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Diffstat (limited to 'Documentation/git-fast-import.txt')
| -rw-r--r-- | Documentation/git-fast-import.txt | 49 |
1 files changed, 33 insertions, 16 deletions
diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt index 2b762654bf..43ab3b1637 100644 --- a/Documentation/git-fast-import.txt +++ b/Documentation/git-fast-import.txt @@ -9,7 +9,7 @@ git-fast-import - Backend for fast Git data importers SYNOPSIS -------- [verse] -frontend | 'git fast-import' [options] +frontend | 'git fast-import' [<options>] DESCRIPTION ----------- @@ -40,9 +40,10 @@ OPTIONS not contain the old commit). --quiet:: - Disable all non-fatal output, making fast-import silent when it - is successful. This option disables the output shown by - --stats. + Disable the output shown by --stats, making fast-import usually + be silent when it is successful. However, if the import stream + has directives intended to show user output (e.g. `progress` + directives), the corresponding messages will still be shown. --stats:: Display some basic statistics about the objects fast-import has @@ -121,7 +122,7 @@ Performance and Compression Tuning --depth=<n>:: Maximum delta depth, for blob and tree deltification. - Default is 10. + Default is 50. --export-pack-edges=<file>:: After creating a packfile, print a line of data to @@ -139,7 +140,7 @@ Performance and Compression Tuning fastimport.unpackLimit:: See linkgit:git-config[1] -Performance +PERFORMANCE ----------- The design of fast-import allows it to import large projects in a minimum amount of memory usage and processing time. Assuming the frontend @@ -155,7 +156,7 @@ faster if the source data is stored on a different drive than the destination Git repository (due to less IO contention). -Development Cost +DEVELOPMENT COST ---------------- A typical frontend for fast-import tends to weigh in at approximately 200 lines of Perl/Python/Ruby code. Most developers have been able to @@ -165,7 +166,7 @@ an ideal situation, given that most conversion tools are throw-away (use once, and never look back). -Parallel Operation +PARALLEL OPERATION ------------------ Like 'git push' or 'git fetch', imports handled by fast-import are safe to run alongside parallel `git repack -a -d` or `git gc` invocations, @@ -186,7 +187,7 @@ this only be used on an otherwise quiet repository. Using --force is not necessary for an initial import into an empty repository. -Technical Discussion +TECHNICAL DISCUSSION -------------------- fast-import tracks a set of branches in memory. Any branch can be created or modified at any point during the import process by sending a @@ -204,7 +205,7 @@ directory also allows fast-import to run very quickly, as it does not need to perform any costly file update operations when switching between branches. -Input Format +INPUT FORMAT ------------ With the exception of raw file data (which Git does not interpret) the fast-import input format is text (ASCII) based. This text based @@ -384,6 +385,7 @@ change to the project. .... 'commit' SP <ref> LF mark? + original-oid? ('author' (SP <name>)? SP LT <email> GT SP <when> LF)? 'committer' (SP <name>)? SP LT <email> GT SP <when> LF data @@ -740,6 +742,19 @@ New marks are created automatically. Existing marks can be moved to another object simply by reusing the same `<idnum>` in another `mark` command. +`original-oid` +~~~~~~~~~~~~~~ +Provides the name of the object in the original source control system. +fast-import will simply ignore this directive, but filter processes +which operate on and modify the stream before feeding to fast-import +may have uses for this information + +.... + 'original-oid' SP <object-identifier> LF +.... + +where `<object-identifer>` is any string not containing LF. + `tag` ~~~~~ Creates an annotated tag referring to a specific commit. To create @@ -748,6 +763,7 @@ lightweight (non-annotated) tags see the `reset` command below. .... 'tag' SP <name> LF 'from' SP <commit-ish> LF + original-oid? 'tagger' (SP <name>)? SP LT <email> GT SP <when> LF data .... @@ -822,6 +838,7 @@ assigned mark. .... 'blob' LF mark? + original-oid? data .... @@ -1131,7 +1148,7 @@ If the `--done` command-line option or `feature done` command is in use, the `done` command is mandatory and marks the end of the stream. -Responses To Commands +RESPONSES TO COMMANDS --------------------- New objects written by fast-import are not available immediately. Most fast-import commands have no visible effect until the next @@ -1160,7 +1177,7 @@ To avoid deadlock, such frontends must completely consume any pending output from `progress`, `ls`, `get-mark`, and `cat-blob` before performing writes to fast-import that might block. -Crash Reports +CRASH REPORTS ------------- If fast-import is supplied invalid input it will terminate with a non-zero exit status and create a crash report in the top level of @@ -1247,7 +1264,7 @@ An example crash: END OF CRASH REPORT ==== -Tips and Tricks +TIPS AND TRICKS --------------- The following tips and tricks have been collected from various users of fast-import, and are offered here as suggestions. @@ -1349,7 +1366,7 @@ Your users will feel better knowing how much of the data stream has been processed. -Packfile Optimization +PACKFILE OPTIMIZATION --------------------- When packing a blob fast-import always attempts to deltify against the last blob written. Unless specifically arranged for by the frontend, @@ -1380,7 +1397,7 @@ to force recomputation of all deltas can significantly reduce the final packfile size (30-50% smaller can be quite typical). -Memory Utilization +MEMORY UTILIZATION ------------------ There are a number of factors which affect how much memory fast-import requires to perform an import. Like critical sections of core @@ -1458,7 +1475,7 @@ and lazy loading of subtrees, allows fast-import to efficiently import projects with 2,000+ branches and 45,114+ files in a very limited memory footprint (less than 2.7 MiB per active branch). -Signals +SIGNALS ------- Sending *SIGUSR1* to the 'git fast-import' process ends the current packfile early, simulating a `checkpoint` command. The impatient |