git/bundle-uri.h

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#ifndef BUNDLE_URI_H
#define BUNDLE_URI_H
bundle-uri: create bundle_list struct and helpers It will likely be rare where a user uses a single bundle URI and expects that URI to point to a bundle. Instead, that URI will likely be a list of bundles provided in some format. Alternatively, the Git server could advertise a list of bundles. In anticipation of these two ways of advertising multiple bundles, create a data structure that represents such a list. This will be populated using a common API, but for now focus on what data can be represented. Each list contains a number of remote_bundle_info structs. These contain an 'id' that is used to uniquely identify them in the list, and also a 'uri' that contains the location of its data. Finally, there is a strbuf containing the filename used when Git downloads the contents to disk. The list itself stores these remote_bundle_info structs in a hashtable using 'id' as the key. The order of the structs in the input is considered unimportant, but future modifications to the format and these data structures will place ordering possibilities on the set. The list also has a few "global" properties, including the version (used when parsing the list) and the mode. The mode is one of these two options: 1. BUNDLE_MODE_ALL: all listed URIs are intended to be combined together. The client should download all of the advertised data to have a complete copy of the data. 2. BUNDLE_MODE_ANY: any one listed item is sufficient to have a complete copy of the data. The client can choose arbitrarily from these options. In the future, the client may use pings to find the closest URI among geodistributed replicas, or use some other heuristic information added to the format. This API is currently unused, but will soon be expanded with parsing logic and then be consumed by the bundle URI download logic. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-10-12 12:52:29 +00:00
#include "hashmap.h"
#include "strbuf.h"
protocol v2: add server-side "bundle-uri" skeleton Add a skeleton server-side implementation of a new "bundle-uri" command to protocol v2. This will allow conforming clients to optionally seed their initial clones or incremental fetches from URLs containing "*.bundle" files created with "git bundle create". This change only performs the basic boilerplate of advertising a new protocol v2 capability. The new 'bundle-uri' capability allows a client to request a list of bundles. Right now, the server only returns a flush packet, which corresponds to an empty advertisement. The bundle.* config namespace describes which key-value pairs will be communicated across this interface in future updates. The critical bit right now is that the new boolean uploadPack.adverstiseBundleURIs config value signals whether or not this capability should be advertised at all. An earlier version of this patch [1] used a different transfer format than the "key=value" pairs in the current implementation. The change was made to unify the protocol v2 command with the bundle lists provided by independent bundle servers. Further, the standard allows for the server to advertise a URI that contains a bundle list. This allows users automatically discovering bundle providers that are loosely associated with the origin server, but without the origin server knowing exactly which bundles are currently available. [1] https://lore.kernel.org/git/RFC-patch-v2-01.13-2fc87ce092b-20220311T155841Z-avarab@gmail.com/ The very-deep headings needed to be modified to stop at level 4 due to documentation build issues. These were not recognized in earlier builds since the file was previously in the Documentation/technical/ directory and was built in a different way. With its current location, the heavily-nested details were causing build issues and they are now replaced with a bulletted list of details. Co-authored-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-22 15:14:07 +00:00
struct packet_reader;
struct repository;
bundle-uri: create bundle_list struct and helpers It will likely be rare where a user uses a single bundle URI and expects that URI to point to a bundle. Instead, that URI will likely be a list of bundles provided in some format. Alternatively, the Git server could advertise a list of bundles. In anticipation of these two ways of advertising multiple bundles, create a data structure that represents such a list. This will be populated using a common API, but for now focus on what data can be represented. Each list contains a number of remote_bundle_info structs. These contain an 'id' that is used to uniquely identify them in the list, and also a 'uri' that contains the location of its data. Finally, there is a strbuf containing the filename used when Git downloads the contents to disk. The list itself stores these remote_bundle_info structs in a hashtable using 'id' as the key. The order of the structs in the input is considered unimportant, but future modifications to the format and these data structures will place ordering possibilities on the set. The list also has a few "global" properties, including the version (used when parsing the list) and the mode. The mode is one of these two options: 1. BUNDLE_MODE_ALL: all listed URIs are intended to be combined together. The client should download all of the advertised data to have a complete copy of the data. 2. BUNDLE_MODE_ANY: any one listed item is sufficient to have a complete copy of the data. The client can choose arbitrarily from these options. In the future, the client may use pings to find the closest URI among geodistributed replicas, or use some other heuristic information added to the format. This API is currently unused, but will soon be expanded with parsing logic and then be consumed by the bundle URI download logic. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-10-12 12:52:29 +00:00
struct string_list;
/**
* The remote_bundle_info struct contains information for a single bundle
* URI. This may be initialized simply by a given URI or might have
* additional metadata associated with it if the bundle was advertised by
* a bundle list.
