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git/fetch-object.c

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C
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introduce fetch-object: fetch one promisor object Introduce fetch-object, providing the ability to fetch one object from a promisor remote. This uses fetch-pack. To do this, the transport mechanism has been updated with 2 flags, "from-promisor" to indicate that the resulting pack comes from a promisor remote (and thus should be annotated as such by index-pack), and "no-dependents" to indicate that only the objects themselves need to be fetched (but fetching additional objects is nevertheless safe). Whenever "no-dependents" is used, fetch-pack will refrain from using any object flags, because it is most likely invoked as part of a dynamic object fetch by another Git command (which may itself use object flags). An alternative to this is to leave fetch-pack alone, and instead update the allocation of flags so that fetch-pack's flags never overlap with any others, but this will end up shrinking the number of flags available to nearly every other Git command (that is, every Git command that accesses objects), so the approach in this commit was used instead. This will be tested in a subsequent commit. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-05 19:58:49 +03:00
#include "cache.h"
#include "packfile.h"
#include "pkt-line.h"
#include "strbuf.h"
#include "transport.h"
#include "fetch-object.h"
unpack-trees: batch fetching of missing blobs When running checkout, first prefetch all blobs that are to be updated but are missing. This means that only one pack is downloaded during such operations, instead of one per missing blob. This operates only on the blob level - if a repository has a missing tree, they are still fetched one at a time. This does not use the delayed checkout mechanism introduced in commit 2841e8f ("convert: add "status=delayed" to filter process protocol", 2017-06-30) due to significant conceptual differences - in particular, for partial clones, we already know what needs to be fetched based on the contents of the local repo alone, whereas for status=delayed, it is the filter process that tells us what needs to be checked in the end. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-08 18:58:47 +03:00
static void fetch_refs(const char *remote_name, struct ref *ref)
introduce fetch-object: fetch one promisor object Introduce fetch-object, providing the ability to fetch one object from a promisor remote. This uses fetch-pack. To do this, the transport mechanism has been updated with 2 flags, "from-promisor" to indicate that the resulting pack comes from a promisor remote (and thus should be annotated as such by index-pack), and "no-dependents" to indicate that only the objects themselves need to be fetched (but fetching additional objects is nevertheless safe). Whenever "no-dependents" is used, fetch-pack will refrain from using any object flags, because it is most likely invoked as part of a dynamic object fetch by another Git command (which may itself use object flags). An alternative to this is to leave fetch-pack alone, and instead update the allocation of flags so that fetch-pack's flags never overlap with any others, but this will end up shrinking the number of flags available to nearly every other Git command (that is, every Git command that accesses objects), so the approach in this commit was used instead. This will be tested in a subsequent commit. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-05 19:58:49 +03:00
{
struct remote *remote;
struct transport *transport;
sha1_file: support lazily fetching missing objects Teach sha1_file to fetch objects from the remote configured in extensions.partialclone whenever an object is requested but missing. The fetching of objects can be suppressed through a global variable. This is used by fsck and index-pack. However, by default, such fetching is not suppressed. This is meant as a temporary measure to ensure that all Git commands work in such a situation. Future patches will update some commands to either tolerate missing objects (without fetching them) or be more efficient in fetching them. In order to determine the code changes in sha1_file.c necessary, I investigated the following: (1) functions in sha1_file.c that take in a hash, without the user regarding how the object is stored (loose or packed) (2) functions in packfile.c (because I need to check callers that know about the loose/packed distinction and operate on both differently, and ensure that they can handle the concept of objects that are neither loose nor packed) (1) is handled by the modification to sha1_object_info_extended(). For (2), I looked at for_each_packed_object and others. For for_each_packed_object, the callers either already work or are fixed in this patch: - reachable - only to find recent objects - builtin/fsck - already knows about missing objects - builtin/cat-file - warning message added in this commit Callers of the other functions do not need to be changed: - parse_pack_index - http - indirectly from http_get_info_packs - find_pack_entry_one - this searches a single pack that is provided as an argument; the caller already knows (through other means) that the sought object is in a specific pack - find_sha1_pack - fast-import - appears to be an optimization to not store a file if it is already in a pack - http-walker - to search through a struct alt_base - http-push - to search through remote packs - has_sha1_pack - builtin/fsck - already knows about promisor objects - builtin/count-objects - informational purposes only (check if loose object is also packed) - builtin/prune-packed - check if object to be pruned is packed (if not, don't prune it) - revision - used to exclude packed objects if requested by user - diff - just for optimization Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-08 18:27:14 +03:00
