Factor out a GcStore interface

Starts progress on #5729.

The idea is that we should not have these default methods throwing
"unimplemented". This is a small step in that direction.

I kept `addTempRoot` because it is a no-op, rather than failure. Also,
as a practical matter, it is called all over the place, while doing
other tasks, so the downcasting would be annoying.

Maybe in the future I could move the "real" `addTempRoot` to `GcStore`,
and the existing usecases use a `tryAddTempRoot` wrapper to downcast or
do nothing, but I wasn't sure whether that was a good idea so with a
bias to less churn I didn't do it yet.
This commit is contained in:
John Ericson 2022-03-01 18:31:36 +00:00
parent 391f4fcabe
commit 6636202356
16 changed files with 143 additions and 93 deletions

View file

@ -1,6 +1,7 @@
#include "globals.hh"
#include "shared.hh"
#include "store-api.hh"
#include "gc-store.hh"
#include "util.hh"
#include "loggers.hh"

View file

@ -1,4 +1,5 @@
#include "local-derivation-goal.hh"
#include "gc-store.hh"
#include "hook-instance.hh"
#include "worker.hh"
#include "builtins.hh"
@ -1127,7 +1128,7 @@ struct RestrictedStoreConfig : virtual LocalFSStoreConfig
/* A wrapper around LocalStore that only allows building/querying of
paths that are in the input closures of the build or were added via
recursive Nix calls. */
struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual LocalFSStore
struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual LocalFSStore, public virtual GcStore
{
ref<LocalStore> next;

View file

@ -3,6 +3,7 @@
#include "worker-protocol.hh"
#include "build-result.hh"
#include "store-api.hh"
#include "gc-store.hh"
#include "path-with-outputs.hh"
#include "finally.hh"
#include "archive.hh"
@ -623,9 +624,12 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
case wopAddIndirectRoot: {
Path path = absPath(readString(from));
logger->startWork();
store->addIndirectRoot(path);
auto & gcStore = requireGcStore(*store);
gcStore.addIndirectRoot(path);
logger->stopWork();
to << 1;
break;
}
@ -640,7 +644,8 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
case wopFindRoots: {
logger->startWork();
Roots roots = store->findRoots(!trusted);
auto & gcStore = requireGcStore(*store);
Roots roots = gcStore.findRoots(!trusted);
logger->stopWork();
size_t size = 0;
@ -671,7 +676,8 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
logger->startWork();
if (options.ignoreLiveness)
throw Error("you are not allowed to ignore liveness");
store->collectGarbage(options, results);
auto & gcStore = requireGcStore(*store);
gcStore.collectGarbage(options, results);
logger->stopWork();
to << results.paths << results.bytesFreed << 0 /* obsolete */;

13
src/libstore/gc-store.cc Normal file
View file

@ -0,0 +1,13 @@
#include "gc-store.hh"
namespace nix {
GcStore & requireGcStore(Store & store)
{
auto * gcStore = dynamic_cast<GcStore *>(&store);
if (!gcStore)
throw UsageError("Garbage collection not supported by this store");
return *gcStore;
}
}

84
src/libstore/gc-store.hh Normal file
View file

@ -0,0 +1,84 @@
#pragma once
#include "store-api.hh"
namespace nix {
typedef std::unordered_map<StorePath, std::unordered_set<std::string>> Roots;
struct GCOptions
{
/* Garbage collector operation:
- `gcReturnLive': return the set of paths reachable from
(i.e. in the closure of) the roots.
- `gcReturnDead': return the set of paths not reachable from
the roots.
- `gcDeleteDead': actually delete the latter set.
- `gcDeleteSpecific': delete the paths listed in
`pathsToDelete', insofar as they are not reachable.
*/
typedef enum {
gcReturnLive,
gcReturnDead,
gcDeleteDead,
gcDeleteSpecific,
} GCAction;
GCAction action{gcDeleteDead};
/* If `ignoreLiveness' is set, then reachability from the roots is
ignored (dangerous!). However, the paths must still be
unreferenced *within* the store (i.e., there can be no other
store paths that depend on them). */
bool ignoreLiveness{false};
/* For `gcDeleteSpecific', the paths to delete. */
StorePathSet pathsToDelete;
/* Stop after at least `maxFreed' bytes have been freed. */
uint64_t maxFreed{std::numeric_limits<uint64_t>::max()};
};
struct GCResults
{
/* Depending on the action, the GC roots, or the paths that would
be or have been deleted. */
PathSet paths;
/* For `gcReturnDead', `gcDeleteDead' and `gcDeleteSpecific', the
number of bytes that would be or was freed. */
uint64_t bytesFreed = 0;
};
struct GcStore : public virtual Store
{
/* Add an indirect root, which is merely a symlink to `path' from
/nix/var/nix/gcroots/auto/<hash of `path'>. `path' is supposed
to be a symlink to a store path. The garbage collector will
automatically remove the indirect root when it finds that
`path' has disappeared. */
virtual void addIndirectRoot(const Path & path) = 0;
/* Find the roots of the garbage collector. Each root is a pair
(link, storepath) where `link' is the path of the symlink
outside of the Nix store that point to `storePath'. If
'censor' is true, privacy-sensitive information about roots
found in /proc is censored. */
virtual Roots findRoots(bool censor) = 0;
/* Perform a garbage collection. */
virtual void collectGarbage(const GCOptions & options, GCResults & results) = 0;
};
GcStore & requireGcStore(Store & store);
}

