.\" It was generated using the DocBook XSL Stylesheets (version 1.69.1).
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-.TH "GIT\-FAST\-IMPORT" "1" "02/07/2007" "" ""
+.TH "GIT\-FAST\-IMPORT" "1" "02/09/2007" "" ""
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.SH "SYNOPSIS"
frontend | \fIgit\-fast\-import\fR [options]
.SH "DESCRIPTION"
-This program is usually not what the end user wants to run directly. Most end users want to use one of the existing frontend programs, which parses a specific type of foreign source and feeds the contents stored there to git\-fast\-import (gfi).
+This program is usually not what the end user wants to run directly. Most end users want to use one of the existing frontend programs, which parses a specific type of foreign source and feeds the contents stored there to git\-fast\-import.
-gfi reads a mixed command/data stream from standard input and writes one or more packfiles directly into the current repository. When EOF is received on standard input, fast import writes out updated branch and tag refs, fully updating the current repository with the newly imported data.
+fast\-import reads a mixed command/data stream from standard input and writes one or more packfiles directly into the current repository. When EOF is received on standard input, fast import writes out updated branch and tag refs, fully updating the current repository with the newly imported data.
-The gfi backend itself can import into an empty repository (one that has already been initialized by \fBgit\-init\fR(1)) or incrementally update an existing populated repository. Whether or not incremental imports are supported from a particular foreign source depends on the frontend program in use.
+The fast\-import backend itself can import into an empty repository (one that has already been initialized by \fBgit\-init\fR(1)) or incrementally update an existing populated repository. Whether or not incremental imports are supported from a particular foreign source depends on the frontend program in use.
.SH "OPTIONS"
.TP
\-\-date\-format=<fmt>
-Specify the type of dates the frontend will supply to gfi within author, committer and tagger commands. See \(lqDate Formats\(rq below for details about which formats are supported, and their syntax.
+Specify the type of dates the frontend will supply to fast\-import within author, committer and tagger commands. See \(lqDate Formats\(rq below for details about which formats are supported, and their syntax.
.TP
\-\-force
Force updating modified existing branches, even if doing so would cause commits to be lost (as the new commit does not contain the old commit).
Dumps the internal marks table to <file> when complete. Marks are written one per line as :markid SHA\-1. Frontends can use this file to validate imports after they have been completed.
.TP
\-\-quiet
-Disable all non\-fatal output, making gfi silent when it is successful. This option disables the output shown by \-\-stats.
+Disable all non\-fatal output, making fast\-import silent when it is successful. This option disables the output shown by \-\-stats.
.TP
\-\-stats
-Display some basic statistics about the objects gfi has created, the packfiles they were stored into, and the memory used by gfi during this run. Showing this output is currently the default, but can be disabled with \-\-quiet.
+Display some basic statistics about the objects fast\-import has created, the packfiles they were stored into, and the memory used by fast\-import during this run. Showing this output is currently the default, but can be disabled with \-\-quiet.
.SH "PERFORMANCE"
-The design of gfi allows it to import large projects in a minimum amount of memory usage and processing time. Assuming the frontend is able to keep up with gfi and feed it a constant stream of data, import times for projects holding 10+ years of history and containing 100,000+ individual commits are generally completed in just 1\-2 hours on quite modest (~$2,000 USD) hardware.
+The design of fast\-import allows it to import large projects in a minimum amount of memory usage and processing time. Assuming the frontend is able to keep up with fast\-import and feed it a constant stream of data, import times for projects holding 10+ years of history and containing 100,000+ individual commits are generally completed in just 1\-2 hours on quite modest (~$2,000 USD) hardware.
-Most bottlenecks appear to be in foreign source data access (the source just cannot extract revisions fast enough) or disk IO (gfi writes as fast as the disk will take the data). Imports will run faster if the source data is stored on a different drive than the destination Git repository (due to less IO contention).
+Most bottlenecks appear to be in foreign source data access (the source just cannot extract revisions fast enough) or disk IO (fast\-import writes as fast as the disk will take the data). Imports will run faster if the source data is stored on a different drive than the destination Git repository (due to less IO contention).
.SH "DEVELOPMENT COST"
-A typical frontend for gfi tends to weigh in at approximately 200 lines of Perl/Python/Ruby code. Most developers have been able to create working importers in just a couple of hours, even though it is their first exposure to gfi, and sometimes even to Git. This is an ideal situation, given that most conversion tools are throw\-away (use once, and never look back).
+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 create working importers in just a couple of hours, even though it is their first exposure to fast\-import, and sometimes even to Git. This is an ideal situation, given that most conversion tools are throw\-away (use once, and never look back).
