Hi Jonathan,
On Tue, 26 Mar 2019, Jonathan Tan wrote:
> When running a command like "git show" or "git diff" in a partial clone,
> batch all missing blobs to be fetched as one request.
>
> This is similar to c0c578b33c ("unpack-trees: batch fetching of missing
> blobs", 2017-12-08), but for another command.
>
> Signed-off-by: Jonathan Tan <jonathantanmy@xxxxxxxxxx>
> ---
> Here's an improvement for those having partial clones.
>
> I couldn't find a good place to place the test (a place that checks how
> diff interfaces with the object store would be ideal), so I created a
> new one. Let me know if there's a better place to put it.
My 2c: that's fine.
> diff --git a/diff.c b/diff.c
> index ec5c095199..0e08d05b14 100644
> --- a/diff.c
> +++ b/diff.c
> @@ -25,6 +25,7 @@
> #include "packfile.h"
> #include "parse-options.h"
> #include "help.h"
> +#include "fetch-object.h"
>
> #ifdef NO_FAST_WORKING_DIRECTORY
> #define FAST_WORKING_DIRECTORY 0
> @@ -6067,6 +6068,32 @@ static void diff_flush_patch_all_file_pairs(struct diff_options *o)
> if (o->color_moved)
> o->emitted_symbols = &esm;
>
> + if (repository_format_partial_clone) {
> + /*
> + * Prefetch the diff pairs that are about to be flushed.
> + */
> + struct oid_array to_fetch = OID_ARRAY_INIT;
> + int fetch_if_missing_store = fetch_if_missing;
> +
> + fetch_if_missing = 0;
> + for (i = 0; i < q->nr; i++) {
> + struct diff_filepair *p = q->queue[i];
> + if (!check_pair_status(p))
> + continue;
> + if (p->one && p->one->oid_valid &&
> + !has_object_file(&p->one->oid))
> + oid_array_append(&to_fetch, &p->one->oid);
> + if (p->two && p->two->oid_valid &&
> + !has_object_file(&p->two->oid))
> + oid_array_append(&to_fetch, &p->two->oid);
> + }
> + if (to_fetch.nr)
> + fetch_objects(repository_format_partial_clone,
> + to_fetch.oid, to_fetch.nr);
> + fetch_if_missing = fetch_if_missing_store;
I am slightly uneasy about the fact that this is totally *not*
multi-thread safe. If only we had a way to pass the `fetch_if_missing`
information as a parameter to `has_object_file()`...
Do you think that would be easy to do? If so, I think now would be as fine
an opportunity as ever to introduce that.
Otherwise the patch looks just fine to me.
Thanks,
Dscho
> + oid_array_clear(&to_fetch);
> + }
> +
> for (i = 0; i < q->nr; i++) {
> struct diff_filepair *p = q->queue[i];
> if (check_pair_status(p))
> diff --git a/t/t4067-diff-partial-clone.sh b/t/t4067-diff-partial-clone.sh
> new file mode 100755
> index 0000000000..38f03be114
> --- /dev/null
> +++ b/t/t4067-diff-partial-clone.sh
> @@ -0,0 +1,76 @@
> +#!/bin/sh
> +
> +test_description='behavior of diff when reading objects in a partial clone'
> +
> +. ./test-lib.sh
> +
> +test_expect_success 'git show batches blobs' '
> + test_create_repo server &&
> + echo a >server/a &&
> + echo b >server/b &&
> + git -C server add a b &&
> + git -C server commit -m x &&
> +
> + test_config -C server uploadpack.allowfilter 1 &&
> + test_config -C server uploadpack.allowanysha1inwant 1 &&
> + git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
> +
> + # Ensure that there is exactly 1 negotiation by checking that there is
> + # only 1 "done" line sent. ("done" marks the end of negotiation.)
> + GIT_TRACE_PACKET="$(pwd)/trace" git -C client show HEAD &&
> + grep "git> done" trace >done_lines &&
> + test_line_count = 1 done_lines
> +'
> +
> +test_expect_success 'diff batches blobs' '
> + rm -rf server client trace &&
> +
> + test_create_repo server &&
> + echo a >server/a &&
> + echo b >server/b &&
> + git -C server add a b &&
> + git -C server commit -m x &&
> + echo c >server/c &&
> + echo d >server/d &&
> + git -C server add c d &&
> + git -C server commit -m x &&
> +
> + test_config -C server uploadpack.allowfilter 1 &&
> + test_config -C server uploadpack.allowanysha1inwant 1 &&
> + git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
> +
> + # Ensure that there is exactly 1 negotiation by checking that there is
> + # only 1 "done" line sent. ("done" marks the end of negotiation.)
> + GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff HEAD^ HEAD &&
> + grep "git> done" trace >done_lines &&
> + test_line_count = 1 done_lines
> +'
> +
> +test_expect_success 'diff skips same-OID blobs' '
> + rm -rf server client trace &&
> +
> + test_create_repo server &&
> + echo a >server/a &&
> + echo b >server/b &&
> + git -C server add a b &&
> + git -C server commit -m x &&
> + echo another-a >server/a &&
> + git -C server add a &&
> + git -C server commit -m x &&
> +
> + test_config -C server uploadpack.allowfilter 1 &&
> + test_config -C server uploadpack.allowanysha1inwant 1 &&
> + git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
> +
> + echo a | git hash-object --stdin >hash-old-a &&
> + echo another-a | git hash-object --stdin >hash-new-a &&
> + echo b | git hash-object --stdin >hash-b &&
> +
> + # Ensure that only a and another-a are fetched.
> + GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff HEAD^ HEAD &&
> + grep "want $(cat hash-old-a)" trace &&
> + grep "want $(cat hash-new-a)" trace &&
> + ! grep "want $(cat hash-b)" trace
> +'
> +
> +test_done
> --
> 2.21.0.155.ge902e9bcae.dirty
>
>
