Wire cache backend

4 files changed, 32 insertions, 4 deletions

diff --git a/cmd/zdns/main.go b/cmd/zdns/main.go
index e1c7243..0fc935d 100644
--- a/cmd/zdns/main.go
+++ b/cmd/zdns/main.go
@@ -81,7 +81,10 @@ func newCli(out io.Writer, args []string, configFile string, sig chan os.Signal)
 	sigHandler := signal.NewHandler(sig, logger)
 
 	// SQL backends
-	var sqlLogger *sql.Logger
+	var (
+		sqlLogger *sql.Logger
+		sqlCache  *sql.Cache
+	)
 	if config.DNS.Database != "" {
 		sqlClient, err := sql.New(config.DNS.Database)
 		fatal(err)
@@ -89,20 +92,30 @@ func newCli(out io.Writer, args []string, configFile string, sig chan os.Signal)
 		// Logger
 		sqlLogger = sql.NewLogger(sqlClient, config.DNS.LogMode, config.DNS.LogTTL)
 		sigHandler.OnClose(sqlLogger)
+
+		// Cache
+		sqlCache = sql.NewCache(sqlClient, logger)
+		sigHandler.OnClose(sqlCache)
 	}
 
 	// DNS client
 	dnsClient := dnsutil.NewClient(config.Resolver.Protocol, config.Resolver.Timeout, config.DNS.Resolvers...)
 
 	// Cache
+	var dnsCache *cache.Cache
 	var cacheDNS *dnsutil.Client
 	if config.DNS.CachePrefetch {
 		cacheDNS = dnsClient
 	}
-	cache := cache.New(config.DNS.CacheSize, cacheDNS)
+	if sqlCache != nil && config.DNS.CachePersist {
+		dnsCache = cache.NewWithBackend(config.DNS.CacheSize, cacheDNS, sqlCache)
+
+	} else {
+		dnsCache = cache.New(config.DNS.CacheSize, cacheDNS)
+	}
 
 	// DNS server
-	proxy, err := dns.NewProxy(cache, dnsClient, logger, sqlLogger)
+	proxy, err := dns.NewProxy(dnsCache, dnsClient, logger, sqlLogger)
 	fatal(err)
 	sigHandler.OnClose(proxy)
 
@@ -114,7 +127,7 @@ func newCli(out io.Writer, args []string, configFile string, sig chan os.Signal)
 
 	// HTTP server
 	if config.DNS.ListenHTTP != "" {
-		httpSrv := http.NewServer(cache, sqlLogger, logger, config.DNS.ListenHTTP)
+		httpSrv := http.NewServer(dnsCache, sqlLogger, logger, config.DNS.ListenHTTP)
 		sigHandler.OnClose(httpSrv)
 		servers = append(servers, httpSrv)
 	}
diff --git a/config.go b/config.go
index 8f78b17..2bee622 100644
--- a/config.go
+++ b/config.go
@@ -26,6 +26,7 @@ type DNSOptions struct {
 	Protocol        string `toml:"protocol"`
 	CacheSize       int    `toml:"cache_size"`
 	CachePrefetch   bool   `toml:"cache_prefetch"`
+	CachePersist    bool   `toml:"cache_persist"`
 	HijackMode      string `toml:"hijack_mode"`
 	hijackMode      int
 	RefreshInterval string `toml:"hosts_refresh_interval"`
@@ -88,6 +89,9 @@ func (c *Config) load() error {
 	if c.DNS.CacheSize < 0 {
 		return fmt.Errorf("cache size must be >= 0")
 	}
+	if c.DNS.CachePersist && c.DNS.Database == "" {
+		return fmt.Errorf("cache_persist = %t requires 'database' to be set", c.DNS.CachePersist)
+	}
 	switch c.DNS.HijackMode {
 	case "", "zero":
 		c.DNS.hijackMode = HijackZero
diff --git a/config_test.go b/config_test.go
index 8d04e00..f18873b 100644
--- a/config_test.go
+++ b/config_test.go
@@ -169,6 +169,9 @@ resolvers = ["http://example.com"]
 [resolver]
 protocol = "https"
 `
+	conf15 := baseConf + `
+cache_persist = true
+`
 	var tests = []struct {
 		in  string
 		err string
@@ -189,6 +192,7 @@ protocol = "https"
 		{conf12, "invalid log mode: foo"},
 		{conf13, `log_mode = "hijacked" requires 'database' to be set`},
 		{conf14, "protocol https requires https scheme for resolver http://example.com"},
+		{conf15, "cache_persist = true requires 'database' to be set"},
 	}
 	for i, tt := range tests {
 		var got string
diff --git a/zdnsrc b/zdnsrc
index b3cdde3..95e9906 100644
--- a/zdnsrc
+++ b/zdnsrc
@@ -22,6 +22,13 @@
 #
 # cache_prefetch = false
 
+# Cache persistence.
+#
+# If enabled, cache contents is periodically written to disk. The persisted
+# content will then be used to pre-populate the cache on startup.
+#
+# cache_persist = false
+
 # Upstream DNS servers to use when answering queries.
 #
 # The default is Cloudflare DNS servers, which support DNS-over-TLS.