From 700c678c2eed5e05c3e68d722c41c2b37d0a2f45 Mon Sep 17 00:00:00 2001 From: "Ricardo M. Correia" Date: Fri, 11 Apr 2014 17:10:20 +0200 Subject: [PATCH] nix-env: Minor change to '--delete-generations Nd' semantics The option '--delete-generations Nd' deletes all generations older than N days. However, most likely the user does not want to delete the generation that was active N days ago. For example, say that you have these 3 generations: 1: <30 days ago> 2: <15 days ago> 3: <1 hour ago> If you do --delete-generations 7d (say, as part of a cron job), most likely you still want to keep generation 2, i.e. the generation that was active 7 days ago (and for most of the past 7 days, in fact). This patch fixes this issue. Note that this also affects 'nix-collect-garbage --delete-older-than Nd'. Thanks to @roconnor for noticing the issue! --- doc/manual/nix-collect-garbage.xml | 5 +++-- doc/manual/nix-env.xml | 3 ++- src/nix-env/nix-env.cc | 14 ++++++++++---- 3 files changed, 15 insertions(+), 7 deletions(-) diff --git a/doc/manual/nix-collect-garbage.xml b/doc/manual/nix-collect-garbage.xml index a97e3b7c6..cf870740f 100644 --- a/doc/manual/nix-collect-garbage.xml +++ b/doc/manual/nix-collect-garbage.xml @@ -45,8 +45,9 @@ which deletes all old generations of all profiles in impossible); and period, where period is a value such as 30d, which deletes -all non-current generations that are older than the specified number of -days in all profiles in /nix/var/nix/profiles. +all generations older than the specified number of days in all profiles +in /nix/var/nix/profiles (except for the generations +that were active at that point in time). diff --git a/doc/manual/nix-env.xml b/doc/manual/nix-env.xml index 3bfcb15db..c44020803 100644 --- a/doc/manual/nix-env.xml +++ b/doc/manual/nix-env.xml @@ -1170,7 +1170,8 @@ $ nix-env --list-generations profile. The generations can be a list of generation numbers, the special value old to delete all non-current generations, or a value such as 30d to delete all -non-current generations older than the specified number of days. +generations older than the specified number of days (except for the +generation that was active at that point in time). Periodically deleting old generations is important to make garbage collection effective. diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc index 8a8052634..3db84ff5c 100644 --- a/src/nix-env/nix-env.cc +++ b/src/nix-env/nix-env.cc @@ -1315,11 +1315,17 @@ static void opDeleteGenerations(Globals & globals, oldTime = curTime - days * 24 * 3600; - for (Generations::iterator j = gens.begin(); j != gens.end(); ++j) { - if (j->number == curGen) continue; - - if (j->creationTime < oldTime) + bool canDelete = false; + for (Generations::reverse_iterator j = gens.rbegin(); j != gens.rend(); ++j) { + if (canDelete) { + assert(j->creationTime < oldTime); deleteGeneration2(globals, j->number); + } else if (j->creationTime < oldTime) { + /* We may now start deleting generations, but we don't delete + this generation yet, because this generation was still the + one that was active at the requested point in time. */ + canDelete = true; + } } } else { int n;