int original_fetch_if_missing = fetch_if_missing;
introduce fetch-object: fetch one promisor object Introduce fetch-object, providing the ability to fetch one object from a promisor remote. This uses fetch-pack. To do this, the transport mechanism has been updated with 2 flags, "from-promisor" to indicate that the resulting pack comes from a promisor remote (and thus should be annotated as such by index-pack), and "no-dependents" to indicate that only the objects themselves need to be fetched (but fetching additional objects is nevertheless safe). Whenever "no-dependents" is used, fetch-pack will refrain from using any object flags, because it is most likely invoked as part of a dynamic object fetch by another Git command (which may itself use object flags). An alternative to this is to leave fetch-pack alone, and instead update the allocation of flags so that fetch-pack's flags never overlap with any others, but this will end up shrinking the number of flags available to nearly every other Git command (that is, every Git command that accesses objects), so the approach in this commit was used instead. This will be tested in a subsequent commit. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-05 19:58:49 +03:00
sha1_file: support lazily fetching missing objects Teach sha1_file to fetch objects from the remote configured in extensions.partialclone whenever an object is requested but missing. The fetching of objects can be suppressed through a global variable. This is used by fsck and index-pack. However, by default, such fetching is not suppressed. This is meant as a temporary measure to ensure that all Git commands work in such a situation. Future patches will update some commands to either tolerate missing objects (without fetching them) or be more efficient in fetching them. In order to determine the code changes in sha1_file.c necessary, I investigated the following: (1) functions in sha1_file.c that take in a hash, without the user regarding how the object is stored (loose or packed) (2) functions in packfile.c (because I need to check callers that know about the loose/packed distinction and operate on both differently, and ensure that they can handle the concept of objects that are neither loose nor packed) (1) is handled by the modification to sha1_object_info_extended(). For (2), I looked at for_each_packed_object and others. For for_each_packed_object, the callers either already work or are fixed in this patch: - reachable - only to find recent objects - builtin/fsck - already knows about missing objects - builtin/cat-file - warning message added in this commit Callers of the other functions do not need to be changed: - parse_pack_index - http - indirectly from http_get_info_packs - find_pack_entry_one - this searches a single pack that is provided as an argument; the caller already knows (through other means) that the sought object is in a specific pack - find_sha1_pack - fast-import - appears to be an optimization to not store a file if it is already in a pack - http-walker - to search through a struct alt_base - http-push - to search through remote packs - has_sha1_pack - builtin/fsck - already knows about promisor objects - builtin/count-objects - informational purposes only (check if loose object is also packed) - builtin/prune-packed - check if object to be pruned is packed (if not, don't prune it) - revision - used to exclude packed objects if requested by user - diff - just for optimization Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-08 18:27:14 +03:00
fetch_if_missing = 0;
introduce fetch-object: fetch one promisor object Introduce fetch-object, providing the ability to fetch one object from a promisor remote. This uses fetch-pack. To do this, the transport mechanism has been updated with 2 flags, "from-promisor" to indicate that the resulting pack comes from a promisor remote (and thus should be annotated as such by index-pack), and "no-dependents" to indicate that only the objects themselves need to be fetched (but fetching additional objects is nevertheless safe). Whenever "no-dependents" is used, fetch-pack will refrain from using any object flags, because it is most likely invoked as part of a dynamic object fetch by another Git command (which may itself use object flags). An alternative to this is to leave fetch-pack alone, and instead update the allocation of flags so that fetch-pack's flags never overlap with any others, but this will end up shrinking the number of flags available to nearly every other Git command (that is, every Git command that accesses objects), so the approach in this commit was used instead. This will be tested in a subsequent commit. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-05 19:58:49 +03:00
remote = remote_get(remote_name);
if (!remote->url[0])
die(_("Remote with no URL"));
transport = transport_get(remote, remote->url[0]);
transport_set_option(transport, TRANS_OPT_FROM_PROMISOR, "1");
transport_set_option(transport, TRANS_OPT_NO_DEPENDENTS, "1");