.SH "PARALLEL OPERATION"
-Like git\-push or git\-fetch, imports handled by gfi are safe to run alongside parallel git repack \-a \-d or git gc invocations, or any other Git operation (including git prune, as loose objects are never used by gfi).
+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, or any other Git operation (including git prune, as loose objects are never used by fast\-import).
-gfi does not lock the branch or tag refs it is actively importing. After the import, during its ref update phase, gfi tests each existing branch ref to verify the update will be a fast\-forward update (the commit stored in the ref is contained in the new history of the commit to be written). If the update is not a fast\-forward update, gfi will skip updating that ref and instead prints a warning message. gfi will always attempt to update all branch refs, and does not stop on the first failure.
+fast\-import does not lock the branch or tag refs it is actively importing. After the import, during its ref update phase, fast\-import tests each existing branch ref to verify the update will be a fast\-forward update (the commit stored in the ref is contained in the new history of the commit to be written). If the update is not a fast\-forward update, fast\-import will skip updating that ref and instead prints a warning message. fast\-import will always attempt to update all branch refs, and does not stop on the first failure.
Branch updates can be forced with \-\-force, but its recommended that this only be used on an otherwise quiet repository. Using \-\-force is not necessary for an initial import into an empty repository.
.SH "TECHNICAL DISCUSSION"
-gfi tracks a set of branches in memory. Any branch can be created or modified at any point during the import process by sending a commit command on the input stream. This design allows a frontend program to process an unlimited number of branches simultaneously, generating commits in the order they are available from the source data. It also simplifies the frontend programs considerably.
+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 commit command on the input stream. This design allows a frontend program to process an unlimited number of branches simultaneously, generating commits in the order they are available from the source data. It also simplifies the frontend programs considerably.
-gfi does not use or alter the current working directory, or any file within it. (It does however update the current Git repository, as referenced by GIT_DIR.) Therefore an import frontend may use the working directory for its own purposes, such as extracting file revisions from the foreign source. This ignorance of the working directory also allows gfi to run very quickly, as it does not need to perform any costly file update operations when switching between branches.
+fast\-import does not use or alter the current working directory, or any file within it. (It does however update the current Git repository, as referenced by GIT_DIR.) Therefore an import frontend may use the working directory for its own purposes, such as extracting file revisions from the foreign source. This ignorance of the working 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.
.SH "INPUT FORMAT"
-With the exception of raw file data (which Git does not interpret) the gfi input format is text (ASCII) based. This text based format simplifies development and debugging of frontend programs, especially when a higher level language such as Perl, Python or Ruby is being used.
+With the exception of raw file data (which Git does not interpret) the fast\-import input format is text (ASCII) based. This text based format simplifies development and debugging of frontend programs, especially when a higher level language such as Perl, Python or Ruby is being used.
-gfi is very strict about its input. Where we say SP below we mean \fBexactly\fR one space. Likewise LF means one (and only one) linefeed. Supplying additional whitespace characters will cause unexpected results, such as branch names or file names with leading or trailing spaces in their name, or early termination of gfi when it encounters unexpected input.
+fast\-import is very strict about its input. Where we say SP below we mean \fBexactly\fR one space. Likewise LF means one (and only one) linefeed. Supplying additional whitespace characters will cause unexpected results, such as branch names or file names with leading or trailing spaces in their name, or early termination of fast\-import when it encounters unexpected input.
.SS "Date Formats"
The following date formats are supported. A frontend should select the format it will use for this import by passing the format name in the \-\-date\-format=<fmt> command line option.
.TP
raw
-This is the Git native format and is <time> SP <offutc>. It is also gfi's default format, if \-\-date\-format was not specified.
+This is the Git native format and is <time> SP <offutc>. It is also fast\-import's default format, if \-\-date\-format was not specified.
The time of the event is specified by <time> as the number of seconds since the UNIX epoch (midnight, Jan 1, 1970, UTC) and is written as an ASCII decimal integer.
The local offset is specified by <offutc> as a positive or negative offset from UTC. For example EST (which is 5 hours behind UTC) would be expressed in <tz> by \(lq\-0500\(rq while UTC is \(lq+0000\(rq. The local offset does not affect <time>; it is used only as an advisement to help formatting routines display the timestamp.
-If the local offset is not available in the source material, use \(lq+0000\(rq, or the most common local offset. For example many organizations have a CVS repository which has only ever been accessed by users who are located in the same location and timezone. In this case the offset from UTC can be easily assumed.
