depot/patches/extra/hercules-ci-agent/nix/GHPR_7489-PDT-TDE-3114-prevent-a-race-condition-when-creating-the-S3-cache.patch

70 lines
2.8 KiB
Diff

diff --git a/src/libstore/nar-info-disk-cache.cc b/src/libstore/nar-info-disk-cache.cc
index f4ea739b05d..3e0689534b6 100644
--- a/src/libstore/nar-info-disk-cache.cc
+++ b/src/libstore/nar-info-disk-cache.cc
@@ -166,16 +166,37 @@ class NarInfoDiskCacheImpl : public NarInfoDiskCache
return i->second;
}
+ std::optional<Cache> queryCacheRaw(State & state, const std::string & uri)
+ {
+ auto i = state.caches.find(uri);
+ if (i == state.caches.end()) {
+ auto queryCache(state.queryCache.use()(uri)(time(0) - cacheInfoTtl));
+ if (!queryCache.next())
+ return std::nullopt;
+ state.caches.emplace(uri,
+ Cache{(int) queryCache.getInt(0), queryCache.getStr(1), queryCache.getInt(2) != 0, (int) queryCache.getInt(3)});
+ }
+ return getCache(state, uri);
+ }
+
void createCache(const std::string & uri, const Path & storeDir, bool wantMassQuery, int priority) override
{
retrySQLite<void>([&]() {
auto state(_state.lock());
+ SQLiteTxn txn(state->db);
+
+ // To avoid the race, we have to check if maybe someone hasn't yet created
+ // the cache for this URI in the meantime.
+ auto cache(queryCacheRaw(*state, uri));
- // FIXME: race
+ if (cache)
+ return;
state->insertCache.use()(uri)(time(0))(storeDir)(wantMassQuery)(priority).exec();
assert(sqlite3_changes(state->db) == 1);
state->caches[uri] = Cache{(int) sqlite3_last_insert_rowid(state->db), storeDir, wantMassQuery, priority};
+
+ txn.commit();
});
}
@@ -183,21 +204,12 @@ class NarInfoDiskCacheImpl : public NarInfoDiskCache
{
return retrySQLite<std::optional<CacheInfo>>([&]() -> std::optional<CacheInfo> {
auto state(_state.lock());
-
- auto i = state->caches.find(uri);
- if (i == state->caches.end()) {
- auto queryCache(state->queryCache.use()(uri)(time(0) - cacheInfoTtl));
- if (!queryCache.next())
- return std::nullopt;
- state->caches.emplace(uri,
- Cache{(int) queryCache.getInt(0), queryCache.getStr(1), queryCache.getInt(2) != 0, (int) queryCache.getInt(3)});
- }
-
- auto & cache(getCache(*state, uri));
-
+ auto cache(queryCacheRaw(*state, uri));
+ if (!cache)
+ return std::nullopt;
return CacheInfo {
- .wantMassQuery = cache.wantMassQuery,
- .priority = cache.priority
+ .wantMassQuery = cache->wantMassQuery,
+ .priority = cache->priority
};
});
}