sparse-index: implement ensure_full_index()

We will mark an in-memory index_state as having sparse directory entries
with the sparse_index bit. These currently cannot exist, but we will add
a mechanism for collapsing a full index to a sparse one in a later
change. That will happen at write time, so we must first allow parsing
the format before writing it.

Commands or methods that require a full index in order to operate can
call ensure_full_index() to expand that index in-memory. This requires
parsing trees using that index's repository.

Sparse directory entries have a specific 'ce_mode' value. The macro
S_ISSPARSEDIR(ce->ce_mode) can check if a cache_entry 'ce' has this type.
This ce_mode is not possible with the existing index formats, so we don't
also verify all properties of a sparse-directory entry, which are:

 1. ce->ce_mode == 0040000
 2. ce->flags & CE_SKIP_WORKTREE is true
 3. ce->name[ce->namelen - 1] == '/' (ends in dir separator)
 4. ce->oid references a tree object.

These are all semi-enforced in ensure_full_index() to some extent. Any
deviation will cause a warning at minimum or a failure in the worst
case.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/cache.h b/cache.h
index bb317abc91fbc1d236047fcb69323b60b35c0f5c..136dd496c95db8c05ac458b445e5c1a216668f52 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -204,6 +204,8 @@ struct cache_entry {
 #error "CE_EXTENDED_FLAGS out of range"
 #endif
 
+#define S_ISSPARSEDIR(m) ((m) == S_IFDIR)
+
 /* Forward structure decls */
 struct pathspec;
 struct child_process;
@@ -319,7 +321,14 @@ struct index_state {
                 drop_cache_tree : 1,
                 updated_workdir : 1,
                 updated_skipworktree : 1,
-                fsmonitor_has_run_once : 1;
+                fsmonitor_has_run_once : 1,
+
+                /*
+                 * sparse_index == 1 when sparse-directory
+                 * entries exist. Requires sparse-checkout
+                 * in cone mode.
+                 */
+                sparse_index : 1;
        struct hashmap name_hash;
        struct hashmap dir_hash;
        struct object_id oid;
@@ -722,6 +731,8 @@ int read_index_from(struct index_state *, const char *path,
                    const char *gitdir);
 int is_index_unborn(struct index_state *);
 
+void ensure_full_index(struct index_state *istate);
+
 /* For use with `write_locked_index()`. */
 #define COMMIT_LOCK            (1 << 0)
 #define SKIP_IF_UNCHANGED      (1 << 1)

diff --git a/read-cache.c b/read-cache.c
index 1e9a50c6c734374aa59ff97b9f9e5432918bf1f8..dd3980c12b5384b4d128d3259b8a2aaf05b531b9 100644 (file)
--- a/read-cache.c
+++ b/read-cache.c
@@ -101,6 +101,9 @@ static const char *alternate_index_output;
 
 static void set_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
 {
+       if (S_ISSPARSEDIR(ce->ce_mode))
+               istate->sparse_index = 1;
+
        istate->cache[nr] = ce;
        add_name_hash(istate, ce);
 }
@@ -2273,6 +2276,12 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
        trace2_data_intmax("index", the_repository, "read/cache_nr",
                           istate->cache_nr);
 
+       if (!istate->repo)
+               istate->repo = the_repository;
+       prepare_repo_settings(istate->repo);
+       if (istate->repo->settings.command_requires_full_index)
+               ensure_full_index(istate);
+
        return istate->cache_nr;
 
 unmap:

diff --git a/sparse-index.c b/sparse-index.c
index 82183ead563b987caf9a48a1d106cca1cb0d787b..7095378a1b287a8ef58707bd5f0f171cf7977b3e 100644 (file)
--- a/sparse-index.c
+++ b/sparse-index.c
@@ -1,8 +1,104 @@
 #include "cache.h"
 #include "repository.h"
 #include "sparse-index.h"
+#include "tree.h"
+#include "pathspec.h"
+#include "trace2.h"
+
+static void set_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
+{
+       ALLOC_GROW(istate->cache, nr + 1, istate->cache_alloc);
+
+       istate->cache[nr] = ce;
+       add_name_hash(istate, ce);
+}
+
+static int add_path_to_index(const struct object_id *oid,
+                            struct strbuf *base, const char *path,
+                            unsigned int mode, void *context)
+{
+       struct index_state *istate = (struct index_state *)context;
+       struct cache_entry *ce;
+       size_t len = base->len;
+
+       if (S_ISDIR(mode))
+               return READ_TREE_RECURSIVE;
+
+       strbuf_addstr(base, path);
+
+       ce = make_cache_entry(istate, mode, oid, base->buf, 0, 0);
+       ce->ce_flags |= CE_SKIP_WORKTREE;
+       set_index_entry(istate, istate->cache_nr++, ce);
+
+       strbuf_setlen(base, len);
+       return 0;
+}
 
 void ensure_full_index(struct index_state *istate)
 {
-       /* intentionally left blank */
+       int i;
+       struct index_state *full;
+       struct strbuf base = STRBUF_INIT;
+
+       if (!istate || !istate->sparse_index)
+               return;
+
+       if (!istate->repo)
+               istate->repo = the_repository;
+
+       trace2_region_enter("index", "ensure_full_index", istate->repo);
+
+       /* initialize basics of new index */
+       full = xcalloc(1, sizeof(struct index_state));
+       memcpy(full, istate, sizeof(struct index_state));
+
+       /* then change the necessary things */
+       full->sparse_index = 0;
+       full->cache_alloc = (3 * istate->cache_alloc) / 2;
+       full->cache_nr = 0;
+       ALLOC_ARRAY(full->cache, full->cache_alloc);
+
+       for (i = 0; i < istate->cache_nr; i++) {
+               struct cache_entry *ce = istate->cache[i];
+               struct tree *tree;
+               struct pathspec ps;
+
+               if (!S_ISSPARSEDIR(ce->ce_mode)) {
+                       set_index_entry(full, full->cache_nr++, ce);
+                       continue;
+               }
+               if (!(ce->ce_flags & CE_SKIP_WORKTREE))
+                       warning(_("index entry is a directory, but not sparse (%08x)"),
+                               ce->ce_flags);
+
+               /* recursively walk into cd->name */
+               tree = lookup_tree(istate->repo, &ce->oid);
+
+               memset(&ps, 0, sizeof(ps));
+               ps.recursive = 1;
+               ps.has_wildcard = 1;
+               ps.max_depth = -1;
+
+               strbuf_setlen(&base, 0);
+               strbuf_add(&base, ce->name, strlen(ce->name));
+
+               read_tree_at(istate->repo, tree, &base, &ps,
+                            add_path_to_index, full);
+
+               /* free directory entries. full entries are re-used */
+               discard_cache_entry(ce);
+       }
+
+       /* Copy back into original index. */
+       memcpy(&istate->name_hash, &full->name_hash, sizeof(full->name_hash));
+       istate->sparse_index = 0;
+       free(istate->cache);
+       istate->cache = full->cache;
+       istate->cache_nr = full->cache_nr;
+       istate->cache_alloc = full->cache_alloc;
+
+       strbuf_release(&base);
+       free(full);
+
+       trace2_region_leave("index", "ensure_full_index", istate->repo);
 }