From ac86510417a0b1713f5fa34acab547f01b716fd2 Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Fri, 7 Jun 2024 12:18:50 -0400 Subject: [PATCH 1/5] backfill: add builtin boilerplate In anticipation of implementing 'git backfill', populate the necessary files with the boilerplate of a new builtin. Signed-off-by: Derrick Stolee --- .gitignore | 1 + Documentation/git-backfill.txt | 23 +++++++++++++++++++++++ Makefile | 1 + builtin.h | 1 + builtin/backfill.c | 29 +++++++++++++++++++++++++++++ command-list.txt | 1 + git.c | 1 + 7 files changed, 57 insertions(+) create mode 100644 Documentation/git-backfill.txt create mode 100644 builtin/backfill.c diff --git a/.gitignore b/.gitignore index 6687bd6db4c0a6..0f9e7de2ec306d 100644 --- a/.gitignore +++ b/.gitignore @@ -20,6 +20,7 @@ /git-apply /git-archimport /git-archive +/git-backfill /git-bisect /git-blame /git-branch diff --git a/Documentation/git-backfill.txt b/Documentation/git-backfill.txt new file mode 100644 index 00000000000000..640144187d33b7 --- /dev/null +++ b/Documentation/git-backfill.txt @@ -0,0 +1,23 @@ +git-backfill(1) +=============== + +NAME +---- +git-backfill - Download missing objects in a partial clone + + +SYNOPSIS +-------- +[verse] +'git backfill' [] + +DESCRIPTION +----------- + +SEE ALSO +-------- +linkgit:git-clone[1]. + +GIT +--- +Part of the linkgit:git[1] suite diff --git a/Makefile b/Makefile index 50413d964920e7..e18e0f4e447e2f 100644 --- a/Makefile +++ b/Makefile @@ -1203,6 +1203,7 @@ BUILTIN_OBJS += builtin/am.o BUILTIN_OBJS += builtin/annotate.o BUILTIN_OBJS += builtin/apply.o BUILTIN_OBJS += builtin/archive.o +BUILTIN_OBJS += builtin/backfill.o BUILTIN_OBJS += builtin/bisect.o BUILTIN_OBJS += builtin/blame.o BUILTIN_OBJS += builtin/branch.o diff --git a/builtin.h b/builtin.h index f7b166b33484d3..89928ccf92f532 100644 --- a/builtin.h +++ b/builtin.h @@ -120,6 +120,7 @@ int cmd_am(int argc, const char **argv, const char *prefix, struct repository *r int cmd_annotate(int argc, const char **argv, const char *prefix, struct repository *repo); int cmd_apply(int argc, const char **argv, const char *prefix, struct repository *repo); int cmd_archive(int argc, const char **argv, const char *prefix, struct repository *repo); +int cmd_backfill(int argc, const char **argv, const char *prefix, struct repository *repo); int cmd_bisect(int argc, const char **argv, const char *prefix, struct repository *repo); int cmd_blame(int argc, const char **argv, const char *prefix, struct repository *repo); int cmd_branch(int argc, const char **argv, const char *prefix, struct repository *repo); diff --git a/builtin/backfill.c b/builtin/backfill.c new file mode 100644 index 00000000000000..38e6aaeaa030ec --- /dev/null +++ b/builtin/backfill.c @@ -0,0 +1,29 @@ +#include "builtin.h" +#include "config.h" +#include "parse-options.h" +#include "repository.h" +#include "object.h" + +static const char * const builtin_backfill_usage[] = { + N_("git backfill []"), + NULL +}; + +int cmd_backfill(int argc, const char **argv, const char *prefix, struct repository *repo) +{ + struct option options[] = { + OPT_END(), + }; + + if (argc == 2 && !strcmp(argv[1], "-h")) + usage_with_options(builtin_backfill_usage, options); + + argc = parse_options(argc, argv, prefix, options, builtin_backfill_usage, + 0); + + repo_config(repo, git_default_config, NULL); + + die(_("not implemented")); + + return 0; +} diff --git a/command-list.txt b/command-list.txt index e0bb87b3b5c278..c537114b4687b8 100644 --- a/command-list.txt +++ b/command-list.txt @@ -60,6 +60,7 @@ git-annotate ancillaryinterrogators git-apply plumbingmanipulators complete git-archimport foreignscminterface git-archive mainporcelain +git-backfill mainporcelain history git-bisect mainporcelain info git-blame ancillaryinterrogators complete git-branch mainporcelain history diff --git a/git.c b/git.c index 2fbea24ec921e0..00d9b3ec8a9106 100644 --- a/git.c +++ b/git.c @@ -509,6 +509,7 @@ static struct cmd_struct commands[] = { { "annotate", cmd_annotate, RUN_SETUP }, { "apply", cmd_apply, RUN_SETUP_GENTLY }, { "archive", cmd_archive, RUN_SETUP_GENTLY }, + { "backfill", cmd_backfill, RUN_SETUP }, { "bisect", cmd_bisect, RUN_SETUP }, { "blame", cmd_blame, RUN_SETUP }, { "branch", cmd_branch, RUN_SETUP | DELAY_PAGER_CONFIG }, From e4e88794cae7edc568dd054b1376caac7fd30076 Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Sun, 1 Sep 2024 12:07:10 -0400 Subject: [PATCH 2/5] backfill: basic functionality and tests The default behavior of 'git backfill' is to fetch all missing blobs that are reachable from HEAD. Document and test this behavior. The implementation is a very simple use of the path-walk API, initializing the revision walk at HEAD to start the path-walk from all commits reachable from HEAD. Ignore the object arrays that correspond to tree entries, assuming that they are all present already. The path-walk API provides lists of objects in batches according to a common path, but that list could be very small. We want to balance the number of requests to the server with