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* [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index
@ 2019-06-10 23:35 Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 02/11] Docs: rearrange subcommands for multi-pack-index Derrick Stolee via GitGitGadget
                   ` (10 more replies)
  0 siblings, 11 replies; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git; +Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano

The multi-pack-index provides a fast way to find an object among a large
list of pack-files. It stores a single pack-reference for each object id, so
duplicate objects are ignored. Among a list of pack-files storing the same
object, the most-recently modified one is used.

Create new subcommands for the multi-pack-index builtin.

 * 'git multi-pack-index expire': If we have a pack-file indexed by the
   multi-pack-index, but all objects in that pack are duplicated in
   more-recently modified packs, then delete that pack (and any others like
   it). Delete the reference to that pack in the multi-pack-index.
   
   
 * 'git multi-pack-index repack --batch-size=': Starting from the oldest
   pack-files covered by the multi-pack-index, find those whose "expected
   size" is below the batch size until we have a collection of packs whose
   expected sizes add up to the batch size. We compute the expected size by
   multiplying the number of referenced objects by the pack-size and
   dividing by the total number of objects in the pack. If the batch-size is
   zero, then select all packs. Create a new pack containing all objects
   that the multi-pack-index references to those packs.
   
   

This allows us to create a new pattern for repacking objects: run 'repack'.
After enough time has passed that all Git commands that started before the
last 'repack' are finished, run 'expire' again. This approach has some
advantages over the existing "repack everything" model:

 1. Incremental. We can repack a small batch of objects at a time, instead
    of repacking all reachable objects. We can also limit ourselves to the
    objects that do not appear in newer pack-files.
    
    
 2. Highly Available. By adding a new pack-file (and not deleting the old
    pack-files) we do not interrupt concurrent Git commands, and do not
    suffer performance degradation. By expiring only pack-files that have no
    referenced objects, we know that Git commands that are doing normal
    object lookups* will not be interrupted.
    
    

 * Note: if someone concurrently runs a Git command that uses
   get_all_packs(), then that command could try to read the pack-files and
   pack-indexes that we are deleting during an expire command. Such commands
   are usually related to object maintenance (i.e. fsck, gc, pack-objects)
   or are related to less-often-used features (i.e. fast-import,
   http-backend, server-info).

We are using this approach in VFS for Git to do background maintenance of
the "shared object cache" which is a Git alternate directory filled with
packfiles containing commits and trees. We currently download pack-files on
an hourly basis to keep up-to-date with the central server. The cache
servers supply packs on an hourly and daily basis, so most of the hourly
packs become useless after a new daily pack is downloaded. The 'expire'
command would clear out most of those packs, but many will still remain with
fewer than 100 objects remaining. The 'repack' command (with a batch size of
1-3gb, probably) can condense the remaining packs in commands that run for
1-3 min at a time. Since the daily packs range from 100-250mb, we will also
combine and condense those packs.

This series is the same as v6 of an earlier series [1].

Thanks, -Stolee

[1] https://public-inbox.org/git/pull.92.git.gitgitgadget@gmail.com/T/#u

Derrick Stolee (11):
  repack: refactor pack deletion for future use
  Docs: rearrange subcommands for multi-pack-index
  multi-pack-index: prepare for 'expire' subcommand
  midx: simplify computation of pack name lengths
  midx: refactor permutation logic and pack sorting
  multi-pack-index: implement 'expire' subcommand
  multi-pack-index: prepare 'repack' subcommand
  midx: implement midx_repack()
  multi-pack-index: test expire while adding packs
  midx: add test that 'expire' respects .keep files
  t5319-multi-pack-index.sh: test batch size zero

 Documentation/git-multi-pack-index.txt |  32 +-
 builtin/multi-pack-index.c             |  14 +-
 builtin/repack.c                       |  14 +-
 midx.c                                 | 440 +++++++++++++++++++------
 midx.h                                 |   2 +
 packfile.c                             |  28 ++
 packfile.h                             |   7 +
 t/t5319-multi-pack-index.sh            | 184 +++++++++++
 8 files changed, 602 insertions(+), 119 deletions(-)


base-commit: af96fe3392fb078cb5447bcb94f2ed8d79d0a4a8
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-261%2Fderrickstolee%2Fmidx-expire%2Fupstream-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-261/derrickstolee/midx-expire/upstream-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/261
-- 
gitgitgadget

^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH 01/11] repack: refactor pack deletion for future use
  2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 02/11] Docs: rearrange subcommands for multi-pack-index Derrick Stolee via GitGitGadget
@ 2019-06-10 23:35 ` Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 03/11] multi-pack-index: prepare for 'expire' subcommand Derrick Stolee via GitGitGadget
                   ` (8 subsequent siblings)
  10 siblings, 0 replies; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git
  Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano,
	Derrick Stolee

From: Derrick Stolee <dstolee@microsoft.com>

The repack builtin deletes redundant pack-files and their
associated .idx, .promisor, .bitmap, and .keep files. We will want
to re-use this logic in the future for other types of repack, so
pull the logic into 'unlink_pack_path()' in packfile.c.

The 'ignore_keep' parameter is enabled for the use in repack, but
will be important for a future caller.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 builtin/repack.c | 14 ++------------
 packfile.c       | 28 ++++++++++++++++++++++++++++
 packfile.h       |  7 +++++++
 3 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/builtin/repack.c b/builtin/repack.c
index 67f8978043..1f9e6fad1b 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -129,19 +129,9 @@ static void get_non_kept_pack_filenames(struct string_list *fname_list,
 
 static void remove_redundant_pack(const char *dir_name, const char *base_name)
 {
-	const char *exts[] = {".pack", ".idx", ".keep", ".bitmap", ".promisor"};
-	int i;
 	struct strbuf buf = STRBUF_INIT;
-	size_t plen;
-
-	strbuf_addf(&buf, "%s/%s", dir_name, base_name);
-	plen = buf.len;
-
-	for (i = 0; i < ARRAY_SIZE(exts); i++) {
-		strbuf_setlen(&buf, plen);
-		strbuf_addstr(&buf, exts[i]);
-		unlink(buf.buf);
-	}
+	strbuf_addf(&buf, "%s/%s.pack", dir_name, base_name);
+	unlink_pack_path(buf.buf, 1);
 	strbuf_release(&buf);
 }
 
diff --git a/packfile.c b/packfile.c
index 060de420d1..683ce5674c 100644
--- a/packfile.c
+++ b/packfile.c
@@ -352,6 +352,34 @@ void close_all_packs(struct raw_object_store *o)
 	}
 }
 
+void unlink_pack_path(const char *pack_name, int force_delete)
+{
+	static const char *exts[] = {".pack", ".idx", ".keep", ".bitmap", ".promisor"};
+	int i;
+	struct strbuf buf = STRBUF_INIT;
+	size_t plen;
+
+	strbuf_addstr(&buf, pack_name);
+	strip_suffix_mem(buf.buf, &buf.len, ".pack");
+	plen = buf.len;
+
+	if (!force_delete) {
+		strbuf_addstr(&buf, ".keep");
+		if (!access(buf.buf, F_OK)) {
+			strbuf_release(&buf);
+			return;
+		}
+	}
+
+	for (i = 0; i < ARRAY_SIZE(exts); i++) {
+		strbuf_setlen(&buf, plen);
+		strbuf_addstr(&buf, exts[i]);
+		unlink(buf.buf);
+	}
+
+	strbuf_release(&buf);
+}
+
 /*
  * The LRU pack is the one with the oldest MRU window, preferring packs
  * with no used windows, or the oldest mtime if it has no windows allocated.
diff --git a/packfile.h b/packfile.h
index 12baa6118a..09f5222113 100644
--- a/packfile.h
+++ b/packfile.h
@@ -94,6 +94,13 @@ void unuse_pack(struct pack_window **);
 void clear_delta_base_cache(void);
 struct packed_git *add_packed_git(const char *path, size_t path_len, int local);
 
+/*
+ * Unlink the .pack and associated extension files.
+ * Does not unlink if 'force_delete' is false and the pack-file is
+ * marked as ".keep".
+ */
+extern void unlink_pack_path(const char *pack_name, int force_delete);
+
 /*
  * Make sure that a pointer access into an mmap'd index file is within bounds,
  * and can provide at least 8 bytes of data.
-- 
gitgitgadget


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH 02/11] Docs: rearrange subcommands for multi-pack-index
  2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
@ 2019-06-10 23:35 ` Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 01/11] repack: refactor pack deletion for future use Derrick Stolee via GitGitGadget
                   ` (9 subsequent siblings)
  10 siblings, 0 replies; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git
  Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano,
	Derrick Stolee

From: Derrick Stolee <dstolee@microsoft.com>

We will add new subcommands to the multi-pack-index, and that will
make the documentation a bit messier. Clean up the 'verb'
descriptions by renaming the concept to 'subcommand' and removing
the reference to the object directory.

