Mercurial > gemma
view pkg/octree/cache.go @ 4723:baabc2b2f094
Avoid creating user profiles without matching role
The INSTEAD OF triggers on users.list_users did that already, but
profile data coming e.g. via restoring a dump had been added also
if there was no matching database role in the cluster.
This also unifies the errors occuring on creation of users with existing
role names that differed between roles with and without profile before.
Note this is no referential integrity. A dropped role still leaves an
orphaned profile behind.
author | Tom Gottfried <tom@intevation.de> |
---|---|
date | Thu, 17 Oct 2019 18:56:59 +0200 |
parents | 4bbfe3dd2ab5 |
children |
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// This is Free Software under GNU Affero General Public License v >= 3.0 // without warranty, see README.md and license for details. // // SPDX-License-Identifier: AGPL-3.0-or-later // License-Filename: LICENSES/AGPL-3.0.txt // // Copyright (C) 2018 by via donau // – Österreichische Wasserstraßen-Gesellschaft mbH // Software engineering by Intevation GmbH // // Author(s): // * Sascha L. Teichmann <sascha.teichmann@intevation.de> package octree import ( "context" "database/sql" "sync" "time" ) type ( cacheKey struct { date time.Time bottleneck string } cacheEntry struct { checksum string tree *STRTree access time.Time } // Cache holds Octrees for a defined amount of time in memory // before they are released. Cache struct { sync.Mutex entries map[cacheKey]*cacheEntry } ) const ( cleanupCacheSleep = 6 * time.Minute maxCacheAge = 5 * time.Minute maxCacheEntries = 4 ) const ( directMeshSQL = ` SELECT mesh_index FROM waterway.sounding_results WHERE id = $1 ` fetchMeshSQL = ` SELECT mesh_checksum, mesh_index FROM waterway.sounding_results WHERE bottleneck_id = $1 AND date_info = $2::date AND mesh_checksum IS NOT NULL AND mesh_index IS NOT NULL ` checkMeshSQL = ` SELECT CASE WHEN mesh_checksum = $3 THEN NULL ELSE mesh_index END FROM waterway.sounding_results WHERE bottleneck_id = $1 AND date_info = $2::date AND mesh_checksum IS NOT NULL AND mesh_index IS NOT NULL ` ) var cache = Cache{ entries: map[cacheKey]*cacheEntry{}, } func init() { go cache.background() } func (c *Cache) background() { for { time.Sleep(cleanupCacheSleep) c.cleanup() } } func (c *Cache) cleanup() { c.Lock() defer c.Unlock() good := time.Now().Add(-maxCacheAge) for k, v := range c.entries { if v.access.Before(good) { delete(c.entries, k) } } } // FromCache fetches an Octree from the global Octree cache. func FromCache( ctx context.Context, conn *sql.Conn, bottleneck string, date time.Time, ) (*STRTree, error) { return cache.get(ctx, conn, bottleneck, date) } // FetchOctreeDirectly loads an octree directly from the database. func FetchMeshDirectly( ctx context.Context, tx *sql.Tx, id int64, ) (*STRTree, error) { var data []byte err := tx.QueryRowContext(ctx, directMeshSQL, id).Scan(&data) if err != nil { return nil, err } tree := new(STRTree) if err := tree.FromBytes(data); err != nil { return nil, err } return tree, nil } func (c *Cache) get( ctx context.Context, conn *sql.Conn, bottleneck string, date time.Time, ) (*STRTree, error) { c.Lock() defer c.Unlock() key := cacheKey{date, bottleneck} entry := c.entries[key] var data []byte var checksum string if entry == nil { // fetch from database err := conn.QueryRowContext( ctx, fetchMeshSQL, bottleneck, date).Scan(&checksum, &data) switch { case err == sql.ErrNoRows: return nil, nil case err != nil: return nil, err } } else { // check if we are not outdated. err := conn.QueryRowContext( ctx, checkMeshSQL, bottleneck, date, entry.checksum).Scan(&data) switch { case err == sql.ErrNoRows: return nil, nil case err != nil: return nil, err } if data == nil { // we are still current entry.access = time.Now() return entry.tree, nil } } tree := new(STRTree) if err := tree.FromBytes(data); err != nil { return nil, err } now := time.Now() if entry != nil { entry.tree = tree entry.access = now return tree, nil } for len(c.entries) >= maxCacheEntries { // Evict the entry that is accessed the longest time ago. var oldestKey cacheKey oldest := now for k, v := range c.entries { if v.access.Before(oldest) { oldest = v.access oldestKey = k } } delete(c.entries, oldestKey) } c.entries[key] = &cacheEntry{ checksum: checksum, tree: tree, access: now, } return tree, nil }