read-cache: force split index mode with GIT_TEST_SPLIT_INDEX

This could be used to run the whole test suite with split
indexes. Index splitting is carried out at random. "git read-tree"
also resets the index and forces splitting at the next update.

I had a lot of headaches with the test suite, which proves it
exercises split index pretty good.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/read-cache.c b/read-cache.c
index b1027f7ee02f0feca35258337a0e3d116c45c7ad..12335a362b035340118dd8e0b202a95ad16d9b00 100644 (file)
--- a/read-cache.c
+++ b/read-cache.c
@@ -1885,8 +1885,11 @@ static int do_write_index(struct index_state *istate, int newfd,
                }
        }
 
-       if (!istate->version)
+       if (!istate->version) {
                istate->version = get_index_format_default();
+               if (getenv("GIT_TEST_SPLIT_INDEX"))
+                       init_split_index(istate);
+       }
 
        /* demote version 3 to version 2 when the latter suffices */
        if (istate->version == 3 || istate->version == 2)
@@ -2077,6 +2080,11 @@ int write_locked_index(struct index_state *istate, struct lock_file *lock,
                return do_write_locked_index(istate, lock, flags);
        }
 
+       if (getenv("GIT_TEST_SPLIT_INDEX")) {
+               int v = si->base_sha1[0];
+               if ((v & 15) < 6)
+                       istate->cache_changed |= SPLIT_INDEX_ORDERED;
+       }
        if (istate->cache_changed & SPLIT_INDEX_ORDERED) {
                int ret = write_shared_index(istate, lock, flags);
                if (ret)