Helped-by: Stefan Beller <sbeller@google.com>
Helped-by: Szeder Gábor <szeder.dev@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 Documentation/git-multi-pack-index.txt | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Documentation/git-multi-pack-index.txt b/Documentation/git-multi-pack-index.txt
index f7778a2c85..1af406aca2 100644
--- a/Documentation/git-multi-pack-index.txt
+++ b/Documentation/git-multi-pack-index.txt
@@ -9,7 +9,7 @@ git-multi-pack-index - Write and verify multi-pack-indexes
 SYNOPSIS
 --------
 [verse]
-'git multi-pack-index' [--object-dir=<dir>] <verb>
+'git multi-pack-index' [--object-dir=<dir>] <subcommand>
 
 DESCRIPTION
 -----------
@@ -23,13 +23,13 @@ OPTIONS
 	`<dir>/packs/multi-pack-index` for the current MIDX file, and
 	`<dir>/packs` for the pack-files to index.
 
+The following subcommands are available:
+
 write::
-	When given as the verb, write a new MIDX file to
-	`<dir>/packs/multi-pack-index`.
+	Write a new MIDX file.
 
 verify::
-	When given as the verb, verify the contents of the MIDX file
-	at `<dir>/packs/multi-pack-index`.
+	Verify the contents of the MIDX file.
 
 
 EXAMPLES
-- 
gitgitgadget


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH 03/11] multi-pack-index: prepare for 'expire' subcommand
  2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 02/11] Docs: rearrange subcommands for multi-pack-index Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 01/11] repack: refactor pack deletion for future use Derrick Stolee via GitGitGadget
@ 2019-06-10 23:35 ` Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 05/11] midx: refactor permutation logic and pack sorting Derrick Stolee via GitGitGadget
                   ` (7 subsequent siblings)
  10 siblings, 0 replies; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git
  Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano,
	Derrick Stolee

From: Derrick Stolee <dstolee@microsoft.com>

The multi-pack-index tracks objects in a collection of pack-files.
Only one copy of each object is indexed, using the modified time
of the pack-files to determine tie-breakers. It is possible to
have a pack-file with no referenced objects because all objects
have a duplicate in a newer pack-file.

Introduce a new 'expire' subcommand to the multi-pack-index builtin.
This subcommand will delete these unused pack-files and rewrite the
multi-pack-index to no longer refer to those files. More details
about the specifics will follow as the method is implemented.

Add a test that verifies the 'expire' subcommand is correctly wired,
but will still be valid when the verb is implemented. Specifically,
create a set of packs that should all have referenced objects and
should not be removed during an 'expire' operation. The packs are
created carefully to ensure they have a specific order when sorted
by size. This will be important in a later test.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 Documentation/git-multi-pack-index.txt |  5 +++
 builtin/multi-pack-index.c             |  4 ++-
 midx.c                                 |  5 +++
 midx.h                                 |  1 +
 t/t5319-multi-pack-index.sh            | 49 ++++++++++++++++++++++++++
 5 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/Documentation/git-multi-pack-index.txt b/Documentation/git-multi-pack-index.txt
index 1af406aca2..6186c4c936 100644
--- a/Documentation/git-multi-pack-index.txt
+++ b/Documentation/git-multi-pack-index.txt
@@ -31,6 +31,11 @@ write::
 verify::
 	Verify the contents of the MIDX file.
 
+expire::
+	Delete the pack-files that are tracked 	by the MIDX file, but
+	have no objects referenced by the MIDX. Rewrite the MIDX file
+	afterward to remove all references to these pack-files.
+
 
 EXAMPLES
 --------
diff --git a/builtin/multi-pack-index.c b/builtin/multi-pack-index.c
index 72dfd3dadc..ad10d40512 100644
--- a/builtin/multi-pack-index.c
+++ b/builtin/multi-pack-index.c
@@ -6,7 +6,7 @@
 #include "trace2.h"
 
 static char const * const builtin_multi_pack_index_usage[] = {
-	N_("git multi-pack-index [--object-dir=<dir>] (write|verify)"),
+	N_("git multi-pack-index [--object-dir=<dir>] (write|verify|expire)"),
 	NULL
 };
 
@@ -47,6 +47,8 @@ int cmd_multi_pack_index(int argc, const char **argv,
 		return write_midx_file(opts.object_dir);
 	if (!strcmp(argv[0], "verify"))
 		return verify_midx_file(the_repository, opts.object_dir);
+	if (!strcmp(argv[0], "expire"))
+		return expire_midx_packs(the_repository, opts.object_dir);
 
 	die(_("unrecognized verb: %s"), argv[0]);
 }
diff --git a/midx.c b/midx.c
index e7e1fe4d65..3b7da1a360 100644
--- a/midx.c
+++ b/midx.c
@@ -1140,3 +1140,8 @@ int verify_midx_file(struct repository *r, const char *object_dir)
 
 	return verify_midx_error;
 }
+
+int expire_midx_packs(struct repository *r, const char *object_dir)
+{
+	return 0;
+}
diff --git a/midx.h b/midx.h
index 3eb29731f2..505f1431b7 100644
--- a/midx.h
+++ b/midx.h
@@ -50,6 +50,7 @@ int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, i
 int write_midx_file(const char *object_dir);
 void clear_midx_file(struct repository *r);
 int verify_midx_file(struct repository *r, const char *object_dir);
+int expire_midx_packs(struct repository *r, const char *object_dir);
 
 void close_midx(struct multi_pack_index *m);
 
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 1ebf19ec3c..1b2d32f475 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -363,4 +363,53 @@ test_expect_success 'verify incorrect 64-bit offset' '
 		"incorrect object offset"
 '
 
+test_expect_success 'setup expire tests' '
+	mkdir dup &&
+	(
+		cd dup &&
+		git init &&
+		test-tool genrandom "data" 4096 >large_file.txt &&
+		git update-index --add large_file.txt &&
+		for i in $(test_seq 1 20)
+		do
+			test_commit $i
+		done &&
+		git branch A HEAD &&
+		git branch B HEAD~8 &&
+		git branch C HEAD~13 &&
+		git branch D HEAD~16 &&
+		git branch E HEAD~18 &&
+		git pack-objects --revs .git/objects/pack/pack-A <<-EOF &&
+		refs/heads/A
+		^refs/heads/B
+		EOF
+		git pack-objects --revs .git/objects/pack/pack-B <<-EOF &&
+		refs/heads/B
+		^refs/heads/C
+		EOF
+		git pack-objects --revs .git/objects/pack/pack-C <<-EOF &&
+		refs/heads/C
+		^refs/heads/D
+		EOF
+		git pack-objects --revs .git/objects/pack/pack-D <<-EOF &&
+		refs/heads/D
+		^refs/heads/E
+		EOF
+		git pack-objects --revs .git/objects/pack/pack-E <<-EOF &&
+		refs/heads/E
+		EOF
+		git multi-pack-index write
+	)
+'
+
+test_expect_success 'expire does not remove any packs' '
+	(
+		cd dup &&
+		ls .git/objects/pack >expect &&
+		git multi-pack-index expire &&
+		ls .git/objects/pack >actual &&
+		test_cmp expect actual
+	)
+'
+
 test_done
-- 
gitgitgadget


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH 05/11] midx: refactor permutation logic and pack sorting
  2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
                   ` (2 preceding siblings ...)
  2019-06-10 23:35 ` [PATCH 03/11] multi-pack-index: prepare for 'expire' subcommand Derrick Stolee via GitGitGadget
@ 2019-06-10 23:35 ` Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 04/11] midx: simplify computation of pack name lengths Derrick Stolee via GitGitGadget
                   ` (6 subsequent siblings)
  10 siblings, 0 replies; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git
  Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano,
	Derrick Stolee

From: Derrick Stolee <dstolee@microsoft.com>

In anticipation of the expire subcommand, refactor the way we sort
the packfiles by name. This will greatly simplify our approach to
dropping expired packs from the list.

First, create 'struct pack_info' to replace 'struct pack_pair'.
This struct contains the necessary information about a pack,
including its name, a pointer to its packfile struct (if not
already in the multi-pack-index), and the original pack-int-id.

Second, track the pack information using an array of pack_info
structs in the pack_list struct. This simplifies the logic around
the multiple arrays we were tracking in that struct.

Finally, update get_sorted_entries() to not permute the pack-int-id
and instead supply the permutation to write_midx_object_offsets().
This requires sorting the packs after get_sorted_entries().

