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lazily connect to PostGIS #106

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merged 1 commit into from
Feb 21, 2022
Merged

lazily connect to PostGIS #106

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47 changes: 28 additions & 19 deletions emissions/aep/srgspec_osm.go
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ import (
"encoding/json"
"fmt"
"io"
"sync"

backoff "github.com/cenkalti/backoff/v4"
"github.com/ctessum/geom"
Expand Down Expand Up @@ -57,6 +58,8 @@ type SrgSpecOSM struct {
// in MergeNames.
MergeMultipliers []float64 `json:"merge_multipliers"`

connectPostGISOnce sync.Once
postGISURL string
conn *pgxpool.Pool
}

Expand All @@ -74,39 +77,43 @@ type SrgSpecOSM struct {
// and the PostGIS database should have the "hstore" extension installed before
// loading the data.
func ReadSrgSpecOSM(ctx context.Context, r io.Reader, postGISURL string) (*SrgSpecs, error) {
if postGISURL == "" {
return nil, fmt.Errorf("PostGIS URL is required")
}
// Connect to database.
var conn *pgxpool.Pool
var err error
err = backoff.Retry(func() error {
conn, err = pgxpool.Connect(ctx, postGISURL)
if err != nil {
return err
}
return nil
}, backoff.WithMaxRetries(backoff.NewExponentialBackOff(), 10))
if err != nil {
return nil, fmt.Errorf("Unable to connect to PostGIS database %s after 10 tries: %w\n", postGISURL, err)
}

// Read the surrogate specification.
d := json.NewDecoder(r)
var o []*SrgSpecOSM
if err = d.Decode(&o); err != nil {
if err := d.Decode(&o); err != nil {
return nil, err
}

// Add the db connection to each surrogate.
srgs := NewSrgSpecs()
for _, s := range o {
s.conn = conn
s.postGISURL = postGISURL
srgs.Add(s)
}
return srgs, nil
}

func (s *SrgSpecOSM) connectPostGIS() {
if s.postGISURL == "" {
panic(fmt.Errorf("PostGIS URL is required"))
}

// Connect to database.
var conn *pgxpool.Pool
var err error
err = backoff.Retry(func() error {
conn, err = pgxpool.Connect(context.Background(), s.postGISURL)
if err != nil {
return err
}
return nil
}, backoff.WithMaxRetries(backoff.NewExponentialBackOff(), 10))
if err != nil {
panic(fmt.Errorf("unable to connect to PostGIS database %s after 10 tries: %w", s.postGISURL, err))
}
s.conn = conn
}

func (srg *SrgSpecOSM) backupSurrogateNames() []string { return srg.BackupSurrogateNames }
func (srg *SrgSpecOSM) region() Country { return srg.Region }
func (srg *SrgSpecOSM) code() string { return srg.Code }
Expand Down Expand Up @@ -164,6 +171,8 @@ func (srg *SrgSpecOSM) getSrgData(gridData *GridDef, inputLoc *Location, tol flo
}
tagKeys = tagKeys[:len(tagKeys)-1] // Remove trailing comma.

srg.connectPostGISOnce.Do(srg.connectPostGIS)

rows, err := srg.conn.Query(ctx, `
SELECT
hstore_to_array(tags) tags, ST_AsBinary(way)
Expand Down