Optimize "diff --cached" performance.

[git.git] / tree.c

diff --git a/tree.c b/tree.c
index 04fe653a8e25feb0fc15f76ba487d0f8dbd52f82..8c0819fa721771f6dc2e727860345376edb3ea60 100644 (file)
--- a/tree.c
+++ b/tree.c
@@ -1,4 +1,5 @@
 #include "cache.h"
+#include "cache-tree.h"
 #include "tree.h"
 #include "blob.h"
 #include "commit.h"
@@ -7,7 +8,7 @@
 
 const char *tree_type = "tree";
 
-static int read_one_entry(const unsigned char *sha1, const char *base, int baselen, const char *pathname, unsigned mode, int stage)
+static int read_one_entry_opt(const unsigned char *sha1, const char *base, int baselen, const char *pathname, unsigned mode, int stage, int opt)
 {
        int len;
        unsigned int size;
@@ -25,7 +26,23 @@ static int read_one_entry(const unsigned char *sha1, const char *base, int basel
        memcpy(ce->name, base, baselen);
        memcpy(ce->name + baselen, pathname, len+1);
        hashcpy(ce->sha1, sha1);
-       return add_cache_entry(ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
+       return add_cache_entry(ce, opt);
+}
+
+static int read_one_entry(const unsigned char *sha1, const char *base, int baselen, const char *pathname, unsigned mode, int stage)
+{
+       return read_one_entry_opt(sha1, base, baselen, pathname, mode, stage,
+                                 ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
+}
+
+/*
+ * This is used when the caller knows there is no existing entries at
+ * the stage that will conflict with the entry being added.
+ */
+static int read_one_entry_quick(const unsigned char *sha1, const char *base, int baselen, const char *pathname, unsigned mode, int stage)
+{
+       return read_one_entry_opt(sha1, base, baselen, pathname, mode, stage,
+                                 ADD_CACHE_JUST_APPEND);
 }
 
 static int match_tree_entry(const char *base, int baselen, const char *path, unsigned int mode, const char **paths)
@@ -119,9 +136,55 @@ int read_tree_recursive(struct tree *tree,
        return 0;
 }
 
+static int cmp_cache_name_compare(const void *a_, const void *b_)
+{
+       const struct cache_entry *ce1, *ce2;
+
+       ce1 = *((const struct cache_entry **)a_);
+       ce2 = *((const struct cache_entry **)b_);
+       return cache_name_compare(ce1->name, ntohs(ce1->ce_flags),
+                                 ce2->name, ntohs(ce2->ce_flags));
+}
+
 int read_tree(struct tree *tree, int stage, const char **match)
 {
-       return read_tree_recursive(tree, "", 0, stage, match, read_one_entry);
+       read_tree_fn_t fn = NULL;
+       int i, err;
+
+       /*
+        * Currently the only existing callers of this function all
+        * call it with stage=1 and after making sure there is nothing
+        * at that stage; we could always use read_one_entry_quick().
+        *
+        * But when we decide to straighten out git-read-tree not to
+        * use unpack_trees() in some cases, this will probably start
+        * to matter.
+        */
+
+       /*
+        * See if we have cache entry at the stage.  If so,
+        * do it the original slow way, otherwise, append and then
+        * sort at the end.
+        */
+       for (i = 0; !fn && i < active_nr; i++) {
+               struct cache_entry *ce = active_cache[i];
+               if (ce_stage(ce) == stage)
+                       fn = read_one_entry;
+       }
+
+       if (!fn)
+               fn = read_one_entry_quick;
+       err = read_tree_recursive(tree, "", 0, stage, match, fn);
+       if (fn == read_one_entry || err)
+               return err;
+
+       /*
+        * Sort the cache entry -- we need to nuke the cache tree, though.
+        */
+       cache_tree_free(&active_cache_tree);
+       qsort(active_cache, active_nr, sizeof(active_cache[0]),
+             cmp_cache_name_compare);
+       return 0;
 }
 
 struct tree *lookup_tree(const unsigned char *sha1)