View file

@ -1,6 +1,7 @@
#pragma once
#include "store-api.hh"
#include "gc-store.hh"
namespace nix {
@ -23,7 +24,7 @@ struct LocalFSStoreConfig : virtual StoreConfig
"physical path to the Nix store"};
};
class LocalFSStore : public virtual LocalFSStoreConfig, public virtual Store
class LocalFSStore : public virtual LocalFSStoreConfig, public virtual Store, virtual GcStore
{
public:

View file

@ -5,6 +5,7 @@
#include "pathlocks.hh"
#include "store-api.hh"
#include "local-fs-store.hh"
#include "gc-store.hh"
#include "sync.hh"
#include "util.hh"
@ -43,7 +44,7 @@ struct LocalStoreConfig : virtual LocalFSStoreConfig
};
class LocalStore : public virtual LocalStoreConfig, public virtual LocalFSStore
class LocalStore : public virtual LocalStoreConfig, public virtual LocalFSStore, public virtual GcStore
{
private:

View file

@ -22,9 +22,9 @@ DerivedPath StorePathWithOutputs::toDerivedPath() const
std::vector<DerivedPath> toDerivedPaths(const std::vector<StorePathWithOutputs> ss)
{
std::vector<DerivedPath> reqs;
for (auto & s : ss) reqs.push_back(s.toDerivedPath());
return reqs;
std::vector<DerivedPath> reqs;
for (auto & s : ss) reqs.push_back(s.toDerivedPath());
return reqs;
}

View file

@ -1,6 +1,7 @@
#include "serialise.hh"
#include "util.hh"
#include "path-with-outputs.hh"
#include "gc-store.hh"
#include "remote-fs-accessor.hh"
#include "build-result.hh"
#include "remote-store.hh"

View file

@ -4,6 +4,7 @@
#include <string>
#include "store-api.hh"
#include "gc-store.hh"
namespace nix {
@ -29,7 +30,7 @@ struct RemoteStoreConfig : virtual StoreConfig
/* FIXME: RemoteStore is a misnomer - should be something like
DaemonStore. */
class RemoteStore : public virtual RemoteStoreConfig, public virtual Store
class RemoteStore : public virtual RemoteStoreConfig, public virtual Store, public virtual GcStore
{
public:

View file

@ -76,59 +76,6 @@ enum AllowInvalidFlag : bool { DisallowInvalid = false, AllowInvalid = true };
const uint32_t exportMagic = 0x4558494e;
typedef std::unordered_map<StorePath, std::unordered_set<std::string>> Roots;
struct GCOptions
{
/* Garbage collector operation:
- `gcReturnLive': return the set of paths reachable from
(i.e. in the closure of) the roots.
- `gcReturnDead': return the set of paths not reachable from
the roots.
- `gcDeleteDead': actually delete the latter set.
- `gcDeleteSpecific': delete the paths listed in
`pathsToDelete', insofar as they are not reachable.
*/
typedef enum {
gcReturnLive,
gcReturnDead,
gcDeleteDead,
gcDeleteSpecific,
} GCAction;
GCAction action{gcDeleteDead};
/* If `ignoreLiveness' is set, then reachability from the roots is
ignored (dangerous!). However, the paths must still be
unreferenced *within* the store (i.e., there can be no other
store paths that depend on them). */
bool ignoreLiveness{false};
/* For `gcDeleteSpecific', the paths to delete. */
StorePathSet pathsToDelete;
/* Stop after at least `maxFreed' bytes have been freed. */
uint64_t maxFreed{std::numeric_limits<uint64_t>::max()};
};
struct GCResults
{
/* Depending on the action, the GC roots, or the paths that would
be or have been deleted. */
PathSet paths;
/* For `gcReturnDead', `gcDeleteDead' and `gcDeleteSpecific', the
number of bytes that would be or was freed. */
uint64_t bytesFreed = 0;
};
enum BuildMode { bmNormal, bmRepair, bmCheck };
struct BuildResult;
@ -531,26 +478,6 @@ public:
virtual void addTempRoot(const StorePath & path)
{ debug("not creating temporary root, store doesn't support GC"); }
/* Add an indirect root, which is merely a symlink to `path' from
/nix/var/nix/gcroots/auto/<hash of `path'>. `path' is supposed
to be a symlink to a store path. The garbage collector will
automatically remove the indirect root when it finds that
`path' has disappeared. */
virtual void addIndirectRoot(const Path & path)
{ unsupported("addIndirectRoot"); }
/* Find the roots of the garbage collector. Each root is a pair
(link, storepath) where `link' is the path of the symlink
outside of the Nix store that point to `storePath'. If
'censor' is true, privacy-sensitive information about roots
found in /proc is censored. */
virtual Roots findRoots(bool censor)
{ unsupported("findRoots"); }
/* Perform a garbage collection. */
virtual void collectGarbage(const GCOptions & options, GCResults & results)
{ unsupported("collectGarbage"); }
/* Return a string representing information about the path that
can be loaded into the database using `nix-store --load-db' or
`nix-store --register-validity'. */

