sparse-index: add SPARSE_INDEX_MEMORY_ONLY flag

The convert_to_sparse() method checks for the GIT_TEST_SPARSE_INDEX
environment variable or the "index.sparse" config setting before
converting the index to a sparse one. This is for ease of use since all
current consumers are preparing to compress the index before writing it
to disk. If these settings are not enabled, then convert_to_sparse()
silently returns without doing anything.

We will add a consumer in the next change that wants to use the sparse
index as an in-memory data structure, regardless of whether the on-disk
format should be sparse.

To that end, create the SPARSE_INDEX_MEMORY_ONLY flag that will skip
these config checks when enabled. All current consumers are modified to
pass '0' in the new 'flags' parameter.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/read-cache.c b/read-cache.c
index 9048ef9e905251bacb516be6afdb474b4e59648f..f5d4385c4080a1b9d2d4e427b698c7e255157a33 100644 (file)
--- a/read-cache.c
+++ b/read-cache.c
@@ -3069,7 +3069,7 @@ static int do_write_locked_index(struct index_state *istate, struct lock_file *l
        int ret;
        int was_full = !istate->sparse_index;
 
-       ret = convert_to_sparse(istate);
+       ret = convert_to_sparse(istate, 0);
 
        if (ret) {
                warning(_("failed to convert to a sparse-index"));
@@ -3182,7 +3182,7 @@ static int write_shared_index(struct index_state *istate,
        int ret, was_full = !istate->sparse_index;
 
        move_cache_to_base_index(istate);
-       convert_to_sparse(istate);
+       convert_to_sparse(istate, 0);
 
        trace2_region_enter_printf("index", "shared/do_write_index",
                                   the_repository, "%s", get_tempfile_path(*temp));

diff --git a/sparse-index.c b/sparse-index.c
index 23f7c3bd3619887f4654bb57018e0df7bc2dc64f..0bc45f60ac5fafe355acd250acb5ecf964480dea 100644 (file)
--- a/sparse-index.c
+++ b/sparse-index.c
@@ -122,30 +122,37 @@ static int index_has_unmerged_entries(struct index_state *istate)
        return 0;
 }
 
-int convert_to_sparse(struct index_state *istate)
+int convert_to_sparse(struct index_state *istate, int flags)
 {
        int test_env;
-       if (istate->split_index || istate->sparse_index || !istate->cache_nr ||
+       if (istate->sparse_index || !istate->cache_nr ||
            !core_apply_sparse_checkout || !core_sparse_checkout_cone)
                return 0;
 
        if (!istate->repo)
                istate->repo = the_repository;
 
-       /*
-        * The GIT_TEST_SPARSE_INDEX environment variable triggers the
-        * index.sparse config variable to be on.
-        */
-       test_env = git_env_bool("GIT_TEST_SPARSE_INDEX", -1);
-       if (test_env >= 0)
-               set_sparse_index_config(istate->repo, test_env);
+       if (!(flags & SPARSE_INDEX_MEMORY_ONLY)) {
+               /*
+                * The sparse index is not (yet) integrated with a split index.
+                */
+               if (istate->split_index)
+                       return 0;
+               /*
+                * The GIT_TEST_SPARSE_INDEX environment variable triggers the
+                * index.sparse config variable to be on.
+                */
+               test_env = git_env_bool("GIT_TEST_SPARSE_INDEX", -1);
+               if (test_env >= 0)
+                       set_sparse_index_config(istate->repo, test_env);
 
-       /*
-        * Only convert to sparse if index.sparse is set.
-        */
-       prepare_repo_settings(istate->repo);
-       if (!istate->repo->settings.sparse_index)
-               return 0;
+               /*
+                * Only convert to sparse if index.sparse is set.
+                */
+               prepare_repo_settings(istate->repo);
+               if (!istate->repo->settings.sparse_index)
+                       return 0;
+       }
 
        if (init_sparse_checkout_patterns(istate))
                return 0;

diff --git a/sparse-index.h b/sparse-index.h
index 1115a0d7dd984b142b0ed8c76db9f1c132e13f6d..9f3d7bc7fafce1968572c0f6b962a4d72f7a064c 100644 (file)
--- a/sparse-index.h
+++ b/sparse-index.h
@@ -2,7 +2,8 @@
 #define SPARSE_INDEX_H__
 
 struct index_state;
-int convert_to_sparse(struct index_state *istate);
+#define SPARSE_INDEX_MEMORY_ONLY (1 << 0)
+int convert_to_sparse(struct index_state *istate, int flags);
 
 /*
  * Some places in the codebase expect to search for a specific path.