the ability to have the process interrupted with minimal repeated work to catch up in the next run. Based on some experiments (detailed in the next change) a minimum batch size of 50,000 is selected for the default. This batch size is a _minimum_. As the path-walk API emits lists of blob IDs, they are collected into a list of objects for a request to the server. When that list is at least the minimum batch size, then the request is sent to the server for the new objects. However, the list of blob IDs from the path-walk API could be much longer than the batch size. At this moment, it is unclear if there is a benefit to split the list when there are too many objects at the same path. Signed-off-by: Derrick Stolee --- Documentation/git-backfill.txt | 31 +++++++ Documentation/technical/api-path-walk.txt | 3 +- builtin/backfill.c | 106 +++++++++++++++++++++- t/t5620-backfill.sh | 94 +++++++++++++++++++ 4 files changed, 230 insertions(+), 4 deletions(-) create mode 100755 t/t5620-backfill.sh diff --git a/Documentation/git-backfill.txt b/Documentation/git-backfill.txt index 640144187d33b7..ece887831f6e88 100644 --- a/Documentation/git-backfill.txt +++ b/Documentation/git-backfill.txt @@ -14,6 +14,37 @@ SYNOPSIS DESCRIPTION ----------- +Blobless partial clones are created using `git clone --filter=blob:none` +and then configure the local repository such that the Git client avoids +downloading blob objects unless they are required for a local operation. +This initially means that the clone and later fetches download reachable +commits and trees but no blobs. Later operations that change the `HEAD` +pointer, such as `git checkout` or `git merge`, may need to download +missing blobs in order to complete their operation. + +In the worst cases, commands that compute blob diffs, such as `git blame`, +become very slow as they download the missing blobs in single-blob +requests to satisfy the missing object as the Git command needs it. This +leads to multiple download requests and no ability for the Git server to +provide delta compression across those objects. + +The `git backfill` command provides a way for the user to request that +Git downloads the missing blobs (with optional filters) such that the +missing blobs representing historical versions of files can be downloaded +in batches. The `backfill` command attempts to optimize the request by +grouping blobs that appear at the same path, hopefully leading to good +delta compression in the packfile sent by the server. + +In this way, `git backfill` provides a mechanism to break a large clone +into smaller chunks. Starting with a blobless partial clone with `git +clone --filter=blob:none` and then running `git backfill` in the local +repository provides a way to download all reachable objects in several +smaller network calls than downloading the entire repository at clone +time. + +By default, `git backfill` downloads all blobs reachable from the `HEAD` +commit. This set can be restricted or expanded using various options. + SEE ALSO -------- linkgit:git-clone[1]. diff --git a/Documentation/technical/api-path-walk.txt b/Documentation/technical/api-path-walk.txt index 7075d0d5ab50fd..1fba0ce04cb787 100644 --- a/Documentation/technical/api-path-walk.txt +++ b/Documentation/technical/api-path-walk.txt @@ -60,4 +60,5 @@ Examples -------- See example usages in: - `t/helper/test-path-walk.c` + `t/helper/test-path-walk.c`, + `builtin/backfill.c` diff --git a/builtin/backfill.c b/builtin/backfill.c index 38e6aaeaa030ec..177fd4286c7cab 100644 --- a/builtin/backfill.c +++ b/builtin/backfill.c @@ -1,16 +1,118 @@ #include "builtin.h" +#include "git-compat-util.h" #include "config.h" #include "parse-options.h" #include "repository.h" +#include "commit.h" +#include "hex.h" +#include "tree.h" +#include "tree-walk.h" #include "object.h" +#include "object-store-ll.h" +#include "oid-array.h" +#include "oidset.h" +#include "promisor-remote.h" +#include "strmap.h" +#include "string-list.h" +#include "revision.h" +#include "trace2.h" +#include "progress.h" +#include "packfile.h" +#include "path-walk.h" static const char * const builtin_backfill_usage[] = { N_("git backfill []"), NULL }; +struct backfill_context { + struct repository *repo; + struct oid_array current_batch; + size_t batch_size; +}; + +static void backfill_context_clear(struct backfill_context *ctx) +{ + oid_array_clear(&ctx->current_batch); +} + +static void download_batch(struct backfill_context *ctx) +{ + promisor_remote_get_direct(ctx->repo, + ctx->current_batch.oid, + ctx->current_batch.nr); + oid_array_clear(&ctx->current_batch); + + /* + * We likely have a new packfile. Add it to the packed list to + * avoid possible duplicate downloads of the same objects. + */ + reprepare_packed_git(ctx->repo); +} + +static int fill_missing_blobs(const char *path UNUSED, + struct oid_array *list, + enum object_type type, + void *data) +{ + struct backfill_context *ctx = data; + + if (type != OBJ_BLOB) + return 0; + + for (size_t i = 0; i < list->nr; i++) { + off_t size = 0; + struct