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[PATCH/RFC v3 04/16] Connect fast-import to the remote-helper via pipe, adding 'bidi-import' capability.

From
Florian Achleitner <florian.achleitner.2.6.31@gmail.com>
Date
Aug 14, 2012, 19:13 UTC
Message-ID
<1344971598-8213-5-git-send-email-florian.achleitner.2.6.31@gmail.com>
In-Reply-To
<1344971598-8213-4-git-send-email-florian.achleitner.2.6.31@gmail.com>

The fast-import commands 'cat-blob' and 'ls' can be used by remote-helpers to retrieve information about blobs and trees that already exist in fast-import's memory. This requires a channel from fast-import to the remote-helper. remote-helpers that use this features shall advertise the new 'bidi-import' capability so signal that they require the communication channel. When forking fast-import in transport-helper.c connect it to a dup of the remote-helper's stdin-pipe. The additional file descriptor is passed to fast-import via it's command line (--cat-blob-fd). It follows that git and fast-import are connected to the remote-helpers's stdin. Because git can send multiple commands to the remote-helper on it's stdin, it is required that helpers that advertise 'bidi-import' buffer all input commands until the batch of 'import' commands is ended by a newline before sending data to fast-import. This is to prevent mixing commands and fast-import responses on the helper's stdin.

Signed-off-by: Florian Achleitner <florian.achleitner.2.6.31@gmail.com>
---
 transport-helper.c |   45 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 32 insertions(+), 13 deletions(-)
diff --git a/transport-helper.c b/transport-helper.c
index cfe0988..257274b 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -10,6 +10,7 @@
 #include "string-list.h"
 #include "thread-utils.h"
 #include "sigchain.h"
+#include "argv-array.h"
 
 static int debug;
 
@@ -19,6 +20,7 @@ struct helper_data {
 	FILE *out;
 	unsigned fetch : 1,
 		import : 1,
+		bidi_import : 1,
 		export : 1,
 		option : 1,
 		push : 1,
@@ -101,6 +103,7 @@ static void do_take_over(struct transport *transport)
 static struct child_process *get_helper(struct transport *transport)
 {
 	struct helper_data *data = transport->data;
+	struct argv_array argv = ARGV_ARRAY_INIT;
 	struct strbuf buf = STRBUF_INIT;
 	struct child_process *helper;
 	const char **refspecs = NULL;
@@ -122,11 +125,10 @@ static struct child_process *get_helper(struct transport *transport)
 	helper->in = -1;
 	helper->out = -1;
 	helper->err = 0;
-	helper->argv = xcalloc(4, sizeof(*helper->argv));
-	strbuf_addf(&buf, "git-remote-%s", data->name);
-	helper->argv[0] = strbuf_detach(&buf, NULL);
-	helper->argv[1] = transport->remote->name;
-	helper->argv[2] = remove_ext_force(transport->url);
+	argv_array_pushf(&argv, "git-remote-%s", data->name);
+	argv_array_push(&argv, transport->remote->name);
+	argv_array_push(&argv, remove_ext_force(transport->url));
+	helper->argv = argv.argv;
 	helper->git_cmd = 0;
 	helper->silent_exec_failure = 1;
 
@@ -141,6 +143,8 @@ static struct child_process *get_helper(struct transport *transport)
 
 	data->helper = helper;
 	data->no_disconnect_req = 0;
+	free((void*) helper_env[1]);
+	argv_array_clear(&argv);
 
 	/*
 	 * Open the output as FILE* so strbuf_getline() can be used.
@@ -178,6 +182,8 @@ static struct child_process *get_helper(struct transport *transport)
 			data->push = 1;
 		else if (!strcmp(capname, "import"))
 			data->import = 1;
+		else if (!strcmp(capname, "bidi-import"))
+			data->bidi_import = 1;
 		else if (!strcmp(capname, "export"))
 			data->export = 1;
 		else if (!data->refspecs && !prefixcmp(capname, "refspec ")) {
@@ -241,8 +247,6 @@ static int disconnect_helper(struct transport *transport)
 		close(data->helper->out);
 		fclose(data->out);
 		res = finish_command(data->helper);
-		free((char *)data->helper->argv[0]);
-		free(data->helper->argv);
 		free(data->helper);
 		data->helper = NULL;
 	}
@@ -376,14 +380,24 @@ static int fetch_with_fetch(struct transport *transport,
 static int get_importer(struct transport *transport, struct child_process *fastimport)
 {
 	struct child_process *helper = get_helper(transport);
+	struct helper_data *data = transport->data;
+	struct argv_array argv = ARGV_ARRAY_INIT;
+	int cat_blob_fd, code;
 	memset(fastimport, 0, sizeof(*fastimport));
 	fastimport->in = helper->out;
-	fastimport->argv = xcalloc(5, sizeof(*fastimport->argv));
-	fastimport->argv[0] = "fast-import";
-	fastimport->argv[1] = "--quiet";
+	argv_array_push(&argv, "fast-import");
+	argv_array_push(&argv, "--quiet");
 
