diff options
| -rw-r--r-- | doc/manual/nix-collect-garbage.xml | 57 | ||||
| -rw-r--r-- | doc/manual/nix-store.xml | 70 | ||||
| -rw-r--r-- | doc/manual/quick-start.xml | 2 | ||||
| -rwxr-xr-x | scripts/nix-collect-garbage.in | 44 | ||||
| -rw-r--r-- | src/nix-store/main.cc | 2 |
5 files changed, 102 insertions, 73 deletions
diff --git a/doc/manual/nix-collect-garbage.xml b/doc/manual/nix-collect-garbage.xml index 8ff741e2212a..adc6c1e730a7 100644 --- a/doc/manual/nix-collect-garbage.xml +++ b/doc/manual/nix-collect-garbage.xml @@ -1,14 +1,16 @@ <refentry> <refnamediv> <refname>nix-collect-garbage</refname> - <refpurpose>determine the set of unreachable store paths</refpurpose> + <refpurpose>remove unreachable store paths</refpurpose> </refnamediv> <refsynopsisdiv> <cmdsynopsis> <command>nix-collect-garbage</command> - <arg><option>--invert</option></arg> - <arg><option>--no-successors</option></arg> + <group choice='opt'> + <arg choice='plain'><option>--print-live</option></arg> + <arg choice='plain'><option>--print-dead</option></arg> + </group> </cmdsynopsis> </refsynopsisdiv> @@ -16,10 +18,22 @@ <title>Description</title> <para> - The command <command>nix-collect-garbage</command> determines - the paths in the Nix store that are garbage, that is, not - reachable from outside of the store. These paths can be safely - deleted without affecting the integrity of the system. + The command <command>nix-collect-garbage</command> performs a + garbage collection on the Nix store: any paths in the Nix store + that are garbage (not reachable from a set of root store + expressions) are deleted. + </para> + + <para> + The roots of the garbage collector are the store expressions + mentioned in the files in the directory + <filename><replaceable>prefix</replaceable>/var/nix/gcroots</filename>. + By default, the roots are all user environments in + <filename><replaceable>prefix</replaceable>/var/nix/profiles</filename>. + You can register other store expressions as roots by writing the + full path of the store expression to an arbitrary file in the + <filename>gcroots</filename> directory (or a subdirectory + thereof). </para> </refsection> @@ -30,27 +44,14 @@ <variablelist> <varlistentry> - <term><option>--invert</option></term> - <listitem> - <para> - Causes the set of <emphasis>reachable</emphasis> paths to - be printed, rather than the unreachable paths. These are - the paths that may <emphasis>not</emphasis> be deleted. - </para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>--no-successors</option></term> + <term><option>--print-live</option> / <option>--print-dead</option></term> <listitem> <para> - Causes <command>nix-collect-garbage</command> not to - follow successor relations. By default, if a derivation - store expression is reachable, its successor (i.e., a - closure store expression) is also considered to be - reachable. This option is always safe, but garbage - collecting successors may cause undesirable rebuilds later - on. + These options cause the set of live or dead paths to be + printed, respectively, rather than performing an actual + garbage collector. They correspond exactly with the + sub-operations in <command>nix-store + <option>--gc</option></command>. </para> </listitem> </varlistentry> @@ -63,10 +64,10 @@ <title>Examples</title> <para> - To delete all unreachable paths, do the following: + To delete all unreachable paths, just do: <screen> -$ nix-collect-garbage | xargs nix-store --delete</screen> +$ nix-collect-garbage</screen> </para> diff --git a/doc/manual/nix-store.xml b/doc/manual/nix-store.xml index a3fcad0631d0..febe02fd4ada 100644 --- a/doc/manual/nix-store.xml +++ b/doc/manual/nix-store.xml @@ -135,17 +135,18 @@ <!--######################################################################--> <refsection> - <title>Operation <option>--delete</option></title> + <title>Operation <option>--gc</option></title> <refsection> <title>Synopsis</title> <cmdsynopsis> <command>nix-store</command> + <arg choice='plain'><option>--gc</option></arg> <group choice='req'> + <arg choice='plain'><option>--print-live</option></arg> + <arg choice='plain'><option>--print-dead</option></arg> <arg choice='plain'><option>--delete</option></arg> - <arg choice='plain'><option>-d</option></arg> </group> - <arg choice='plain' rep='repeat'><replaceable>paths</replaceable></arg> </cmdsynopsis> </refsection> @@ -153,19 +154,64 @@ <title>Description</title> <para> - The operation <option>--delete</option> unconditionally deletes the - paths <replaceable>paths</replaceable> from the Nix store. It is an - error to attempt to delete paths outside of the store. + The operation <option>--gc</option> performs a garbage + collection on the Nix store. What it does specifically is + determined by the sub-operation, which is one of the + following: + </para> + + <variablelist> + + <varlistentry> + <term><option>--print-live</option></term> + <listitem> + <para> + This operation prints on standard output the set of + <quote>live</quote> store paths, which are all the store + paths reachable from a set of <quote>root</quote> store + expressions read from standard input. Live paths should + never be deleted, since that would break consistency + — it would become possible that applications are + installed that reference things that are no longer + present in the store. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>--print-dead</option></term> + <listitem> + <para> + This operation prints out on standard output the set of + <quote>dead</quote> store paths, which is just the + opposite of the set of live paths: any path in the store + that is not live (with respect to the roots) is dead. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>--delete</option></term> + <listitem> + <para> + This operation performs an actual garbage collection. + All dead paths are removed from the store. + </para> + </listitem> + </varlistentry> + + </variablelist> + + <para> + The set of root store expressions is read from standard input. + Each line should contain exactly one store path. </para> <warning> <para> - This operation should almost never be called directly, since no - attempt is made to verify that no references exist to the paths to - be deleted. Therefore, careless deletion can result in an - inconsistent system. Deletion of paths in the store is done by the - garbage collector (which uses <option>--delete</option> to delete - unreferenced paths). + You generally will want to use the command + <command>nix-collect-garbage</command>, which figures out + the roots and then calls this command automatically. </para> </warning> diff --git a/doc/manual/quick-start.xml b/doc/manual/quick-start.xml index 294fbcba29f5..badbfa29461c 100644 --- a/doc/manual/quick-start.xml +++ b/doc/manual/quick-start.xml @@ -131,7 +131,7 @@ $ nix-env -uBf nixpkgs-<replaceable>version</replaceable>/ '*'</screen> actual delete them: <screen> -$ nix-collect-garbage | xargs nix-store --delete</screen> +$ nix-collect-garbage</screen> </para> </listitem> diff --git a/scripts/nix-collect-garbage.in b/scripts/nix-collect-garbage.in index 8b571536d87f..539979cbb6c0 100755 --- a/scripts/nix-collect-garbage.in +++ b/scripts/nix-collect-garbage.in @@ -8,17 +8,17 @@ my $storeDir = "@storedir@"; my %alive; +my $gcOper = "--delete"; my $keepSuccessors = 1; -my $invert = 0; my @roots = (); # Parse the command line. foreach my $arg (@ARGV) { - if ($arg eq "--no-successors") { $keepSuccessors = 0; } - elsif ($arg eq "--invert") { $invert = 1; } - else { die "unknown argument `$arg'" }; + if ($arg eq "--delete" || $arg eq "--print-live" || $arg eq "--print-dead") { + $gcOper = $arg; + } else { die "unknown argument `$arg'" }; } @@ -68,33 +68,15 @@ sub findRoots { findRoots 1, $rootsDir; -# Determine all store paths reachable from the roots. -my $extraarg = ""; -if ($keepSuccessors) { $extraarg = "--include-successors"; }; -my $pid = open2(\*READ, \*WRITE, "@bindir@/nix-store --query --requisites $extraarg @roots") - or die "determining live paths"; -close WRITE; -while (<READ>) { - chomp; - $alive{$_} = 1; - if ($invert) { print "$_\n"; }; -} -close READ; +# Run the collector with the roots we found. +my $pid = open2(">&1", \*WRITE, "@bindir@/nix-store --gc $gcOper") + or die "cannot run `nix-store --gc'"; -waitpid $pid, 0; -$? == 0 or die "determining live paths"; - -exit 0 if ($invert); +foreach my $root (@roots) { + print WRITE "$root\n"; +} +close WRITE; -# Using that information, find all store paths *not* reachable from -# the roots. -opendir(DIR, $storeDir) or die "cannot open directory $storeDir: $!"; -foreach my $name (readdir DIR) { - next if ($name eq "." || $name eq ".."); - $name = "$storeDir/$name"; - if (!$alive{$name}) { - print "$name\n"; - } -} -closedir DIR; +waitpid $pid, 0; +$? == 0 or die "`nix-store --gc' failed"; diff --git a/src/nix-store/main.cc b/src/nix-store/main.cc index 78599e30869c..7bc8565d293d 100644 --- a/src/nix-store/main.cc +++ b/src/nix-store/main.cc @@ -222,7 +222,7 @@ static void opGC(Strings opFlags, Strings opArgs) if (flag == "--print-live") subOp = soPrintLive; else if (flag == "--print-dead") subOp = soPrintDead; else if (flag == "--delete") subOp = soDelete; - else throw UsageError(format("bad sub-operation `%1% in GC") % flag); + else throw UsageError(format("bad sub-operation `%1%' in GC") % flag); Paths roots; while (1) { |