object_info info = OBJECT_INFO_INIT; + info.disk_sizep = &size; + if (oid_object_info_extended(ctx->repo, + &list->oid[i], + &info, + OBJECT_INFO_FOR_PREFETCH) || + !size) + oid_array_append(&ctx->current_batch, &list->oid[i]); + } + + if (ctx->current_batch.nr >= ctx->batch_size) + download_batch(ctx); + + return 0; +} + +static int do_backfill(struct backfill_context *ctx) +{ + struct rev_info revs; + struct path_walk_info info = PATH_WALK_INFO_INIT; + int ret; + + repo_init_revisions(ctx->repo, &revs, ""); + handle_revision_arg("HEAD", &revs, 0, 0); + + info.blobs = 1; + info.tags = info.commits = info.trees = 0; + + info.revs = &revs; + info.path_fn = fill_missing_blobs; + info.path_fn_data = ctx; + + ret = walk_objects_by_path(&info); + + /* Download the objects that did not fill a batch. */ + if (!ret) + download_batch(ctx); + + backfill_context_clear(ctx); + path_walk_info_clear(&info); + release_revisions(&revs); + return ret; +} + int cmd_backfill(int argc, const char **argv, const char *prefix, struct repository *repo) { + struct backfill_context ctx = { + .repo = repo, + .current_batch = OID_ARRAY_INIT, + .batch_size = 50000, + }; struct option options[] = { OPT_END(), }; @@ -23,7 +125,5 @@ int cmd_backfill(int argc, const char **argv, const char *prefix, struct reposit repo_config(repo, git_default_config, NULL); - die(_("not implemented")); - - return 0; + return do_backfill(&ctx); } diff --git a/t/t5620-backfill.sh b/t/t5620-backfill.sh new file mode 100755 index 00000000000000..64326362d80f8f --- /dev/null +++ b/t/t5620-backfill.sh @@ -0,0 +1,94 @@ +#!/bin/sh + +test_description='git backfill on partial clones' + +GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main +export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME + +. ./test-lib.sh + +# We create objects in the 'src' repo. +test_expect_success 'setup repo for object creation' ' + echo "{print \$1}" >print_1.awk && + echo "{print \$2}" >print_2.awk && + + git init src && + + mkdir -p src/a/b/c && + mkdir -p src/d/e && + + for i in 1 2 + do + for n in 1 2 3 4 + do + echo "Version $i of file $n" > src/file.$n.txt && + echo "Version $i of file a/$n" > src/a/file.$n.txt && + echo "Version $i of file a/b/$n" > src/a/b/file.$n.txt && + echo "Version $i of file a/b/c/$n" > src/a/b/c/file.$n.txt && + echo "Version $i of file d/$n" > src/d/file.$n.txt && + echo "Version $i of file d/e/$n" > src/d/e/file.$n.txt && + git -C src add . && + git -C src commit -m "Iteration $n" || return 1 + done + done +' + +# Clone 'src' into 'srv.bare' so we have a bare repo to be our origin +# server for the partial clone. +test_expect_success 'setup bare clone for server' ' + git clone --bare "file://$(pwd)/src" srv.bare && + git -C srv.bare config --local uploadpack.allowfilter 1 && + git -C srv.bare config --local uploadpack.allowanysha1inwant 1 +' + +# do basic partial clone from "srv.bare" +test_expect_success 'do partial clone 1, backfill gets all objects' ' + git clone --no-checkout --filter=blob:none \ + --single-branch --branch=main \ + "file://$(pwd)/srv.bare" backfill1 && + + # Backfill with no options gets everything reachable from HEAD. + GIT_TRACE2_EVENT="$(pwd)/backfill-file-trace" git \ + -C backfill1 backfill && + + # We should have engaged the partial clone machinery + test_trace2_data promisor fetch_count 48 revs2 && + test_line_count = 0 revs2 +' + +. "$TEST_DIRECTORY"/lib-httpd.sh +start_httpd + +test_expect_success 'create a partial clone over HTTP' ' + SERVER="$HTTPD_DOCUMENT_ROOT_PATH/server" && + rm -rf "$SERVER" repo && + git clone --bare "file://$(pwd)/src" "$SERVER" && + test_config -C "$SERVER" uploadpack.allowfilter 1 && + test_config -C "$SERVER" uploadpack.allowanysha1inwant 1 && + + git clone --no-checkout --filter=blob:none \ + "$HTTPD_URL/smart/server" backfill-http +' + +test_expect_success 'backfilling over HTTP succeeds' ' + GIT_TRACE2_EVENT="$(pwd)/backfill-http-trace" git \ + -C backfill-http backfill && + + # We should have engaged the partial clone machinery + test_trace2_data promisor fetch_count 48 rev-list-out && + awk "{print \$1;}" oids && + GIT_TRACE2_EVENT="$(pwd)/walk-trace" git -C backfill-http \ + cat-file --batch-check batch-out && + ! grep missing batch-out +' + +# DO NOT add non-httpd-specific tests here, because the last part of this +# test script is only executed when httpd is available and enabled. + +test_done From 3fa32822dabb64266a0625c50530ae2ae0797de6 Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Sun, 1 Sep 2024 12:22:10 -0400 Subject: [PATCH 3/5] backfill: add --min-batch-size= option Users may want to specify a minimum batch size for their needs. This is only a minimum: the path-walk API provides a list of OIDs that correspond to the same path, and thus it is optimal to allow delta compression across those objects in a single server request. We could consider limiting the request to have a maximum batch size in the future. For now, we let the path-walk API batches determine the boundaries. To get a feeling for the value of specifying the --batch-size parameter, I tested a number of open source repositories available on GitHub. The procedure was generally: 1. git clone --filter=blob:none 2. git backfill Checking the number of packfiles and the size of the .git/objects/pack directory helps to identify the effects of different batch sizes. For the Git repository, we get these results: | Batch Size | Pack Count | Pack Size | Time | |-----------------|------------|-----------|-------| | (Initial clone) | 2 | 119 MB | | | 25K | 8 | 290 MB | 24s | | 50K | 5 | 290 MB | 24s | | 100K | 4 | 290 MB | 29s | Other than the packfile counts decreasing as we need fewer batches, the size and time required is not changing much for this small example. For the nodejs/node repository, we see these results: | Batch Size | Pack Count | Pack Size | Time | |-----------------|------------|-----------|--------| | (Initial clone) | 2 | 330 MB | | | 25K | 19 | 1,222 MB | 1m 22s | | 50K | 11 | 1,221 MB | 1m 24s | | 100K | 7 | 1,223 MB | 1m 40s | | 250K | 4 | 1,224 MB | 2m 23s | | 500K | 3 | 1,216 MB | 4m 38s | Here, we don't have much difference in the size of the repo, though the 500K batch size results in a few MB gained. That comes at a cost of a much longer time. This extra time is due to server-side delta compression happening as the on-disk deltas don't appear to be reusable all the time. But for smaller batch sizes, the server is able to find reasonable deltas partly because we are asking for objects that appear in the same region of the directory tree and include all versions of a file at a specific path. To contrast this example, I tested the microsoft/fluentui repo, which has been known to have inefficient packing due to name hash collisions. These results are found before GitHub had the opportunity to repack the server with more advanced name hash versions: | Batch Size | Pack Count | Pack Size | Time | |-----------------|------------|-----------|--------| | (Initial clone) | 2 | 105 MB | | | 5K | 53 | 348 MB | 2m 26s | | 10K | 28 | 365 MB | 2m 22s | | 15K | 19 | 407 MB | 2m 21s | | 20K | 15 | 393 MB | 2m 28s | | 25K | 13 | 417 MB | 2m 06s | | 50K | 8 | 509 MB | 1m 34s | | 100K | 5 | 535 MB | 1m 56s | | 250K | 4 | 698 MB | 1m 33s | | 500K | 3 | 696 MB | 1m 42s | Here, a larger variety of batch sizes were chosen because of the great variation in results. By asking the server to download small batches corresponding to fewer paths at a time, the server is able to provide better compression for these batches than it would for a regular clone. A typical full clone for this repository would require 738 MB. This example justifies the choice to batch requests by path name, leading to improved communication with a server that is not optimally packed. Finally, the same experiment for the Linux repository had these results: | Batch Size | Pack Count | Pack Size | Time | |-----------------|------------|-----------|---------| | (Initial clone) | 2 | 2,153 MB | | | 25K | 63 | 6,380 MB | 14m 08s | | 50K | 58 | 6,126 MB | 15m 11s | | 100K | 30 | 6,135 MB | 18m 11s | | 250K | 14 | 6,146 MB | 18m 22s | | 500K | 8 | 6,143 MB | 33m 29s | Even in this example, where the default name hash algorithm leads to decent compression of the Linux kernel repository, there is value for selecting a smaller batch size, to a limit. The 25K batch size has the fastest time, but uses 250 MB more than the 50K batch size. The 500K batch size took much more time due to server compression time and thus we should avoid large batch sizes like this. Based on these experiments, a batch size of 50,000 was chosen as the default value. Signed-off-by: Derrick Stolee --- Documentation/git-backfill.txt | 11 ++++++++++- builtin/backfill.c | 10 ++++++---- t/t5620-backfill.sh | 18 ++++++++++++++++++ 3 files changed, 34 insertions(+), 5 deletions(-) diff --git a/Documentation/git-backfill.txt b/Documentation/git-backfill.txt index ece887831f6e88..e392517869c139 100644 --- a/Documentation/git-backfill.txt +++ b/Documentation/git-backfill.txt @@ -9,7 +9,7 @@ git-backfill - Download missing objects in a partial clone SYNOPSIS -------- [verse] -'git backfill' [] +'git backfill' [--batch-size=] DESCRIPTION ----------- @@ -45,6 +45,15 @@ time. By default, `git backfill` downloads all blobs reachable from the `HEAD` commit. This set can be restricted or expanded using various options. +OPTIONS +------- + +--min-batch-size=:: + Specify a minimum size for a batch of missing objects to request + from the server. This size may be exceeded by the last set of + blobs seen at a given path. The default minimum batch size is + 50,000. + SEE ALSO -------- linkgit:git-clone[1]. diff --git a/builtin/backfill.c b/builtin/backfill.c index 177fd4286c7cab..ddccececc365ef 100644 --- a/builtin/backfill.c +++ b/builtin/backfill.c @@ -21,14 +21,14 @@ #include "path-walk.h" static const char * const builtin_backfill_usage[] = { - N_("git backfill []"), + N_("git backfill [--batch-size=]"), NULL }; struct backfill_context { struct repository *repo; struct oid_array current_batch; - size_t batch_size; + size_t