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 midx.c | 156 +++++++++++++++++++++++++--------------------------------
 1 file changed, 69 insertions(+), 87 deletions(-)

diff --git a/midx.c b/midx.c
index 62404620ad..6d4b84e243 100644
--- a/midx.c
+++ b/midx.c
@@ -427,12 +427,23 @@ static size_t write_midx_header(struct hashfile *f,
 	return MIDX_HEADER_SIZE;
 }
 
+struct pack_info {
+	uint32_t orig_pack_int_id;
+	char *pack_name;
+	struct packed_git *p;
+};
+
+static int pack_info_compare(const void *_a, const void *_b)
+{
+	struct pack_info *a = (struct pack_info *)_a;
+	struct pack_info *b = (struct pack_info *)_b;
+	return strcmp(a->pack_name, b->pack_name);
+}
+
 struct pack_list {
-	struct packed_git **list;
-	char **names;
+	struct pack_info *info;
 	uint32_t nr;
-	uint32_t alloc_list;
-	uint32_t alloc_names;
+	uint32_t alloc;
 	struct multi_pack_index *m;
 };
 
@@ -445,66 +456,32 @@ static void add_pack_to_midx(const char *full_path, size_t full_path_len,
 		if (packs->m && midx_contains_pack(packs->m, file_name))
 			return;
 
-		ALLOC_GROW(packs->list, packs->nr + 1, packs->alloc_list);
-		ALLOC_GROW(packs->names, packs->nr + 1, packs->alloc_names);
+		ALLOC_GROW(packs->info, packs->nr + 1, packs->alloc);
 
-		packs->list[packs->nr] = add_packed_git(full_path,
-							full_path_len,
-							0);
+		packs->info[packs->nr].p = add_packed_git(full_path,
+							  full_path_len,
+							  0);
 
-		if (!packs->list[packs->nr]) {
+		if (!packs->info[packs->nr].p) {
 			warning(_("failed to add packfile '%s'"),
 				full_path);
 			return;
 		}
 
-		if (open_pack_index(packs->list[packs->nr])) {
+		if (open_pack_index(packs->info[packs->nr].p)) {
 			warning(_("failed to open pack-index '%s'"),
 				full_path);
-			close_pack(packs->list[packs->nr]);
-			FREE_AND_NULL(packs->list[packs->nr]);
+			close_pack(packs->info[packs->nr].p);
+			FREE_AND_NULL(packs->info[packs->nr].p);
 			return;
 		}
 
-		packs->names[packs->nr] = xstrdup(file_name);
+		packs->info[packs->nr].pack_name = xstrdup(file_name);
+		packs->info[packs->nr].orig_pack_int_id = packs->nr;
 		packs->nr++;
 	}
 }
 
-struct pack_pair {
-	uint32_t pack_int_id;
-	char *pack_name;
-};
-
-static int pack_pair_compare(const void *_a, const void *_b)
-{
-	struct pack_pair *a = (struct pack_pair *)_a;
-	struct pack_pair *b = (struct pack_pair *)_b;
-	return strcmp(a->pack_name, b->pack_name);
-}
-
-static void sort_packs_by_name(char **pack_names, uint32_t nr_packs, uint32_t *perm)
-{
-	uint32_t i;
-	struct pack_pair *pairs;
-
-	ALLOC_ARRAY(pairs, nr_packs);
-
-	for (i = 0; i < nr_packs; i++) {
-		pairs[i].pack_int_id = i;
-		pairs[i].pack_name = pack_names[i];
-	}
-
-	QSORT(pairs, nr_packs, pack_pair_compare);
-
-	for (i = 0; i < nr_packs; i++) {
-		pack_names[i] = pairs[i].pack_name;
-		perm[pairs[i].pack_int_id] = i;
-	}
-
-	free(pairs);
-}
-
 struct pack_midx_entry {
 	struct object_id oid;
 	uint32_t pack_int_id;
@@ -530,7 +507,6 @@ static int midx_oid_compare(const void *_a, const void *_b)
 }
 
 static int nth_midxed_pack_midx_entry(struct multi_pack_index *m,
-				      uint32_t *pack_perm,
 				      struct pack_midx_entry *e,
 				      uint32_t pos)
 {
@@ -538,7 +514,7 @@ static int nth_midxed_pack_midx_entry(struct multi_pack_index *m,
 		return 1;
 
 	nth_midxed_object_oid(&e->oid, m, pos);
-	e->pack_int_id = pack_perm[nth_midxed_pack_int_id(m, pos)];
+	e->pack_int_id = nth_midxed_pack_int_id(m, pos);
 	e->offset = nth_midxed_offset(m, pos);
 
 	/* consider objects in midx to be from "old" packs */
@@ -572,8 +548,7 @@ static void fill_pack_entry(uint32_t pack_int_id,
  * of a packfile containing the object).
  */
 static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
-						  struct packed_git **p,
-						  uint32_t *perm,
+						  struct pack_info *info,
 						  uint32_t nr_packs,
 						  uint32_t *nr_objects)
 {
@@ -584,7 +559,7 @@ static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
 	uint32_t start_pack = m ? m->num_packs : 0;
 
 	for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++)
-		total_objects += p[cur_pack]->num_objects;
+		total_objects += info[cur_pack].p->num_objects;
 
 	/*
 	 * As we de-duplicate by fanout value, we expect the fanout
@@ -609,7 +584,7 @@ static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
 
 			for (cur_object = start; cur_object < end; cur_object++) {
 				ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
-				nth_midxed_pack_midx_entry(m, perm,
+				nth_midxed_pack_midx_entry(m,
 							   &entries_by_fanout[nr_fanout],
 							   cur_object);
 				nr_fanout++;
@@ -620,12 +595,12 @@ static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
 			uint32_t start = 0, end;
 
 			if (cur_fanout)
-				start = get_pack_fanout(p[cur_pack], cur_fanout - 1);
-			end = get_pack_fanout(p[cur_pack], cur_fanout);
+				start = get_pack_fanout(info[cur_pack].p, cur_fanout - 1);
+			end = get_pack_fanout(info[cur_pack].p, cur_fanout);
 
 			for (cur_object = start; cur_object < end; cur_object++) {
 				ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
-				fill_pack_entry(perm[cur_pack], p[cur_pack], cur_object, &entries_by_fanout[nr_fanout]);
+				fill_pack_entry(cur_pack, info[cur_pack].p, cur_object, &entries_by_fanout[nr_fanout]);
 				nr_fanout++;
 			}
 		}
@@ -654,7 +629,7 @@ static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
 }
 
 static size_t write_midx_pack_names(struct hashfile *f,
-				    char **pack_names,
+				    struct pack_info *info,
 				    uint32_t num_packs)
 {
 	uint32_t i;
@@ -662,14 +637,14 @@ static size_t write_midx_pack_names(struct hashfile *f,
 	size_t written = 0;
 
 	for (i = 0; i < num_packs; i++) {
-		size_t writelen = strlen(pack_names[i]) + 1;
+		size_t writelen = strlen(info[i].pack_name) + 1;
 
-		if (i && strcmp(pack_names[i], pack_names[i - 1]) <= 0)
+		if (i && strcmp(info[i].pack_name, info[i - 1].pack_name) <= 0)
 			BUG("incorrect pack-file order: %s before %s",
-			    pack_names[i - 1],
-			    pack_names[i]);
+			    info[i - 1].pack_name,
+			    info[i].pack_name);
 
-		hashwrite(f, pack_names[i], writelen);
+		hashwrite(f, info[i].pack_name, writelen);
 		written += writelen;
 	}
 
@@ -740,6 +715,7 @@ static size_t write_midx_oid_lookup(struct hashfile *f, unsigned char hash_len,
 }
 
 static size_t write_midx_object_offsets(struct hashfile *f, int large_offset_needed,
+					uint32_t *perm,
 					struct pack_midx_entry *objects, uint32_t nr_objects)
 {
 	struct pack_midx_entry *list = objects;
@@ -749,7 +725,7 @@ static size_t write_midx_object_offsets(struct hashfile *f, int large_offset_nee
 	for (i = 0; i < nr_objects; i++) {
 		struct pack_midx_entry *obj = list++;
 
-		hashwrite_be32(f, obj->pack_int_id);
+		hashwrite_be32(f, perm[obj->pack_int_id]);
 
 		if (large_offset_needed && obj->offset >> 31)
 			hashwrite_be32(f, MIDX_LARGE_OFFSET_NEEDED | nr_large_offset++);
@@ -822,20 +798,17 @@ int write_midx_file(const char *object_dir)
 	packs.m = load_multi_pack_index(object_dir, 1);
 
 	packs.nr = 0;
-	packs.alloc_list = packs.m ? packs.m->num_packs : 16;
-	packs.alloc_names = packs.alloc_list;
-	packs.list = NULL;
-	packs.names = NULL;
-	ALLOC_ARRAY(packs.list, packs.alloc_list);
-	ALLOC_ARRAY(packs.names, packs.alloc_names);
+	packs.alloc = packs.m ? packs.m->num_packs : 16;
+	packs.info = NULL;
+	ALLOC_ARRAY(packs.info, packs.alloc);
 
 	if (packs.m) {
 		for (i = 0; i < packs.m->num_packs; i++) {
-			ALLOC_GROW(packs.list, packs.nr + 1, packs.alloc_list);
-			ALLOC_GROW(packs.names, packs.nr + 1, packs.alloc_names);
+			ALLOC_GROW(packs.info, packs.nr + 1, packs.alloc);
 
-			packs.list[packs.nr] = NULL;
-			packs.names[packs.nr] = xstrdup(packs.m->pack_names[i]);
+			packs.info[packs.nr].orig_pack_int_id = i;
+			packs.info[packs.nr].pack_name = xstrdup(packs.m->pack_names[i]);
+			packs.info[packs.nr].p = NULL;
 			packs.nr++;
 		}
 	}
@@ -845,10 +818,7 @@ int write_midx_file(const char *object_dir)
 	if (packs.m && packs.nr == packs.m->num_packs)
 		goto cleanup;
 
