[SERVER] Reload server config on SIGHUP

Most config settings can now be changed at runtime
using SIGHUP. This currently excludes the basePath,
listenPort, and the client and image count limits,
as well as vmdkLegacyMode.

1 files changed, 75 insertions, 51 deletions

diff --git a/src/server/globals.c b/src/server/globals.c
index aca7551..ee4de19 100644
--- a/src/server/globals.c
+++ b/src/server/globals.c
@@ -9,29 +9,36 @@
 #include <errno.h>
 
 char *_configDir = NULL;
-volatile bool _shutdown = false;
+atomic_bool _shutdown = false;
 // [dnbd3]
-int _listenPort = PORT;
+atomic_int _listenPort = PORT;
 char *_basePath = NULL;
-int _serverPenalty = 0;
-int _clientPenalty = 0;
-bool _isProxy = false;
-int _backgroundReplication = BGR_FULL;
-int _bgrMinClients = 0;
-bool _lookupMissingForProxy = true;
-bool _sparseFiles = false;
-bool _removeMissingImages = true;
-int _uplinkTimeout = SOCKET_TIMEOUT_UPLINK;
-int _clientTimeout = SOCKET_TIMEOUT_CLIENT;
-bool _closeUnusedFd = false;
-bool _vmdkLegacyMode = false;
+atomic_int _serverPenalty = 0;
+atomic_int _clientPenalty = 0;
+atomic_bool _isProxy = false;
+atomic_int _backgroundReplication = BGR_FULL;
+atomic_int _bgrMinClients = 0;
+atomic_bool _lookupMissingForProxy = true;
+atomic_bool _sparseFiles = false;
+atomic_bool _removeMissingImages = true;
+atomic_int _uplinkTimeout = SOCKET_TIMEOUT_UPLINK;
+atomic_int _clientTimeout = SOCKET_TIMEOUT_CLIENT;
+atomic_bool _closeUnusedFd = false;
+atomic_bool _vmdkLegacyMode = false;
 // Not really needed anymore since we have '+' and '-' in alt-servers
-bool _proxyPrivateOnly = false;
+atomic_bool _proxyPrivateOnly = false;
 // [limits]
-int _maxClients = SERVER_MAX_CLIENTS;
-int _maxImages = SERVER_MAX_IMAGES;
-int _maxPayload = 9000000; // 9MB
-uint64_t _maxReplicationSize = (uint64_t)100000000000LL;
+atomic_int _maxClients = SERVER_MAX_CLIENTS;
+atomic_int _maxImages = SERVER_MAX_IMAGES;
+atomic_int _maxPayload = 9000000; // 9MB
+atomic_uint_fast64_t _maxReplicationSize = (uint64_t)100000000000LL;
+
+/**
+ * True when loading config the first time. Consecutive loads will
+ * ignore certain values which cannot be changed safely at runtime.
+ */
+static atomic_bool initialLoad = true;
+static pthread_mutex_t loadLock = PTHREAD_MUTEX_INITIALIZER;
 
 #define IS_TRUE(value) (atoi(value) != 0 || strcmp(value, "true") == 0 || strcmp(value, "True") == 0 || strcmp(value, "TRUE") == 0)
 #define SAVE_TO_VAR_STR(ss, kk) do { if (strcmp(section, #ss) == 0 && strcmp(key, #kk) == 0) { if (_ ## kk != NULL) free(_ ## kk); _ ## kk = strdup(value); } } while (0)
@@ -40,19 +47,26 @@ uint64_t _maxReplicationSize = (uint64_t)100000000000LL;
 #define SAVE_TO_VAR_UINT(ss, kk) do { if (strcmp(section, #ss) == 0 && strcmp(key, #kk) == 0) parse32u(value, &_ ## kk, #ss); } while (0)
 #define SAVE_TO_VAR_UINT64(ss, kk) do { if (strcmp(section, #ss) == 0 && strcmp(key, #kk) == 0) parse64u(value, &_ ## kk, #ss); } while (0)
 
