pack-mtimes: support writing pack .mtimes files

Now that the `.mtimes` format is defined, supplement the pack-write API
to be able to conditionally write an `.mtimes` file along with a pack by
setting an additional flag and passing an oidmap that contains the
timestamps corresponding to each object in the pack.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/pack-objects.c b/pack-objects.c
index fe2a4eace9910b487aae56447b7fc6bd93fe1392..272e8d451739e8466a35df155520c9c54d85e75c 100644 (file)
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -170,6 +170,9 @@ struct object_entry *packlist_alloc(struct packing_data *pdata,
 
                if (pdata->layer)
                        REALLOC_ARRAY(pdata->layer, pdata->nr_alloc);
+
+               if (pdata->cruft_mtime)
+                       REALLOC_ARRAY(pdata->cruft_mtime, pdata->nr_alloc);
        }
 
        new_entry = pdata->objects + pdata->nr_objects++;
@@ -198,6 +201,9 @@ struct object_entry *packlist_alloc(struct packing_data *pdata,
        if (pdata->layer)
                pdata->layer[pdata->nr_objects - 1] = 0;
 
+       if (pdata->cruft_mtime)
+               pdata->cruft_mtime[pdata->nr_objects - 1] = 0;
+
        return new_entry;
 }
 

diff --git a/pack-objects.h b/pack-objects.h
index dca2351ef94ecf4e8d4aa51cd81b38cb03eb8b4f..393b9db546433d71de6f821a58d2a58a9ebc5ecb 100644 (file)
--- a/pack-objects.h
+++ b/pack-objects.h
@@ -168,6 +168,14 @@ struct packing_data {
        /* delta islands */
        unsigned int *tree_depth;
        unsigned char *layer;
+
+       /*
+        * Used when writing cruft packs.
+        *
+        * Object mtimes are stored in pack order when writing, but
+        * written out in lexicographic (index) order.
+        */
+       uint32_t *cruft_mtime;
 };
 
 void prepare_packing_data(struct repository *r, struct packing_data *pdata);
@@ -289,4 +297,21 @@ static inline void oe_set_layer(struct packing_data *pack,
        pack->layer[e - pack->objects] = layer;
 }
 
+static inline uint32_t oe_cruft_mtime(struct packing_data *pack,
+                                     struct object_entry *e)
+{
+       if (!pack->cruft_mtime)
+               return 0;
+       return pack->cruft_mtime[e - pack->objects];
+}
+
+static inline void oe_set_cruft_mtime(struct packing_data *pack,
+                                     struct object_entry *e,
+                                     uint32_t mtime)
+{
+       if (!pack->cruft_mtime)
+               CALLOC_ARRAY(pack->cruft_mtime, pack->nr_alloc);
+       pack->cruft_mtime[e - pack->objects] = mtime;
+}
+
 #endif

diff --git a/pack-write.c b/pack-write.c
index 27b171e440bfcb5ccf7c24bc41731846af5c5497..23c0342018fa1f76831b0d83fe1e7249d18090bf 100644 (file)
--- a/pack-write.c
+++ b/pack-write.c
@@ -3,6 +3,10 @@
 #include "csum-file.h"
 #include "remote.h"
 #include "chunk-format.h"
+#include "pack-mtimes.h"
+#include "oidmap.h"
+#include "chunk-format.h"
+#include "pack-objects.h"
 
 void reset_pack_idx_option(struct pack_idx_option *opts)
 {
@@ -277,6 +281,70 @@ const char *write_rev_file_order(const char *rev_name,
        return rev_name;
 }
 