-	ALLOC_ARRAY(pack_perm, packs.nr);
-	sort_packs_by_name(packs.names, packs.nr, pack_perm);
-
-	entries = get_sorted_entries(packs.m, packs.list, pack_perm, packs.nr, &nr_entries);
+	entries = get_sorted_entries(packs.m, packs.info, packs.nr, &nr_entries);
 
 	for (i = 0; i < nr_entries; i++) {
 		if (entries[i].offset > 0x7fffffff)
@@ -857,8 +827,21 @@ int write_midx_file(const char *object_dir)
 			large_offsets_needed = 1;
 	}
 
+	QSORT(packs.info, packs.nr, pack_info_compare);
+
+	/*
+	 * pack_perm stores a permutation between pack-int-ids from the
+	 * previous multi-pack-index to the new one we are writing:
+	 *
+	 * pack_perm[old_id] = new_id
+	 */
+	ALLOC_ARRAY(pack_perm, packs.nr);
+	for (i = 0; i < packs.nr; i++) {
+		pack_perm[packs.info[i].orig_pack_int_id] = i;
+	}
+
 	for (i = 0; i < packs.nr; i++)
-		pack_name_concat_len += strlen(packs.names[i]) + 1;
+		pack_name_concat_len += strlen(packs.info[i].pack_name) + 1;
 
 	if (pack_name_concat_len % MIDX_CHUNK_ALIGNMENT)
 		pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
@@ -929,7 +912,7 @@ int write_midx_file(const char *object_dir)
 
 		switch (chunk_ids[i]) {
 			case MIDX_CHUNKID_PACKNAMES:
-				written += write_midx_pack_names(f, packs.names, packs.nr);
+				written += write_midx_pack_names(f, packs.info, packs.nr);
 				break;
 
 			case MIDX_CHUNKID_OIDFANOUT:
@@ -941,7 +924,7 @@ int write_midx_file(const char *object_dir)
 				break;
 
 			case MIDX_CHUNKID_OBJECTOFFSETS:
-				written += write_midx_object_offsets(f, large_offsets_needed, entries, nr_entries);
+				written += write_midx_object_offsets(f, large_offsets_needed, pack_perm, entries, nr_entries);
 				break;
 
 			case MIDX_CHUNKID_LARGEOFFSETS:
@@ -964,15 +947,14 @@ int write_midx_file(const char *object_dir)
 
 cleanup:
 	for (i = 0; i < packs.nr; i++) {
-		if (packs.list[i]) {
-			close_pack(packs.list[i]);
-			free(packs.list[i]);
+		if (packs.info[i].p) {
+			close_pack(packs.info[i].p);
+			free(packs.info[i].p);
 		}
-		free(packs.names[i]);
+		free(packs.info[i].pack_name);
 	}
 
-	free(packs.list);
-	free(packs.names);
+	free(packs.info);
 	free(entries);
 	free(pack_perm);
 	free(midx_name);
-- 
gitgitgadget


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH 04/11] midx: simplify computation of pack name lengths
  2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
                   ` (3 preceding siblings ...)
  2019-06-10 23:35 ` [PATCH 05/11] midx: refactor permutation logic and pack sorting Derrick Stolee via GitGitGadget
@ 2019-06-10 23:35 ` Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 06/11] multi-pack-index: implement 'expire' subcommand Derrick Stolee via GitGitGadget
                   ` (5 subsequent siblings)
  10 siblings, 0 replies; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git
  Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano,
	Derrick Stolee

From: Derrick Stolee <dstolee@microsoft.com>

Before writing the multi-pack-index, we compute the length of the
pack-index names concatenated together. This forms the data in the
pack name chunk, and we precompute it to compute chunk offsets.
The value is also modified to fit alignment needs.

Previously, this computation was coupled with adding packs from
the existing multi-pack-index and the remaining packs in the object
dir not already covered by the multi-pack-index.

In anticipation of this becoming more complicated with the 'expire'
subcommand, simplify the computation by centralizing it to a single
loop before writing the file.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 midx.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/midx.c b/midx.c
index 3b7da1a360..62404620ad 100644
--- a/midx.c
+++ b/midx.c
@@ -433,7 +433,6 @@ struct pack_list {
 	uint32_t nr;
 	uint32_t alloc_list;
 	uint32_t alloc_names;
-	size_t pack_name_concat_len;
 	struct multi_pack_index *m;
 };
 
@@ -468,7 +467,6 @@ static void add_pack_to_midx(const char *full_path, size_t full_path_len,
 		}
 
 		packs->names[packs->nr] = xstrdup(file_name);
-		packs->pack_name_concat_len += strlen(file_name) + 1;
 		packs->nr++;
 	}
 }
@@ -812,6 +810,7 @@ int write_midx_file(const char *object_dir)
 	uint32_t nr_entries, num_large_offsets = 0;
 	struct pack_midx_entry *entries = NULL;
 	int large_offsets_needed = 0;
+	int pack_name_concat_len = 0;
 
 	midx_name = get_midx_filename(object_dir);
 	if (safe_create_leading_directories(midx_name)) {
@@ -827,7 +826,6 @@ int write_midx_file(const char *object_dir)
 	packs.alloc_names = packs.alloc_list;
 	packs.list = NULL;
 	packs.names = NULL;
-	packs.pack_name_concat_len = 0;
 	ALLOC_ARRAY(packs.list, packs.alloc_list);
 	ALLOC_ARRAY(packs.names, packs.alloc_names);
 
@@ -838,7 +836,6 @@ int write_midx_file(const char *object_dir)
 
 			packs.list[packs.nr] = NULL;
 			packs.names[packs.nr] = xstrdup(packs.m->pack_names[i]);
-			packs.pack_name_concat_len += strlen(packs.names[packs.nr]) + 1;
 			packs.nr++;
 		}
 	}
@@ -848,10 +845,6 @@ int write_midx_file(const char *object_dir)
 	if (packs.m && packs.nr == packs.m->num_packs)
 		goto cleanup;
 
-	if (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT)
-		packs.pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
-					      (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT);
-
 	ALLOC_ARRAY(pack_perm, packs.nr);
 	sort_packs_by_name(packs.names, packs.nr, pack_perm);
 
@@ -864,6 +857,13 @@ int write_midx_file(const char *object_dir)
 			large_offsets_needed = 1;
 	}
 
+	for (i = 0; i < packs.nr; i++)
+		pack_name_concat_len += strlen(packs.names[i]) + 1;
+
+	if (pack_name_concat_len % MIDX_CHUNK_ALIGNMENT)
+		pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
+					(pack_name_concat_len % MIDX_CHUNK_ALIGNMENT);
+
 	hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
 	f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 	FREE_AND_NULL(midx_name);
@@ -881,7 +881,7 @@ int write_midx_file(const char *object_dir)
 
 	cur_chunk++;
 	chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDFANOUT;
-	chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + packs.pack_name_concat_len;
+	chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + pack_name_concat_len;
 
 	cur_chunk++;
 	chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
-- 
gitgitgadget


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH 06/11] multi-pack-index: implement 'expire' subcommand
  2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
                   ` (4 preceding siblings ...)
  2019-06-10 23:35 ` [PATCH 04/11] midx: simplify computation of pack name lengths Derrick Stolee via GitGitGadget
@ 2019-06-10 23:35 ` Derrick Stolee via GitGitGadget
  2019-06-11 18:51   ` Junio C Hamano
  2019-06-10 23:35 ` [PATCH 07/11] multi-pack-index: prepare 'repack' subcommand Derrick Stolee via GitGitGadget
                   ` (4 subsequent siblings)
  10 siblings, 1 reply; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git
  Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano,
	Derrick Stolee

From: Derrick Stolee <dstolee@microsoft.com>

The 'git multi-pack-index expire' subcommand looks at the existing
mult-pack-index, counts the number of objects referenced in each
pack-file, deletes the pack-fils with no referenced objects, and
rewrites the multi-pack-index to no longer reference those packs.

Refactor the write_midx_file() method to call write_midx_internal()
which now takes an existing 'struct multi_pack_index' and a list
of pack-files to drop (as specified by the names of their pack-
indexes). As we write the new multi-pack-index, we drop those
file names from the list of known pack-files.

The expire_midx_packs() method removes the unreferenced pack-files
after carefully closing the packs to avoid open handles.