fetch-pack: put shallow info in output parameter Expand the transport fetch method signature, by adding an output parameter, to allow transports to return information about the refs they have fetched. Then communicate shallow status information through this mechanism instead of by modifying the input list of refs. This does require clients to sometimes generate the ref map twice: once from the list of refs provided by the remote (as is currently done) and potentially once from the new list of refs that the fetch mechanism provides. Signed-off-by: Brandon Williams <bmwill@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-06-28 01:30:22 +03:00
transport_fetch_refs(transport, ref, NULL);
sha1_file: support lazily fetching missing objects Teach sha1_file to fetch objects from the remote configured in extensions.partialclone whenever an object is requested but missing. The fetching of objects can be suppressed through a global variable. This is used by fsck and index-pack. However, by default, such fetching is not suppressed. This is meant as a temporary measure to ensure that all Git commands work in such a situation. Future patches will update some commands to either tolerate missing objects (without fetching them) or be more efficient in fetching them. In order to determine the code changes in sha1_file.c necessary, I investigated the following: (1) functions in sha1_file.c that take in a hash, without the user regarding how the object is stored (loose or packed) (2) functions in packfile.c (because I need to check callers that know about the loose/packed distinction and operate on both differently, and ensure that they can handle the concept of objects that are neither loose nor packed) (1) is handled by the modification to sha1_object_info_extended(). For (2), I looked at for_each_packed_object and others. For for_each_packed_object, the callers either already work or are fixed in this patch: - reachable - only to find recent objects - builtin/fsck - already knows about missing objects - builtin/cat-file - warning message added in this commit Callers of the other functions do not need to be changed: - parse_pack_index - http - indirectly from http_get_info_packs - find_pack_entry_one - this searches a single pack that is provided as an argument; the caller already knows (through other means) that the sought object is in a specific pack - find_sha1_pack - fast-import - appears to be an optimization to not store a file if it is already in a pack - http-walker - to search through a struct alt_base - http-push - to search through remote packs - has_sha1_pack - builtin/fsck - already knows about promisor objects - builtin/count-objects - informational purposes only (check if loose object is also packed) - builtin/prune-packed - check if object to be pruned is packed (if not, don't prune it) - revision - used to exclude packed objects if requested by user - diff - just for optimization Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-08 18:27:14 +03:00
fetch_if_missing = original_fetch_if_missing;
introduce fetch-object: fetch one promisor object Introduce fetch-object, providing the ability to fetch one object from a promisor remote. This uses fetch-pack. To do this, the transport mechanism has been updated with 2 flags, "from-promisor" to indicate that the resulting pack comes from a promisor remote (and thus should be annotated as such by index-pack), and "no-dependents" to indicate that only the objects themselves need to be fetched (but fetching additional objects is nevertheless safe). Whenever "no-dependents" is used, fetch-pack will refrain from using any object flags, because it is most likely invoked as part of a dynamic object fetch by another Git command (which may itself use object flags). An alternative to this is to leave fetch-pack alone, and instead update the allocation of flags so that fetch-pack's flags never overlap with any others, but this will end up shrinking the number of flags available to nearly every other Git command (that is, every Git command that accesses objects), so the approach in this commit was used instead. This will be tested in a subsequent commit. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-05 19:58:49 +03:00
}
unpack-trees: batch fetching of missing blobs When running checkout, first prefetch all blobs that are to be updated but are missing. This means that only one pack is downloaded during such operations, instead of one per missing blob. This operates only on the blob level - if a repository has a missing tree, they are still fetched one at a time. This does not use the delayed checkout mechanism introduced in commit 2841e8f ("convert: add "status=delayed" to filter process protocol", 2017-06-30) due to significant conceptual differences - in particular, for partial clones, we already know what needs to be fetched based on the contents of the local repo alone, whereas for status=delayed, it is the filter process that tells us what needs to be checked in the end. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-08 18:58:47 +03:00
void fetch_object(const char *remote_name, const unsigned char *sha1)
{
struct ref *ref = alloc_ref(sha1_to_hex(sha1));
hashcpy(ref->old_oid.hash, sha1);
fetch_refs(remote_name, ref);
}
void fetch_objects(const char *remote_name, const struct oid_array *to_fetch)
{
struct ref *ref = NULL;
int i;
for (i = 0; i < to_fetch->nr; i++) {
struct ref *new_ref = alloc_ref(oid_to_hex(&to_fetch->oid[i]));
oidcpy(&new_ref->old_oid, &to_fetch->oid[i]);
new_ref->next = ref;
ref = new_ref;
}
fetch_refs(remote_name, ref);
}