min_batch_size; }; static void backfill_context_clear(struct backfill_context *ctx) @@ -72,7 +72,7 @@ static int fill_missing_blobs(const char *path UNUSED, oid_array_append(&ctx->current_batch, &list->oid[i]); } - if (ctx->current_batch.nr >= ctx->batch_size) + if (ctx->current_batch.nr >= ctx->min_batch_size) download_batch(ctx); return 0; @@ -111,9 +111,11 @@ int cmd_backfill(int argc, const char **argv, const char *prefix, struct reposit struct backfill_context ctx = { .repo = repo, .current_batch = OID_ARRAY_INIT, - .batch_size = 50000, + .min_batch_size = 50000, }; struct option options[] = { + OPT_INTEGER(0, "min-batch-size", &ctx.min_batch_size, + N_("Minimum number of objects to request at a time")), OPT_END(), }; diff --git a/t/t5620-backfill.sh b/t/t5620-backfill.sh index 64326362d80f8f..36107a51c54040 100755 --- a/t/t5620-backfill.sh +++ b/t/t5620-backfill.sh @@ -59,6 +59,24 @@ test_expect_success 'do partial clone 1, backfill gets all objects' ' test_line_count = 0 revs2 ' +test_expect_success 'do partial clone 2, backfill min batch size' ' + git clone --no-checkout --filter=blob:none \ + --single-branch --branch=main \ + "file://$(pwd)/srv.bare" backfill2 && + + GIT_TRACE2_EVENT="$(pwd)/batch-trace" git \ + -C backfill2 backfill --min-batch-size=20 && + + # Batches were used + test_trace2_data promisor fetch_count 20 matches && + test_line_count = 2 matches && + test_trace2_data promisor fetch_count 8 revs2 && + test_line_count = 0 revs2 +' + . "$TEST_DIRECTORY"/lib-httpd.sh start_httpd From 2723143afb397507cbc794375525c37497046dc2 Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Sun, 1 Sep 2024 13:39:18 -0400 Subject: [PATCH 4/5] backfill: add --sparse option One way to significantly reduce the cost of a Git clone and later fetches is to use a blobless partial clone and combine that with a sparse-checkout that reduces the paths that need to be populated in the working directory. Not only does this reduce the cost of clones and fetches, the sparse-checkout reduces the number of objects needed to download from a promisor remote. However, history investigations can be expensive as computing blob diffs will trigger promisor remote requests for one object at a time. This can be avoided by downloading the blobs needed for the given sparse-checkout using 'git backfill' and its new '--sparse' mode, at a time that the user is willing to pay that extra cost. Note that this is distinctly different from the '--filter=sparse:' option, as this assumes that the partial clone has all reachable trees and we are using client-side logic to avoid downloading blobs outside of the sparse-checkout cone. This avoids the server-side cost of walking trees while also achieving a similar goal. It also downloads in batches based on similar path names, presenting a resumable download if things are interrupted. This augments the path-walk API to have a possibly-NULL 'pl' member that may point to a 'struct pattern_list'. This could be more general than the sparse-checkout definition at HEAD, but 'git backfill --sparse' is currently the only consumer. Be sure to test this in both cone mode and not cone mode. Cone mode has the benefit that the path-walk can skip certain paths once they would expand beyond the sparse-checkout. To test this, we can create a blobless sparse clone, expand the sparse-checkout slightly, and then run 'git backfill --sparse' to see how much data is downloaded. The general steps are 1. git clone --filter=blob:none --sparse 2. git sparse-checkout set ... 3. git backfill --sparse For the Git repository with the 'builtin' directory in the sparse-checkout, we get these results for various batch sizes: | Batch Size | Pack Count | Pack Size | Time | |-----------------|------------|-----------|-------| | (Initial clone) | 3 | 110 MB | | | 10K | 12 | 192 MB | 17.2s | | 15K | 9 | 192 MB | 15.5s | | 20K | 8 | 192 MB | 15.5s | | 25K | 7 | 192 MB | 14.7s | This case matters less because a full clone of the Git repository from GitHub is currently at 277 MB. Using a copy of the Linux repository with the 'kernel/' directory in the sparse-checkout, we get these results: | Batch Size | Pack Count | Pack Size | Time | |-----------------|------------|-----------|------| | (Initial clone) | 2 | 1,876 MB | | | 10K | 11 | 2,187 MB | 46s | | 25K | 7 | 2,188 MB | 43s | | 50K | 5 | 2,194 MB | 44s | | 100K | 4 | 2,194 MB | 48s | This case is more meaningful because a full clone of the Linux repository is currently over 6 GB, so this is a valuable way to download a fraction of the repository and no longer need network access for all reachable objects within the sparse-checkout. Choosing a batch size will depend on a lot of factors, including the user's network speed or reliability, the repository's file structure, and how many versions there are of the file within the sparse-checkout scope. There will not be a one-size-fits-all solution. Signed-off-by: Derrick Stolee --- Documentation/git-backfill.txt | 6 ++- Documentation/technical/api-path-walk.txt | 8 ++++ builtin/backfill.c | 15 ++++++- dir.c | 10 ++--- dir.h | 3 ++ path-walk.c | 28 +++++++++--- path-walk.h | 11 +++++ t/helper/test-path-walk.c | 22 ++++++++- t/t5620-backfill.sh | 55 +++++++++++++++++++++++ t/t6601-path-walk.sh | 32 +++++++++++++ 10 files changed, 175 insertions(+), 15 deletions(-) diff --git a/Documentation/git-backfill.txt b/Documentation/git-backfill.txt index e392517869c139..4710e2c12e3769 100644 --- a/Documentation/git-backfill.txt +++ b/Documentation/git-backfill.txt @@ -9,7 +9,7 @@ git-backfill - Download missing objects in a partial clone SYNOPSIS -------- [verse] -'git backfill' [--batch-size=] +'git backfill' [--batch-size=] [--[no-]sparse] DESCRIPTION ----------- @@ -54,6 +54,10 @@ OPTIONS blobs seen at a given path. The default minimum batch size is 50,000. +--[no-]sparse:: + Only download objects if they appear at a path that matches the + current sparse-checkout. + SEE ALSO -------- linkgit:git-clone[1]. diff --git a/Documentation/technical/api-path-walk.txt b/Documentation/technical/api-path-walk.txt index 1fba0ce04cb787..3e089211fb4d69 100644 --- a/Documentation/technical/api-path-walk.txt +++ b/Documentation/technical/api-path-walk.txt @@ -56,6 +56,14 @@ better off using the revision walk API instead. the revision walk so that the walk emits commits marked with the `UNINTERESTING` flag. +`pl`:: + This pattern list pointer allows focusing the path-walk search to + a set of patterns, only emitting paths that match the given + patterns. See linkgit:gitignore[5] or + linkgit:git-sparse-checkout[1] for details about pattern lists. + When the pattern list uses cone-mode patterns, then the path-walk + API can prune the set of paths it walks to improve performance. + Examples -------- diff --git a/builtin/backfill.c b/builtin/backfill.c index ddccececc365ef..b9f1cc9850120b 100644 --- a/builtin/backfill.c +++ b/builtin/backfill.c @@ -4,6 +4,7 @@ #include "parse-options.h" #include "repository.h" #include "commit.h" +#include "dir.h" #include "hex.h" #include "tree.h" #include "tree-walk.h" @@ -21,7 +22,7 @@ #include "path-walk.h" static const char * const builtin_backfill_usage[] = { - N_("git backfill [--batch-size=]"), + N_("git backfill [--batch-size=] [--[no-]sparse]"), NULL }; @@ -29,6 +30,7 @@ struct backfill_context { struct repository *repo; struct oid_array current_batch; size_t min_batch_size; + int sparse; }; static void backfill_context_clear(struct backfill_context *ctx) @@ -84,6 +86,14 @@ static int do_backfill(struct backfill_context *ctx) struct path_walk_info info = PATH_WALK_INFO_INIT; int ret; + if (ctx->sparse) { + CALLOC_ARRAY(info.pl, 1); + if (get_sparse_checkout_patterns(info.pl)) { + path_walk_info_clear(&info); + return error(_("problem loading sparse-checkout")); + } + } + repo_init_revisions(ctx->repo, &revs, ""); handle_revision_arg("HEAD", &revs, 0, 0); @@ -112,10 +122,13 @@ int cmd_backfill(int argc, const char **argv, const char *prefix, struct reposit .repo = repo, .current_batch = OID_ARRAY_INIT, .min_batch_size = 50000, + .sparse = 0, }; struct option options[] = { OPT_INTEGER(0, "min-batch-size", &ctx.min_batch_size, N_("Minimum number of objects to request at a time")), + OPT_BOOL(0, "sparse", &ctx.sparse, + N_("Restrict the missing objects to the current sparse-checkout")), OPT_END(), }; diff --git a/dir.c b/dir.c index c43b5e30813a8f..32af7ee294ddfb 100644 --- a/dir.c +++ b/dir.c @@ -1088,10 +1088,6 @@ static void invalidate_directory(struct untracked_cache *uc, dir->dirs[i]->recurse = 0; } -static int add_patterns_from_buffer(char *buf, size_t size, - const char *base, int baselen, - struct pattern_list *pl); - /* Flags for add_patterns() */ #define PATTERN_NOFOLLOW (1<<0) @@ -1181,9 +1177,9 @@ static int add_patterns(const char *fname, const char *base, int baselen, return 0; } -static int add_patterns_from_buffer(char *buf, size_t size, - const char *base, int baselen, - struct pattern_list *pl) +int add_patterns_from_buffer(char *buf, size_t size, + const char *base, int baselen, + struct pattern_list *pl) { char *orig = buf; int i, lineno = 1; diff --git a/dir.h b/dir.h index a3a2f00f5d9273..6cfef5df66091b 100644 --- a/dir.h +++ b/dir.h @@ -467,6 +467,9 @@ void add_patterns_from_file(struct dir_struct *, const char *fname); int add_patterns_from_blob_to_list(struct object_id *oid, const char *base, int baselen, struct pattern_list *pl); +int add_patterns_from_buffer(char *buf, size_t size, + const char *base, int baselen, + struct pattern_list *pl); void parse_path_pattern(const char **string, int *patternlen, unsigned *flags, int *nowildcardlen); void add_pattern(const char *string, const char *base, int baselen, struct pattern_list *pl, int srcpos); diff --git a/path-walk.c b/path-walk.c index 136ec08fb0ed72..c7456a9c1c0c8d 100644 --- a/path-walk.c +++ b/path-walk.c @@ -12,6 +12,7 @@ #include "object.h" #include "oid-array.h" #include "prio-queue.h" +#include "repository.h" #include "revision.h" #include "string-list.h" #include "strmap.h" @@ -173,6 +174,23 @@ static int add_tree_entries(struct path_walk_context *ctx, if (type == OBJ_TREE) strbuf_addch(&path, '/'); + if (ctx->info->pl) { + int dtype; + enum pattern_match_result match; + match = path_matches_pattern_list(path.buf, path.len, + path.buf + base_len, &dtype, + ctx->info->pl, + ctx->repo->index); + + if (ctx->info->pl->use_cone_patterns && + match == NOT_MATCHED) + continue; + else if (!ctx->info->pl->use_cone_patterns && + type == OBJ_BLOB && + match != MATCHED) + continue; + } + if (!