From: Derrick Stolee Date: Mon, 05 Feb 2018 14:14:59 GMT Subject: Re: [PATCH v2 10/27] protocol: introduce enum protocol_version value protocol_v2 Message-ID: <592b2701-de7d-293b-f374-a885bdd827df@gmail.com> In-Reply-To: <20180202224454.GB187827@google.com> On 2/2/2018 5:44 PM, Brandon Williams wrote: > On 01/31, Derrick Stolee wrote: >> On 1/25/2018 6:58 PM, Brandon Williams wrote: >>> Introduce protocol_v2, a new value for 'enum protocol_version'. >>> Subsequent patches will fill in the implementation of protocol_v2. >>> >>> Signed-off-by: Brandon Williams >>> --- >>> builtin/fetch-pack.c | 3 +++ >>> builtin/receive-pack.c | 6 ++++++ >>> builtin/send-pack.c | 3 +++ >>> builtin/upload-pack.c | 7 +++++++ >>> connect.c | 3 +++ >>> protocol.c | 2 ++ >>> protocol.h | 1 + >>> remote-curl.c | 3 +++ >>> transport.c | 9 +++++++++ >>> 9 files changed, 37 insertions(+) >>> >>> diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c >>> index 85d4faf76..f492e8abd 100644 >>> --- a/builtin/fetch-pack.c >>> +++ b/builtin/fetch-pack.c >>> @@ -201,6 +201,9 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix) >>> PACKET_READ_GENTLE_ON_EOF); >>> switch (discover_version(&reader)) { >>> + case protocol_v2: >>> + die("support for protocol v2 not implemented yet"); >>> + break; >>> case protocol_v1: >>> case protocol_v0: >>> get_remote_heads(&reader, &ref, 0, NULL, &shallow); >>> diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c >>> index b7ce7c7f5..3656e94fd 100644 >>> --- a/builtin/receive-pack.c >>> +++ b/builtin/receive-pack.c >>> @@ -1963,6 +1963,12 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix) >>> unpack_limit = receive_unpack_limit; >>> switch (determine_protocol_version_server()) { >>> + case protocol_v2: >>> + /* >>> + * push support for protocol v2 has not been implemented yet, >>> + * so ignore the request to use v2 and fallback to using v0. >>> + */ >>> + break; >>> case protocol_v1: >>> /* >>> * v1 is just the original protocol with a version string, >>> diff --git a/builtin/send-pack.c b/builtin/send-pack.c >>> index 83cb125a6..b5427f75e 100644 >>> --- a/builtin/send-pack.c >>> +++ b/builtin/send-pack.c >>> @@ -263,6 +263,9 @@ int cmd_send_pack(int argc, const char **argv, const char *prefix) >>> PACKET_READ_GENTLE_ON_EOF); >>> switch (discover_version(&reader)) { >>> + case protocol_v2: >>> + die("support for protocol v2 not implemented yet"); >>> + break; >>> case protocol_v1: >>> case protocol_v0: >>> get_remote_heads(&reader, &remote_refs, REF_NORMAL, >>> diff --git a/builtin/upload-pack.c b/builtin/upload-pack.c >>> index 2cb5cb35b..8d53e9794 100644 >>> --- a/builtin/upload-pack.c >>> +++ b/builtin/upload-pack.c >>> @@ -47,6 +47,13 @@ int cmd_upload_pack(int argc, const char **argv, const char *prefix) >>> die("'%s' does not appear to be a git repository", dir); >>> switch (determine_protocol_version_server()) { >>> + case protocol_v2: >>> + /* >>> + * fetch support for protocol v2 has not been implemented yet, >>> + * so ignore the request to use v2 and fallback to using v0. >>> + */ >>> + upload_pack(&opts); >>> + break; >>> case protocol_v1: >>> /* >>> * v1 is just the original protocol with a version string, >>> diff --git a/connect.c b/connect.c >>> index db3c9d24c..f2157a821 100644 >>> --- a/connect.c >>> +++ b/connect.c >>> @@ -84,6 +84,9 @@ enum protocol_version discover_version(struct packet_reader *reader) >>> /* Maybe process capabilities here, at least for v2 */ >>> switch (version) { >>> + case protocol_v2: >>> + die("support for protocol v2 not implemented yet"); >>> + break; >>> case protocol_v1: >>> /* Read the peeked version line */ >>> packet_reader_read(reader); >>> diff --git a/protocol.c b/protocol.c >>> index 43012b7eb..5e636785d 100644 >>> --- a/protocol.c >>> +++ b/protocol.c >>> @@ -8,6 +8,8 @@ static enum protocol_version