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Merge branch 'master' into no-manifests

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This commit is contained in:
Eelco Dolstra 2012-08-27 11:09:07 -04:00
commit e94806d030
20 changed files with 325 additions and 139 deletions
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74
src/libstore/optimise-store.cc
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@ -102,11 +102,11 @@ void LocalStore::optimisePath_(OptimiseStats & stats, const Path & path)
/* Nope, create a hard link in the links directory. */
makeMutable(path);
MakeImmutable mk1(path);
if (link(path.c_str(), linkPath.c_str()) == -1)
if (link(path.c_str(), linkPath.c_str()) == 0) return;
if (errno != EEXIST)
throw SysError(format("cannot link `%1%' to `%2%'") % linkPath % path);
return;
/* Fall through if another process created ‘linkPath’ before
we did. */
}
/* Yes! We've seen a file with the same contents. Replace the
@ -123,9 +123,6 @@ void LocalStore::optimisePath_(OptimiseStats & stats, const Path & path)
printMsg(lvlTalkative, format("linking `%1%' to `%2%'") % path % linkPath);
Path tempLink = (format("%1%/.tmp-link-%2%-%3%")
% settings.nixStore % getpid() % rand()).str();
/* Make the containing directory writable, but only if it's not
the store itself (we don't want or need to mess with its
permissions). */
@ -140,40 +137,55 @@ void LocalStore::optimisePath_(OptimiseStats & stats, const Path & path)
so make it mutable first (and make it immutable again when
we're done). We also have to make ‘path’ mutable, otherwise
rename() will fail to delete it. */
makeMutable(linkPath);
MakeImmutable mk1(linkPath);
makeMutable(path);
MakeImmutable mk2(path);
if (link(linkPath.c_str(), tempLink.c_str()) == -1) {
if (errno == EMLINK) {
/* Too many links to the same file (>= 32000 on most file
systems). This is likely to happen with empty files.
Just shrug and ignore. */
printMsg(lvlInfo, format("`%1%' has maximum number of links") % linkPath);
return;
/* Another process might be doing the same thing (creating a new
link to ‘linkPath’) and make ‘linkPath’ immutable before we're
done. In that case, just retry. */
unsigned int retries = 1024;
while (--retries > 0) {
makeMutable(linkPath);
MakeImmutable mk1(linkPath);
Path tempLink = (format("%1%/.tmp-link-%2%-%3%")
% settings.nixStore % getpid() % rand()).str();
if (link(linkPath.c_str(), tempLink.c_str()) == -1) {
if (errno == EMLINK) {
/* Too many links to the same file (>= 32000 on most
file systems). This is likely to happen with empty
files. Just shrug and ignore. */
if (st.st_size)
printMsg(lvlInfo, format("`%1%' has maximum number of links") % linkPath);
return;
}
if (errno == EPERM) continue;
throw SysError(format("cannot link `%1%' to `%2%'") % tempLink % linkPath);
}
throw SysError(format("cannot link `%1%' to `%2%'") % tempLink % linkPath);
}
/* Atomically replace the old file with the new hard link. */
if (rename(tempLink.c_str(), path.c_str()) == -1) {
if (errno == EMLINK) {
/* Some filesystems generate too many links on the rename,
rather than on the original link. (Probably it
temporarily increases the st_nlink field before
decreasing it again.) */
printMsg(lvlInfo, format("`%1%' has maximum number of links") % linkPath);
/* Unlink the temp link. */
/* Atomically replace the old file with the new hard link. */
if (rename(tempLink.c_str(), path.c_str()) == -1) {
if (unlink(tempLink.c_str()) == -1)
printMsg(lvlError, format("unable to unlink `%1%'") % tempLink);
return;
if (errno == EMLINK) {
/* Some filesystems generate too many links on the
rename, rather than on the original link.
(Probably it temporarily increases the st_nlink
field before decreasing it again.) */
if (st.st_size)
printMsg(lvlInfo, format("`%1%' has maximum number of links") % linkPath);
return;
}
if (errno == EPERM) continue;
throw SysError(format("cannot rename `%1%' to `%2%'") % tempLink % path);
}
throw SysError(format("cannot rename `%1%' to `%2%'") % tempLink % path);
break;
}
if (retries == 0) throw Error(format("cannot link `%1%' to `%2%'") % path % linkPath);
stats.filesLinked++;
stats.bytesFreed += st.st_size;
stats.blocksFreed += st.st_blocks;