Test that a new pack-file that covers the contents of two other
pack-files leads to those pack-files being deleted during the
expire subcommand. Be sure to read the multi-pack-index to ensure
it no longer references those packs.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 midx.c                      | 119 +++++++++++++++++++++++++++++++++---
 t/t5319-multi-pack-index.sh |  20 ++++++
 2 files changed, 129 insertions(+), 10 deletions(-)

diff --git a/midx.c b/midx.c
index 6d4b84e243..9b0b4c1520 100644
--- a/midx.c
+++ b/midx.c
@@ -34,6 +34,8 @@
 #define MIDX_CHUNK_LARGE_OFFSET_WIDTH (sizeof(uint64_t))
 #define MIDX_LARGE_OFFSET_NEEDED 0x80000000
 
+#define PACK_EXPIRED UINT_MAX
+
 static char *get_midx_filename(const char *object_dir)
 {
 	return xstrfmt("%s/pack/multi-pack-index", object_dir);
@@ -431,6 +433,7 @@ struct pack_info {
 	uint32_t orig_pack_int_id;
 	char *pack_name;
 	struct packed_git *p;
+	unsigned expired : 1;
 };
 
 static int pack_info_compare(const void *_a, const void *_b)
@@ -478,6 +481,7 @@ static void add_pack_to_midx(const char *full_path, size_t full_path_len,
 
 		packs->info[packs->nr].pack_name = xstrdup(file_name);
 		packs->info[packs->nr].orig_pack_int_id = packs->nr;
+		packs->info[packs->nr].expired = 0;
 		packs->nr++;
 	}
 }
@@ -637,13 +641,17 @@ static size_t write_midx_pack_names(struct hashfile *f,
 	size_t written = 0;
 
 	for (i = 0; i < num_packs; i++) {
-		size_t writelen = strlen(info[i].pack_name) + 1;
+		size_t writelen;
+
+		if (info[i].expired)
+			continue;
 
 		if (i && strcmp(info[i].pack_name, info[i - 1].pack_name) <= 0)
 			BUG("incorrect pack-file order: %s before %s",
 			    info[i - 1].pack_name,
 			    info[i].pack_name);
 
+		writelen = strlen(info[i].pack_name) + 1;
 		hashwrite(f, info[i].pack_name, writelen);
 		written += writelen;
 	}
@@ -725,6 +733,11 @@ static size_t write_midx_object_offsets(struct hashfile *f, int large_offset_nee
 	for (i = 0; i < nr_objects; i++) {
 		struct pack_midx_entry *obj = list++;
 
+		if (perm[obj->pack_int_id] == PACK_EXPIRED)
+			BUG("object %s is in an expired pack with int-id %d",
+			    oid_to_hex(&obj->oid),
+			    obj->pack_int_id);
+
 		hashwrite_be32(f, perm[obj->pack_int_id]);
 
 		if (large_offset_needed && obj->offset >> 31)
@@ -771,7 +784,8 @@ static size_t write_midx_large_offsets(struct hashfile *f, uint32_t nr_large_off
 	return written;
 }
 
-int write_midx_file(const char *object_dir)
+static int write_midx_internal(const char *object_dir, struct multi_pack_index *m,
+			       struct string_list *packs_to_drop)
 {
 	unsigned char cur_chunk, num_chunks = 0;
 	char *midx_name;
@@ -787,6 +801,8 @@ int write_midx_file(const char *object_dir)
 	struct pack_midx_entry *entries = NULL;
 	int large_offsets_needed = 0;
 	int pack_name_concat_len = 0;
+	int dropped_packs = 0;
+	int result = 0;
 
 	midx_name = get_midx_filename(object_dir);
 	if (safe_create_leading_directories(midx_name)) {
@@ -795,7 +811,10 @@ int write_midx_file(const char *object_dir)
 			  midx_name);
 	}
 
-	packs.m = load_multi_pack_index(object_dir, 1);
+	if (m)
+		packs.m = m;
+	else
+		packs.m = load_multi_pack_index(object_dir, 1);
 
 	packs.nr = 0;
 	packs.alloc = packs.m ? packs.m->num_packs : 16;
@@ -809,13 +828,14 @@ int write_midx_file(const char *object_dir)
 			packs.info[packs.nr].orig_pack_int_id = i;
 			packs.info[packs.nr].pack_name = xstrdup(packs.m->pack_names[i]);
 			packs.info[packs.nr].p = NULL;
+			packs.info[packs.nr].expired = 0;
 			packs.nr++;
 		}
 	}
 
 	for_each_file_in_pack_dir(object_dir, add_pack_to_midx, &packs);
 
-	if (packs.m && packs.nr == packs.m->num_packs)
+	if (packs.m && packs.nr == packs.m->num_packs && !packs_to_drop)
 		goto cleanup;
 
 	entries = get_sorted_entries(packs.m, packs.info, packs.nr, &nr_entries);
@@ -829,6 +849,34 @@ int write_midx_file(const char *object_dir)
 
 	QSORT(packs.info, packs.nr, pack_info_compare);
 
+	if (packs_to_drop && packs_to_drop->nr) {
+		int drop_index = 0;
+		int missing_drops = 0;
+
+		for (i = 0; i < packs.nr && drop_index < packs_to_drop->nr; i++) {
+			int cmp = strcmp(packs.info[i].pack_name,
+					 packs_to_drop->items[drop_index].string);
+
+			if (!cmp) {
+				drop_index++;
+				packs.info[i].expired = 1;
+			} else if (cmp > 0) {
+				error(_("did not see pack-file %s to drop"),
+				      packs_to_drop->items[drop_index].string);
+				drop_index++;
+				missing_drops++;
+				i--;
+			} else {
+				packs.info[i].expired = 0;
+			}
+		}
+
+		if (missing_drops) {
+			result = 1;
+			goto cleanup;
+		}
+	}
+
 	/*
 	 * pack_perm stores a permutation between pack-int-ids from the
 	 * previous multi-pack-index to the new one we are writing:
@@ -837,11 +885,18 @@ int write_midx_file(const char *object_dir)
 	 */
 	ALLOC_ARRAY(pack_perm, packs.nr);
 	for (i = 0; i < packs.nr; i++) {
-		pack_perm[packs.info[i].orig_pack_int_id] = i;
+		if (packs.info[i].expired) {
+			dropped_packs++;
+			pack_perm[packs.info[i].orig_pack_int_id] = PACK_EXPIRED;
+		} else {
+			pack_perm[packs.info[i].orig_pack_int_id] = i - dropped_packs;
+		}
 	}
 
-	for (i = 0; i < packs.nr; i++)
-		pack_name_concat_len += strlen(packs.info[i].pack_name) + 1;
+	for (i = 0; i < packs.nr; i++) {
+		if (!packs.info[i].expired)
+			pack_name_concat_len += strlen(packs.info[i].pack_name) + 1;
+	}
 
 	if (pack_name_concat_len % MIDX_CHUNK_ALIGNMENT)
 		pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
@@ -857,7 +912,7 @@ int write_midx_file(const char *object_dir)
 	cur_chunk = 0;
 	num_chunks = large_offsets_needed ? 5 : 4;
 
-	written = write_midx_header(f, num_chunks, packs.nr);
+	written = write_midx_header(f, num_chunks, packs.nr - dropped_packs);
 
 	chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKNAMES;
 	chunk_offsets[cur_chunk] = written + (num_chunks + 1) * MIDX_CHUNKLOOKUP_WIDTH;
@@ -958,7 +1013,12 @@ int write_midx_file(const char *object_dir)
 	free(entries);
 	free(pack_perm);
 	free(midx_name);
-	return 0;
+	return result;
+}
+
+int write_midx_file(const char *object_dir)
+{
+	return write_midx_internal(object_dir, NULL, NULL);
 }
 
 void clear_midx_file(struct repository *r)
@@ -1125,5 +1185,44 @@ int verify_midx_file(struct repository *r, const char *object_dir)
 
 int expire_midx_packs(struct repository *r, const char *object_dir)
 {
-	return 0;
+	uint32_t i, *count, result = 0;
+	struct string_list packs_to_drop = STRING_LIST_INIT_DUP;
+	struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
+
+	if (!m)
+		return 0;
+
+	count = xcalloc(m->num_packs, sizeof(uint32_t));
+	for (i = 0; i < m->num_objects; i++) {
+		int pack_int_id = nth_midxed_pack_int_id(m, i);
+		count[pack_int_id]++;
+	}
+
+	for (i = 0; i < m->num_packs; i++) {
+		char *pack_name;
+
+		if (count[i])
+			continue;
+
+		if (prepare_midx_pack(r, m, i))
+			continue;
+
+		if (m->packs[i]->pack_keep)
+			continue;
+
+		pack_name = xstrdup(m->packs[i]->pack_name);
+		close_pack(m->packs[i]);
+
+		string_list_insert(&packs_to_drop, m->pack_names[i]);
+		unlink_pack_path(pack_name, 0);
+		free(pack_name);
+	}
+
+	free(count);
+
+	if (packs_to_drop.nr)
+		result = write_midx_internal(object_dir, m, &packs_to_drop);
+
+	string_list_clear(&packs_to_drop, 0);
+	return result;
 }
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 1b2d32f475..12570fe7ac 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -412,4 +412,24 @@ test_expect_success 'expire does not remove any packs' '
 	)
 '
 
+test_expect_success 'expire removes unreferenced packs' '
+	(
+		cd dup &&
+		git pack-objects --revs .git/objects/pack/pack-combined <<-EOF &&
+		refs/heads/A
+		^refs/heads/C
+		EOF
+		git multi-pack-index write &&
+		ls .git/objects/pack | grep -v -e pack-[AB] >expect &&
+		git multi-pack-index expire &&
+		ls .git/objects/pack >actual &&
+		test_cmp expect actual &&
+		ls .git/objects/pack/ | grep idx >expect-idx &&
+		test-tool read-midx .git/objects | grep idx >actual-midx &&
+		test_cmp expect-idx actual-midx &&
+		git multi-pack-index verify &&
+		git fsck
+	)
+'
+
 test_done
-- 
gitgitgadget


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH 07/11] multi-pack-index: prepare 'repack' subcommand
  2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
                   ` (5 preceding siblings ...)
  2019-06-10 23:35 ` [PATCH 06/11] multi-pack-index: implement 'expire' subcommand Derrick Stolee via GitGitGadget
@ 2019-06-10 23:35 ` Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 09/11] multi-pack-index: test expire while adding packs Derrick Stolee via GitGitGadget
                   ` (3 subsequent siblings)
  10 siblings, 0 replies; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git
  Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano,
	Derrick Stolee

From: Derrick Stolee <dstolee@microsoft.com>

In an environment where the multi-pack-index is useful, it is due
to many pack-files and an inability to repack the object store
into a single pack-file. However, it is likely that many of these
pack-files are rather small, and could be repacked into a slightly
larger pack-file without too much effort. It may also be important
to ensure the object store is highly available and the repack
operation does not interrupt concurrent git commands.

