Marco Cetica
e26f7ff164
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94 lines
2.0 KiB
Go
94 lines
2.0 KiB
Go
package cache
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import (
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"fmt"
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"strings"
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"sync"
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"time"
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"github.com/ceticamarco/zephyr/types"
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)
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// statistic cache data type, representing a mapping between a location+date and its daily average temperature
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type StatCache struct {
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mu sync.RWMutex
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db map[string]float64
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}
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func InitStatCache() *StatCache {
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return &StatCache{
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db: make(map[string]float64),
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}
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}
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func (cache *StatCache) AddStatistic(cityName string, statDate string, dailyTemp float64) {
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cache.mu.Lock()
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defer cache.mu.Unlock()
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// Format key as '<DATE>@<LOCATION>
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key := fmt.Sprintf("%s@%s", statDate, cityName)
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// Insert weather statistic into the database if it doesn't already exist
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if _, exists := cache.db[key]; exists {
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return
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}
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cache.db[key] = dailyTemp
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}
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func (cache *StatCache) IsKeyInvalid(key string) bool {
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cache.mu.RLock()
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defer cache.mu.RUnlock()
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// A key is invalid if it has less than 2 entries within the last 2 days
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threshold := time.Now().AddDate(0, 0, -2)
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var validEntries uint = 0
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for storedKey := range cache.db {
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if !strings.HasSuffix(storedKey, key) {
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continue
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}
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// Get <DATE> from <DATE>@<LOCATION>
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keyDate, err := time.Parse("2006-01-02", strings.Split(storedKey, "@")[0])
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if err != nil {
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keyDate = time.Now() // Add a fallback date if parsing fails
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}
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if !keyDate.Before(threshold) {
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validEntries++
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// Early skip if we already found two valid entries
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if validEntries >= 2 {
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return false
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}
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}
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}
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return true
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}
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func (cache *StatCache) GetCityStatistics(cityName string) []types.StatElement {
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cache.mu.RLock()
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defer cache.mu.RUnlock()
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result := make([]types.StatElement, 0)
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for key, record := range cache.db {
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if strings.HasSuffix(key, cityName) {
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// Get <DATE> from <DATE>@<LOCATION>
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keyDate, err := time.Parse("2006-01-02", strings.Split(key, "@")[0])
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if err != nil {
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keyDate = time.Now() // Add a fallback date if parsing fails
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}
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result = append(result, types.StatElement{
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Temperature: record,
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Date: keyDate,
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})
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}
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}
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return result
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}
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