*/
struct remote_bundle_info {
struct hashmap_entry ent;
/**
* The 'id' is a name given to the bundle for reference
* by other bundle infos.
*/
char *id;
/**
* The 'uri' is the location of the remote bundle so
* it can be downloaded on-demand. This will be NULL
* if there was no table of contents.
*/
char *uri;
bundle-uri: fetch a list of bundles When the content at a given bundle URI is not understood as a bundle (based on inspecting the initial content), then Git currently gives up and ignores that content. Independent bundle providers may want to split up the bundle content into multiple bundles, but still make them available from a single URI. Teach Git to attempt parsing the bundle URI content as a Git config file providing the key=value pairs for a bundle list. Git then looks at the mode of the list to see if ANY single bundle is sufficient or if ALL bundles are required. The content at the selected URIs are downloaded and the content is inspected again, creating a recursive process. To guard the recursion against malformed or malicious content, limit the recursion depth to a reasonable four for now. This can be converted to a configured value in the future if necessary. The value of four is twice as high as expected to be useful (a bundle list is unlikely to point to more bundle lists). To test this scenario, create an interesting bundle topology where three incremental bundles are built on top of a single full bundle. By using a merge commit, the two middle bundles are "independent" in that they do not require each other in order to unbundle themselves. They each only need the base bundle. The bundle containing the merge commit requires both of the middle bundles, though. This leads to some interesting decisions when unbundling, especially when we later implement heuristics that promote downloading bundles until the prerequisite commits are satisfied. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-10-12 12:52:36 +00:00
/**
* If the bundle has been downloaded, then 'file' is a
* filename storing its contents. Otherwise, 'file' is
* NULL.
*/
char *file;
/**
* If the bundle has been unbundled successfully, then
* this boolean is true.
*/
unsigned unbundled:1;
/**
* If the bundle is part of a list with the creationToken
* heuristic, then we use this member for sorting the bundles.
*/
uint64_t creationToken;
bundle-uri: create bundle_list struct and helpers It will likely be rare where a user uses a single bundle URI and expects that URI to point to a bundle. Instead, that URI will likely be a list of bundles provided in some format. Alternatively, the Git server could advertise a list of bundles. In anticipation of these two ways of advertising multiple bundles, create a data structure that represents such a list. This will be populated using a common API, but for now focus on what data can be represented. Each list contains a number of remote_bundle_info structs. These contain an 'id' that is used to uniquely identify them in the list, and also a 'uri' that contains the location of its data. Finally, there is a strbuf containing the filename used when Git downloads the contents to disk. The list itself stores these remote_bundle_info structs in a hashtable using 'id' as the key. The order of the structs in the input is considered unimportant, but future modifications to the format and these data structures will place ordering possibilities on the set. The list also has a few "global" properties, including the version (used when parsing the list) and the mode. The mode is one of these two options: 1. BUNDLE_MODE_ALL: all listed URIs are intended to be combined together. The client should download all of the advertised data to have a complete copy of the data. 2. BUNDLE_MODE_ANY: any one listed item is sufficient to have a complete copy of the data. The client can choose arbitrarily from these options. In the future, the client may use pings to find the closest URI among geodistributed replicas, or use some other heuristic information added to the format. This API is currently unused, but will soon be expanded with parsing logic and then be consumed by the bundle URI download logic. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-10-12 12:52:29 +00:00
};
#define REMOTE_BUNDLE_INFO_INIT { 0 }
enum bundle_list_mode {
BUNDLE_MODE_NONE = 0,
BUNDLE_MODE_ALL,
BUNDLE_MODE_ANY
};
enum bundle_list_heuristic {
BUNDLE_HEURISTIC_NONE = 0,
BUNDLE_HEURISTIC_CREATIONTOKEN,
/* Must be last. */
BUNDLE_HEURISTIC__COUNT
};
bundle-uri: create bundle_list struct and helpers It will likely be rare where a user uses a single bundle URI and expects that URI to point to a bundle. Instead, that URI will likely be a list of bundles provided in some format. Alternatively, the Git server could advertise a list of bundles. In anticipation of these two ways of advertising multiple bundles, create a data structure that represents such a list. This will be populated using a common API, but for now focus on what data can be represented. Each list contains a number of remote_bundle_info structs. These contain an 'id' that is used to uniquely identify them in the list, and also a 'uri' that contains the location of its data. Finally, there is a strbuf containing the filename used when Git downloads the contents to disk. The list itself stores these remote_bundle_info structs in a hashtable using 'id' as the key. The order of the structs in the input is considered unimportant, but future modifications to the format and these data structures will place ordering possibilities on the set. The list also has a few "global" properties, including the version (used when parsing the list) and the mode. The mode is one of these two options: 1. BUNDLE_MODE_ALL: all listed URIs are intended to be combined together. The client should download all of the advertised data to have a complete copy of the data. 2. BUNDLE_MODE_ANY: any one listed item is sufficient to have a complete copy of the data. The client can choose arbitrarily from these options. In the future, the client may use pings to find the closest URI among geodistributed replicas, or use some other heuristic information added to the format. This API is currently unused, but will soon be expanded with parsing logic and then be consumed by the bundle URI download logic. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-10-12 12:52:29 +00:00