View file

@ -1,4 +1,5 @@
#include "store-api.hh"
#include "gc-store.hh"
#include "profiles.hh"
#include "shared.hh"
#include "globals.hh"
@ -80,10 +81,11 @@ static int main_nix_collect_garbage(int argc, char * * argv)
// Run the actual garbage collector.
if (!dryRun) {
auto store = openStore();
auto & gcStore = requireGcStore(*store);
options.action = GCOptions::gcDeleteDead;
GCResults results;
PrintFreed freed(true, results);
store->collectGarbage(options, results);
gcStore.collectGarbage(options, results);
}
return 0;

View file

@ -3,6 +3,7 @@
#include "dotgraph.hh"
#include "globals.hh"
#include "build-result.hh"
#include "gc-store.hh"
#include "local-store.hh"
#include "monitor-fd.hh"
#include "serve-protocol.hh"
@ -428,11 +429,12 @@ static void opQuery(Strings opFlags, Strings opArgs)
store->computeFSClosure(
args, referrers, true, settings.gcKeepOutputs, settings.gcKeepDerivations);
Roots roots = store->findRoots(false);
auto & gcStore = requireGcStore(*store);
Roots roots = gcStore.findRoots(false);
for (auto & [target, links] : roots)
if (referrers.find(target) != referrers.end())
for (auto & link : links)
cout << fmt("%1% -> %2%\n", link, store->printStorePath(target));
cout << fmt("%1% -> %2%\n", link, gcStore.printStorePath(target));
break;
}
@ -588,20 +590,22 @@ static void opGC(Strings opFlags, Strings opArgs)
if (!opArgs.empty()) throw UsageError("no arguments expected");
auto & gcStore = requireGcStore(*store);
if (printRoots) {
Roots roots = store->findRoots(false);
Roots roots = gcStore.findRoots(false);
std::set<std::pair<Path, StorePath>> roots2;
// Transpose and sort the roots.
for (auto & [target, links] : roots)
for (auto & link : links)
roots2.emplace(link, target);
for (auto & [link, target] : roots2)
std::cout << link << " -> " << store->printStorePath(target) << "\n";
std::cout << link << " -> " << gcStore.printStorePath(target) << "\n";
}
else {
PrintFreed freed(options.action == GCOptions::gcDeleteDead, results);
store->collectGarbage(options, results);
gcStore.collectGarbage(options, results);
if (options.action != GCOptions::gcDeleteDead)
for (auto & i : results.paths)
@ -625,9 +629,11 @@ static void opDelete(Strings opFlags, Strings opArgs)
for (auto & i : opArgs)
options.pathsToDelete.insert(store->followLinksToStorePath(i));
auto & gcStore = requireGcStore(*store);
GCResults results;
PrintFreed freed(true, results);
store->collectGarbage(options, results);
gcStore.collectGarbage(options, results);
}

View file

@ -2,6 +2,7 @@
#include "common-args.hh"
#include "shared.hh"
#include "store-api.hh"
#include "gc-store.hh"
using namespace nix;
@ -32,12 +33,14 @@ struct CmdStoreDelete : StorePathsCommand
void run(ref<Store> store, std::vector<StorePath> && storePaths) override
{
auto & gcStore = requireGcStore(*store);
for (auto & path : storePaths)
options.pathsToDelete.insert(path);
GCResults results;
PrintFreed freed(true, results);
store->collectGarbage(options, results);
gcStore.collectGarbage(options, results);
}
};

View file

@ -2,6 +2,7 @@
#include "common-args.hh"
#include "shared.hh"
#include "store-api.hh"
#include "gc-store.hh"
using namespace nix;
@ -33,10 +34,12 @@ struct CmdStoreGC : StoreCommand, MixDryRun
void run(ref<Store> store) override
{
auto & gcStore = requireGcStore(*store);
options.action = dryRun ? GCOptions::gcReturnDead : GCOptions::gcDeleteDead;
GCResults results;
PrintFreed freed(options.action == GCOptions::gcDeleteDead, results);
store->collectGarbage(options, results);
gcStore.collectGarbage(options, results);
}
};