Add a realisations disk cache

Similar to the nar-info disk cache (and using the same db).
This makes rebuilds muuch faster.

- This works regardless of the ca-derivations experimental feature.
  I could modify the logic to not touch the db if the flag isn’t there,
  but given that this is a trash-able local cache, it doesn’t seem to be
  really worth it.
- We could unify the `NARs` and `Realisation` tables to only have one
  generic kv table. This is left as an exercise to the reader.
- I didn’t update the cache db version number as the new schema just
  adds a new table to the previous one, so the db will be transparently
  migrated and is backwards-compatible.

Fix #4746
This commit is contained in:
regnat 2021-05-06 16:45:09 +02:00
parent fe3a10a9b2
commit b66234134f
4 changed files with 149 additions and 3 deletions

View file

@ -450,18 +450,43 @@ StorePath BinaryCacheStore::addTextToStore(const string & name, const string & s
std::optional<const Realisation> BinaryCacheStore::queryRealisation(const DrvOutput & id)
{
if (diskCache) {
auto [cacheOutcome, maybeCachedRealisation] =
diskCache->lookupRealisation(getUri(), id);
switch (cacheOutcome) {
case (NarInfoDiskCache::oValid):
debug("Returning a cached realisation for %s", id.to_string());
return *maybeCachedRealisation;
case (NarInfoDiskCache::oInvalid):
debug("Returning a cached missing realisation for %s", id.to_string());
return {};
case (NarInfoDiskCache::oUnknown):
break;
}
}
auto outputInfoFilePath = realisationsPrefix + "/" + id.to_string() + ".doi";
auto rawOutputInfo = getFile(outputInfoFilePath);
if (rawOutputInfo) {
return {Realisation::fromJSON(
nlohmann::json::parse(*rawOutputInfo), outputInfoFilePath)};
auto realisation = Realisation::fromJSON(
nlohmann::json::parse(*rawOutputInfo), outputInfoFilePath);
if (diskCache)
diskCache->upsertRealisation(
getUri(), realisation);
return {realisation};
} else {
if (diskCache)
diskCache->upsertAbsentRealisation(getUri(), id);
return std::nullopt;
}
}
void BinaryCacheStore::registerDrvOutput(const Realisation& info) {
if (diskCache)
diskCache->upsertRealisation(getUri(), info);
auto filePath = realisationsPrefix + "/" + info.id.to_string() + ".doi";
upsertFile(filePath, info.toJSON().dump(), "application/json");
}

