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git/t/t5558-clone-bundle-uri.sh
Derrick Stolee 7903efb717 bundle-uri: download in creationToken order
The creationToken heuristic provides an ordering on the bundles
advertised by a bundle list. Teach the Git client to download bundles
differently when this heuristic is advertised.

The bundles in the list are sorted by their advertised creationToken
values, then downloaded in decreasing order. This avoids the previous
strategy of downloading bundles in an arbitrary order and attempting
to apply them (likely failing in the case of required commits) until
discovering the order through attempted unbundling.

During a fresh 'git clone', it may make sense to download the bundles in
increasing order, since that would prevent the need to attempt
unbundling a bundle with required commits that do not exist in our empty
object store. The cost of testing an unbundle is quite low, and instead
the chosen order is optimizing for a future bundle download during a
'git fetch' operation with a non-empty object store.

Since the Git client continues fetching from the Git remote after
downloading and unbundling bundles, the client's object store can be
ahead of the bundle provider's object store. The next time it attempts
to download from the bundle list, it makes most sense to download only
the most-recent bundles until all tips successfully unbundle. The
strategy implemented here provides that short-circuit where the client
downloads a minimal set of bundles.

However, we are not satisfied by the naive approach of downloading
bundles until one successfully unbundles, expecting the earlier bundles
to successfully unbundle now. The example repository in t5558
demonstrates this well:

 ---------------- bundle-4

       4
      / \
 ----|---|------- bundle-3
     |   |
     |   3
     |   |
 ----|---|------- bundle-2
     |   |
     2   |
     |   |
 ----|---|------- bundle-1
      \ /
       1
       |
 (previous commits)

In this repository, if we already have the objects for bundle-1 and then
try to fetch from this list, the naive approach will fail. bundle-4
requires both bundle-3 and bundle-2, though bundle-3 will successfully
unbundle without bundle-2. Thus, the algorithm needs to keep this in
mind.

A later implementation detail will store the maximum creationToken seen
during such a bundle download, and the client will avoid downloading a
bundle unless its creationToken is strictly greater than that stored
value. For now, if the client seeks to download from an identical
bundle list since its previous download, it will download the
most-recent bundle then stop since its required commits are already in
the object store.

Add tests that exercise this behavior, but we will expand upon these
tests when incremental downloads during 'git fetch' make use of
creationToken values.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-01-31 08:57:48 -08:00