+static void sanitizeFixedConfig();
+
 static void handleMaskString( const char *value, void(*func)(logmask_t) );
 
 static const char* units = "KMGTPEZY";
 
-static bool parse64(const char *in, int64_t *out, const char *optname);
-static bool parse64u(const char *in, uint64_t *out, const char *optname);
-static bool parse32(const char *in, int *out, const char *optname) UNUSED;
-static bool parse32u(const char *in, int *out, const char *optname);
+static bool parse64(const char *in, atomic_int_fast64_t *out, const char *optname);
+static bool parse64u(const char *in, atomic_uint_fast64_t *out, const char *optname);
+static bool parse32(const char *in, atomic_int *out, const char *optname) UNUSED;
+static bool parse32u(const char *in, atomic_int *out, const char *optname);
 
 static int ini_handler(void *custom UNUSED, const char* section, const char* key, const char* value)
 {
-	if ( _basePath == NULL ) SAVE_TO_VAR_STR( dnbd3, basePath );
-	SAVE_TO_VAR_BOOL( dnbd3, vmdkLegacyMode );
+	if ( initialLoad ) {
+		if ( _basePath == NULL ) SAVE_TO_VAR_STR( dnbd3, basePath );
+		SAVE_TO_VAR_BOOL( dnbd3, vmdkLegacyMode );
+		SAVE_TO_VAR_UINT( dnbd3, listenPort );
+		SAVE_TO_VAR_UINT( limits, maxClients );
+		SAVE_TO_VAR_UINT( limits, maxImages );
+	}
 	SAVE_TO_VAR_BOOL( dnbd3, isProxy );
 	SAVE_TO_VAR_BOOL( dnbd3, proxyPrivateOnly );
 	SAVE_TO_VAR_INT( dnbd3, bgrMinClients );
@@ -64,9 +78,6 @@ static int ini_handler(void *custom UNUSED, const char* section, const char* key
 	SAVE_TO_VAR_UINT( dnbd3, clientPenalty );
 	SAVE_TO_VAR_UINT( dnbd3, uplinkTimeout );
 	SAVE_TO_VAR_UINT( dnbd3, clientTimeout );
-	SAVE_TO_VAR_UINT( dnbd3, listenPort );
-	SAVE_TO_VAR_UINT( limits, maxClients );
-	SAVE_TO_VAR_UINT( limits, maxImages );
 	SAVE_TO_VAR_UINT( limits, maxPayload );
 	SAVE_TO_VAR_UINT64( limits, maxReplicationSize );
 	if ( strcmp( section, "dnbd3" ) == 0 && strcmp( key, "backgroundReplication" ) == 0 ) {
@@ -97,8 +108,29 @@ void globals_loadConfig()
 	char *name = NULL;
 	asprintf( &name, "%s/%s", _configDir, CONFIG_FILENAME );
 	if ( name == NULL ) return;
+	if ( pthread_mutex_trylock( &loadLock ) != 0 ) {
+		logadd( LOG_INFO, "Ignoring config reload request due to already running reload" );
+		return;
+	}
 	ini_parse( name, &ini_handler, NULL );
 	free( name );
+	if ( initialLoad ) {
+		sanitizeFixedConfig();
+	}
+	if ( _backgroundReplication == BGR_FULL && _sparseFiles && _bgrMinClients < 5 ) {
+		logadd( LOG_WARNING, "Ignoring 'sparseFiles=true' since backgroundReplication is set to true and bgrMinClients is too low" );
+		_sparseFiles = false;
+	}
+	// Dump config as interpreted
+	char buffer[2000];
+	globals_dumpConfig( buffer, sizeof(buffer) );
+	logadd( LOG_DEBUG1, "Effective configuration:\n%s", buffer );
+	initialLoad = false;
+	pthread_mutex_unlock( &loadLock );
+}
+
+static void sanitizeFixedConfig()
+{
 	// Validate settings after loading:
 	// base path for images valid?
 	if ( _basePath == NULL || _basePath[0] == '\0' ) {
@@ -160,14 +192,6 @@ void globals_loadConfig()
 			}
 		}
 	}
-	if ( _backgroundReplication == BGR_FULL && _sparseFiles && _bgrMinClients < 5 ) {
-		logadd( LOG_WARNING, "Ignoring 'sparseFiles=true' since backgroundReplication is set to true and bgrMinClients is too low" );
-		_sparseFiles = false;
-	}
-	// Dump config as interpreted
-	char buffer[2000];
-	globals_dumpConfig( buffer, sizeof(buffer) );
-	logadd( LOG_DEBUG1, "Effective configuration:\n%s", buffer );
 }
 
