refactor: replace Exec with Consume method in MssqlTransformer; enhance retry handling and streamline transformation logic

internal/app/etl/transformers/mssql.go

@@ -1,20 +1,9 @@
 package transformers
 
 import (
-	"context"
-	"errors"
-	"fmt"
-	"strings"
-	"sync"
-	"time"
-
 	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/azure"
 	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
-	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
 	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
-	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
-	"github.com/google/uuid"
-	log "github.com/sirupsen/logrus"
 )
 
 type MssqlTransformer struct {
@@ -30,196 +19,3 @@ func NewMssqlTransformer(toStorage config.ToStorageConfig, sourceTable config.So
 		azureClient: azureClient,
 	}
 }
-
-func computeTransformationPlan(columns []models.ColumnType) []etl.ColumnTransformPlan {
-	var plan []etl.ColumnTransformPlan
-
-	for i, col := range columns {
-		switch col.SystemType() {
-		case "uniqueidentifier":
-			plan = append(plan, etl.ColumnTransformPlan{
-				Index: i,
-				Fn: func(v any) (any, error) {
-					if b, ok := v.([]byte); ok && b != nil {
-						return mssqlUuidToBigEndian(b)
-					}
-					return v, nil
-				},
-			})
-
-		case "geometry", "geography":
-			plan = append(plan, etl.ColumnTransformPlan{
-				Index: i,
-				Fn: func(v any) (any, error) {
-					if b, ok := v.([]byte); ok && b != nil {
-						return wkbToEwkbWithSrid(b, 4326)
-					}
-					return v, nil
-				},
-			})
-
-		case "datetime", "datetime2":
-			plan = append(plan, etl.ColumnTransformPlan{
-				Index: i,
-				Fn: func(v any) (any, error) {
-					if t, ok := v.(time.Time); ok {
-						return ensureUTC(t), nil
-					}
-					return v, nil
-				},
-			})
-		}
-	}
-
-	return plan
-}
-
-func computeStorageTransformationPlan(
-	ctx context.Context,
-	azureClient *azure.Client,
-	toStorage config.ToStorageConfig,
-	sourceColumns []models.ColumnType,
-	sourceTable config.SourceTableInfo,
-) []etl.ColumnTransformPlan {
-	if azureClient == nil || len(toStorage.Columns) == 0 {
-		return nil
-	}
-
-	colIndex := make(map[string]int, len(sourceColumns))
-	for i, col := range sourceColumns {
-		colIndex[strings.ToUpper(col.Name())] = i
-	}
-
-	var plan []etl.ColumnTransformPlan
-	for _, storageCol := range toStorage.Columns {
-		if storageCol.Mode != "REFERENCE_ONLY" {
-			log.Warnf("to_storage: unsupported mode %q for column %s — skipping", storageCol.Mode, storageCol.Source)
-			continue
-		}
-
-		idx, ok := colIndex[strings.ToUpper(storageCol.Source)]
-		if !ok {
-			log.Warnf("to_storage: source column %q not found in source schema — skipping", storageCol.Source)
-			continue
-		}
-
-		sourceColName := storageCol.Source
-		schema := sourceTable.Schema
-		table := sourceTable.Table
-
-		plan = append(plan, etl.ColumnTransformPlan{
-			Index: idx,
-			Fn: func(v any) (any, error) {
-				if v == nil {
-					return nil, nil
-				}
-				b, ok := v.([]byte)
-				if !ok {
-					log.Warnf("to_storage: expected []byte for %s.%s.%s, got %T — passing through",
-						schema, table, sourceColName, v)
-					return v, nil
-				}
-				start := time.Now()
-				blobPath := fmt.Sprintf("%s/%s/%s", schema, table, uuid.New().String())
-				blobURL, err := azureClient.UploadAndGetURL(ctx, blobPath, b)
-				if err != nil {
-					return nil, fmt.Errorf("uploading %s.%s.%s: %w", schema, table, sourceColName, err)
-				}
-				log.Debugf(`Succesfully uploaded "%s", (%vms)`, blobURL, time.Since(start).Milliseconds())
-				return blobURL, nil
-			},
-		})
-	}
-	return plan
-}
-
-const processBatchCtxCheck = 4096
-
-func (mssqlTr *MssqlTransformer) ProcessBatch(
-	ctx context.Context,
-	batch *models.Batch,
-	transformationPlan []etl.ColumnTransformPlan,
-) error {
-	for i, rowValues := range batch.Rows {
-		if i%processBatchCtxCheck == 0 {
-			if err := ctx.Err(); err != nil {
-				return err
-			}
-		}
-
-		for _, task := range transformationPlan {
-			val := rowValues[task.Index]
-			if val == nil {
-				continue
-			}
-
-			transformed, err := task.Fn(val)
-			if err != nil {
-				return err
-			}
-			rowValues[task.Index] = transformed
-		}
-	}
-
-	return nil
-}
-
-func (mssqlTr *MssqlTransformer) Exec(
-	ctx context.Context,
-	columns []models.ColumnType,
-	chBatchesIn <-chan models.Batch,
-	chBatchesOut chan<- models.Batch,
-	chJobErrorsOut chan<- custom_errors.JobError,
-	wgActiveBatches *sync.WaitGroup,
-) {
-	transformationPlan := computeTransformationPlan(columns)
-	storagePlan := computeStorageTransformationPlan(ctx, mssqlTr.azureClient, mssqlTr.toStorage, columns, mssqlTr.sourceTable)
-	transformationPlan = append(transformationPlan, storagePlan...)
-
-	for {
-		if ctx.Err() != nil {
-			return
-		}
-
-		select {
-		case <-ctx.Done():
-			return
-
-		case batch, ok := <-chBatchesIn:
-			if !ok {
-				return
-			}
-
-			if len(transformationPlan) == 0 {
-				select {
-				case chBatchesOut <- batch:
-					wgActiveBatches.Add(1)
-					continue
-				case <-ctx.Done():
-					return
-				}
-			}
-
-			err := mssqlTr.ProcessBatch(ctx, &batch, transformationPlan)
-			if err != nil {
-				if errors.Is(err, ctx.Err()) {
-					return
-				}
-
-				select {
-				case chJobErrorsOut <- custom_errors.JobError{ShouldCancelJob: true, Msg: "Transformation failed", Prev: err}:
-				case <-ctx.Done():
-				}
-				return
-			}
-
-			select {
-			case chBatchesOut <- batch:
-			case <-ctx.Done():
-				return
-			}
-
-			wgActiveBatches.Add(1)
-		}
-	}
-}