+static void write_mtimes_header(struct hashfile *f)
+{
+       hashwrite_be32(f, MTIMES_SIGNATURE);
+       hashwrite_be32(f, MTIMES_VERSION);
+       hashwrite_be32(f, oid_version(the_hash_algo));
+}
+
+/*
+ * Writes the object mtimes of "objects" for use in a .mtimes file.
+ * Note that objects must be in lexicographic (index) order, which is
+ * the expected ordering of these values in the .mtimes file.
+ */
+static void write_mtimes_objects(struct hashfile *f,
+                                struct packing_data *to_pack,
+                                struct pack_idx_entry **objects,
+                                uint32_t nr_objects)
+{
+       uint32_t i;
+       for (i = 0; i < nr_objects; i++) {
+               struct object_entry *e = (struct object_entry*)objects[i];
+               hashwrite_be32(f, oe_cruft_mtime(to_pack, e));
+       }
+}
+
+static void write_mtimes_trailer(struct hashfile *f, const unsigned char *hash)
+{
+       hashwrite(f, hash, the_hash_algo->rawsz);
+}
+
+static const char *write_mtimes_file(const char *mtimes_name,
+                                    struct packing_data *to_pack,
+                                    struct pack_idx_entry **objects,
+                                    uint32_t nr_objects,
+                                    const unsigned char *hash)
+{
+       struct hashfile *f;
+       int fd;
+
+       if (!to_pack)
+               BUG("cannot call write_mtimes_file with NULL packing_data");
+
+       if (!mtimes_name) {
+               struct strbuf tmp_file = STRBUF_INIT;
+               fd = odb_mkstemp(&tmp_file, "pack/tmp_mtimes_XXXXXX");
+               mtimes_name = strbuf_detach(&tmp_file, NULL);
+       } else {
+               unlink(mtimes_name);
+               fd = xopen(mtimes_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
+       }
+       f = hashfd(fd, mtimes_name);
+
+       write_mtimes_header(f);
+       write_mtimes_objects(f, to_pack, objects, nr_objects);
+       write_mtimes_trailer(f, hash);
+
+       if (adjust_shared_perm(mtimes_name) < 0)
+               die(_("failed to make %s readable"), mtimes_name);
+
+       finalize_hashfile(f, NULL, FSYNC_COMPONENT_PACK_METADATA,
+                         CSUM_HASH_IN_STREAM | CSUM_CLOSE | CSUM_FSYNC);
+
+       return mtimes_name;
+}
+
 off_t write_pack_header(struct hashfile *f, uint32_t nr_entries)
 {
        struct pack_header hdr;
@@ -479,6 +547,7 @@ void stage_tmp_packfiles(struct strbuf *name_buffer,
                         char **idx_tmp_name)
 {
        const char *rev_tmp_name = NULL;
+       const char *mtimes_tmp_name = NULL;
 
        if (adjust_shared_perm(pack_tmp_name))
                die_errno("unable to make temporary pack file readable");
@@ -491,9 +560,17 @@ void stage_tmp_packfiles(struct strbuf *name_buffer,
        rev_tmp_name = write_rev_file(NULL, written_list, nr_written, hash,
                                      pack_idx_opts->flags);
 
+       if (pack_idx_opts->flags & WRITE_MTIMES) {
+               mtimes_tmp_name = write_mtimes_file(NULL, to_pack, written_list,
+                                                   nr_written,
+                                                   hash);
+       }
+
        rename_tmp_packfile(name_buffer, pack_tmp_name, "pack");
        if (rev_tmp_name)
                rename_tmp_packfile(name_buffer, rev_tmp_name, "rev");
+       if (mtimes_tmp_name)
+               rename_tmp_packfile(name_buffer, mtimes_tmp_name, "mtimes");
 }
 
 void write_promisor_file(const char *promisor_name, struct ref **sought, int nr_sought)

diff --git a/pack.h b/pack.h
index fd27cfdfd7ee83ee379f65f5f19863c97abab623..01d385903adcba22f46633aec3f7c2fff78776f3 100644 (file)
--- a/pack.h
+++ b/pack.h
@@ -44,6 +44,7 @@ struct pack_idx_option {
 #define WRITE_IDX_STRICT 02
 #define WRITE_REV 04
 #define WRITE_REV_VERIFY 010
+#define WRITE_MTIMES 020
 
        uint32_t version;
        uint32_t off32_limit;