(list = strmap_get(&ctx->paths_to_lists, path.buf))) { CALLOC_ARRAY(list, 1); list->type = type; @@ -583,10 +601,10 @@ void path_walk_info_init(struct path_walk_info *info) memcpy(info, &empty, sizeof(empty)); } -void path_walk_info_clear(struct path_walk_info *info UNUSED) +void path_walk_info_clear(struct path_walk_info *info) { - /* - * This destructor is empty for now, as info->revs - * is not owned by 'struct path_walk_info'. - */ + if (info->pl) { + clear_pattern_list(info->pl); + free(info->pl); + } } diff --git a/path-walk.h b/path-walk.h index 414d6db23c23b6..473ee9d361c864 100644 --- a/path-walk.h +++ b/path-walk.h @@ -6,6 +6,7 @@ struct rev_info; struct oid_array; +struct pattern_list; /** * The type of a function pointer for the method that is called on a list of @@ -48,6 +49,16 @@ struct path_walk_info { * walk the children of such trees. */ int prune_all_uninteresting; + + /** + * Specify a sparse-checkout definition to match our paths to. Do not + * walk outside of this sparse definition. If the patterns are in + * cone mode, then the search may prune directories that are outside + * of the cone. If not in cone mode, then all tree paths will be + * explored but the path_fn will only be called when the path matches + * the sparse-checkout patterns. + */ + struct pattern_list *pl; }; #define PATH_WALK_INFO_INIT { \ diff --git a/t/helper/test-path-walk.c b/t/helper/test-path-walk.c index 7f2d409c5bca63..61e845e5ec2560 100644 --- a/t/helper/test-path-walk.c +++ b/t/helper/test-path-walk.c @@ -1,6 +1,7 @@ #define USE_THE_REPOSITORY_VARIABLE #include "test-tool.h" +#include "dir.h" #include "environment.h" #include "hex.h" #include "object-name.h" @@ -9,6 +10,7 @@ #include "revision.h" #include "setup.h" #include "parse-options.h" +#include "strbuf.h" #include "path-walk.h" #include "oid-array.h" @@ -65,7 +67,7 @@ static int emit_block(const char *path, struct oid_array *oids, int cmd__path_walk(int argc, const char **argv) { - int res; + int res, stdin_pl = 0; struct rev_info revs = REV_INFO_INIT; struct path_walk_info info = PATH_WALK_INFO_INIT; struct path_walk_test_data data = { 0 }; @@ -80,6 +82,8 @@ int cmd__path_walk(int argc, const char **argv) N_("toggle inclusion of tree objects")), OPT_BOOL(0, "prune", &info.prune_all_uninteresting, N_("toggle pruning of uninteresting paths")), + OPT_BOOL(0, "stdin-pl", &stdin_pl, + N_("read a pattern list over stdin")), OPT_END(), }; @@ -99,6 +103,17 @@ int cmd__path_walk(int argc, const char **argv) info.path_fn = emit_block; info.path_fn_data = &data; + if (stdin_pl) { + struct strbuf in = STRBUF_INIT; + CALLOC_ARRAY(info.pl, 1); + + info.pl->use_cone_patterns = 1; + + strbuf_fread(&in, 2048, stdin); + add_patterns_from_buffer(in.buf, in.len, "", 0, info.pl); + strbuf_release(&in); + } + res = walk_objects_by_path(&info); printf("commits:%" PRIuMAX "\n" @@ -107,6 +122,11 @@ int cmd__path_walk(int argc, const char **argv) "tags:%" PRIuMAX "\n", data.commit_nr, data.tree_nr, data.blob_nr, data.tag_nr); + if (info.pl) { + clear_pattern_list(info.pl); + free(info.pl); + } + release_revisions(&revs); return res; } diff --git a/t/t5620-backfill.sh b/t/t5620-backfill.sh index 36107a51c54040..f87a471c2211a4 100755 --- a/t/t5620-backfill.sh +++ b/t/t5620-backfill.sh @@ -77,6 +77,61 @@ test_expect_success 'do partial clone 2, backfill min batch size' ' test_line_count = 0 revs2 ' +test_expect_success 'backfill --sparse' ' + git clone --sparse --filter=blob:none \ + --single-branch --branch=main \ + "file://$(pwd)/srv.bare" backfill3 && + + # Initial checkout includes four files at root. + git -C backfill3 rev-list --quiet --objects --missing=print HEAD >missing && + test_line_count = 44 missing && + + # Initial sparse-checkout is just the files at root, so we get the + # older versions of the four files at tip. + GIT_TRACE2_EVENT="$(pwd)/sparse-trace1" git \ + -C backfill3 backfill --sparse && + test_trace2_data promisor fetch_count 4 missing && + test_line_count = 40 missing && + + # Expand the sparse-checkout to include 'd' recursively. This + # engages the algorithm to skip the trees for 'a'. Note that + # the "sparse-checkout set" command downloads the objects at tip + # to satisfy the current checkout. + git -C backfill3 sparse-checkout set d && + GIT_TRACE2_EVENT="$(pwd)/sparse-trace2" git \ + -C backfill3 backfill --sparse && + test_trace2_data promisor fetch_count 8 missing && + test_line_count = 24 missing +' + +test_expect_success 'backfill --sparse without cone mode' ' + git clone --no-checkout --filter=blob:none \ + --single-branch --branch=main \ + "file://$(pwd)/srv.bare" backfill4 && + + # No blobs yet + git -C backfill4 rev-list --quiet --objects --missing=print HEAD >missing && + test_line_count = 48 missing && + + # Define sparse-checkout by filename regardless of parent directory. + # This downloads 6 blobs to satisfy the checkout. + git -C backfill4 sparse-checkout set --no-cone "**/file.1.txt" && + git -C backfill4 checkout main && + + GIT_TRACE2_EVENT="$(pwd)/no-cone-trace1" git \ + -C backfill4 backfill --sparse && + test_trace2_data promisor fetch_count 6 missing && + test_line_count = 36 missing +' + . "$TEST_DIRECTORY"/lib-httpd.sh start_httpd diff --git a/t/t6601-path-walk.sh b/t/t6601-path-walk.sh index 5f04acb8a2f79a..c89b0f1e19d9fb 100755 --- a/t/t6601-path-walk.sh +++ b/t/t6601-path-walk.sh @@ -176,6 +176,38 @@ test_expect_success 'branches and indexed objects mix well' ' test_cmp_sorted expect out ' +test_expect_success 'base & topic, sparse' ' + cat >patterns <<-EOF && + /* + !/*/ + /left/ + EOF + + test-tool path-walk --stdin-pl -- base topic out && + + cat >expect <<-EOF && + 0:commit::$(git rev-parse topic) + 0:commit::$(git rev-parse base) + 0:commit::$(git rev-parse base~1) + 0:commit::$(git rev-parse base~2) + 1:tree::$(git rev-parse topic^{tree}) + 1:tree::$(git rev-parse base^{tree}) + 1:tree::$(git rev-parse base~1^{tree}) + 1:tree::$(git rev-parse base~2^{tree}) + 2:blob:a:$(git rev-parse base~2:a) + 3:tree:left/:$(git rev-parse base:left) + 3:tree:left/:$(git rev-parse base~2:left) + 4:blob:left/b:$(git rev-parse base~2:left/b) + 4:blob:left/b:$(git rev-parse base:left/b) + blobs:3 + commits:4 + tags:0 + trees:6 + EOF + + test_cmp_sorted expect out +' + test_expect_success 'topic only' ' test-tool path-walk -- topic >out && From 1f765409eaf0576de52948ed0a0eb8a5b3493977 Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Sun, 1 Sep 2024 14:06:11 -0400 Subject: [PATCH 5/5] backfill: assume --sparse when sparse-checkout is enabled The previous change introduced the '--[no-]sparse' option for the 'git backfill' command, but did not assume it as enabled by default. However, this is likely the behavior that users will most often want to happen. Without this default, users with a small sparse-checkout may be confused when 'git backfill' downloads every version of every object in the full history. However, this is left as a separate change so this decision can be reviewed independently of the value of the '--[no-]sparse' option. Add a test of adding the '--sparse' option to a repo without sparse-checkout to make it clear that supplying it without a sparse-checkout is an error. Signed-off-by: Derrick Stolee --- Documentation/git-backfill.txt | 3 ++- builtin/backfill.c | 7 +++++++ t/t5620-backfill.sh | 13 ++++++++++++- 3 files changed, 21 insertions(+), 2 deletions(-) diff --git a/Documentation/git-backfill.txt b/Documentation/git-backfill.txt index 4710e2c12e3769..9eecc6210c0cd1 100644 --- a/Documentation/git-backfill.txt +++ b/Documentation/git-backfill.txt @@ -56,7 +56,8 @@ OPTIONS --[no-]sparse:: Only download objects if they appear at a path that matches the - current sparse-checkout. + current sparse-checkout. If the sparse-checkout feature is enabled, + then `--sparse` is assumed and can be disabled with `--no-sparse`. SEE ALSO -------- diff --git a/builtin/backfill.c b/builtin/backfill.c index b9f1cc9850120b..d7c300dbe678f8 100644 --- a/builtin/backfill.c +++ b/builtin/backfill.c @@ -1,3 +1,6 @@ +/* We need this macro to access core_apply_sparse_checkout */ +#define USE_THE_REPOSITORY_VARIABLE + #include "builtin.h" #include "git-compat-util.h" #include "config.h" @@ -5,6 +8,7 @@ #include "repository.h" #include "commit.h" #include "dir.h" +#include "environment.h" #include "hex.h" #include "tree.h" #include "tree-walk.h" @@ -140,5 +144,8 @@ int cmd_backfill(int argc, const char **argv, const char *prefix, struct reposit repo_config(repo, git_default_config, NULL); + if (ctx.sparse < 0) + ctx.sparse = core_apply_sparse_checkout; + return do_backfill(&ctx); } diff --git a/t/t5620-backfill.sh b/t/t5620-backfill.sh index f87a471c2211a4..3fafcf99b5816a 100755 --- a/t/t5620-backfill.sh +++ b/t/t5620-backfill.sh @@ -77,6 +77,12 @@ test_expect_success 'do partial clone 2, backfill min batch size' ' test_line_count = 0 revs2 ' +test_expect_success 'backfill --sparse without sparse-checkout fails' ' + git init not-sparse && + test_must_fail git -C not-sparse backfill --sparse 2>err && + grep "problem loading sparse-checkout" err +' + test_expect_success 'backfill --sparse' ' git clone --sparse --filter=blob:none \ --single-branch --branch=main \ @@ -105,7 +111,12 @@ test_expect_success 'backfill --sparse' ' test_trace2_data promisor fetch_count 8 missing && - test_line_count = 24 missing + test_line_count = 24 missing && + + # Disabling the --sparse option (on by default) will download everything + git -C backfill3 backfill --no-sparse && + git -C backfill3 rev-list --quiet --objects --missing=print HEAD >missing && + test_line_count = 0 missing ' test_expect_success 'backfill --sparse without cone mode' '