+If the local offset is not available in the source material, use \(lq+0000\(rq, or the most common local offset. For example many organizations have a CVS repository which has only ever been accessed by users who are located in the same location and timezone. In this case a reasonable offset from UTC could be assumed.
-Unlike the rfc2822 format, this format is very strict. Any variation in formatting will cause gfi to reject the value.
+Unlike the rfc2822 format, this format is very strict. Any variation in formatting will cause fast\-import to reject the value.
.TP
rfc2822
This is the standard email format as described by RFC 2822.
-An example value is \(lqTue Feb 6 11:22:18 2007 \-0500\(rq. The Git parser is accurate, but a little on the lenient side. Its the same parser used by \fBgit\-am\fR(1) when applying patches received from email.
+An example value is \(lqTue Feb 6 11:22:18 2007 \-0500\(rq. The Git parser is accurate, but a little on the lenient side. It is the same parser used by \fBgit\-am\fR(1) when applying patches received from email.
Some malformed strings may be accepted as valid dates. In some of these cases Git will still be able to obtain the correct date from the malformed string. There are also some types of malformed strings which Git will parse wrong, and yet consider valid. Seriously malformed strings will be rejected.
Unlike the raw format above, the timezone/UTC offset information contained in an RFC 2822 date string is used to adjust the date value to UTC prior to storage. Therefore it is important that this information be as accurate as possible.
-If the source material is formatted in RFC 2822 style dates, the frontend should let gfi handle the parsing and conversion (rather than attempting to do it itself) as the Git parser has been well tested in the wild.
+If the source material uses RFC 2822 style dates, the frontend should let fast\-import handle the parsing and conversion (rather than attempting to do it itself) as the Git parser has been well tested in the wild.
-Frontends should prefer the raw format if the source material is already in UNIX\-epoch format, or is easily convertible to that format, as there is no ambiguity in parsing.
+Frontends should prefer the raw format if the source material already uses UNIX\-epoch format, can be coaxed to give dates in that format, or its format is easiliy convertible to it, as there is no ambiguity in parsing.
.TP
now
Always use the current time and timezone. The literal now must always be supplied for <when>.
-This is a toy format. The current time and timezone of this system is always copied into the identity string at the time it is being created by gfi. There is no way to specify a different time or timezone.
+This is a toy format. The current time and timezone of this system is always copied into the identity string at the time it is being created by fast\-import. There is no way to specify a different time or timezone.
This particular format is supplied as its short to implement and may be useful to a process that wants to create a new commit right now, without needing to use a working directory or \fBgit\-update\-index\fR(1).
If separate author and committer commands are used in a commit the timestamps may not match, as the system clock will be polled twice (once for each command). The only way to ensure that both author and committer identity information has the same timestamp is to omit author (thus copying from committer) or to use a date format other than now.
.SS "Commands"
-gfi accepts several commands to update the current repository and control the current import process. More detailed discussion (with examples) of each command follows later.
+fast\-import accepts several commands to update the current repository and control the current import process. More detailed discussion (with examples) of each command follows later.
.TP
commit
Creates a new branch or updates an existing branch by creating a new commit and updating the branch to point at the newly created commit.
Convert raw file data into a blob, for future use in a commit command. This command is optional and is not needed to perform an import.
.TP
checkpoint
-Forces gfi to close the current packfile, generate its unique SHA\-1 checksum and index, and start a new packfile. This command is optional and is not needed to perform an import.
+Forces fast\-import to close the current packfile, generate its unique SHA\-1 checksum and index, and start a new packfile. This command is optional and is not needed to perform an import.
.SS "commit"
Create or update a branch with a new commit, recording one logical change to the project.
.sp
.fi
where <ref> is the name of the branch to make the commit on. Typically branch names are prefixed with refs/heads/ in Git, so importing the CVS branch symbol RELENG\-1_0 would use refs/heads/RELENG\-1_0 for the value of <ref>. The value of <ref> must be a valid refname in Git. As LF is not valid in a Git refname, no quoting or escaping syntax is supported here.
-A mark command may optionally appear, requesting gfi to save a reference to the newly created commit for future use by the frontend (see below for format). It is very common for frontends to mark every commit they create, thereby allowing future branch creation from any imported commit.
+A mark command may optionally appear, requesting fast\-import to save a reference to the newly created commit for future use by the frontend (see below for format). It is very common for frontends to mark every commit they create, thereby allowing future branch creation from any imported commit.
-The data command following committer must supply the commit message (see below for data command syntax). To import an empty commit message use a 0 length data. Commit messages are free\-form and are not interpreted by Git. Currently they must be encoded in UTF\-8, as gfi does not permit other encodings to be specified.