/**
* A bundle_list contains an unordered set of remote_bundle_info structs,
* as well as information about the bundle listing, such as version and
* mode.
*/
struct bundle_list {
int version;
enum bundle_list_mode mode;
struct hashmap bundles;
/**
* The baseURI of a bundle_list is the URI that provided the list.
*
* In the case of the 'bundle-uri' protocol v2 command, the base
* URI is the URI of the Git remote.
*
* Otherwise, the bundle list was downloaded over HTTP from some
* known URI. 'baseURI' is set to that value.
*
* The baseURI is used as the base for any relative URIs
* advertised by the bundle list at that location.
*/
char *baseURI;
/**
* A list can have a heuristic, which helps reduce the number of
* downloaded bundles.
*/
enum bundle_list_heuristic heuristic;
bundle-uri: create bundle_list struct and helpers It will likely be rare where a user uses a single bundle URI and expects that URI to point to a bundle. Instead, that URI will likely be a list of bundles provided in some format. Alternatively, the Git server could advertise a list of bundles. In anticipation of these two ways of advertising multiple bundles, create a data structure that represents such a list. This will be populated using a common API, but for now focus on what data can be represented. Each list contains a number of remote_bundle_info structs. These contain an 'id' that is used to uniquely identify them in the list, and also a 'uri' that contains the location of its data. Finally, there is a strbuf containing the filename used when Git downloads the contents to disk. The list itself stores these remote_bundle_info structs in a hashtable using 'id' as the key. The order of the structs in the input is considered unimportant, but future modifications to the format and these data structures will place ordering possibilities on the set. The list also has a few "global" properties, including the version (used when parsing the list) and the mode. The mode is one of these two options: 1. BUNDLE_MODE_ALL: all listed URIs are intended to be combined together. The client should download all of the advertised data to have a complete copy of the data. 2. BUNDLE_MODE_ANY: any one listed item is sufficient to have a complete copy of the data. The client can choose arbitrarily from these options. In the future, the client may use pings to find the closest URI among geodistributed replicas, or use some other heuristic information added to the format. This API is currently unused, but will soon be expanded with parsing logic and then be consumed by the bundle URI download logic. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-10-12 12:52:29 +00:00
};
void init_bundle_list(struct bundle_list *list);
void clear_bundle_list(struct bundle_list *list);
typedef int (*bundle_iterator)(struct remote_bundle_info *bundle,
void *data);
int for_all_bundles_in_list(struct bundle_list *list,
bundle_iterator iter,
void *data);
struct FILE;
void print_bundle_list(FILE *fp, struct bundle_list *list);
bundle-uri: parse bundle list in config format When a bundle provider wants to operate independently from a Git remote, they want to provide a single, consistent URI that users can use in their 'git clone --bundle-uri' commands. At this point, the Git client expects that URI to be a single bundle that can be unbundled and used to bootstrap the rest of the clone from the Git server. This single bundle cannot be re-used to assist with future incremental fetches. To allow for the incremental fetch case, teach Git to understand a bundle list that could be advertised at an independent bundle URI. Such a bundle list is likely to be inspected by human readers, even if only by the bundle provider creating the list. For this reason, we can take our expected "key=value" pairs and instead format them using Git config format. Create bundle_uri_parse_config_format() to parse a file in config format and convert that into a 'struct bundle_list' filled with its understanding of the contents. Be careful to use error_action CONFIG_ERROR_ERROR when calling git_config_from_file_with_options() because the default action for git_config_from_file() is to die() on a parsing error. The current warning isn't particularly helpful if it arises to a user, but it will be made more verbose at a higher layer later. Update 'test-tool bundle-uri' to take this config file format as input. It uses a filename instead of stdin because there is no existing way to parse a FILE pointer in the config machinery. Using git_config_from_mem() is overly complicated and more likely to introduce bugs than this simpler version. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-10-12 12:52:33 +00:00
/**
* A bundle URI may point to a bundle list where the key=value
* pairs are provided in config file format. This method is
* exposed publicly for testing purposes.