 #define SETLOGBIT(name) do { if ( strstr( value, #name ) != NULL ) mask |= LOG_ ## name; } while (0)
@@ -183,7 +207,7 @@ static void handleMaskString( const char *value, void(*func)(logmask_t) )
 	(*func)( mask );
 }
 
-static bool parse64(const char *in, int64_t *out, const char *optname)
+static bool parse64(const char *in, atomic_int_fast64_t *out, const char *optname)
 {
 	if ( *in == '\0' ) {
 		logadd( LOG_WARNING, "Ignoring empty numeric setting '%s'", optname );
@@ -212,43 +236,43 @@ static bool parse64(const char *in, int64_t *out, const char *optname)
 		}
 	}
 	while ( exp-- > 0 ) num *= base;
-	*out = (int64_t)num;
+	*out = (atomic_int_fast64_t)num;
 	return true;
 }
 
-static bool parse64u(const char *in, uint64_t *out, const char *optname)
+static bool parse64u(const char *in, atomic_uint_fast64_t *out, const char *optname)
 {
-	int64_t v;
+	atomic_int_fast64_t v;
 	if ( !parse64( in, &v, optname ) ) return false;
 	if ( v < 0 ) {
 		logadd( LOG_WARNING, "Ignoring value '%s' for '%s': Cannot be negative", in, optname );
 		return false;
 	}
-	*out = (uint64_t)v;
+	*out = (atomic_uint_fast64_t)v;
 	return true;
 }
 
-static bool parse32(const char *in, int *out, const char *optname)
+static bool parse32(const char *in, atomic_int *out, const char *optname)
 {
-	int64_t v;
+	atomic_int_fast64_t v;
 	if ( !parse64( in, &v, optname ) ) return false;
 	if ( v < INT_MIN || v > INT_MAX ) {
 		logadd( LOG_WARNING, "'%s' must be between %d and %d, but is '%s'", optname, (int)INT_MIN, (int)INT_MAX, in );
 		return false;
 	}
-	*out = (int)v;
+	*out = (atomic_int)v;
 	return true;
 }
 
-static bool parse32u(const char *in, int *out, const char *optname)
+static bool parse32u(const char *in, atomic_int *out, const char *optname)
 {
-	int64_t v;
+	atomic_int_fast64_t v;
 	if ( !parse64( in, &v, optname ) ) return false;
 	if ( v < 0 || v > INT_MAX ) {
 		logadd( LOG_WARNING, "'%s' must be between %d and %d, but is '%s'", optname, (int)0, (int)INT_MAX, in );
 		return false;
 	}
-	*out = (int)v;
+	*out = (atomic_int)v;
 	return true;
 }
 
@@ -258,10 +282,10 @@ static bool parse32u(const char *in, int *out, const char *optname)
 	rem -= r; \
 	buffer += r; \
 } while (0)
-#define PVAR(var,type) P_ARG(#var "=%" type "\n", _ ## var)
-#define PINT(var) PVAR(var, "d")
-#define PUINT64(var) PVAR(var, PRIu64)
-#define PSTR(var) PVAR(var, "s")
+#define PVAR(var,type,cast) P_ARG(#var "=%" type "\n", (cast) _ ## var)
+#define PINT(var) PVAR(var, "d", int)
+#define PUINT64(var) PVAR(var, PRIu64, uint64_t)
+#define PSTR(var) PVAR(var, "s", const char*)
 #define PBOOL(var) P_ARG(#var "=%s\n", _ ## var ? "true" : "false")
 
 size_t globals_dumpConfig(char *buffer, size_t size)