Batch data writes.

This will be done as part of a system where the database file is
compressed and moved periodically.

main/datalog.go

@@ -27,14 +27,14 @@ const (
 )
 
 type StratuxTimestamp struct {
-	id                   int64
 	Time_type_preference int // 0 = stratuxClock, 1 = gpsClock, 2 = gpsClock extrapolated via stratuxClock.
 	StratuxClock_value   time.Time
 	GPSClock_value       time.Time
 	PreferredTime_value  time.Time
 }
 
-var dataLogTimestamp StratuxTimestamp // Current timestamp bucket.
+var dataLogTimestamps map[int64]StratuxTimestamp
+var dataLogCurTimestamp int64 // Current timestamp bucket. This is an index on dataLogTimestamps which is not necessarily the db id.
 
 /*
 	checkTimestamp().
@@ -42,15 +42,17 @@ var dataLogTimestamp StratuxTimestamp // Current timestamp bucket.
 		 Returns false if the timestamp was changed, true if it is still valid.
 */
 
-//FIXME: time -> stratuxClock
 func checkTimestamp() bool {
-	if stratuxClock.Since(dataLogTimestamp.StratuxClock_value) >= LOG_TIMESTAMP_RESOLUTION {
+	if stratuxClock.Since(dataLogTimestamps[dataLogCurTimestamp].StratuxClock_value) >= LOG_TIMESTAMP_RESOLUTION {
 		//FIXME: mutex.
-		dataLogTimestamp.id = 0
-		dataLogTimestamp.Time_type_preference = 0 // stratuxClock.
-		dataLogTimestamp.StratuxClock_value = stratuxClock.Time
-		dataLogTimestamp.GPSClock_value = time.Time{}
-		dataLogTimestamp.PreferredTime_value = stratuxClock.Time
+		var ts StratuxTimestamp
+		ts.id = 0
+		ts.Time_type_preference = 0 // stratuxClock.
+		ts.StratuxClock_value = stratuxClock.Time
+		ts.GPSClock_value = time.Time{}
+		ts.PreferredTime_value = stratuxClock.Time
+		dataLogCurTimestamp++
+		dataLogTimestamps[dataLogCurTimestamp] = ts
 
 		return false
 	}
@@ -182,7 +184,7 @@ func makeTable(i interface{}, tbl string, db *sql.DB) {
 	}
 }
 
-func insertData(i interface{}, tbl string, db *sql.DB) int64 {
+func insertData(i interface{}, tbl string, db *sql.DB, ts_num int64) int64 {
 	val := reflect.ValueOf(i)
 
 	keys := make([]string, 0)
@@ -205,7 +207,13 @@ func insertData(i interface{}, tbl string, db *sql.DB) int64 {
 	// Add the timestamp_id field to link up with the timestamp table.
 	if tbl != "timestamp" {
 		keys = append(keys, "timestamp_id")
-		values = append(values, strconv.FormatInt(dataLogTimestamp.id, 10))
+		if dataLogTimestamps[ts_num].id == 0 {
+			//FIXME: This is somewhat convoluted. When insertData() is called for a ts_num that corresponds to a timestamp with no database id,
+			// then it inserts that timestamp via the same interface and the id is updated in the structure via the below lines
+			// (dataLogTimestamps[ts_num].id = id).
+			insertData(dataLogTimestamps[ts_num], "timestamp", db, ts_num) // Updates dataLogTimestamps[ts_num].id.
+		}
+		values = append(values, strconv.FormatInt(dataLogTimestamps[ts_num].id, 10))
 	}
 
 	tblInsert := fmt.Sprintf("INSERT INTO %s (%s) VALUES(%s)", tbl, strings.Join(keys, ","),
@@ -222,7 +230,7 @@ func insertData(i interface{}, tbl string, db *sql.DB) int64 {
 	id, err := res.LastInsertId()
 	if err == nil {
 		if tbl == "timestamp" {
-			dataLogTimestamp.id = id
+			dataLogTimestamps[ts_num].id = id
 		}
 		return id
 	}
@@ -231,8 +239,9 @@ func insertData(i interface{}, tbl string, db *sql.DB) int64 {
 }
 