Introduce a 'repack' subcommand to 'git multi-pack-index' that
takes a '--batch-size' option. The subcommand will inspect the
multi-pack-index for referenced pack-files whose size is smaller
than the batch size, until collecting a list of pack-files whose
sizes sum to larger than the batch size. Then, a new pack-file
will be created containing the objects from those pack-files that
are referenced by the multi-pack-index. The resulting pack is
likely to actually be smaller than the batch size due to
compression and the fact that there may be objects in the pack-
files that have duplicate copies in other pack-files.

The current change introduces the command-line arguments, and we
add a test that ensures we parse these options properly. Since
we specify a small batch size, we will guarantee that future
implementations do not change the list of pack-files.

In addition, we hard-code the modified times of the packs in
the pack directory to ensure the list of packs sorted by modified
time matches the order if sorted by size (ascending). This will
be important in a future test.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 Documentation/git-multi-pack-index.txt | 17 +++++++++++++++++
 builtin/multi-pack-index.c             | 12 ++++++++++--
 midx.c                                 |  5 +++++
 midx.h                                 |  1 +
 t/t5319-multi-pack-index.sh            | 20 +++++++++++++++++++-
 5 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-multi-pack-index.txt b/Documentation/git-multi-pack-index.txt
index 6186c4c936..233b2b7862 100644
--- a/Documentation/git-multi-pack-index.txt
+++ b/Documentation/git-multi-pack-index.txt
@@ -36,6 +36,23 @@ expire::
 	have no objects referenced by the MIDX. Rewrite the MIDX file
 	afterward to remove all references to these pack-files.
 
+repack::
+	Create a new pack-file containing objects in small pack-files
+	referenced by the multi-pack-index. If the size given by the
+	`--batch-size=<size>` argument is zero, then create a pack
+	containing all objects referenced by the multi-pack-index. For
+	a non-zero batch size, Select the pack-files by examining packs
+	from oldest-to-newest, computing the "expected size" by counting
+	the number of objects in the pack referenced by the
+	multi-pack-index, then divide by the total number of objects in
+	the pack and multiply by the pack size. We select packs with
+	expected size below the batch size until the set of packs have
+	total expected size at least the batch size. If the total size
+	does not reach the batch size, then do nothing. If a new pack-
+	file is created, rewrite the multi-pack-index to reference the
+	new pack-file. A later run of 'git multi-pack-index expire' will
+	delete the pack-files that were part of this batch.
+
 
 EXAMPLES
 --------
diff --git a/builtin/multi-pack-index.c b/builtin/multi-pack-index.c
index ad10d40512..b1ea1a6aa1 100644
--- a/builtin/multi-pack-index.c
+++ b/builtin/multi-pack-index.c
@@ -6,12 +6,13 @@
 #include "trace2.h"
 
 static char const * const builtin_multi_pack_index_usage[] = {
-	N_("git multi-pack-index [--object-dir=<dir>] (write|verify|expire)"),
+	N_("git multi-pack-index [--object-dir=<dir>] (write|verify|expire|repack --batch-size=<size>)"),
 	NULL
 };
 
 static struct opts_multi_pack_index {
 	const char *object_dir;
+	unsigned long batch_size;
 } opts;
 
 int cmd_multi_pack_index(int argc, const char **argv,
@@ -20,6 +21,8 @@ int cmd_multi_pack_index(int argc, const char **argv,
 	static struct option builtin_multi_pack_index_options[] = {
 		OPT_FILENAME(0, "object-dir", &opts.object_dir,
 		  N_("object directory containing set of packfile and pack-index pairs")),
+		OPT_MAGNITUDE(0, "batch-size", &opts.batch_size,
+		  N_("during repack, collect pack-files of smaller size into a batch that is larger than this size")),
 		OPT_END(),
 	};
 
@@ -43,6 +46,11 @@ int cmd_multi_pack_index(int argc, const char **argv,
 
 	trace2_cmd_mode(argv[0]);
 
+	if (!strcmp(argv[0], "repack"))
+		return midx_repack(the_repository, opts.object_dir, (size_t)opts.batch_size);
+	if (opts.batch_size)
+		die(_("--batch-size option is only for 'repack' subcommand"));
+
 	if (!strcmp(argv[0], "write"))
 		return write_midx_file(opts.object_dir);
 	if (!strcmp(argv[0], "verify"))
@@ -50,5 +58,5 @@ int cmd_multi_pack_index(int argc, const char **argv,
 	if (!strcmp(argv[0], "expire"))
 		return expire_midx_packs(the_repository, opts.object_dir);
 
-	die(_("unrecognized verb: %s"), argv[0]);
+	die(_("unrecognized subcommand: %s"), argv[0]);
 }
diff --git a/midx.c b/midx.c
index 9b0b4c1520..fbed8a8adb 100644
--- a/midx.c
+++ b/midx.c
@@ -1226,3 +1226,8 @@ int expire_midx_packs(struct repository *r, const char *object_dir)
 	string_list_clear(&packs_to_drop, 0);
 	return result;
 }
+
+int midx_repack(struct repository *r, const char *object_dir, size_t batch_size)
+{
+	return 0;
+}
diff --git a/midx.h b/midx.h
index 505f1431b7..f0ae656b5d 100644
--- a/midx.h
+++ b/midx.h
@@ -51,6 +51,7 @@ int write_midx_file(const char *object_dir);
 void clear_midx_file(struct repository *r);
 int verify_midx_file(struct repository *r, const char *object_dir);
 int expire_midx_packs(struct repository *r, const char *object_dir);
+int midx_repack(struct repository *r, const char *object_dir, size_t batch_size);
 
 void close_midx(struct multi_pack_index *m);
 
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 12570fe7ac..133d5b7068 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -398,7 +398,8 @@ test_expect_success 'setup expire tests' '
 		git pack-objects --revs .git/objects/pack/pack-E <<-EOF &&
 		refs/heads/E
 		EOF
-		git multi-pack-index write
+		git multi-pack-index write &&
+		cp -r .git/objects/pack .git/objects/pack-backup
 	)
 '
 
@@ -432,4 +433,21 @@ test_expect_success 'expire removes unreferenced packs' '
 	)
 '
 
+test_expect_success 'repack with minimum size does not alter existing packs' '
+	(
+		cd dup &&
+		rm -rf .git/objects/pack &&
+		mv .git/objects/pack-backup .git/objects/pack &&
+		touch -m -t 201901010000 .git/objects/pack/pack-D* &&
+		touch -m -t 201901010001 .git/objects/pack/pack-C* &&
+		touch -m -t 201901010002 .git/objects/pack/pack-B* &&
+		touch -m -t 201901010003 .git/objects/pack/pack-A* &&
+		ls .git/objects/pack >expect &&
+		MINSIZE=$(ls -l .git/objects/pack/*pack | awk "{print \$5;}" | sort -n | head -n 1) &&
+		git multi-pack-index repack --batch-size=$MINSIZE &&
+		ls .git/objects/pack >actual &&
+		test_cmp expect actual
+	)
+'
+
 test_done
-- 
gitgitgadget


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH 08/11] midx: implement midx_repack()
  2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
                   ` (7 preceding siblings ...)
  2019-06-10 23:35 ` [PATCH 09/11] multi-pack-index: test expire while adding packs Derrick Stolee via GitGitGadget
@ 2019-06-10 23:35 ` Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 10/11] midx: add test that 'expire' respects .keep files Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 11/11] t5319-multi-pack-index.sh: test batch size zero Derrick Stolee via GitGitGadget
  10 siblings, 0 replies; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git
  Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano,
	Derrick Stolee

From: Derrick Stolee <dstolee@microsoft.com>

To repack with a non-zero batch-size, first sort all pack-files by
their modified time. Second, walk those pack-files from oldest
to newest, compute their expected size, and add the packs to a list
if they are smaller than the given batch-size. Stop when the total
expected size is at least the batch size.

If the batch size is zero, select all packs in the multi-pack-index.

Finally, collect the objects from the multi-pack-index that are in
the selected packs and send them to 'git pack-objects'. Write a new
multi-pack-index that includes the new pack.