*/
int bundle_uri_parse_config_format(const char *uri,
const char *filename,
struct bundle_list *list);
/**
* Fetch data from the given 'uri' and unbundle the bundle data found
* based on that information.
*
* Returns non-zero if no bundle information is found at the given 'uri'.
*
* If the pointer 'has_heuristic' is non-NULL, then the value it points to
* will be set to be non-zero if and only if the fetched list has a
* heuristic value. Such a value indicates that the list was designed for
* incremental fetches.
*/
int fetch_bundle_uri(struct repository *r, const char *uri,
int *has_heuristic);
/**
* Given a bundle list that was already advertised (likely by the
* bundle-uri protocol v2 verb) at the given uri, fetch and unbundle the
* bundles according to the bundle strategy of that list.
*
* It is expected that the given 'list' is initialized, including its
* 'baseURI' value.
*
* Returns non-zero if there was an error trying to download the list
* or any of its advertised bundles.
*/
int fetch_bundle_list(struct repository *r,
struct bundle_list *list);
protocol v2: add server-side "bundle-uri" skeleton Add a skeleton server-side implementation of a new "bundle-uri" command to protocol v2. This will allow conforming clients to optionally seed their initial clones or incremental fetches from URLs containing "*.bundle" files created with "git bundle create". This change only performs the basic boilerplate of advertising a new protocol v2 capability. The new 'bundle-uri' capability allows a client to request a list of bundles. Right now, the server only returns a flush packet, which corresponds to an empty advertisement. The bundle.* config namespace describes which key-value pairs will be communicated across this interface in future updates. The critical bit right now is that the new boolean uploadPack.adverstiseBundleURIs config value signals whether or not this capability should be advertised at all. An earlier version of this patch [1] used a different transfer format than the "key=value" pairs in the current implementation. The change was made to unify the protocol v2 command with the bundle lists provided by independent bundle servers. Further, the standard allows for the server to advertise a URI that contains a bundle list. This allows users automatically discovering bundle providers that are loosely associated with the origin server, but without the origin server knowing exactly which bundles are currently available. [1] https://lore.kernel.org/git/RFC-patch-v2-01.13-2fc87ce092b-20220311T155841Z-avarab@gmail.com/ The very-deep headings needed to be modified to stop at level 4 due to documentation build issues. These were not recognized in earlier builds since the file was previously in the Documentation/technical/ directory and was built in a different way. With its current location, the heavily-nested details were causing build issues and they are now replaced with a bulletted list of details. Co-authored-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-22 15:14:07 +00:00
/**
* API for serve.c.
*/
int bundle_uri_advertise(struct repository *r, struct strbuf *value);
int bundle_uri_command(struct repository *r, struct packet_reader *request);
/**
* General API for {transport,connect}.c etc.
*/
/**
* Parse a "key=value" packet line from the bundle-uri verb.
*
* Returns 0 on success and non-zero on error.
*/
int bundle_uri_parse_line(struct bundle_list *list,
const char *line);
#endif