Print logs

08-problem-print-logs/main.go

@@ -0,0 +1,182 @@
+package main
+
+import (
+ "fmt"
+ "regexp"
+ "sort"
+ "strconv"
+ "strings"
+ "sync"
+)
+
+// Log entry
+type log struct {
+ method string
+ status string
+ endpoint string
+ hit_count int32
+}
+
+// Map of log entries
+var logs map[string]*log
+
+// Slice of sorted (by hits count) logs map keys in descending order
+var sortedLogKeys []string
+
+// List of active users
+var activeUsers map[int]bool
+
+// Get log entries
+// Split logs by new line character (\n), write
+// individual log strings to output channel
+// and return output channel
+func getLogEntries(logs string) <-chan string {
+ out := make(chan string)
+
+ // Write individual log entries to output channel
+ go func(out chan<- string) {
+ defer close(out)
+ logsSlice := strings.Split(logs, "\n") // Split logs by newline character (\n)
+
+ for _, log := range logsSlice {
+ out <- log // Write to output channel
+ }
+ }(out)
+
+ return out
+}
+
+// Replace numeric userId in URI with a character
+func replaceUserIdsWithChar(endpoint string, replaceWith string) string {
+ // numRegex := regexp.MustCompile(`\d`)
+ numRegex := regexp.MustCompile(`[0-9]+`)
+ return numRegex.ReplaceAllString(endpoint, replaceWith)
+}
+
+// Build key from "method", "endpoint" and "status_code"
+func getLogKey(logFields []string) string {
+ endpoint := replaceUserIdsWithChar(logFields[2], "#")
+ key := logFields[1] + endpoint + logFields[3]
+ return strings.ToLower(key)
+}
+
+// Extract userId from endpoint URI
+func getUserId(endpoint string) int {
+ fields := strings.Split(strings.ToLower(endpoint), "/")
+
+ if len(fields) > 2 && strings.Contains(fields[1], "user") {
+ uid, err := strconv.Atoi(fields[2])
+ if err != nil {
+ fmt.Println(err)
+ return 0
+ }
+ return uid
+ }
+ return 0
+}
+
+// Process independent log entries and build logs map
+func processLogs(in <-chan string) {
+ var wg sync.WaitGroup
+ var mu sync.Mutex
+ logs = make(map[string]*log)
+ activeUsers = make(map[int]bool)
+
+ for logEntry := range in {
+ logFields := strings.Split(logEntry, " ")
+ if len(logFields) >= 4 {
+ wg.Add(1)
+
+ go func() {
+ defer wg.Done()
+ defer mu.Unlock()
+ mu.Lock()
+
+ userId := getUserId(logFields[2])
+ if userId > 0 {
+ activeUsers[userId] = true
+ }
+
+ key := getLogKey(logFields)
+ if _, ok := logs[key]; ok {
+ logs[key].hit_count++
+ return
+ } else {
+ logs[key] = &log{
+ method: logFields[1],
+ status: logFields[3],
+ endpoint: replaceUserIdsWithChar(logFields[2], "#"),
+ hit_count: 1,
+ }
+ }
+ }()
+ }
+ }
+
+ wg.Wait()
+}
+
+// Sort logs by hits count
+func sortLogsByHits() {
+ for key := range logs {
+ sortedLogKeys = append(sortedLogKeys, key)
+ }
+ sort.Slice(sortedLogKeys, func(i, j int) bool {
+ return logs[sortedLogKeys[i]].hit_count > logs[sortedLogKeys[j]].hit_count
+ })
+}
+
+// Print output
+func printOutput() {
+ fmt.Printf("%-10s %-20s %-10s %-10s\n", "Method", "Endpoint", "Status", "Hits")
+ fmt.Println("+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+")
+ // for _, log := range logs {
+ // fmt.Printf("%-10s %-20s %-10s %-10d\n", log.method, log.endpoint, log.status, log.hit_count)
+ // }
+ for _, logKey := range sortedLogKeys {
+ fmt.Printf("%-10s %-20s %-10s %-10d\n", logs[logKey].method, logs[logKey].endpoint, logs[logKey].status, logs[logKey].hit_count)
+ }
+ fmt.Println("+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+")
+
+ actUsers := "Active Users: "
+ for uid := range activeUsers {
+ actUsers += fmt.Sprintf("%d, ", uid)
+ }
+ fmt.Println(actUsers[:len(actUsers)-2])
+}
+
+func main() {
+ logs := "[01-02-2021:08:22:32] GET /users/12 200\n" +
+ "[01-03-2021:08:22:32] GET /users/12 200\n" +
+ "[01-03-2021:09:22:32] GET /users/13 200\n" +
+ "[22-03-2021:01:22:32] POST /users/15 200\n" +
+ "[22-03-2021:01:22:32] GET /users/55/friends 200\n" +
+ "[22-03-2021:01:22:32] DELETE /users/64 200\n" +
+ "[10-03-2021:01:22:32] GET /cart 200\n" +
+ "-------SERVER DOWN-------\n" +
+ "[02-03-2021:01:22:32] GET /cart 200\n" +
+ "[11-03-2021:01:22:32] POST /users/16 200\n" +
+ "[01-03-2021:01:22:32] POST /users 201\n" +
+ "[02-03-2021:01:22:32] GET /orders 200\n" +
+ "[20-03-2021:01:22:32] POST /logout 200\n"
+
+ processLogs(getLogEntries(logs))
+ sortLogsByHits()
+ printOutput()
+}
+
+// Output:
+/*
+Method Endpoint Status Hits
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+GET /users/# 200 3
+POST /users/# 200 2
+GET /cart 200 2
+GET /orders 200 1
+POST /users 201 1
+DELETE /users/# 200 1
+POST /logout 200 1
+GET /users/#/friends 200 1
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+Active Users: 64, 12, 15, 55, 13, 16
+*/