+The data command following committer must supply the commit message (see below for data command syntax). To import an empty commit message use a 0 length data. Commit messages are free\-form and are not interpreted by Git. Currently they must be encoded in UTF\-8, as fast\-import does not permit other encodings to be specified.
Zero or more filemodify, filedelete and filedeleteall commands may be included to update the contents of the branch prior to creating the commit. These commands may be supplied in any order. However it is recommended that a filedeleteall command preceed all filemodify commands in the same commit, as filedeleteall wipes the branch clean (see below).
.sp
.br
\fBauthor\fR
.RS 3
-An author command may optionally appear, if the author information might differ from the committer information. If author is omitted then gfi will automatically use the committer's information for the author portion of the commit. See below for a description of the fields in author, as they are identical to committer.
+An author command may optionally appear, if the author information might differ from the committer information. If author is omitted then fast\-import will automatically use the committer's information for the author portion of the commit. See below for a description of the fields in author, as they are identical to committer.
.RE
.sp
.it 1 an-trap
.br
\fBfrom\fR
.RS 3
-Only valid for the first commit made on this branch by this gfi process. The from command is used to specify the commit to initialize this branch from. This revision will be the first ancestor of the new commit.
+Only valid for the first commit made on this branch by this fast\-import process. The from command is used to specify the commit to initialize this branch from. This revision will be the first ancestor of the new commit.
-Omitting the from command in the first commit of a new branch will cause gfi to create that commit with no ancestor. This tends to be desired only for the initial commit of a project. Omitting the from command on existing branches is required, as the current commit on that branch is automatically assumed to be the first ancestor of the new commit.
+Omitting the from command in the first commit of a new branch will cause fast\-import to create that commit with no ancestor. This tends to be desired only for the initial commit of a project. Omitting the from command on existing branches is required, as the current commit on that branch is automatically assumed to be the first ancestor of the new commit.
As LF is not valid in a Git refname or SHA\-1 expression, no quoting or escaping syntax is supported within <committish>.
Here <committish> is any of the following:
.TP 3
\(bu
-The name of an existing branch already in gfi's internal branch table. If gfi doesn't know the name, its treated as a SHA\-1 expression.
+The name of an existing branch already in fast\-import's internal branch table. If fast\-import doesn't know the name, its treated as a SHA\-1 expression.
.TP
\(bu
A mark reference, :<idnum>, where <idnum> is the mark number.
-The reason gfi uses : to denote a mark reference is this character is not legal in a Git branch name. The leading : makes it easy to distingush between the mark 42 (:42) and the branch 42 (42 or refs/heads/42), or an abbreviated SHA\-1 which happened to consist only of base\-10 digits.
+The reason fast\-import uses : to denote a mark reference is this character is not legal in a Git branch name. The leading : makes it easy to distingush between the mark 42 (:42) and the branch 42 (42 or refs/heads/42), or an abbreviated SHA\-1 which happened to consist only of base\-10 digits.
Marks must be declared (via mark) before they can be used.
.TP
.nf
from refs/heads/branch^0
.fi
-The ^0 suffix is necessary as gfi does not permit a branch to start from itself, and the branch is created in memory before the from command is even read from the input. Adding ^0 will force gfi to resolve the commit through Git's revision parsing library, rather than its internal branch table, thereby loading in the existing value of the branch.
+The ^0 suffix is necessary as fast\-import does not permit a branch to start from itself, and the branch is created in memory before the from command is even read from the input. Adding ^0 will force fast\-import to resolve the commit through Git's revision parsing library, rather than its internal branch table, thereby loading in the existing value of the branch.
.RE
.sp
.it 1 an-trap
.br
\fBmerge\fR
.RS 3
-Includes one additional ancestor commit, and makes the current commit a merge commit. An unlimited number of merge commands per commit are permitted by gfi, thereby establishing an n\-way merge. However Git's other tools never create commits with more than 15 additional ancestors (forming a 16\-way merge). For this reason it is suggested that frontends do not use more than 15 merge commands per commit.
+Includes one additional ancestor commit, and makes the current commit a merge commit. An unlimited number of merge commands per commit are permitted by fast\-import, thereby establishing an n\-way merge. However Git's other tools never create commits with more than 15 additional ancestors (forming a 16\-way merge). For this reason it is suggested that frontends do not use more than 15 merge commands per commit.
Here <committish> is any of the commit specification expressions also accepted by from (see above).
.RE
.fi
This command is extremely useful if the frontend does not know (or does not care to know) what files are currently on the branch, and therefore cannot generate the proper filedelete commands to update the content.