 type DataLogRow struct {
-	tbl  string
-	data interface{}
+	tbl    string
+	data   interface{}
+	ts_num int64
 }
 
 var dataLogChan chan DataLogRow
@@ -241,6 +250,7 @@ var shutdownDataLog chan bool
 func dataLogWriter() {
 	dataLogChan = make(chan DataLogRow, 10240)
 	shutdownDataLog = make(chan bool)
+	dataLogTimestamps = make(map[int64]StratuxTimestamp, 0)
 
 	// Check if we need to create a new database.
 	createDatabase := false
@@ -258,7 +268,7 @@ func dataLogWriter() {
 
 	// Do we need to create the database?
 	if createDatabase {
-		makeTable(dataLogTimestamp, "timestamp", db)
+		makeTable(StratuxTimestamp{}, "timestamp", db)
 		makeTable(mySituation, "mySituation", db)
 		makeTable(globalStatus, "status", db)
 		makeTable(globalSettings, "settings", db)
@@ -267,30 +277,50 @@ func dataLogWriter() {
 		makeTable(Dump1090TermMessage{}, "dump1090_terminal", db)
 	}
 
+	// The write queue. As data comes in via dataLogChan, it is timestamped and stored.
+	//  When writeTicker comes up, the queue is emptied.
+	rowsQueuedForWrite := make([]DataLogRow, 0)
+	writeTicker := time.NewTicker(5 * time.Second)
+
 	for {
 		select {
 		//FIXME: measure latency from here to end of block. Messages may need to be timestamped *before* executing everything here.
 		case r := <-dataLogChan:
 
 			// Check if our time bucket has expired or has never been entered.
-			if !checkTimestamp() || dataLogTimestamp.id == 0 {
-				insertData(dataLogTimestamp, "timestamp", db) // Updates dataLogTimestamp.id.
+			checkTimestamp()
+			// Mark the row with the current timestamp ID, in case it gets entered later.
+			r.ts_num = dataLogCurTimestamp
+			// Queue it for the scheduled write.
+			rowsQueuedForWrite = append(rowsQueuedForWrite, r)
+		case <-writeTicker.C:
+			for _, r := range rowsQueuedForWrite {
+				insertData(r.data, r.tbl, db, r.ts_num)
 			}
-			insertData(r.data, r.tbl, db)
+			rowsQueuedForWrite = make([]DataLogRow, 0) // Zero the queue.
 		case <-shutdownDataLog: // Received a message on the channel (anything). Graceful shutdown (defer statement).
 			return
 		}
 	}
 }
 
+/*
+	setDataLogTimeWithGPS().
+		Create a timestamp entry using GPS time.
+*/
+
 func setDataLogTimeWithGPS(sit SituationData) {
 	if isGPSClockValid() {
+		//FIXME: mutex.
+		var ts StratuxTimestamp
 		// Piggyback a GPS time update from this update.
-		dataLogTimestamp.id = 0
-		dataLogTimestamp.Time_type_preference = 1 // gpsClock.
-		dataLogTimestamp.StratuxClock_value = stratuxClock.Time
-		dataLogTimestamp.GPSClock_value = sit.GPSTime
-		dataLogTimestamp.PreferredTime_value = sit.GPSTime
+		ts.id = 0
+		ts.Time_type_preference = 1 // gpsClock.
+		ts.StratuxClock_value = stratuxClock.Time
+		ts.GPSClock_value = sit.GPSTime
+		ts.PreferredTime_value = sit.GPSTime
+		dataLogCurTimestamp++
+		dataLogTimestamps[dataLogCurTimestamp] = ts
 	}
 }