From 94e4cd964d21a4eda57dc0b651a361e44b67c5f9 Mon Sep 17 00:00:00 2001
From: Fred Boniface <fred@fjla.uk>
Date: Tue, 9 Apr 2024 21:26:56 +0100
Subject: [PATCH] Improve CIF Parsing to acheive 60% memory reduction

---
 cif/parse.go   | 35 +++++++++++++++--------------------
 cif/process.go |  1 +
 cif/update.go  |  2 ++
 3 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/cif/parse.go b/cif/parse.go
index 9b5579c..d339522 100644
--- a/cif/parse.go
+++ b/cif/parse.go
@@ -11,60 +11,55 @@ import (
 )
 
 // Unmarshalls data into the correct types for processing
-// This function suffers from extremely high memory usage
 func parseCifData(data *[]byte) (*parsedData, error) {
+	log.Msg.Debug("Starting CIF Data parsing")
 	if data == nil {
-		err := errors.New("unable to parse nil pointer")
-		return nil, err
+		return nil, errors.New("unable to parse nil pointer")
 	}
-	// Split the data into lines
-	lines := bytes.Split(*data, []byte("\n"))
 
-	// Initialise variable for the parsed data
+	// Initialise data structures
 	var parsed parsedData
 	parsed.assoc = make([]upstreamApi.JsonAssociationV1, 0)
 	parsed.sched = make([]upstreamApi.JsonScheduleV1, 0)
 
-	for _, line := range lines {
+	// Create JSON Decoder
+	decoder := json.NewDecoder(bytes.NewReader(*data))
 
-		// Skip empty lines to avoid logging errors when there is no error
-		if len(bytes.TrimSpace(line)) == 0 {
-			continue
-		}
-
-		// Map each line for processing
+	// Iterate over JSON Objects using stream decoder
+	for decoder.More() {
 		var obj map[string]json.RawMessage
-		if err := json.Unmarshal(line, &obj); err != nil {
-			log.Msg.Error("Error decoding line", zap.String("line", string(line)), zap.Error(err))
-			continue
+		if err := decoder.Decode(&obj); err != nil {
+			log.Msg.Error("Error decoding JSON String")
+			return nil, err
 		}
 
-		// Loop through the mapped data and unmarshal to the correct type
+		// 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("Unable to parse JSON Timetable", zap.Error(err), zap.String("line", string(value)))
+					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 JSON Association", zap.Error(err))
+					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 JSON Schedule", zap.Error(err))
+					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
 }
diff --git a/cif/process.go b/cif/process.go
index d644fad..3d73208 100644
--- a/cif/process.go
+++ b/cif/process.go
@@ -12,6 +12,7 @@ import (
 
 // Processes parsed CIF data and applies the data to the database
 func processParsedCif(data *parsedData) error {
+	log.Msg.Debug("Starting CIF Processing")
 	createTasks := make([]*upstreamApi.JsonScheduleV1, 0)
 	deleteTasks := make([]*upstreamApi.JsonScheduleV1, 0)
 
diff --git a/cif/update.go b/cif/update.go
index bbdac84..9ffb947 100644
--- a/cif/update.go
+++ b/cif/update.go
@@ -98,6 +98,7 @@ func runCifUpdateDownload(cfg *helpers.Configuration, metadata *dbAccess.CifMeta
 			debugWriteFile(&parsed.header, &parsed.sched)
 		}
 
+		log.Msg.Debug("Starting metadata checks")
 		// Check CIF Sequence
 		// Skip if LastSequence is >= to this sequence
 		if metadata.LastSequence >= parsed.header.Metadata.Sequence {
@@ -111,6 +112,7 @@ func runCifUpdateDownload(cfg *helpers.Configuration, metadata *dbAccess.CifMeta
 			log.Msg.Error("CIF sequence not as expected", zap.Error(err), zap.Int64("LastSequence", metadata.LastSequence), zap.Int64("New Sequence", parsed.header.Metadata.Sequence))
 			return err
 		}
+		log.Msg.Debug("Metadata checks complete")
 
 		// Do further sequence checks - parsed.header.Metadata.Sequence MUST = metadata.LastSequence + 1