Mercurial > gemma
view pkg/mesh/cache.go @ 5718:3d497077f888 uploadwg
Implemented direct file upload as alternative import method for WG.
For testing and data corrections it is useful to be able to import
waterway gauges data directly by uploading a xml file.
author | Sascha Wilde <wilde@sha-bang.de> |
---|---|
date | Thu, 18 Apr 2024 19:23:19 +0200 |
parents | 03dfbe675842 |
children | 1ea1d3ef2258 |
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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 mesh 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, coalesce(mesh_index_version, 1) AS mesh_index_version FROM waterway.sounding_results WHERE id = $1 ` fetchMeshSQL = ` SELECT mesh_checksum, mesh_index, coalesce(mesh_index_version, 1) AS mesh_index_version 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, coalesce(mesh_index_version, 1) AS mesh_index_version 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 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) } // FetchMeshDirectly loads a mesh directly from the database. func FetchMeshDirectly( ctx context.Context, tx *sql.Tx, id int64, ) (*STRTree, error) { var data []byte var version int err := tx.QueryRowContext(ctx, directMeshSQL, id).Scan(&data, &version) if err != nil { return nil, err } tree := new(STRTree) if err := tree.FromBytes(data, version); 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() // Start background cleanup lazily. if c.entries == nil { c.entries = map[cacheKey]*cacheEntry{} go c.background() } key := cacheKey{date, bottleneck} entry := c.entries[key] var data []byte var checksum string var version int if entry == nil { // fetch from database err := conn.QueryRowContext( ctx, fetchMeshSQL, bottleneck, date).Scan(&checksum, &data, &version) 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, &version) 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, version); 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 }