-Issuing a filedeleteall followed by the needed filemodify commands to set the correct content will produce the same results as sending only the needed filemodify and filedelete commands. The filedeleteall approach may however require gfi to use slightly more memory per active branch (less than 1 MiB for even most large projects); so frontends that can easily obtain only the affected paths for a commit are encouraged to do so.
+Issuing a filedeleteall followed by the needed filemodify commands to set the correct content will produce the same results as sending only the needed filemodify and filedelete commands. The filedeleteall approach may however require fast\-import to use slightly more memory per active branch (less than 1 MiB for even most large projects); so frontends that can easily obtain only the affected paths for a commit are encouraged to do so.
.RE
.SS "mark"
-Arranges for gfi to save a reference to the current object, allowing the frontend to recall this object at a future point in time, without knowing its SHA\-1. Here the current object is the object creation command the mark command appears within. This can be commit, tag, and blob, but commit is the most common usage.
+Arranges for fast\-import to save a reference to the current object, allowing the frontend to recall this object at a future point in time, without knowing its SHA\-1. Here the current object is the object creation command the mark command appears within. This can be commit, tag, and blob, but commit is the most common usage.
.sp
.nf
'mark' SP ':' <idnum> LF
.fi
where <name> is the name of the tag to create.
-Tag names are automatically prefixed with refs/tags/ when stored in Git, so importing the CVS branch symbol RELENG\-1_0\-FINAL would use just RELENG\-1_0\-FINAL for <name>, and gfi will write the corresponding ref as refs/tags/RELENG\-1_0\-FINAL.
+Tag names are automatically prefixed with refs/tags/ when stored in Git, so importing the CVS branch symbol RELENG\-1_0\-FINAL would use just RELENG\-1_0\-FINAL for <name>, and fast\-import will write the corresponding ref as refs/tags/RELENG\-1_0\-FINAL.
The value of <name> must be a valid refname in Git and therefore may contain forward slashes. As LF is not valid in a Git refname, no quoting or escaping syntax is supported here.
The tagger command uses the same format as committer within commit; again see above for details.
-The data command following tagger must supply the annotated tag message (see below for data command syntax). To import an empty tag message use a 0 length data. Tag messages are free\-form and are not interpreted by Git. Currently they must be encoded in UTF\-8, as gfi does not permit other encodings to be specified.
+The data command following tagger must supply the annotated tag message (see below for data command syntax). To import an empty tag message use a 0 length data. Tag messages are free\-form and are not interpreted by Git. Currently they must be encoded in UTF\-8, as fast\-import does not permit other encodings to be specified.
-Signing annotated tags during import from within gfi is not supported. Trying to include your own PGP/GPG signature is not recommended, as the frontend does not (easily) have access to the complete set of bytes which normally goes into such a signature. If signing is required, create lightweight tags from within gfi with reset, then create the annotated versions of those tags offline with the standard \fBgit\-tag\fR(1) process.
+Signing annotated tags during import from within fast\-import is not supported. Trying to include your own PGP/GPG signature is not recommended, as the frontend does not (easily) have access to the complete set of bytes which normally goes into such a signature. If signing is required, create lightweight tags from within fast\-import with reset, then create the annotated versions of those tags offline with the standard \fBgit\-tag\fR(1) process.
.SS "reset"
Creates (or recreates) the named branch, optionally starting from a specific revision. The reset command allows a frontend to issue a new from command for an existing branch, or to create a new branch from an existing commit without creating a new commit.
.sp
.fi
The mark command is optional here as some frontends have chosen to generate the Git SHA\-1 for the blob on their own, and feed that directly to commit. This is typically more work than its worth however, as marks are inexpensive to store and easy to use.
.SS "data"
-Supplies raw data (for use as blob/file content, commit messages, or annotated tag messages) to gfi. Data can be supplied using an exact byte count or delimited with a terminating line. Real frontends intended for production\-quality conversions should always use the exact byte count format, as it is more robust and performs better. The delimited format is intended primarily for testing gfi.
+Supplies raw data (for use as blob/file content, commit messages, or annotated tag messages) to fast\-import. Data can be supplied using an exact byte count or delimited with a terminating line. Real frontends intended for production\-quality conversions should always use the exact byte count format, as it is more robust and performs better. The delimited format is intended primarily for testing fast\-import.
.TP
Exact byte count format
The frontend must specify the number of bytes of data.
where <count> is the exact number of bytes appearing within <raw>. The value of <count> is expressed as an ASCII decimal integer. The LF on either side of <raw> is not included in <count> and will not be included in the imported data.
