Add an option to set the priority of the dispatch queue

GCDWebServer/Core/GCDWebServer.h

@@ -176,6 +176,15 @@ extern NSString* const GCDWebServerOption_AutomaticallyMapHEADToGET;
  */
 extern NSString* const GCDWebServerOption_ConnectedStateCoalescingInterval;
 
+/**
+ *  Set the dispatch queue priority on which server connection will be 
+ *  run (NSNumber / long).
+ *
+ *
+ *  The default value is DISPATCH_QUEUE_PRIORITY_DEFAULT.
+ */
+extern NSString* const GCDWebServerOption_DispatchQueuePriority;
+
 #if TARGET_OS_IPHONE
 
 /**

GCDWebServer/Core/GCDWebServer.m

@@ -63,6 +63,7 @@ NSString* const GCDWebServerOption_AuthenticationAccounts = @"AuthenticationAcco
 NSString* const GCDWebServerOption_ConnectionClass = @"ConnectionClass";
 NSString* const GCDWebServerOption_AutomaticallyMapHEADToGET = @"AutomaticallyMapHEADToGET";
 NSString* const GCDWebServerOption_ConnectedStateCoalescingInterval = @"ConnectedStateCoalescingInterval";
+NSString* const GCDWebServerOption_DispatchQueuePriority = @"DispatchQueuePriority";
 #if TARGET_OS_IPHONE
 NSString* const GCDWebServerOption_AutomaticallySuspendInBackground = @"AutomaticallySuspendInBackground";
 #endif
@@ -170,6 +171,7 @@ static void _ExecuteMainThreadRunLoopSources() {
   Class _connectionClass;
   BOOL _mapHEADToGET;
   CFTimeInterval _disconnectDelay;
+  dispatch_queue_priority_t _dispatchQueuePriority;
   NSUInteger _port;
   dispatch_source_t _source4;
   dispatch_source_t _source6;
@@ -195,7 +197,7 @@ static void _ExecuteMainThreadRunLoopSources() {
 
 @synthesize delegate=_delegate, handlers=_handlers, port=_port, serverName=_serverName, authenticationRealm=_authenticationRealm,
             authenticationBasicAccounts=_authenticationBasicAccounts, authenticationDigestAccounts=_authenticationDigestAccounts,
-            shouldAutomaticallyMapHEADToGET=_mapHEADToGET;
+            shouldAutomaticallyMapHEADToGET=_mapHEADToGET, dispatchQueuePriority=_dispatchQueuePriority;
 
 + (void)initialize {
   GCDWebServerInitializeFunctions();
@@ -493,7 +495,7 @@ static inline NSString* _EncodeBase64(NSString* string) {
 
 - (dispatch_source_t)_createDispatchSourceWithListeningSocket:(int)listeningSocket isIPv6:(BOOL)isIPv6 {
   dispatch_group_enter(_sourceGroup);
-  dispatch_source_t source = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, listeningSocket, 0, kGCDWebServerGCDQueue);
+  dispatch_source_t source = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, listeningSocket, 0, dispatch_get_global_queue(_dispatchQueuePriority, 0));
   dispatch_source_set_cancel_handler(source, ^{
     
     @autoreleasepool {
@@ -599,6 +601,7 @@ static inline NSString* _EncodeBase64(NSString* string) {
   _connectionClass = _GetOption(_options, GCDWebServerOption_ConnectionClass, [GCDWebServerConnection class]);
   _mapHEADToGET = [_GetOption(_options, GCDWebServerOption_AutomaticallyMapHEADToGET, @YES) boolValue];
   _disconnectDelay = [_GetOption(_options, GCDWebServerOption_ConnectedStateCoalescingInterval, @1.0) doubleValue];
+  _dispatchQueuePriority = [_GetOption(_options, GCDWebServerOption_DispatchQueuePriority, @(DISPATCH_QUEUE_PRIORITY_DEFAULT)) longValue];
   
   _source4 = [self _createDispatchSourceWithListeningSocket:listeningSocket4 isIPv6:NO];
   _source6 = [self _createDispatchSourceWithListeningSocket:listeningSocket6 isIPv6:YES];

GCDWebServer/Core/GCDWebServerConnection.m

@@ -88,7 +88,7 @@ static int32_t _connectionCounter = 0;
 @implementation GCDWebServerConnection (Read)
 
 - (void)_readData:(NSMutableData*)data withLength:(NSUInteger)length completionBlock:(ReadDataCompletionBlock)block {
-  dispatch_read(_socket, length, kGCDWebServerGCDQueue, ^(dispatch_data_t buffer, int error) {
+  dispatch_read(_socket, length, dispatch_get_global_queue(_server.dispatchQueuePriority, 0), ^(dispatch_data_t buffer, int error) {
     
     @autoreleasepool {
       if (error == 0) {
@@ -247,10 +247,10 @@ static inline NSUInteger _ScanHexNumber(const void* bytes, NSUInteger size) {
 @implementation GCDWebServerConnection (Write)
 
 - (void)_writeData:(NSData*)data withCompletionBlock:(WriteDataCompletionBlock)block {
-  dispatch_data_t buffer = dispatch_data_create(data.bytes, data.length, kGCDWebServerGCDQueue, ^{
+  dispatch_data_t buffer = dispatch_data_create(data.bytes, data.length, dispatch_get_global_queue(_server.dispatchQueuePriority, 0), ^{
     [data self];  // Keeps ARC from releasing data too early
   });
-  dispatch_write(_socket, buffer, kGCDWebServerGCDQueue, ^(dispatch_data_t remainingData, int error) {
+  dispatch_write(_socket, buffer, dispatch_get_global_queue(_server.dispatchQueuePriority, 0), ^(dispatch_data_t remainingData, int error) {
     
     @autoreleasepool {
       if (error == 0) {

GCDWebServer/Core/GCDWebServerPrivate.h

@@ -168,7 +168,6 @@ extern void GCDWebServerLogMessage(GCDWebServerLoggingLevel level, NSString* for
  */
 
 #define kGCDWebServerDefaultMimeType @"application/octet-stream"
-#define kGCDWebServerGCDQueue dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
 #define kGCDWebServerErrorDomain @"GCDWebServerErrorDomain"
 
 static inline BOOL GCDWebServerIsValidByteRange(NSRange range) {
@@ -200,6 +199,7 @@ extern NSString* GCDWebServerStringFromSockAddr(const struct sockaddr* addr, BOO
 @property(nonatomic, readonly) NSDictionary* authenticationBasicAccounts;
 @property(nonatomic, readonly) NSDictionary* authenticationDigestAccounts;
 @property(nonatomic, readonly) BOOL shouldAutomaticallyMapHEADToGET;
+@property(nonatomic, readonly) dispatch_queue_priority_t dispatchQueuePriority;
 - (void)willStartConnection:(GCDWebServerConnection*)connection;
 - (void)didEndConnection:(GCDWebServerConnection*)connection;
 @end