Nguyễn Thái Ngọc Duy <pclo...@gmail.com> writes: > If an entry is "watched", git lets an external program decide if the > entry is modified or not. It's more like --assume-unchanged, but > designed to be controlled by machine. > > We are running out of on-disk ce_flags, so instead of extending > on-disk entry format again, "watched" flags are in-core only and > stored as extension instead.
As you said yourself in http://thread.gmane.org/gmane.comp.version-control.git/240339/focus=240385 this is not quite true. As for your explanation there, > Anyway using extended flags means 2 extra bytes per entry for > almost every entry in this case (and for index v5 it means redoing > crc32 for almost every entry too when the bit is updated) so it may > still be a good idea to keep the new flag separate. I don't think adding 2 extra bytes would be too bad, since we are already using 62 bytes plus the bytes for the filename for each index entry, so it would be a less than 3% increase in the index file size. (And the extended flags may be used anyway in some cases) As for index-v5 (if that's ever going to happen), it depends mostly on how often the CE_WATCHED is going to be updated, to decide whether it makes sense to store this as extension. That said, I don't care too deeply if it's stored one way or another, but I think it would be good to update the commit message with a better rationale for the choice. > Signed-off-by: Nguyễn Thái Ngọc Duy <pclo...@gmail.com> > --- > cache.h | 2 ++ > read-cache.c | 41 ++++++++++++++++++++++++++++++++++++++++- > 2 files changed, 42 insertions(+), 1 deletion(-) > > diff --git a/cache.h b/cache.h > index a09d622..069dce7 100644 > --- a/cache.h > +++ b/cache.h > @@ -168,6 +168,8 @@ struct cache_entry { > /* used to temporarily mark paths matched by pathspecs */ > #define CE_MATCHED (1 << 26) > > +#define CE_WATCHED (1 << 27) > + > /* > * Extended on-disk flags > */ > diff --git a/read-cache.c b/read-cache.c > index fe1d153..6f21e3f 100644 > --- a/read-cache.c > +++ b/read-cache.c > @@ -33,6 +33,7 @@ static struct cache_entry *refresh_cache_entry(struct > cache_entry *ce, int reall > #define CACHE_EXT(s) ( (s[0]<<24)|(s[1]<<16)|(s[2]<<8)|(s[3]) ) > #define CACHE_EXT_TREE 0x54524545 /* "TREE" */ > #define CACHE_EXT_RESOLVE_UNDO 0x52455543 /* "REUC" */ > +#define CACHE_EXT_WATCH 0x57415443 /* "WATC" */ > > struct index_state the_index; > > @@ -1293,6 +1294,19 @@ static int verify_hdr(struct cache_header *hdr, > return 0; > } > > +static void read_watch_extension(struct index_state *istate, uint8_t *data, > + unsigned long sz) > +{ > + int i; > + if ((istate->cache_nr + 7) / 8 != sz) { > + error("invalid 'WATC' extension"); > + return; > + } > + for (i = 0; i < istate->cache_nr; i++) > + if (data[i / 8] & (1 << (i % 8))) > + istate->cache[i]->ce_flags |= CE_WATCHED; > +} > + > static int read_index_extension(struct index_state *istate, > const char *ext, void *data, unsigned long sz) > { > @@ -1303,6 +1317,9 @@ static int read_index_extension(struct index_state > *istate, > case CACHE_EXT_RESOLVE_UNDO: > istate->resolve_undo = resolve_undo_read(data, sz); > break; > + case CACHE_EXT_WATCH: > + read_watch_extension(istate, data, sz); > + break; > default: > if (*ext < 'A' || 'Z' < *ext) > return error("index uses %.4s extension, which we do > not understand", > @@ -1781,7 +1798,7 @@ int write_index(struct index_state *istate, int newfd) > { > git_SHA_CTX c; > struct cache_header hdr; > - int i, err, removed, extended, hdr_version; > + int i, err, removed, extended, hdr_version, has_watches = 0; > struct cache_entry **cache = istate->cache; > int entries = istate->cache_nr; > struct stat st; > @@ -1790,6 +1807,8 @@ int write_index(struct index_state *istate, int newfd) > for (i = removed = extended = 0; i < entries; i++) { > if (cache[i]->ce_flags & CE_REMOVE) > removed++; > + else if (cache[i]->ce_flags & CE_WATCHED) > + has_watches++; > > /* reduce extended entries if possible */ > cache[i]->ce_flags &= ~CE_EXTENDED; > @@ -1861,6 +1880,26 @@ int write_index(struct index_state *istate, int newfd) > if (err) > return -1; > } > + if (has_watches) { > + int id, sz = (entries - removed + 7) / 8; > + uint8_t *data = xmalloc(sz); > + memset(data, 0, sz); > + for (i = 0, id = 0; i < entries && has_watches; i++) { > + struct cache_entry *ce = cache[i]; > + if (ce->ce_flags & CE_REMOVE) > + continue; > + if (ce->ce_flags & CE_WATCHED) { > + data[id / 8] |= 1 << (id % 8); > + has_watches--; > + } > + id++; > + } > + err = write_index_ext_header(&c, newfd, CACHE_EXT_WATCH, sz) < 0 > + || ce_write(&c, newfd, data, sz) < 0; > + free(data); > + if (err) > + return -1; > + } > > if (ce_flush(&c, newfd) || fstat(newfd, &st)) > return -1; > -- > 1.8.5.1.208.g05b12ea > > -- > To unsubscribe from this list: send the line "unsubscribe git" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Thomas -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