parse_protocol_version(const char *value) >>> return protocol_v0; >>> else if (!strcmp(value, "1")) >>> return protocol_v1; >>> + else if (!strcmp(value, "2")) >>> + return protocol_v2; >>> else >>> return protocol_unknown_version; >>> } >>> diff --git a/protocol.h b/protocol.h >>> index 1b2bc94a8..2ad35e433 100644 >>> --- a/protocol.h >>> +++ b/protocol.h >>> @@ -5,6 +5,7 @@ enum protocol_version { >>> protocol_unknown_version = -1, >>> protocol_v0 = 0, >>> protocol_v1 = 1, >>> + protocol_v2 = 2, >>> }; >>> /* >>> diff --git a/remote-curl.c b/remote-curl.c >>> index 9f6d07683..dae8a4a48 100644 >>> --- a/remote-curl.c >>> +++ b/remote-curl.c >>> @@ -185,6 +185,9 @@ static struct ref *parse_git_refs(struct discovery *heads, int for_push) >>> PACKET_READ_GENTLE_ON_EOF); >>> switch (discover_version(&reader)) { >>> + case protocol_v2: >>> + die("support for protocol v2 not implemented yet"); >>> + break; >>> case protocol_v1: >>> case protocol_v0: >>> get_remote_heads(&reader, &list, for_push ? REF_NORMAL : 0, >>> diff --git a/transport.c b/transport.c >>> index 2378dcb38..83d9dd1df 100644 >>> --- a/transport.c >>> +++ b/transport.c >>> @@ -203,6 +203,9 @@ static struct ref *get_refs_via_connect(struct transport *transport, int for_pus >>> data->version = discover_version(&reader); >>> switch (data->version) { >>> + case protocol_v2: >>> + die("support for protocol v2 not implemented yet"); >>> + break; >>> case protocol_v1: >>> case protocol_v0: >>> get_remote_heads(&reader, &refs, >>> @@ -250,6 +253,9 @@ static int fetch_refs_via_pack(struct transport *transport, >>> refs_tmp = get_refs_via_connect(transport, 0); >>> switch (data->version) { >>> + case protocol_v2: >>> + die("support for protocol v2 not implemented yet"); >>> + break; >>> case protocol_v1: >>> case protocol_v0: >>> refs = fetch_pack(&args, data->fd, data->conn, >>> @@ -585,6 +591,9 @@ static int git_transport_push(struct transport *transport, struct ref *remote_re >>> args.push_cert = SEND_PACK_PUSH_CERT_NEVER; >>> switch (data->version) { >>> + case protocol_v2: >>> + die("support for protocol v2 not implemented yet"); >>> + break; >>> case protocol_v1: >>> case protocol_v0: >>> ret = send_pack(&args, data->fd, data->conn, remote_refs, >> With a macro approach to version selection, this change becomes simpler in >> some ways and harder in others. >> >> It is simpler in that we can have the macro from the previous commits just >> fall back to version 0 behavior. >> >> It is harder in that this commit would need one of two options: >> >> 1. A macro that performs an arbitrary statement when given v2, which would >> be the die() for these actions not in v2. >> 2. A macro that clearly states v2 is not supported and calls die() on v2. >> >> Here is my simple, untested attempt at a union of these options: >> >> #define ON_PROTOCOL_VERSION(version,v0,v2) switch(version) {\ >> case protocol_v2:\ >>     (v2);\ >>     break;\ >> case protocol_v1:\ >> case protocol_v0:\ >>     (v0);\ >>     break;\ >> case protocol_unknown_version:\ >>     BUG("unknown protocol version");\ >> } >> #define ON_PROTOCOL_VERSION_V0_FALLBACK(version,v0) switch(version) {\ >> case protocol_v2:\ >> case protocol_v1:\ >> case protocol_v0:\ >>     (v0);\ >>     break;\ >> case protocol_unknown_version:\ >>     BUG("unknown protocol version");\ >> } >> #define ON_PROTOCOL_VERSION_V0_ONLY(version,v0) \ >>     ON_PROTOCOL_VERSION(version,v0,\ >>                 BUG("support for protocol v2 not implemented yet")) > > While I understand wanting to isolate the switch statement code, I think > that creating such a macro would make reading the code much more > difficult (and a pain to get right). Really I don't want to try my hand > at crafting such a macro :D > Sounds good. You're right that the macro approach is more likely to be used incorrectly. -Stolee