.TP
Delimited format
-A delimiter string is used to mark the end of the data. gfi will compute the length by searching for the delimiter. This format is primarly useful for testing and is not recommended for real data.
+A delimiter string is used to mark the end of the data. fast\-import will compute the length by searching for the delimiter. This format is primarly useful for testing and is not recommended for real data.
.sp
.nf
'data' SP '<<' <delim> LF
<raw> LF
<delim> LF
.fi
-where <delim> is the chosen delimiter string. The string <delim> must not appear on a line by itself within <raw>, as otherwise gfi will think the data ends earlier than it really does. The LF immediately trailing <raw> is part of <raw>. This is one of the limitations of the delimited format, it is impossible to supply a data chunk which does not have an LF as its last byte.
+where <delim> is the chosen delimiter string. The string <delim> must not appear on a line by itself within <raw>, as otherwise fast\-import will think the data ends earlier than it really does. The LF immediately trailing <raw> is part of <raw>. This is one of the limitations of the delimited format, it is impossible to supply a data chunk which does not have an LF as its last byte.
.SS "checkpoint"
-Forces gfi to close the current packfile, start a new one, and to save out all current branch refs, tags and marks.
+Forces fast\-import to close the current packfile, start a new one, and to save out all current branch refs, tags and marks.
.sp
.nf
'checkpoint' LF
LF
.fi
-Note that gfi automatically switches packfiles when the current packfile reaches \-\-max\-pack\-size, or 4 GiB, whichever limit is smaller. During an automatic packfile switch gfi does not update the branch refs, tags or marks.
+Note that fast\-import automatically switches packfiles when the current packfile reaches \-\-max\-pack\-size, or 4 GiB, whichever limit is smaller. During an automatic packfile switch fast\-import does not update the branch refs, tags or marks.
As a checkpoint can require a significant amount of CPU time and disk IO (to compute the overall pack SHA\-1 checksum, generate the corresponding index file, and update the refs) it can easily take several minutes for a single checkpoint command to complete.
-Frontends may choose to issue checkpoints during extremely large and long running imports, or when they need to allow another Git process access to a branch. However given that a 30 GiB Subversion repository can be loaded into Git through gfi in about 3 hours, explicit checkpointing may not be necessary.
+Frontends may choose to issue checkpoints during extremely large and long running imports, or when they need to allow another Git process access to a branch. However given that a 30 GiB Subversion repository can be loaded into Git through fast\-import in about 3 hours, explicit checkpointing may not be necessary.
.SH "TIPS AND TRICKS"
-The following tips and tricks have been collected from various users of gfi, and are offered here as suggestions.
+The following tips and tricks have been collected from various users of fast\-import, and are offered here as suggestions.
.SS "Use One Mark Per Commit"
-When doing a repository conversion, use a unique mark per commit (mark :<n>) and supply the \-\-export\-marks option on the command line. gfi will dump a file which lists every mark and the Git object SHA\-1 that corresponds to it. If the frontend can tie the marks back to the source repository, it is easy to verify the accuracy and completeness of the import by comparing each Git commit to the corresponding source revision.
+When doing a repository conversion, use a unique mark per commit (mark :<n>) and supply the \-\-export\-marks option on the command line. fast\-import will dump a file which lists every mark and the Git object SHA\-1 that corresponds to it. If the frontend can tie the marks back to the source repository, it is easy to verify the accuracy and completeness of the import by comparing each Git commit to the corresponding source revision.
-Coming from a system such as Perforce or Subversion this should be quite simple, as the gfi mark can also be the Perforce changeset number or the Subversion revision number.
+Coming from a system such as Perforce or Subversion this should be quite simple, as the fast\-import mark can also be the Perforce changeset number or the Subversion revision number.
.SS "Freely Skip Around Branches"
-Don't bother trying to optimize the frontend to stick to one branch at a time during an import. Although doing so might be slightly faster for gfi, it tends to increase the complexity of the frontend code considerably.
+Don't bother trying to optimize the frontend to stick to one branch at a time during an import. Although doing so might be slightly faster for fast\-import, it tends to increase the complexity of the frontend code considerably.
-The branch LRU builtin to gfi tends to behave very well, and the cost of activating an inactive branch is so low that bouncing around between branches has virtually no impact on import performance.
+The branch LRU builtin to fast\-import tends to behave very well, and the cost of activating an inactive branch is so low that bouncing around between branches has virtually no impact on import performance.
.SS "Use Tag Fixup Branches"
Some other SCM systems let the user create a tag from multiple files which are not from the same commit/changeset. Or to create tags which are a subset of the files available in the repository.
