Method clear_impl

fdbserver/VersionedBTree.actor.cpp:2048–2066

	// Clears the cache, saving the entries to second cache, then waits for each item to be evictable and evicts it.
	ACTOR static Future<Void> clear_impl(ObjectCache* self, bool waitForSafeEviction) {
		// Claim ownership of all of our cached items, removing them from the evictor's control and quota.
		for (auto& ie : self->cache) {
			self->pEvictor->reclaim(ie.second);
		}

		// All items are in the cache so we don't need the prioritized eviction order anymore, and the cache is about
		// to be destroyed so the prioritizedEvictions head/tail will become invalid.
		self->prioritizedEvictions.clear();

		state typename CacheT::iterator i = self->cache.begin();
		while (i != self->cache.end()) {
			wait(waitForSafeEviction ? i->second.item.onEvictable() : i->second.item.cancel());
			++i;
		}
		self->cache.clear();

		return Void();
	}

	Future<Void> clear(bool waitForSafeEviction = false) { return clear_impl(this, waitForSafeEviction); }