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#!/bin/sh
test_description='test fetching bundles with --bundle-uri'
. ./test-lib.sh
test_expect_success 'fail to clone from non-existent file' '
test_when_finished rm -rf test &&
git clone --bundle-uri="$(pwd)/does-not-exist" . test 2>err &&
grep "failed to download bundle from URI" err
'
test_expect_success 'fail to clone from non-bundle file' '
test_when_finished rm -rf test &&
echo bogus >bogus &&
git clone --bundle-uri="$(pwd)/bogus" . test 2>err &&
grep "is not a bundle" err
'
test_expect_success 'create bundle' '
git init clone-from &&
git -C clone-from checkout -b topic &&
test_commit -C clone-from A &&
test_commit -C clone-from B &&
git -C clone-from bundle create B.bundle topic
'
test_expect_success 'clone with path bundle' '
git clone --bundle-uri="clone-from/B.bundle" \
clone-from clone-path &&
git -C clone-path rev-parse refs/bundles/topic >actual &&
git -C clone-from rev-parse topic >expect &&
test_cmp expect actual
'
test_expect_success 'clone with file:// bundle' '
git clone --bundle-uri="file://$(pwd)/clone-from/B.bundle" \
clone-from clone-file &&
git -C clone-file rev-parse refs/bundles/topic >actual &&
git -C clone-from rev-parse topic >expect &&
test_cmp expect actual
'
# To get interesting tests for bundle lists, we need to construct a
# somewhat-interesting commit history.
#
# ---------------- bundle-4
#
# 4
# / \
# ----|---|------- bundle-3
# | |
# | 3
# | |
# ----|---|------- bundle-2
# | |
# 2 |
# | |
# ----|---|------- bundle-1
# \ /
# 1
# |
# (previous commits)
test_expect_success 'construct incremental bundle list' '
(
cd clone-from &&
git checkout -b base &&
test_commit 1 &&
git checkout -b left &&
test_commit 2 &&
git checkout -b right base &&
test_commit 3 &&
git checkout -b merge left &&
git merge right -m "4" &&
git bundle create bundle-1.bundle base &&
git bundle create bundle-2.bundle base..left &&
git bundle create bundle-3.bundle base..right &&
git bundle create bundle-4.bundle merge --not left right
)
'
test_expect_success 'clone bundle list (file, no heuristic)' '
cat >bundle-list <<-EOF &&
[bundle]
version = 1
mode = all
[bundle "bundle-1"]
uri = file://$(pwd)/clone-from/bundle-1.bundle
[bundle "bundle-2"]
uri = file://$(pwd)/clone-from/bundle-2.bundle
[bundle "bundle-3"]
uri = file://$(pwd)/clone-from/bundle-3.bundle
[bundle "bundle-4"]
uri = file://$(pwd)/clone-from/bundle-4.bundle
EOF
git clone --bundle-uri="file://$(pwd)/bundle-list" \
clone-from clone-list-file 2>err &&
! grep "Repository lacks these prerequisite commits" err &&
git -C clone-from for-each-ref --format="%(objectname)" >oids &&
git -C clone-list-file cat-file --batch-check <oids &&
git -C clone-list-file for-each-ref --format="%(refname)" >refs &&
grep "refs/bundles/" refs >actual &&
cat >expect <<-\EOF &&
refs/bundles/base
refs/bundles/left
refs/bundles/merge
refs/bundles/right
EOF
test_cmp expect actual
'
test_expect_success 'clone bundle list (file, all mode, some failures)' '
cat >bundle-list <<-EOF &&
[bundle]
version = 1
mode = all
# Does not exist. Should be skipped.
[bundle "bundle-0"]
uri = file://$(pwd)/clone-from/bundle-0.bundle
[bundle "bundle-1"]
uri = file://$(pwd)/clone-from/bundle-1.bundle
[bundle "bundle-2"]
uri = file://$(pwd)/clone-from/bundle-2.bundle
# No bundle-3 means bundle-4 will not apply.
[bundle "bundle-4"]
uri = file://$(pwd)/clone-from/bundle-4.bundle
# Does not exist. Should be skipped.
[bundle "bundle-5"]
uri = file://$(pwd)/clone-from/bundle-5.bundle
EOF
GIT_TRACE2_PERF=1 \
git clone --bundle-uri="file://$(pwd)/bundle-list" \
clone-from clone-all-some 2>err &&
! grep "Repository lacks these prerequisite commits" err &&
! grep "fatal" err &&
grep "warning: failed to download bundle from URI" err &&