-Importing these tags as\-is in Git is impossible without making at least one commit which \(lqfixes up\(rq the files to match the content of the tag. Use gfi's reset command to reset a dummy branch outside of your normal branch space to the base commit for the tag, then commit one or more file fixup commits, and finally tag the dummy branch.
+Importing these tags as\-is in Git is impossible without making at least one commit which \(lqfixes up\(rq the files to match the content of the tag. Use fast\-import's reset command to reset a dummy branch outside of your normal branch space to the base commit for the tag, then commit one or more file fixup commits, and finally tag the dummy branch.
For example since all normal branches are stored under refs/heads/ name the tag fixup branch TAG_FIXUP. This way it is impossible for the fixup branch used by the importer to have namespace conflicts with real branches imported from the source (the name TAG_FIXUP is not refs/heads/TAG_FIXUP).
When committing fixups, consider using merge to connect the commit(s) which are supplying file revisions to the fixup branch. Doing so will allow tools such as \fBgit\-blame\fR(1) to track through the real commit history and properly annotate the source files.
-After gfi terminates the frontend will need to do rm .git/TAG_FIXUP to remove the dummy branch.
+After fast\-import terminates the frontend will need to do rm .git/TAG_FIXUP to remove the dummy branch.
.SS "Import Now, Repack Later"
-As soon as gfi completes the Git repository is completely valid and ready for use. Typicallly this takes only a very short time, even for considerably large projects (100,000+ commits).
+As soon as fast\-import completes the Git repository is completely valid and ready for use. Typicallly this takes only a very short time, even for considerably large projects (100,000+ commits).
However repacking the repository is necessary to improve data locality and access performance. It can also take hours on extremely large projects (especially if \-f and a large \-\-window parameter is used). Since repacking is safe to run alongside readers and writers, run the repack in the background and let it finish when it finishes. There is no reason to wait to explore your new Git project!
-If you choose to wait for the repack, don't try to run benchmarks or performance tests until repacking is completed. gfi outputs suboptimal packfiles that are simply never seen in real use situations.
+If you choose to wait for the repack, don't try to run benchmarks or performance tests until repacking is completed. fast\-import outputs suboptimal packfiles that are simply never seen in real use situations.
.SS "Repacking Historical Data"
If you are repacking very old imported data (e.g. older than the last year), consider expending some extra CPU time and supplying \-\-window=50 (or higher) when you run \fBgit\-repack\fR(1). This will take longer, but will also produce a smaller packfile. You only need to expend the effort once, and everyone using your project will benefit from the smaller repository.
.SH "PACKFILE OPTIMIZATION"
-When packing a blob gfi always attempts to deltify against the last blob written. Unless specifically arranged for by the frontend, this will probably not be a prior version of the same file, so the generated delta will not be the smallest possible. The resulting packfile will be compressed, but will not be optimal.
+When packing a blob fast\-import always attempts to deltify against the last blob written. Unless specifically arranged for by the frontend, this will probably not be a prior version of the same file, so the generated delta will not be the smallest possible. The resulting packfile will be compressed, but will not be optimal.
-Frontends which have efficient access to all revisions of a single file (for example reading an RCS/CVS ,v file) can choose to supply all revisions of that file as a sequence of consecutive blob commands. This allows gfi to deltify the different file revisions against each other, saving space in the final packfile. Marks can be used to later identify individual file revisions during a sequence of commit commands.
+Frontends which have efficient access to all revisions of a single file (for example reading an RCS/CVS ,v file) can choose to supply all revisions of that file as a sequence of consecutive blob commands. This allows fast\-import to deltify the different file revisions against each other, saving space in the final packfile. Marks can be used to later identify individual file revisions during a sequence of commit commands.
-The packfile(s) created by gfi do not encourage good disk access patterns. This is caused by gfi writing the data in the order it is received on standard input, while Git typically organizes data within packfiles to make the most recent (current tip) data appear before historical data. Git also clusters commits together, speeding up revision traversal through better cache locality.
+The packfile(s) created by fast\-import do not encourage good disk access patterns. This is caused by fast\-import writing the data in the order it is received on standard input, while Git typically organizes data within packfiles to make the most recent (current tip) data appear before historical data. Git also clusters commits together, speeding up revision traversal through better cache locality.
-For this reason it is strongly recommended that users repack the repository with git repack \-a \-d after gfi completes, allowing Git to reorganize the packfiles for faster data access. If blob deltas are suboptimal (see above) then also adding the \-f option to force recomputation of all deltas can significantly reduce the final packfile size (30\-50% smaller can be quite typical).