+	if (data->bidi_import) {
+		cat_blob_fd = xdup(helper->in);
+		argv_array_pushf(&argv, "--cat-blob-fd=%d", cat_blob_fd);
+	}
+	fastimport->argv = argv.argv;
 	fastimport->git_cmd = 1;
-	return start_command(fastimport);
+
+	code = start_command(fastimport);
+	argv_array_clear(&argv);
+	return code;
 }
 
 static int get_exporter(struct transport *transport,
@@ -438,11 +452,16 @@ static int fetch_with_import(struct transport *transport,
 	}
 
 	write_constant(data->helper->in, "\n");
+	/*
+	 * remote-helpers that advertise the bidi-import capability are required to
+	 * buffer the complete batch of import commands until this newline before
+	 * sending data to fast-import.
+	 * These helpers read back data from fast-import on their stdin, which could
+	 * be mixed with import commands, otherwise.
+	 */
 
 	if (finish_command(&fastimport))
 		die("Error while running fast-import");
-	free(fastimport.argv);
-	fastimport.argv = NULL;
 
 	/*
 	 * The fast-import stream of a remote helper that advertises
-- 
1.7.9.5
Previous: Florian AchleitnerNext: Florian Achleitner
Message 5 of 36 in “GSOC remote-svn”
  1. 00/16 GSOC remote-svnFlorian Achleitner, Aug 14, 2012
  2. 01/16 Implement a remote helper for svn in C.Florian Achleitner, Aug 14, 2012
  3. 02/16 Integrate remote-svn into svn-fe/Makefile.Florian Achleitner, Aug 14, 2012
  4. 03/16 Add svndump_init_fd to allow reading dumps from arbitrary FDs.Florian Achleitner, Aug 14, 2012
  5. 04/16 Connect fast-import to the remote-helper via pipe, adding 'bidi-import' capability.Florian Achleitner, Aug 14, 2012
  6. 05/16 Add documentation for the 'bidi-import' capability of remote-helpers.Florian Achleitner, Aug 14, 2012
  7. 06/16 remote-svn, vcs-svn: Enable fetching to private refs.Florian Achleitner, Aug 14, 2012
  8. 07/16 Add a symlink 'git-remote-svn' in base dir.Florian Achleitner, Aug 14, 2012
  9. 08/16 Allow reading svn dumps from files via file:// urls.Florian Achleitner, Aug 14, 2012
  10. 09/16 vcs-svn: add fast_export_note to create notesFlorian Achleitner, Aug 14, 2012
  11. 10/16 Create a note for every imported commit containing svn metadata.Florian Achleitner, Aug 14, 2012
  12. 11/16 When debug==1, start fast-import with "--stats" instead of "--quiet".Florian Achleitner, Aug 14, 2012
  13. 12/16 remote-svn: add incremental import.Florian Achleitner, Aug 14, 2012
  14. 13/16 Add a svnrdump-simulator replaying a dump file for testing.Florian Achleitner, Aug 14, 2012
  15. 14/16 transport-helper: add import|export-marks to fast-import command line.Florian Achleitner, Aug 14, 2012
  16. 15/16 remote-svn: add marks-file regeneration.Florian Achleitner, Aug 14, 2012
  17. 16/16 Add a test script for remote-svn.Florian Achleitner, Aug 14, 2012
  18. Florian AchleitnerAug 15, 2012
  19. Junio C HamanoAug 15, 2012
  20. Florian AchleitnerAug 15, 2012
  21. Florian AchleitnerAug 15, 2012
  22. Junio C HamanoAug 15, 2012
  23. Junio C HamanoAug 15, 2012
  24. Florian AchleitnerAug 15, 2012
  25. Junio C HamanoAug 14, 2012
  26. Junio C HamanoAug 14, 2012
  27. Florian AchleitnerAug 15, 2012
  28. Junio C HamanoAug 14, 2012
  29. Florian AchleitnerAug 15, 2012
  30. Junio C HamanoAug 15, 2012
  31. Junio C HamanoAug 14, 2012
  32. Junio C HamanoAug 14, 2012
  33. Florian AchleitnerAug 15, 2012
  34. Junio C HamanoAug 14, 2012
  35. Florian AchleitnerAug 15, 2012
  36. David Michael BarrAug 14, 2012

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