hash: do the mlock after loading the table

The mlock runs much faster, probably because the hash fetches are
doing most of the work that mlock does.

It makes bees startup latency for testing smaller, even if it takes more
time in absolute terms.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

src/bees-hash.cc

@@ -185,14 +185,8 @@ percent(size_t num, size_t den)
 void
 BeesHashTable::prefetch_loop()
 {
-	// Always do the mlock, whether shared or not
-	THROW_CHECK1(runtime_error, m_size, m_size > 0);
-	catch_all([&]() {
-		BEESNOTE("mlock " << pretty(m_size));
-		DIE_IF_NON_ZERO(mlock(m_byte_ptr, m_size));
-	});
-
-	while (1) {
+	bool not_locked = true;
+	while (true) {
 		size_t width = 64;
 		vector<size_t> occupancy(width, 0);
 		size_t occupied_count = 0;
@@ -203,11 +197,11 @@ BeesHashTable::prefetch_loop()
 		size_t unaligned_eof_count = 0;
 
 		for (uint64_t ext = 0; ext < m_extents; ++ext) {
-			BEESNOTE("prefetching hash table extent " << ext << " of " << m_extents);
+			BEESNOTE("prefetching hash table extent #" << ext << " of " << m_extents);
 			catch_all([&]() {
 				fetch_missing_extent_by_index(ext);
 
-				BEESNOTE("analyzing hash table extent " << ext << " of " << m_extents);
+				BEESNOTE("analyzing hash table extent #" << ext << " of " << m_extents);
 				bool duplicate_bugs_found = false;
 				auto lock = lock_extent_by_index(ext);
 				for (Bucket *bucket = m_extent_ptr[ext].p_buckets; bucket < m_extent_ptr[ext + 1].p_buckets; ++bucket) {
@@ -309,6 +303,19 @@ BeesHashTable::prefetch_loop()
 			m_stats_file.write(graph_blob.str());
 		});
 
+		if (not_locked) {
+			// Always do the mlock, whether shared or not
+			THROW_CHECK1(runtime_error, m_size, m_size > 0);
+			BEESLOG("mlock(" << pretty(m_size) << ")...");
+			Timer lock_time;
+			catch_all([&]() {
+				BEESNOTE("mlock " << pretty(m_size));
+				DIE_IF_NON_ZERO(mlock(m_byte_ptr, m_size));
+			});
+			BEESLOG("mlock(" << pretty(m_size) << ") done in " << lock_time << " sec");
+			not_locked = false;
+		}
+
 		BEESNOTE("idle " << BEES_HASH_TABLE_ANALYZE_INTERVAL << "s");
 		nanosleep(BEES_HASH_TABLE_ANALYZE_INTERVAL);
 	}