git -C clone-from for-each-ref --format="%(objectname)" >oids &&
git -C clone-all-some cat-file --batch-check <oids &&
git -C clone-all-some for-each-ref --format="%(refname)" >refs &&
grep "refs/bundles/" refs >actual &&
cat >expect <<-\EOF &&
refs/bundles/base
refs/bundles/left
EOF
test_cmp expect actual
'
test_expect_success 'clone bundle list (file, all mode, all failures)' '
cat >bundle-list <<-EOF &&
[bundle]
version = 1
mode = all
# Does not exist. Should be skipped.
[bundle "bundle-0"]
uri = file://$(pwd)/clone-from/bundle-0.bundle
# Does not exist. Should be skipped.
[bundle "bundle-5"]
uri = file://$(pwd)/clone-from/bundle-5.bundle
EOF
git clone --bundle-uri="file://$(pwd)/bundle-list" \
clone-from clone-all-fail 2>err &&
! grep "Repository lacks these prerequisite commits" err &&
! grep "fatal" err &&
grep "warning: failed to download bundle from URI" err &&
git -C clone-from for-each-ref --format="%(objectname)" >oids &&
git -C clone-all-fail cat-file --batch-check <oids &&
git -C clone-all-fail for-each-ref --format="%(refname)" >refs &&
! grep "refs/bundles/" refs
'
test_expect_success 'clone bundle list (file, any mode)' '
cat >bundle-list <<-EOF &&
[bundle]
version = 1
mode = any
# Does not exist. Should be skipped.
[bundle "bundle-0"]
uri = file://$(pwd)/clone-from/bundle-0.bundle
[bundle "bundle-1"]
uri = file://$(pwd)/clone-from/bundle-1.bundle
# Does not exist. Should be skipped.
[bundle "bundle-5"]
uri = file://$(pwd)/clone-from/bundle-5.bundle
EOF
git clone --bundle-uri="file://$(pwd)/bundle-list" \
clone-from clone-any-file 2>err &&
! grep "Repository lacks these prerequisite commits" err &&
git -C clone-from for-each-ref --format="%(objectname)" >oids &&
git -C clone-any-file cat-file --batch-check <oids &&
git -C clone-any-file for-each-ref --format="%(refname)" >refs &&
grep "refs/bundles/" refs >actual &&
cat >expect <<-\EOF &&
refs/bundles/base
EOF
test_cmp expect actual
'
test_expect_success 'clone bundle list (file, any mode, all failures)' '
cat >bundle-list <<-EOF &&
[bundle]
version = 1
mode = any
# Does not exist. Should be skipped.
[bundle "bundle-0"]
uri = $HTTPD_URL/bundle-0.bundle
# Does not exist. Should be skipped.
[bundle "bundle-5"]
uri = $HTTPD_URL/bundle-5.bundle
EOF
git clone --bundle-uri="file://$(pwd)/bundle-list" \
clone-from clone-any-fail 2>err &&
! grep "fatal" err &&
grep "warning: failed to download bundle from URI" err &&
git -C clone-from for-each-ref --format="%(objectname)" >oids &&
git -C clone-any-fail cat-file --batch-check <oids &&
git -C clone-any-fail for-each-ref --format="%(refname)" >refs &&
! grep "refs/bundles/" refs
'
#########################################################################
# HTTP tests begin here
. "$TEST_DIRECTORY"/lib-httpd.sh
start_httpd
test_expect_success 'fail to fetch from non-existent HTTP URL' '
test_when_finished rm -rf test &&
git clone --bundle-uri="$HTTPD_URL/does-not-exist" . test 2>err &&
grep "failed to download bundle from URI" err
'
test_expect_success 'fail to fetch from non-bundle HTTP URL' '
test_when_finished rm -rf test &&
echo bogus >"$HTTPD_DOCUMENT_ROOT_PATH/bogus" &&
git clone --bundle-uri="$HTTPD_URL/bogus" . test 2>err &&
grep "is not a bundle" err
'
test_expect_success 'clone HTTP bundle' '
cp clone-from/B.bundle "$HTTPD_DOCUMENT_ROOT_PATH/B.bundle" &&
git clone --no-local --mirror clone-from \
"$HTTPD_DOCUMENT_ROOT_PATH/fetch.git" &&
git clone --bundle-uri="$HTTPD_URL/B.bundle" \
"$HTTPD_URL/smart/fetch.git" clone-http &&
git -C clone-http rev-parse refs/bundles/topic >actual &&
git -C clone-from rev-parse topic >expect &&
test_cmp expect actual &&
test_config -C clone-http log.excludedecoration refs/bundle/
'
test_expect_success 'clone bundle list (HTTP, no heuristic)' '
test_when_finished rm -f trace*.txt &&
