Mercurial > gemma
view pkg/models/reproject.go @ 5520:05db984d3db1
Improve performance of bottleneck area calculation
Avoid buffer calculations by replacing them with simple distance comparisons
and calculate the boundary of the result geometry only once per iteration.
In some edge cases with very large numbers of iterations, this reduced
the runtime of a bottleneck import by a factor of more than twenty.
author | Tom Gottfried <tom@intevation.de> |
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date | Thu, 21 Oct 2021 19:50:39 +0200 |
parents | d753ce6cf588 |
children | 1222b777f51f |
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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 models import ( "context" "database/sql" ) const reprojectSQL = ` SELECT ST_X(p), ST_Y(p) FROM ST_Transform(ST_SetSRID(ST_MakePoint($1, $2), $3::integer), $4::integer) AS p` type Reprojector struct { stmt *sql.Stmt FromEPSG uint32 ToEPSG uint32 } func NewReprojector( ctx context.Context, conn *sql.Conn, fromEPSG, toEPSG uint32, ) (*Reprojector, error) { stmt, err := conn.PrepareContext(ctx, reprojectSQL) if err != nil { return nil, err } return &Reprojector{ stmt: stmt, FromEPSG: fromEPSG, ToEPSG: toEPSG, }, nil } func (r *Reprojector) Close() error { if s := r.stmt; s != nil { r.stmt = nil return s.Close() } return nil } func (r *Reprojector) Reproject( ctx context.Context, x, y float64, ) (v, w float64, err error) { err = r.stmt.QueryRowContext(ctx, x, y, r.FromEPSG, r.ToEPSG).Scan(&v, &w) return }