, MADV_WILLNEED);
+       /* It also speeds up a bit for us to sequentially load everything
+          into memory, although at least Linux catches up quite fast even
+          without this code. Compiler can quite easily optimize away this
+          entire for loop, but volatile seems to help with gcc 4.2. */
+       for (i = 0; i < uidlist->mmap_size; i += page_size)
+               x = ((const volatile char *)uidlist->data)[i];
+       return 0;
+}
+
+static void squat_uidlist_free_from_memory(struct squat_uidlist *uidlist)
+{
+       size_t page_size = mmap_get_page_size();
+
+       if (uidlist->file_cache != NULL) {
+               file_cache_invalidate(uidlist->file_cache,
+                                     page_size, (uoff_t)-1);
+       } else {
+               (void)madvise(uidlist->mmap_base, uidlist->mmap_size,
+                             MADV_DONTNEED);
+       }
+}
+
 struct squat_uidlist *squat_uidlist_init(struct squat_trie *trie)
 {
        struct squat_uidlist *uidlist;
@@ -881,6 +915,12 @@ int squat_uidlist_rebuild_init(struct squat_uidlist_build_context *build_ctx,
                        return 0;
        }
 
+       /* make sure the entire uidlist is in memory before beginning,
+          otherwise the pages are faulted to memory in random order which
+          takes forever. */
+       if (squat_uidlist_read_to_memory(build_ctx->uidlist) < 0)
+               return -1;
+
        temp_path = t_strconcat(build_ctx->uidlist->path, ".tmp", NULL);
        fd = open(temp_path, O_RDWR | O_TRUNC | O_CREAT, 0600);
        if (fd < 0) {
@@ -1042,6 +1082,10 @@ int squat_uidlist_rebuild_finish(struct squat_uidlist_rebuild_context *ctx,
                ctx->build_ctx->need_reopen = TRUE;
        }
 
+       /* we no longer require the entire uidlist to be in memory,
+          let it be used for something more useful. */
+       squat_uidlist_free_from_memory(ctx->uidlist);
+
        o_stream_unref(&ctx->output);
        if (close(ctx->fd) < 0)
                i_error("close(%s) failed: %m", temp_path);