wroclaw-git-backups/nix
1
0
Fork 0
mirror of https://github.com/NixOS/nix synced 2025-07-06 21:41:48 +02:00
Code Activity

* nix-build: use an indirection scheme to make it easier for users to

Browse source 
get rid of GC roots.  Nix-build places a symlink `result' in the
  current directory.  Previously, removing that symlink would not
  remove the store path being linked to as a GC root.  Now, the GC
  root created by nix-build is actually a symlink in
  `/nix/var/nix/gcroots/auto' to `result'.  So if that symlink is
  removed the GC root automatically becomes invalid (since it can no
  longer be resolved).  The root itself is not automatically removed -
  the garbage collector should delete dangling roots.
This commit is contained in:
Eelco Dolstra 2005-02-01 13:48:46 +00:00
parent dcc37c236c
commit 630ae0c9d7
7 changed files with 101 additions and 50 deletions
Download patch file Download diff file Expand all files Collapse all files

61
src/libstore/gc.cc
View file

@ -13,6 +13,8 @@
static string gcLockName = "gc.lock";
static string tempRootsDir = "temproots";
static string gcRootsDir = "gcroots";
/* Acquire the global GC lock. This is used to prevent new Nix
@ -49,40 +51,61 @@ static void createDirs(const Path & path)
}
Path addPermRoot(const Path & _storePath, const Path & _gcRoot)
void createSymlink(const Path & link, const Path & target, bool careful)
{
/* Create directories up to `gcRoot'. */
createDirs(dirOf(link));
/* Remove the old symlink. */
if (pathExists(link)) {
if (careful && (!isLink(link) || !isStorePath(readLink(link))))
throw Error(format("cannot create symlink `%1%'; already exists") % link);
unlink(link.c_str());
}
/* And create the new own. */
if (symlink(target.c_str(), link.c_str()) == -1)
throw SysError(format("symlinking `%1%' to `%2%'")
% link % target);
}
Path addPermRoot(const Path & _storePath, const Path & _gcRoot,
bool indirect)
{
Path storePath(canonPath(_storePath));
Path gcRoot(canonPath(_gcRoot));
Path rootsDir = canonPath((format("%1%/%2%") % nixStateDir % "gcroots").str());
if (string(gcRoot, 0, rootsDir.size() + 1) != rootsDir + "/")
throw Error(format(
"path `%1%' is not a valid garbage collector root; "
"it's not in the `%1%' directory")
% gcRoot % rootsDir);
assertStorePath(storePath);
/* Grab the global GC root. This prevents the set of permanent
roots from increasing while a GC is in progress. */
AutoCloseFD fdGCLock = openGCLock(ltRead);
/* Create directories up to `gcRoot'. */
createDirs(dirOf(gcRoot));
if (indirect) {
string hash = printHash32(hashString(htSHA1, gcRoot));
Path realRoot = canonPath((format("%1%/%2%/auto/%3%")
% nixStateDir % gcRootsDir % hash).str());
/* Remove the old symlink. */
unlink(gcRoot.c_str());
createSymlink(gcRoot, storePath, true);
createSymlink(realRoot, gcRoot, false);
}
/* And create the new own. */
if (symlink(storePath.c_str(), gcRoot.c_str()) == -1)
throw SysError(format("symlinking `%1%' to `%2%'")
% gcRoot % storePath);
else {
Path rootsDir = canonPath((format("%1%/%2%") % nixStateDir % gcRootsDir).str());
if (string(gcRoot, 0, rootsDir.size() + 1) != rootsDir + "/")
throw Error(format(
"path `%1%' is not a valid garbage collector root; "
"it's not in the directory `%2%'")
% gcRoot % rootsDir);
createSymlink(gcRoot, storePath, false);
}
return gcRoot;
}
static string tempRootsDir = "temproots";
/* The file to which we write our temporary roots. */
static Path fnTempRoots;
static AutoCloseFD fdTempRoots;