View file

@ -4,6 +4,7 @@
#include "globals.hh"
#include <sqlite3.h>
#include <nlohmann/json.hpp>
namespace nix {
@ -38,6 +39,16 @@ create table if not exists NARs (
foreign key (cache) references BinaryCaches(id) on delete cascade
);
create table if not exists Realisations (
cache integer not null,
outputId text not null,
content blob, -- Json serialisation of the realisation, or empty if present is true
timestamp integer not null,
present integer not null,
primary key (cache, outputId),
foreign key (cache) references BinaryCaches(id) on delete cascade
);
create table if not exists LastPurge (
dummy text primary key,
value integer
@ -63,7 +74,9 @@ public:
struct State
{
SQLite db;
SQLiteStmt insertCache, queryCache, insertNAR, insertMissingNAR, queryNAR, purgeCache;
SQLiteStmt insertCache, queryCache, insertNAR, insertMissingNAR,
queryNAR, insertRealisation, insertMissingRealisation,
queryRealisation, purgeCache;
std::map<std::string, Cache> caches;
};
@ -98,6 +111,26 @@ public:
state->queryNAR.create(state->db,
"select present, namePart, url, compression, fileHash, fileSize, narHash, narSize, refs, deriver, sigs, ca from NARs where cache = ? and hashPart = ? and ((present = 0 and timestamp > ?) or (present = 1 and timestamp > ?))");
state->insertRealisation.create(state->db,
R"(
insert or replace into Realisations(cache, outputId, content, timestamp, present)
values (?, ?, ?, ?, 1)
)");
state->insertMissingRealisation.create(state->db,
R"(
insert or replace into Realisations(cache, outputId, timestamp, present)
values (?, ?, ?, 0)
)");
state->queryRealisation.create(state->db,
R"(
select present, content from Realisations
where cache = ? and outputId = ? and
((present = 0 and timestamp > ?) or
(present = 1 and timestamp > ?))
)");
/* Periodically purge expired entries from the database. */
retrySQLite<void>([&]() {
auto now = time(0);
@ -212,6 +245,38 @@ public:
});
}
std::pair<Outcome, std::shared_ptr<Realisation>> lookupRealisation(
const std::string & uri, const DrvOutput & id) override
{
return retrySQLite<std::pair<Outcome, std::shared_ptr<Realisation>>>(
[&]() -> std::pair<Outcome, std::shared_ptr<Realisation>> {
auto state(_state.lock());
auto & cache(getCache(*state, uri));
auto now = time(0);
auto queryRealisation(state->queryRealisation.use()
(cache.id)
(id.to_string())
(now - settings.ttlNegativeNarInfoCache)
(now - settings.ttlPositiveNarInfoCache));
if (!queryRealisation.next())
return {oUnknown, 0};
if (queryRealisation.getInt(0) == 0)
return {oInvalid, 0};
auto realisation =
std::make_shared<Realisation>(Realisation::fromJSON(
nlohmann::json::parse(queryRealisation.getStr(1)),
"Local disk cache"));
return {oValid, realisation};
});
}
void upsertNarInfo(
const std::string & uri, const std::string & hashPart,
std::shared_ptr<const ValidPathInfo> info) override
@ -251,6 +316,39 @@ public:
}
});
}
void upsertRealisation(
const std::string & uri,
const Realisation & realisation) override
{
retrySQLite<void>([&]() {
auto state(_state.lock());
auto & cache(getCache(*state, uri));
state->insertRealisation.use()
(cache.id)
(realisation.id.to_string())
(realisation.toJSON().dump())
(time(0)).exec();
});
}
virtual void upsertAbsentRealisation(
const std::string & uri,
const DrvOutput & id) override
{
retrySQLite<void>([&]() {
auto state(_state.lock());
auto & cache(getCache(*state, uri));
state->insertMissingRealisation.use()
(cache.id)
(id.to_string())
(time(0)).exec();
});
}
};
ref<NarInfoDiskCache> getNarInfoDiskCache()

View file

@ -2,6 +2,7 @@
#include "ref.hh"
#include "nar-info.hh"
#include "realisation.hh"
namespace nix {
@ -29,6 +30,15 @@ public:
virtual void upsertNarInfo(
const std::string & uri, const std::string & hashPart,
std::shared_ptr<const ValidPathInfo> info) = 0;
virtual void upsertRealisation(
const std::string & uri,
const Realisation & realisation) = 0;
virtual void upsertAbsentRealisation(
const std::string & uri,
const DrvOutput & id) = 0;
virtual std::pair<Outcome, std::shared_ptr<Realisation>> lookupRealisation(
const std::string & uri, const DrvOutput & id) = 0;
};
/* Return a singleton cache object that can be used concurrently by

View file

@ -45,3 +45,16 @@ if [[ -z "$(ls "$REMOTE_STORE_DIR/realisations")" ]]; then
echo "Realisations not rebuilt"
exit 1
fi
# Test the local realisation disk cache
buildDrvs --post-build-hook ../push-to-store.sh
clearStore
# Add the realisations of rootCA to the cachecache
clearCacheCache
export _NIX_FORCE_HTTP=1
buildDrvs --substitute --substituters $REMOTE_STORE --no-require-sigs -j0
# Try rebuilding, but remove the realisations from the remote cache to force
# using the cachecache
clearStore
rm $REMOTE_STORE_DIR/realisations/*
buildDrvs --substitute --substituters $REMOTE_STORE --no-require-sigs -j0