Using a batch size of zero is very similar to a standard 'git repack'
command, except that we do not delete the old packs and instead rely
on the new multi-pack-index to prevent new processes from reading the
old packs. This does not disrupt other Git processes that are currently
reading the old packs based on the old multi-pack-index.

While first designing a 'git multi-pack-index repack' operation, I
started by collecting the batches based on the actual size of the
objects instead of the size of the pack-files. This allows repacking
a large pack-file that has very few referencd objects. However, this
came at a significant cost of parsing pack-files instead of simply
reading the multi-pack-index and getting the file information for
the pack-files. The "expected size" version provides similar
behavior, but could skip a pack-file if the average object size is
much larger than the actual size of the referenced objects, or
can create a large pack if the actual size of the referenced objects
is larger than the expected size.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 midx.c                      | 151 +++++++++++++++++++++++++++++++++++-
 t/t5319-multi-pack-index.sh |  28 +++++++
 2 files changed, 178 insertions(+), 1 deletion(-)

diff --git a/midx.c b/midx.c
index fbed8a8adb..d649644420 100644
--- a/midx.c
+++ b/midx.c
@@ -9,6 +9,7 @@
 #include "midx.h"
 #include "progress.h"
 #include "trace2.h"
+#include "run-command.h"
 
 #define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
 #define MIDX_VERSION 1
@@ -1227,7 +1228,155 @@ int expire_midx_packs(struct repository *r, const char *object_dir)
 	return result;
 }
 
-int midx_repack(struct repository *r, const char *object_dir, size_t batch_size)
+struct repack_info {
+	timestamp_t mtime;
+	uint32_t referenced_objects;
+	uint32_t pack_int_id;
+};
+
+static int compare_by_mtime(const void *a_, const void *b_)
 {
+	const struct repack_info *a, *b;
+
+	a = (const struct repack_info *)a_;
+	b = (const struct repack_info *)b_;
+
+	if (a->mtime < b->mtime)
+		return -1;
+	if (a->mtime > b->mtime)
+		return 1;
+	return 0;
+}
+
+static int fill_included_packs_all(struct multi_pack_index *m,
+				   unsigned char *include_pack)
+{
+	uint32_t i;
+
+	for (i = 0; i < m->num_packs; i++)
+		include_pack[i] = 1;
+
+	return m->num_packs < 2;
+}
+
+static int fill_included_packs_batch(struct repository *r,
+				     struct multi_pack_index *m,
+				     unsigned char *include_pack,
+				     size_t batch_size)
+{
+	uint32_t i, packs_to_repack;
+	size_t total_size;
+	struct repack_info *pack_info = xcalloc(m->num_packs, sizeof(struct repack_info));
+
+	for (i = 0; i < m->num_packs; i++) {
+		pack_info[i].pack_int_id = i;
+
+		if (prepare_midx_pack(r, m, i))
+			continue;
+
+		pack_info[i].mtime = m->packs[i]->mtime;
+	}
+
+	for (i = 0; batch_size && i < m->num_objects; i++) {
+		uint32_t pack_int_id = nth_midxed_pack_int_id(m, i);
+		pack_info[pack_int_id].referenced_objects++;
+	}
+
+	QSORT(pack_info, m->num_packs, compare_by_mtime);
+
+	total_size = 0;
+	packs_to_repack = 0;
+	for (i = 0; total_size < batch_size && i < m->num_packs; i++) {
+		int pack_int_id = pack_info[i].pack_int_id;
+		struct packed_git *p = m->packs[pack_int_id];
+		size_t expected_size;
+
+		if (!p)
+			continue;
+		if (open_pack_index(p) || !p->num_objects)
+			continue;
+
+		expected_size = (size_t)(p->pack_size
+					 * pack_info[i].referenced_objects);
+		expected_size /= p->num_objects;
+
+		if (expected_size >= batch_size)
+			continue;
+
+		packs_to_repack++;
+		total_size += expected_size;
+		include_pack[pack_int_id] = 1;
+	}
+
+	free(pack_info);
+
+	if (total_size < batch_size || packs_to_repack < 2)
+		return 1;
+
 	return 0;
 }
+
+int midx_repack(struct repository *r, const char *object_dir, size_t batch_size)
+{
+	int result = 0;
+	uint32_t i;
+	unsigned char *include_pack;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	struct strbuf base_name = STRBUF_INIT;
+	struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
+
+	if (!m)
+		return 0;
+
+	include_pack = xcalloc(m->num_packs, sizeof(unsigned char));
+
+	if (batch_size) {
+		if (fill_included_packs_batch(r, m, include_pack, batch_size))
+			goto cleanup;
+	} else if (fill_included_packs_all(m, include_pack))
+		goto cleanup;
+
+	argv_array_push(&cmd.args, "pack-objects");
+
+	strbuf_addstr(&base_name, object_dir);
+	strbuf_addstr(&base_name, "/pack/pack");
+	argv_array_push(&cmd.args, base_name.buf);
+	strbuf_release(&base_name);
+
+	cmd.git_cmd = 1;
+	cmd.in = cmd.out = -1;
+
+	if (start_command(&cmd)) {
+		error(_("could not start pack-objects"));
+		result = 1;
+		goto cleanup;
+	}
+
+	for (i = 0; i < m->num_objects; i++) {
+		struct object_id oid;
+		uint32_t pack_int_id = nth_midxed_pack_int_id(m, i);
+
+		if (!include_pack[pack_int_id])
+			continue;
+
+		nth_midxed_object_oid(&oid, m, i);
+		xwrite(cmd.in, oid_to_hex(&oid), the_hash_algo->hexsz);
+		xwrite(cmd.in, "\n", 1);
+	}
+	close(cmd.in);
+
+	if (finish_command(&cmd)) {
+		error(_("could not finish pack-objects"));
+		result = 1;
+		goto cleanup;
+	}
+
+	result = write_midx_internal(object_dir, m, NULL);
+	m = NULL;
+
+cleanup:
+	if (m)
+		close_midx(m);
+	free(include_pack);
+	return result;
+}
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 133d5b7068..6e47e5d0b2 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -450,4 +450,32 @@ test_expect_success 'repack with minimum size does not alter existing packs' '
 	)
 '
 
+test_expect_success 'repack creates a new pack' '
+	(
+		cd dup &&
+		ls .git/objects/pack/*idx >idx-list &&
+		test_line_count = 5 idx-list &&
+		THIRD_SMALLEST_SIZE=$(ls -l .git/objects/pack/*pack | awk "{print \$5;}" | sort -n | head -n 3 | tail -n 1) &&
+		BATCH_SIZE=$(($THIRD_SMALLEST_SIZE + 1)) &&
+		git multi-pack-index repack --batch-size=$BATCH_SIZE &&
+		ls .git/objects/pack/*idx >idx-list &&
+		test_line_count = 6 idx-list &&
+		test-tool read-midx .git/objects | grep idx >midx-list &&
+		test_line_count = 6 midx-list
+	)
+'
+
+test_expect_success 'expire removes repacked packs' '
+	(
+		cd dup &&
+		ls -al .git/objects/pack/*pack &&
+		ls -S .git/objects/pack/*pack | head -n 4 >expect &&
+		git multi-pack-index expire &&
+		ls -S .git/objects/pack/*pack >actual &&
+		test_cmp expect actual &&
+		test-tool read-midx .git/objects | grep idx >midx-list &&
+		test_line_count = 4 midx-list
+	)
+'
+
 test_done
-- 
gitgitgadget


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH 09/11] multi-pack-index: test expire while adding packs
  2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
                   ` (6 preceding siblings ...)
  2019-06-10 23:35 ` [PATCH 07/11] multi-pack-index: prepare 'repack' subcommand Derrick Stolee via GitGitGadget
@ 2019-06-10 23:35 ` Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 08/11] midx: implement midx_repack() Derrick Stolee via GitGitGadget
                   ` (2 subsequent siblings)
  10 siblings, 0 replies; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git
  Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano,
	Derrick Stolee

From: Derrick Stolee <dstolee@microsoft.com>

During development of the multi-pack-index expire subcommand, a
version went out that improperly computed the pack order if a new
pack was introduced while other packs were being removed. Part of
the subtlety of the bug involved the new pack being placed before
other packs that already existed in the multi-pack-index.

