From d5a63b99835017d2638e55a7e34a35a3c1e80f1f Mon Sep 17 00:00:00 2001 From: Junio C Hamano Date: Sun, 14 Aug 2005 17:25:57 -0700 Subject: [PATCH] Alternate object pool mechanism updates. It was a mistake to use GIT_ALTERNATE_OBJECT_DIRECTORIES environment variable to specify what alternate object pools to look for missing objects when working with an object database. It is not a property of the process running the git commands, but a property of the object database that is partial and needs other object pools to complete the set of objects it lacks. This patch allows you to have $GIT_OBJECT_DIRECTORY/info/alternates whose contents is in exactly the same format as the environment variable, to let an object database name alternate object pools it depends on. Signed-off-by: Junio C Hamano --- cache.h | 5 +- fsck-cache.c | 8 +-- sha1_file.c | 146 ++++++++++++++++++++++++++++----------------------- 3 files changed, 88 insertions(+), 71 deletions(-) diff --git a/cache.h b/cache.h index efd2a2c59..dbde95a0b 100644 --- a/cache.h +++ b/cache.h @@ -278,9 +278,10 @@ struct checkout { extern int checkout_entry(struct cache_entry *ce, struct checkout *state); extern struct alternate_object_database { - char *base; + struct alternate_object_database *next; char *name; -} *alt_odb; + char base[0]; /* more */ +} *alt_odb_list; extern void prepare_alt_odb(void); extern struct packed_git { diff --git a/fsck-cache.c b/fsck-cache.c index e40c64332..809178019 100644 --- a/fsck-cache.c +++ b/fsck-cache.c @@ -456,13 +456,13 @@ int main(int argc, char **argv) fsck_head_link(); fsck_object_dir(get_object_directory()); if (check_full) { - int j; + struct alternate_object_database *alt; struct packed_git *p; prepare_alt_odb(); - for (j = 0; alt_odb[j].base; j++) { + for (alt = alt_odb_list; alt; alt = alt->next) { char namebuf[PATH_MAX]; - int namelen = alt_odb[j].name - alt_odb[j].base; - memcpy(namebuf, alt_odb[j].base, namelen); + int namelen = alt->name - alt->base; + memcpy(namebuf, alt->base, namelen); namebuf[namelen - 1] = 0; fsck_object_dir(namebuf); } diff --git a/sha1_file.c b/sha1_file.c index 8d189d491..2d109f928 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -222,84 +222,100 @@ char *sha1_pack_index_name(const unsigned char *sha1) return base; } -struct alternate_object_database *alt_odb; +struct alternate_object_database *alt_odb_list; +static struct alternate_object_database **alt_odb_tail; /* * Prepare alternate object database registry. - * alt_odb points at an array of struct alternate_object_database. - * This array is terminated with an element that has both its base - * and name set to NULL. alt_odb[n] comes from n'th non-empty - * element from colon separated ALTERNATE_DB_ENVIRONMENT environment - * variable, and its base points at a statically allocated buffer - * that contains "/the/directory/corresponding/to/.git/objects/...", - * while its name points just after the slash at the end of - * ".git/objects/" in the example above, and has enough space to hold - * 40-byte hex SHA1, an extra slash for the first level indirection, - * and the terminating NUL. - * This function allocates the alt_odb array and all the strings - * pointed by base fields of the array elements with one xmalloc(); - * the string pool immediately follows the array. + * + * The variable alt_odb_list points at the list of struct + * alternate_object_database. The elements on this list come from + * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT + * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates, + * whose contents is exactly in the same format as that environment + * variable. Its base points at a statically allocated buffer that + * contains "/the/directory/corresponding/to/.git/objects/...", while + * its name points just after the slash at the