Streaming data into the CIF Parse function reduces memory down to 4.1GB - also looking to stream the parsed data directly into the database if feasable.

cif/parse.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"errors"
+	"io"
 
 	"git.fjla.uk/owlboard/go-types/pkg/upstreamApi"
 	"git.fjla.uk/owlboard/timetable-mgr/log"
@@ -63,3 +64,56 @@ func parseCifData(data *[]byte) (*parsedData, error) {
 	log.Msg.Debug("CIF Parsing completed")
 	return &parsed, nil
 }
+
+func parseCifDataStream(dataStream io.ReadCloser) (*parsedData, error) {
+	log.Msg.Debug("STREAM-Starting CIF Datastream parsing")
+	if dataStream == nil {
+		return nil, errors.New("unable to parse nil pointer")
+	}
+
+	// Initialise data structures
+	var parsed parsedData
+	parsed.assoc = make([]upstreamApi.JsonAssociationV1, 0)
+	parsed.sched = make([]upstreamApi.JsonScheduleV1, 0)
+
+	// Create JSON Decoder
+	decoder := json.NewDecoder(dataStream)
+
+	// Iterate over JSON Objects using stream decoder
+	for decoder.More() {
+		var obj map[string]json.RawMessage
+		if err := decoder.Decode(&obj); err != nil {
+			log.Msg.Error("Error decoding JSON String")
+			return nil, err
+		}
+
+		// Handle parsed data
+		for key, value := range obj {
+			switch key {
+			case "JsonTimetableV1":
+				var timetable upstreamApi.JsonTimetableV1
+				if err := json.Unmarshal(value, &timetable); err != nil {
+					log.Msg.Error("Error decoding JSONTimetableV1 object", zap.Error(err))
+					continue
+				}
+				parsed.header = timetable
+			case "JsonAssociationV1":
+				var association upstreamApi.JsonAssociationV1
+				if err := json.Unmarshal(value, &association); err != nil {
+					log.Msg.Error("Error decoding JSONAssociationV1 object", zap.Error(err))
+					continue
+				}
+				parsed.assoc = append(parsed.assoc, association)
+			case "JsonScheduleV1":
+				var schedule upstreamApi.JsonScheduleV1
+				if err := json.Unmarshal(value, &schedule); err != nil {
+					log.Msg.Error("Error decoding JSONScheduleV1 object", zap.Error(err))
+					continue
+				}
+				parsed.sched = append(parsed.sched, schedule)
+			}
+		}
+	}
+	log.Msg.Debug("CIF Parsing completed")
+	return &parsed, nil
+}

cif/update.go

@@ -20,25 +20,25 @@ func runCifFullDownload(cfg *helpers.Configuration) error {
 	if err != nil {
 		log.Msg.Error("Error getting download URL", zap.Error(err))
 	}
-	data, err := nrod.NrodDownload(url, cfg)
+	dataStream, err := nrod.NrodStream(url, cfg)
 	if err != nil {
 		log.Msg.Error("Error downloading CIF data", zap.Error(err))
 	}
 
 	// If debug mode is on, call debugWriteDownload
-	if helpers.Runtime == "debug" {
-		debugWriteDownload(data)
-	}
+	//	if helpers.Runtime == "debug" {
+	//		debugWriteDownload(dataStream)
+	//	}
 
 	// Parse CIF file
-	parsed, err := parseCifData(data)
+	parsed, err := parseCifDataStream(dataStream)
 	if err != nil {
 		log.Msg.Error("Error parsing CIF data", zap.Error(err))
 		return err
 	}
 
 	// Make `data` a nil pointer as it is no longer required
-	data = nil
+	dataStream = nil
 
 	// Drop timetable collection
 	dbAccess.DropCollection(dbAccess.TimetableCollection) // I should edit this to prevent removal of VSTP entries in the database.

nrod/download.go

@@ -39,7 +39,7 @@ func NrodDownload(url string, cfg *helpers.Configuration) (*[]byte, error) {
 	}
 
 	// Yes, I know `readedData` is not proper English.  But readData reads more like a verb action.
-	readedData, err := nrodExtract(*resp)
+	readedData, err := nrodExtract(resp)
 	if err != nil {
 		log.Msg.Error("Unable to read response data")
 		return nil, err
@@ -49,7 +49,7 @@ func NrodDownload(url string, cfg *helpers.Configuration) (*[]byte, error) {
 }
 
 // Extracts GZIP Data from an HTTP Response and returns the decompresses data as a byte array
-func nrodExtract(resp http.Response) (*[]byte, error) {
+func nrodExtract(resp *http.Response) (*[]byte, error) {
 	log.Msg.Debug("Extracting HTTP Response Data")
 	gzReader, err := gzip.NewReader(resp.Body)
 	if err != nil {

nrod/streams.go

@@ -0,0 +1,60 @@
+package nrod
+
+import (
+	"compress/gzip"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"git.fjla.uk/owlboard/timetable-mgr/helpers"
+	"git.fjla.uk/owlboard/timetable-mgr/log"
+	"go.uber.org/zap"
+)
+
+// Downloads NROD Data and extracts if GZIP, returns a io.Reader
+func NrodStream(url string, cfg *helpers.Configuration) (io.ReadCloser, error) {
+	log.Msg.Debug("Fetching NROD data stream", zap.String("Request URL", url))
+
+	client := http.Client{
+		Timeout: time.Second * 300,
+	}
+
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		log.Msg.Error("Error creating HTTP Request", zap.Error(err))
+		return nil, err
+	}
+
+	req.Header.Add("Authorization", "Basic "+helpers.BasicAuth(cfg.NrodUser, cfg.NrodPass))
+
+	resp, err := client.Do(req)
+	if err != nil {
+		log.Msg.Error("Error carrying out HTTP Request", zap.Error(err), zap.Int("STATUS", resp.StatusCode))
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		err := fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+		log.Msg.Error("Non-successful status code", zap.Error(err))
+		return nil, err
+	}
+
+	// Run the data through the extractor function and return io.ReadCloser, error from
+	// directly
+	return NrodStreamExtract(resp)
+}
+
+func NrodStreamExtract(resp *http.Response) (io.ReadCloser, error) {
+	log.Msg.Debug("Extracting NROD Download")
+
+	log.Msg.Debug("Content Type", zap.String("Content-Encoding", resp.Header.Get("Content-Encoding")))
+
+	gzReader, err := gzip.NewReader(resp.Body)
+	if err != nil {
+		log.Msg.Warn("Unable to create GZIP Reader, data probably not gzipped")
+		return resp.Body, err
+	}
+
+	return gzReader, nil
+}