Add a test to t5319-multi-pack-index.sh that catches this issue.
The test adds new packs that cause another pack to be expired, and
creates new packs that are lexicographically sorted before and
after the existing packs.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 t/t5319-multi-pack-index.sh | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 6e47e5d0b2..8e04ce2821 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -478,4 +478,36 @@ test_expect_success 'expire removes repacked packs' '
 	)
 '
 
+test_expect_success 'expire works when adding new packs' '
+	(
+		cd dup &&
+		git pack-objects --revs .git/objects/pack/pack-combined <<-EOF &&
+		refs/heads/A
+		^refs/heads/B
+		EOF
+		git pack-objects --revs .git/objects/pack/pack-combined <<-EOF &&
+		refs/heads/B
+		^refs/heads/C
+		EOF
+		git pack-objects --revs .git/objects/pack/pack-combined <<-EOF &&
+		refs/heads/C
+		^refs/heads/D
+		EOF
+		git multi-pack-index write &&
+		git pack-objects --revs .git/objects/pack/a-pack <<-EOF &&
+		refs/heads/D
+		^refs/heads/E
+		EOF
+		git multi-pack-index write &&
+		git pack-objects --revs .git/objects/pack/z-pack <<-EOF &&
+		refs/heads/E
+		EOF
+		git multi-pack-index expire &&
+		ls .git/objects/pack/ | grep idx >expect &&
+		test-tool read-midx .git/objects | grep idx >actual &&
+		test_cmp expect actual &&
+		git multi-pack-index verify
+	)
+'
+
 test_done
-- 
gitgitgadget


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH 10/11] midx: add test that 'expire' respects .keep files
  2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
                   ` (8 preceding siblings ...)
  2019-06-10 23:35 ` [PATCH 08/11] midx: implement midx_repack() Derrick Stolee via GitGitGadget
@ 2019-06-10 23:35 ` Derrick Stolee via GitGitGadget
  2019-06-10 23:35 ` [PATCH 11/11] t5319-multi-pack-index.sh: test batch size zero Derrick Stolee via GitGitGadget
  10 siblings, 0 replies; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git
  Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano,
	Derrick Stolee

From: Derrick Stolee <dstolee@microsoft.com>

The 'git multi-pack-index expire' subcommand may delete packs that
are not needed from the perspective of the multi-pack-index. If
a pack has a .keep file, then we should not delete that pack. Add
a test that ensures we preserve a pack that would otherwise be
expired. First, create a new pack that contains every object in
the repo, then add it to the multi-pack-index. Then create a .keep
file for a pack starting with "a-pack" that was added in the
previous test. Finally, expire and verify that the pack remains
and the other packs were expired.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 t/t5319-multi-pack-index.sh | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 8e04ce2821..c288901401 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -510,4 +510,22 @@ test_expect_success 'expire works when adding new packs' '
 	)
 '
 
+test_expect_success 'expire respects .keep files' '
+	(
+		cd dup &&
+		git pack-objects --revs .git/objects/pack/pack-all <<-EOF &&
+		refs/heads/A
+		EOF
+		git multi-pack-index write &&
+		PACKA=$(ls .git/objects/pack/a-pack*\.pack | sed s/\.pack\$//) &&
+		touch $PACKA.keep &&
+		git multi-pack-index expire &&
+		ls -S .git/objects/pack/a-pack* | grep $PACKA >a-pack-files &&
+		test_line_count = 3 a-pack-files &&
+		test-tool read-midx .git/objects | grep idx >midx-list &&
+		test_line_count = 2 midx-list
+	)
+'
+
+
 test_done
-- 
gitgitgadget


^ permalink raw reply	[flat|nested] 13+ messages in thread

* [PATCH 11/11] t5319-multi-pack-index.sh: test batch size zero
  2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
                   ` (9 preceding siblings ...)
  2019-06-10 23:35 ` [PATCH 10/11] midx: add test that 'expire' respects .keep files Derrick Stolee via GitGitGadget
@ 2019-06-10 23:35 ` Derrick Stolee via GitGitGadget
  10 siblings, 0 replies; 13+ messages in thread
From: Derrick Stolee via GitGitGadget @ 2019-06-10 23:35 UTC (permalink / raw)
  To: git
  Cc: sbeller, peff, jrnieder, avarab, jonathantanmy, Junio C Hamano,
	Derrick Stolee

From: Derrick Stolee <dstolee@microsoft.com>

The 'git multi-pack-index repack' command can take a batch size of
zero, which creates a new pack-file containing all objects in the
multi-pack-index. The first 'repack' command will create one new
pack-file, and an 'expire' command after that will delete the old
pack-files, as they no longer contain any referenced objects in the
multi-pack-index.

We must remove the .keep file that was added in the previous test
in order to expire that pack-file.

Also test that a 'repack' will do nothing if there is only one
pack-file.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 t/t5319-multi-pack-index.sh | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index c288901401..79bfaeafa9 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -527,5 +527,24 @@ test_expect_success 'expire respects .keep files' '
 	)
 '
 
+test_expect_success 'repack --batch-size=0 repacks everything' '
+	(
+		cd dup &&
+		rm .git/objects/pack/*.keep &&
+		ls .git/objects/pack/*idx >idx-list &&
+		test_line_count = 2 idx-list &&
+		git multi-pack-index repack --batch-size=0 &&
+		ls .git/objects/pack/*idx >idx-list &&
+		test_line_count = 3 idx-list &&
+		test-tool read-midx .git/objects | grep idx >midx-list &&
+		test_line_count = 3 midx-list &&
+		git multi-pack-index expire &&
+		ls -al .git/objects/pack/*idx >idx-list &&
+		test_line_count = 1 idx-list &&
+		git multi-pack-index repack --batch-size=0 &&
+		ls -al .git/objects/pack/*idx >new-idx-list &&
+		test_cmp idx-list new-idx-list
+	)
+'
 
 test_done
-- 
gitgitgadget

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH 06/11] multi-pack-index: implement 'expire' subcommand
  2019-06-10 23:35 ` [PATCH 06/11] multi-pack-index: implement 'expire' subcommand Derrick Stolee via GitGitGadget
@ 2019-06-11 18:51   ` Junio C Hamano
  0 siblings, 0 replies; 13+ messages in thread
From: Junio C Hamano @ 2019-06-11 18:51 UTC (permalink / raw)
  To: Derrick Stolee via GitGitGadget
  Cc: git, sbeller, peff, jrnieder, avarab, jonathantanmy, Derrick Stolee

"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Derrick Stolee <dstolee@microsoft.com>
>
> The 'git multi-pack-index expire' subcommand looks at the existing
> mult-pack-index, counts the number of objects referenced in each

s/mult/&i/

> pack-file, deletes the pack-fils with no referenced objects, and

s/fils/files/

> rewrites the multi-pack-index to no longer reference those packs.

As we do *not* want to expire a packfile that was created after the
last run of "git multi-pack-index write", "... in each pack-file" in
the above paragraph is a bit tricky.  It cannot literally be "in
each packfile", but a subset of all existing packfiles that are
known to the midx we are looking at.

An obvious alternative is to actually update midx file (so it no
longer "looks at the existing multi-pack-index", but "makes sure we
have up-to-date view of the multi-pack-index that covers all packs).

And I actually suspect that you implemented that alternative here.
IOW, "looks at the existing multi-pack-index" in the first paragraph
is misleading.

I wondered if the error behaviour of add_pack_to_midx() that ignores
a pack that cannot be added to midx for whatever reason can cause
issues, but such a pack would not become part of m->packs[] so it
may not have anything count[]ed from it, but it will not be eligible
for expiration, either.  So we'd be safe there, I think.

> Test that a new pack-file that covers the contents of two other
> pack-files leads to those pack-files being deleted during the
> expire subcommand. Be sure to read the multi-pack-index to ensure
> it no longer references those packs.

I am curious to learn how we guarantee that the midx logic chooses
to record the copy of an object in the new single packfile over the
other copy of the same object in one of the two older and presumably
smaller packfiles for all objects in the latter two packfiles,
because they cannot be expired if even one object were used from
there.

^ permalink raw reply	[flat|nested] 13+ messages in thread

end of thread, back to index

Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-06-10 23:35 [PATCH 00/11] Create 'expire' and 'repack' verbs for git-multi-pack-index Derrick Stolee via GitGitGadget
2019-06-10 23:35 ` [PATCH 02/11] Docs: rearrange subcommands for multi-pack-index Derrick Stolee via GitGitGadget
2019-06-10 23:35 ` [PATCH 01/11] repack: refactor pack deletion for future use Derrick Stolee via GitGitGadget
2019-06-10 23:35 ` [PATCH 03/11] multi-pack-index: prepare for 'expire' subcommand Derrick Stolee via GitGitGadget
2019-06-10 23:35 ` [PATCH 05/11] midx: refactor permutation logic and pack sorting Derrick Stolee via GitGitGadget
2019-06-10 23:35 ` [PATCH 04/11] midx: simplify computation of pack name lengths Derrick Stolee via GitGitGadget
2019-06-10 23:35 ` [PATCH 06/11] multi-pack-index: implement 'expire' subcommand Derrick Stolee via GitGitGadget
2019-06-11 18:51   ` Junio C Hamano
2019-06-10 23:35 ` [PATCH 07/11] multi-pack-index: prepare 'repack' subcommand Derrick Stolee via GitGitGadget
2019-06-10 23:35 ` [PATCH 09/11] multi-pack-index: test expire while adding packs Derrick Stolee via GitGitGadget
2019-06-10 23:35 ` [PATCH 08/11] midx: implement midx_repack() Derrick Stolee via GitGitGadget
2019-06-10 23:35 ` [PATCH 10/11] midx: add test that 'expire' respects .keep files Derrick Stolee via GitGitGadget
2019-06-10 23:35 ` [PATCH 11/11] t5319-multi-pack-index.sh: test batch size zero Derrick Stolee via GitGitGadget

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