Mercurial > gemma
view pkg/octree/cache.go @ 2549:9bf6b767a56a
client: refactored and improved splitscreen for diagrams
To make different diagrams possible, the splitscreen view needed to be decoupled from the cross profiles.
Also the style has changed to make it more consistent with the rest of the app. The standard box header
is now used and there are collapse and expand animations.
author | Markus Kottlaender <markus@intevation.de> |
---|---|
date | Fri, 08 Mar 2019 08:50:47 +0100 |
parents | 86c7a023400e |
children | 49564382ffff |
line wrap: on
line source
// 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 *Tree 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 ( fetchOctreeSQL = ` SELECT octree_checksum, octree_index FROM waterway.sounding_results WHERE bottleneck_id = $1 AND date_info = $2::date AND octree_checksum IS NOT NULL AND octree_index IS NOT NULL ` checkOctreeSQL = ` SELECT CASE WHEN octree_checksum = $3 THEN NULL ELSE octree_index END FROM waterway.sounding_results WHERE bottleneck_id = $1 AND date_info = $2::date AND octree_checksum IS NOT NULL AND octree_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, ) (*Tree, error) { return cache.get(ctx, conn, bottleneck, date) } func (c *Cache) get( ctx context.Context, conn *sql.Conn, bottleneck string, date time.Time, ) (*Tree, 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, fetchOctreeSQL, 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, checkOctreeSQL, 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, err := Deserialize(data) if 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 }