• Linus Torvalds's avatar
    tree_entry(): new tree-walking helper function · 4c068a98
    Linus Torvalds authored
    This adds a "tree_entry()" function that combines the common operation of
    doing a "tree_entry_extract()" + "update_tree_entry()".
    
    It also has a simplified calling convention, designed for simple loops
    that traverse over a whole tree: the arguments are pointers to the tree
    descriptor and a name_entry structure to fill in, and it returns a boolean
    "true" if there was an entry left to be gotten in the tree.
    
    This allows tree traversal with
    
    	struct tree_desc desc;
    	struct name_entry entry;
    
    	desc.buf = tree->buffer;
    	desc.size = tree->size;
    	while (tree_entry(&desc, &entry) {
    		... use "entry.{path, sha1, mode, pathlen}" ...
    	}
    
    which is not only shorter than writing it out in full, it's hopefully less
    error prone too.
    
    [ It's actually a tad faster too - we don't need to recalculate the entry
      pathlength in both extract and update, but need to do it only once.
      Also, some callers can avoid doing a "strlen()" on the result, since
      it's returned as part of the name_entry structure.
    
      However, by now we're talking just 1% speedup on "git-rev-list --objects
      --all", and we're definitely at the point where tree walking is no
      longer the issue any more. ]
    
    NOTE! Not everybody wants to use this new helper function, since some of
    the tree walkers very much on purpose do the descriptor update separately
    from the entry extraction. So the "extract + update" sequence still
    remains as the core sequence, this is just a simplified interface.
    
    We should probably add a silly two-line inline helper function for
    initializing the descriptor from the "struct tree" too, just to cut down
    on the noise from that common "desc" initializer.
    Signed-off-by: default avatarLinus Torvalds <[email protected]>
    Signed-off-by: default avatarJunio C Hamano <[email protected]>
    4c068a98
tree-walk.h 863 Bytes