+For this reason it is strongly recommended that users repack the repository with git repack \-a \-d after fast\-import completes, allowing Git to reorganize the packfiles for faster data access. If blob deltas are suboptimal (see above) then also adding the \-f option to force recomputation of all deltas can significantly reduce the final packfile size (30\-50% smaller can be quite typical).
.SH "MEMORY UTILIZATION"
-There are a number of factors which affect how much memory gfi requires to perform an import. Like critical sections of core Git, gfi uses its own memory allocators to ammortize any overheads associated with malloc. In practice gfi tends to ammoritize any malloc overheads to 0, due to its use of large block allocations.
+There are a number of factors which affect how much memory fast\-import requires to perform an import. Like critical sections of core Git, fast\-import uses its own memory allocators to ammortize any overheads associated with malloc. In practice fast\-import tends to ammoritize any malloc overheads to 0, due to its use of large block allocations.
.SS "per object"
-gfi maintains an in\-memory structure for every object written in this execution. On a 32 bit system the structure is 32 bytes, on a 64 bit system the structure is 40 bytes (due to the larger pointer sizes). Objects in the table are not deallocated until gfi terminates. Importing 2 million objects on a 32 bit system will require approximately 64 MiB of memory.
+fast\-import maintains an in\-memory structure for every object written in this execution. On a 32 bit system the structure is 32 bytes, on a 64 bit system the structure is 40 bytes (due to the larger pointer sizes). Objects in the table are not deallocated until fast\-import terminates. Importing 2 million objects on a 32 bit system will require approximately 64 MiB of memory.
-The object table is actually a hashtable keyed on the object name (the unique SHA\-1). This storage configuration allows gfi to reuse an existing or already written object and avoid writing duplicates to the output packfile. Duplicate blobs are surprisingly common in an import, typically due to branch merges in the source.
+The object table is actually a hashtable keyed on the object name (the unique SHA\-1). This storage configuration allows fast\-import to reuse an existing or already written object and avoid writing duplicates to the output packfile. Duplicate blobs are surprisingly common in an import, typically due to branch merges in the source.
.SS "per mark"
Marks are stored in a sparse array, using 1 pointer (4 bytes or 8 bytes, depending on pointer size) per mark. Although the array is sparse, frontends are still strongly encouraged to use marks between 1 and n, where n is the total number of marks required for this import.
.SS "per branch"
Branches are classified as active and inactive. The memory usage of the two classes is significantly different.
-Inactive branches are stored in a structure which uses 96 or 120 bytes (32 bit or 64 bit systems, respectively), plus the length of the branch name (typically under 200 bytes), per branch. gfi will easily handle as many as 10,000 inactive branches in under 2 MiB of memory.
+Inactive branches are stored in a structure which uses 96 or 120 bytes (32 bit or 64 bit systems, respectively), plus the length of the branch name (typically under 200 bytes), per branch. fast\-import will easily handle as many as 10,000 inactive branches in under 2 MiB of memory.
Active branches have the same overhead as inactive branches, but also contain copies of every tree that has been recently modified on that branch. If subtree include has not been modified since the branch became active, its contents will not be loaded into memory, but if subtree src has been modified by a commit since the branch became active, then its contents will be loaded in memory.
As active branches store metadata about the files contained on that branch, their in\-memory storage size can grow to a considerable size (see below).
-gfi automatically moves active branches to inactive status based on a simple least\-recently\-used algorithm. The LRU chain is updated on each commit command. The maximum number of active branches can be increased or decreased on the command line with \-\-active\-branches=.
+fast\-import automatically moves active branches to inactive status based on a simple least\-recently\-used algorithm. The LRU chain is updated on each commit command. The maximum number of active branches can be increased or decreased on the command line with \-\-active\-branches=.
.SS "per active tree"
Trees (aka directories) use just 12 bytes of memory on top of the memory required for their entries (see \(lqper active file\(rq below). The cost of a tree is virtually 0, as its overhead ammortizes out over the individual file entries.
.SS "per active file entry"
Files (and pointers to subtrees) within active trees require 52 or 64 bytes (32/64 bit platforms) per entry. To conserve space, file and tree names are pooled in a common string table, allowing the filename \(lqMakefile\(rq to use just 16 bytes (after including the string header overhead) no matter how many times it occurs within the project.
-The active branch LRU, when coupled with the filename string pool and lazy loading of subtrees, allows gfi 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).
+The active branch LRU, when coupled with the filename string pool 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).
.SH "AUTHOR"
Written by Shawn O. Pearce <spearce@spearce.org>.
.SH "DOCUMENTATION"
projects / git.git / commitdiff