end of ".git/objects/" + * in the example above, and has enough space to hold 40-byte hex + * SHA1, an extra slash for the first level indirection, and the + * terminating NUL. */ -void prepare_alt_odb(void) +static void link_alt_odb_entries(const char *alt, const char *ep) { - int pass, totlen, i; const char *cp, *last; - char *op = NULL; - const char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : ""; + struct alternate_object_database *ent; + + last = alt; + do { + for (cp = last; cp < ep && *cp != ':'; cp++) + ; + if (last != cp) { + /* 43 = 40-byte + 2 '/' + terminating NUL */ + int pfxlen = cp - last; + int entlen = pfxlen + 43; + + ent = xmalloc(sizeof(*ent) + entlen); + *alt_odb_tail = ent; + alt_odb_tail = &(ent->next); + ent->next = NULL; + + memcpy(ent->base, last, pfxlen); + ent->name = ent->base + pfxlen + 1; + ent->base[pfxlen] = ent->base[pfxlen + 3] = '/'; + ent->base[entlen-1] = 0; + } + while (cp < ep && *cp == ':') + cp++; + last = cp; + } while (cp < ep); +} - if (alt_odb) +void prepare_alt_odb(void) +{ + char path[PATH_MAX]; + char *map, *ep; + int fd; + struct stat st; + char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : ""; + + sprintf(path, "%s/info/alternates", get_object_directory()); + if (alt_odb_tail) + return; + alt_odb_tail = &alt_odb_list; + link_alt_odb_entries(alt, alt + strlen(alt)); + + fd = open(path, O_RDONLY); + if (fd < 0) + return; + if (fstat(fd, &st) || (st.st_size == 0)) { + close(fd); return; - /* The first pass counts how large an area to allocate to - * hold the entire alt_odb structure, including array of - * structs and path buffers for them. The second pass fills - * the structure and prepares the path buffers for use by - * fill_sha1_path(). - */ - for (totlen = pass = 0; pass < 2; pass++) { - last = alt; - i = 0; - do { - cp = strchr(last, ':') ? : last + strlen(last); - if (last != cp) { - /* 43 = 40-byte + 2 '/' + terminating NUL */ - int pfxlen = cp - last; - int entlen = pfxlen + 43; - if (pass == 0) - totlen += entlen; - else { - alt_odb[i].base = op; - alt_odb[i].name = op + pfxlen + 1; - memcpy(op, last, pfxlen); - op[pfxlen] = op[pfxlen + 3] = '/'; - op[entlen-1] = 0; - op += entlen; - } - i++; - } - while (*cp && *cp == ':') - cp++; - last = cp; - } while (*cp); - if (pass) - break; - alt_odb = xmalloc(sizeof(*alt_odb) * (i + 1) + totlen); - alt_odb[i].base = alt_odb[i].name = NULL; - op = (char*)(&alt_odb[i+1]); } + map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); + close(fd); + if (map == MAP_FAILED) + return; + + /* Remove the trailing newline */ + for (ep = map + st.st_size - 1; map < ep && ep[-1] == '\n'; ep--) + ; + link_alt_odb_entries(map, ep); + munmap(map, st.st_size); } static char *find_sha1_file(const unsigned char *sha1, struct stat *st) { - int i; char *name = sha1_file_name(sha1); + struct alternate_object_database *alt; if (!stat(name, st)) return name; prepare_alt_odb(); - for (i = 0; (name = alt_odb[i].name) != NULL; i++) { + for (alt = alt_odb_list; alt; alt = alt->next) { + name = alt->name; fill_sha1_path(name, sha1); - if (!stat(alt_odb[i].base, st)) - return alt_odb[i].base; + if (!stat(alt->base, st)) + return alt->base; } return NULL; } @@ -522,18 +538,18 @@ static void prepare_packed_git_one(char *objdir) void prepare_packed_git(void) { - int i; static int run_once = 0; + struct alternate_object_database *alt; - if (run_once++) + if (run_once) return; - prepare_packed_git_one(get_object_directory()); prepare_alt_odb(); - for (i = 0; alt_odb[i].base != NULL; i++) { - alt_odb[i].name[0] = 0; - prepare_packed_git_one(alt_odb[i].base); + for (alt = alt_odb_list; alt; alt = alt->next) { + alt->name[0] = 0; + prepare_packed_git_one(alt->base); } + run_once = 1; } int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type) -- 2.26.2