feat(pgsql): implement application_name handling in connection

pkg/pgsql/connection.go

@@ -0,0 +1,85 @@
+package pgsql
+
+import (
+	"context"
+	"fmt"
+	"runtime/debug"
+	"strings"
+
+	"github.com/jackc/pgx/v5"
+)
+
+const (
+	defaultApplicationPrefix = "relspecgo"
+	postgresIdentifierMaxLen = 63
+)
+
+// BuildApplicationName returns a PostgreSQL application_name in the form:
+// relspecgo/<version>[:<component>]
+func BuildApplicationName(component string) string {
+	appName := fmt.Sprintf("%s/%s", defaultApplicationPrefix, relspecVersion())
+	component = strings.TrimSpace(component)
+	if component != "" {
+		appName = appName + ":" + component
+	}
+	if len(appName) > postgresIdentifierMaxLen {
+		appName = appName[:postgresIdentifierMaxLen]
+	}
+	return appName
+}
+
+// ParseConfigWithApplicationName parses a connection string and applies a default
+// application_name when one is not explicitly provided by the caller.
+func ParseConfigWithApplicationName(connString, component string) (*pgx.ConnConfig, error) {
+	cfg, err := pgx.ParseConfig(connString)
+	if err != nil {
+		return nil, err
+	}
+
+	if cfg.RuntimeParams == nil {
+		cfg.RuntimeParams = map[string]string{}
+	}
+
+	if strings.TrimSpace(cfg.RuntimeParams["application_name"]) == "" {
+		cfg.RuntimeParams["application_name"] = BuildApplicationName(component)
+	}
+
+	return cfg, nil
+}
+
+// Connect establishes a PostgreSQL connection with a default relspec
+// application_name when the caller does not provide one in the DSN.
+func Connect(ctx context.Context, connString, component string) (*pgx.Conn, error) {
+	cfg, err := ParseConfigWithApplicationName(connString, component)
+	if err != nil {
+		return nil, err
+	}
+
+	return pgx.ConnectConfig(ctx, cfg)
+}
+
+func relspecVersion() string {
+	info, ok := debug.ReadBuildInfo()
+	if !ok {
+		return "dev"
+	}
+
+	version := strings.TrimSpace(info.Main.Version)
+	if version != "" && version != "(devel)" {
+		return version
+	}
+
+	for _, setting := range info.Settings {
+		if setting.Key == "vcs.revision" {
+			revision := strings.TrimSpace(setting.Value)
+			if len(revision) >= 7 {
+				return revision[:7]
+			}
+			if revision != "" {
+				return revision
+			}
+		}
+	}
+
+	return "dev"
+}

pkg/readers/dbml/reader.go

@@ -664,7 +664,7 @@ func (r *Reader) parseColumn(line, tableName, schemaName string) (*models.Column
 	return column, constraint
 }
 
-func splitInlineComment(line string) (string, string) {
+func splitInlineComment(line string) (content string, inlineComment string) {
 	commentStart := strings.Index(line, "//")
 	if commentStart == -1 {
 		return line, ""
@@ -673,7 +673,7 @@ func splitInlineComment(line string) (string, string) {
 	return strings.TrimSpace(line[:commentStart]), strings.TrimSpace(line[commentStart+2:])
 }
 
-func splitColumnSignatureAndAttrs(line string) (string, string) {
+func splitColumnSignatureAndAttrs(line string) (signature string, attrs string) {
 	trimmed := strings.TrimSpace(line)
 	if trimmed == "" || !strings.HasSuffix(trimmed, "]") {
 		return trimmed, ""
@@ -699,7 +699,7 @@ func splitColumnSignatureAndAttrs(line string) (string, string) {
 	return trimmed, ""
 }
 
-func parseColumnSignature(signature string) (string, string, bool) {
+func parseColumnSignature(signature string) (columnName string, columnType string, ok bool) {
 	signature = strings.TrimSpace(signature)
 	if signature == "" {
 		return "", "", false
@@ -726,8 +726,8 @@ func parseColumnSignature(signature string) (string, string, bool) {
 		return "", "", false
 	}
 
-	columnName := stripQuotes(strings.TrimSpace(signature[:splitAt]))
-	columnType := stripWrappingQuotes(strings.TrimSpace(signature[splitAt:]))
+	columnName = stripQuotes(strings.TrimSpace(signature[:splitAt]))
+	columnType = stripWrappingQuotes(strings.TrimSpace(signature[splitAt:]))
 	if columnName == "" || columnType == "" {
 		return "", "", false
 	}

pkg/readers/pgsql/reader.go

@@ -5,11 +5,10 @@ import (
 	"fmt"
 	"strings"
 
-	"github.com/jackc/pgx/v5"
-
 	"git.warky.dev/wdevs/relspecgo/pkg/models"
 	"git.warky.dev/wdevs/relspecgo/pkg/pgsql"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers"
+	"github.com/jackc/pgx/v5"
 )
 
 // Reader implements the readers.Reader interface for PostgreSQL databases
@@ -244,7 +243,7 @@ func (r *Reader) ReadTable() (*models.Table, error) {
 
 // connect establishes a connection to the PostgreSQL database
 func (r *Reader) connect() error {
-	conn, err := pgx.Connect(r.ctx, r.options.ConnectionString)
+	conn, err := pgsql.Connect(r.ctx, r.options.ConnectionString, "reader-pgsql")
 	if err != nil {
 		return err
 	}

pkg/writers/pgsql/writer.go

@@ -10,8 +10,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/jackc/pgx/v5"
-
 	"git.warky.dev/wdevs/relspecgo/pkg/models"
 	"git.warky.dev/wdevs/relspecgo/pkg/pgsql"
 	"git.warky.dev/wdevs/relspecgo/pkg/writers"
@@ -1353,7 +1351,7 @@ func (w *Writer) executeDatabaseSQL(db *models.Database, connString string) erro
 
 	// Connect to database
 	ctx := context.Background()
-	conn, err := pgx.Connect(ctx, connString)
+	conn, err := pgsql.Connect(ctx, connString, "writer-pgsql")
 	if err != nil {
 		return fmt.Errorf("failed to connect to database: %w", err)
 	}