cp clone-from/bundle-*.bundle "$HTTPD_DOCUMENT_ROOT_PATH/" &&
cat >"$HTTPD_DOCUMENT_ROOT_PATH/bundle-list" <<-EOF &&
[bundle]
version = 1
mode = all
[bundle "bundle-1"]
uri = $HTTPD_URL/bundle-1.bundle
[bundle "bundle-2"]
uri = $HTTPD_URL/bundle-2.bundle
[bundle "bundle-3"]
uri = $HTTPD_URL/bundle-3.bundle
[bundle "bundle-4"]
uri = $HTTPD_URL/bundle-4.bundle
EOF
GIT_TRACE2_EVENT="$(pwd)/trace-clone.txt" \
git clone --bundle-uri="$HTTPD_URL/bundle-list" \
clone-from clone-list-http 2>err &&
! grep "Repository lacks these prerequisite commits" err &&
git -C clone-from for-each-ref --format="%(objectname)" >oids &&
git -C clone-list-http cat-file --batch-check <oids &&
cat >expect <<-EOF &&
$HTTPD_URL/bundle-1.bundle
$HTTPD_URL/bundle-2.bundle
$HTTPD_URL/bundle-3.bundle
$HTTPD_URL/bundle-4.bundle
$HTTPD_URL/bundle-list
EOF
# Sort the list, since the order is not well-defined
# without a heuristic.
test_remote_https_urls <trace-clone.txt | sort >actual &&
test_cmp expect actual
'
test_expect_success 'clone bundle list (HTTP, any mode)' '
cp clone-from/bundle-*.bundle "$HTTPD_DOCUMENT_ROOT_PATH/" &&
cat >"$HTTPD_DOCUMENT_ROOT_PATH/bundle-list" <<-EOF &&
[bundle]
version = 1
mode = any
# Does not exist. Should be skipped.
[bundle "bundle-0"]
uri = $HTTPD_URL/bundle-0.bundle
[bundle "bundle-1"]
uri = $HTTPD_URL/bundle-1.bundle
# Does not exist. Should be skipped.
[bundle "bundle-5"]
uri = $HTTPD_URL/bundle-5.bundle
EOF
git clone --bundle-uri="$HTTPD_URL/bundle-list" \
clone-from clone-any-http 2>err &&
! grep "fatal" err &&
grep "warning: failed to download bundle from URI" err &&
git -C clone-from for-each-ref --format="%(objectname)" >oids &&
git -C clone-any-http cat-file --batch-check <oids &&
git -C clone-list-file for-each-ref --format="%(refname)" >refs &&
grep "refs/bundles/" refs >actual &&
cat >expect <<-\EOF &&
refs/bundles/base
refs/bundles/left
refs/bundles/merge
refs/bundles/right
EOF
test_cmp expect actual
'
test_expect_success 'clone bundle list (http, creationToken)' '
test_when_finished rm -f trace*.txt &&
cp clone-from/bundle-*.bundle "$HTTPD_DOCUMENT_ROOT_PATH/" &&
cat >"$HTTPD_DOCUMENT_ROOT_PATH/bundle-list" <<-EOF &&
[bundle]
version = 1
mode = all
heuristic = creationToken
[bundle "bundle-1"]
uri = bundle-1.bundle
creationToken = 1
[bundle "bundle-2"]
uri = bundle-2.bundle
creationToken = 2
[bundle "bundle-3"]
uri = bundle-3.bundle
creationToken = 3
[bundle "bundle-4"]
uri = bundle-4.bundle
creationToken = 4
EOF
GIT_TRACE2_EVENT="$(pwd)/trace-clone.txt" git \
clone --bundle-uri="$HTTPD_URL/bundle-list" \
"$HTTPD_URL/smart/fetch.git" clone-list-http-2 &&
git -C clone-from for-each-ref --format="%(objectname)" >oids &&
git -C clone-list-http-2 cat-file --batch-check <oids &&
cat >expect <<-EOF &&
$HTTPD_URL/bundle-list
$HTTPD_URL/bundle-4.bundle
$HTTPD_URL/bundle-3.bundle
$HTTPD_URL/bundle-2.bundle
$HTTPD_URL/bundle-1.bundle
EOF
test_remote_https_urls <trace-clone.txt >actual &&
test_cmp expect actual
'
test_expect_success 'clone incomplete bundle list (http, creationToken)' '
test_when_finished rm -f trace*.txt &&
cp clone-from/bundle-*.bundle "$HTTPD_DOCUMENT_ROOT_PATH/" &&
cat >"$HTTPD_DOCUMENT_ROOT_PATH/bundle-list" <<-EOF &&
[bundle]
version = 1
mode = all
heuristic = creationToken
[bundle "bundle-1"]
uri = bundle-1.bundle
creationToken = 1
EOF
GIT_TRACE2_EVENT=$(pwd)/trace-clone.txt \
git clone --bundle-uri="$HTTPD_URL/bundle-list" \
--single-branch --branch=base --no-tags \
"$HTTPD_URL/smart/fetch.git" clone-token-http &&
cat >expect <<-EOF &&
$HTTPD_URL/bundle-list
$HTTPD_URL/bundle-1.bundle
EOF
test_remote_https_urls <trace-clone.txt >actual &&
test_cmp expect actual
'
# Do not add tests here unless they use the HTTP server, as they will
# not run unless the HTTP dependencies exist.
test_done