Merge pull request #7489 from mupdt/nar-info-disk-cache-race-condition
[PDT] TDE-3114: prevent a race-condition when creating the S3 cache
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commit
b1223e1b62
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@ -166,16 +166,37 @@ public:
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return i->second;
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}
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std::optional<Cache> queryCacheRaw(State & state, const std::string & uri)
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{
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auto i = state.caches.find(uri);
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if (i == state.caches.end()) {
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auto queryCache(state.queryCache.use()(uri)(time(0) - cacheInfoTtl));
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if (!queryCache.next())
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return std::nullopt;
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state.caches.emplace(uri,
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Cache{(int) queryCache.getInt(0), queryCache.getStr(1), queryCache.getInt(2) != 0, (int) queryCache.getInt(3)});
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}
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return getCache(state, uri);
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}
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void createCache(const std::string & uri, const Path & storeDir, bool wantMassQuery, int priority) override
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{
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retrySQLite<void>([&]() {
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auto state(_state.lock());
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SQLiteTxn txn(state->db);
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// FIXME: race
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// To avoid the race, we have to check if maybe someone hasn't yet created
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// the cache for this URI in the meantime.
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auto cache(queryCacheRaw(*state, uri));
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if (cache)
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return;
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state->insertCache.use()(uri)(time(0))(storeDir)(wantMassQuery)(priority).exec();
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assert(sqlite3_changes(state->db) == 1);
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state->caches[uri] = Cache{(int) sqlite3_last_insert_rowid(state->db), storeDir, wantMassQuery, priority};
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txn.commit();
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});
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}
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@ -183,21 +204,12 @@ public:
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{
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return retrySQLite<std::optional<CacheInfo>>([&]() -> std::optional<CacheInfo> {
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auto state(_state.lock());
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auto i = state->caches.find(uri);
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if (i == state->caches.end()) {
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auto queryCache(state->queryCache.use()(uri)(time(0) - cacheInfoTtl));
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if (!queryCache.next())
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auto cache(queryCacheRaw(*state, uri));
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if (!cache)
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return std::nullopt;
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state->caches.emplace(uri,
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Cache{(int) queryCache.getInt(0), queryCache.getStr(1), queryCache.getInt(2) != 0, (int) queryCache.getInt(3)});
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}
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auto & cache(getCache(*state, uri));
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return CacheInfo {
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.wantMassQuery = cache.wantMassQuery,
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.priority = cache.priority
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.wantMassQuery = cache->wantMassQuery,
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.priority = cache->priority
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};
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});
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}
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