Merge branch 'develop' into MXS-1209

Documentation/Getting-Started/Configuration-Guide.md

@@ -970,6 +970,24 @@ closed.
 For more information about persistent connections, please read the
 [Administration Tutorial](../Tutorials/Administration-Tutorial.md).
 
+#### `use_proxy_protocol`
+
+If `use_proxy_protocol` is set to `yes`, MaxScale will send a proxy protocol
+header when connecting client sessions to the server. The header contains the
+original client IP address and port, as seen by MaxScale. The server will then
+read the header and perform authentication as if the connection originated from
+this address instead of the MaxScale IP address. With this feature, the user
+accounts on the backend server can be simplified to only contain the actual
+client hosts and not the MaxScale host.
+
+Currently, using this feature is unpractical due to the restrictiveness of the
+proxy protocol. The protocol requires that *all* connections from proxy enabled
+addresses must send a valid proxy header. MaxScale has other connections to the
+servers in addition to client sessions, e.g. monitors, and the server will
+refuse these due to the lack of the header. To bypass this restriction, the
+server monitor needs to be disabled and the service listener needs to be
+configured to disregard authentication errors (`skip_authentication=true`).
+
 ### Server and SSL
 
 This section describes configuration parameters for servers that control the

include/maxscale/atomic.h

@@ -20,6 +20,17 @@
 
 MXS_BEGIN_DECLS
 
+/**
+ * Pre 4.7 GCC doesn't support the __atomic builtin functions. The older __sync
+ * builtins don't have proper store/load functionality so we use a somewhat ugly
+ * hack to emulate the store/load.
+ */
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7)
+#ifndef MXS_USE_ATOMIC_BUILTINS
+#define MXS_USE_ATOMIC_BUILTINS 1
+#endif
+#endif
+
 /**
  * Implementation of an atomic add operations for the GCC environment.
  *
@@ -76,7 +87,13 @@ void atomic_store_uint64(uint64_t *variable, uint64_t value);
 static inline void atomic_synchronize()
 {
 #ifdef __GNUC__
+
+#ifdef MXS_USE_ATOMIC_BUILTINS
+    __atomic_thread_fence(__ATOMIC_SEQ_CST);
+#else
     __sync_synchronize(); /* Memory barrier. */
+#endif
+
 #else
 #error "No GNUC atomics available."
 #endif

include/maxscale/platform.h

@@ -38,8 +38,8 @@ MXS_BEGIN_DECLS
 
 #else // __cplusplus
 
-// C++11 supports thread_local natively.
+// GCC 4.8 added support for native thread_local.
-#if __cplusplus < 201103
+#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8)
 
 #if defined(__GNUC__)
 #define thread_local __thread
@@ -47,7 +47,7 @@ MXS_BEGIN_DECLS
 #error Do not know how to define thread_local on this compiler/OS platform.
 #endif
 
-#endif // __cplusplus < 201103
+#endif
 
 #endif // __cplusplus
 

server/core/atomic.cc

@@ -19,45 +19,81 @@
 
 int atomic_add(int *variable, int value)
 {
+#ifdef MXS_USE_ATOMIC_BUILTINS
+    return __atomic_fetch_add(variable, value, __ATOMIC_SEQ_CST);
+#else
     return __sync_fetch_and_add(variable, value);
+#endif
 }
 
 int64_t atomic_add_int64(int64_t *variable, int64_t value)
 {
+#ifdef MXS_USE_ATOMIC_BUILTINS
+    return __atomic_fetch_add(variable, value, __ATOMIC_SEQ_CST);
+#else
     return __sync_fetch_and_add(variable, value);
+#endif
 }
 
 uint64_t atomic_add_uint64(uint64_t *variable, int64_t value)
 {
+#ifdef MXS_USE_ATOMIC_BUILTINS
+    return __atomic_fetch_add(variable, value, __ATOMIC_SEQ_CST);
+#else
     return __sync_fetch_and_add(variable, value);
+#endif
 }
 
 int atomic_load_int32(int *variable)
 {
+#ifdef MXS_USE_ATOMIC_BUILTINS
     return __atomic_load_n(variable, __ATOMIC_SEQ_CST);
+#else
+    return __sync_fetch_and_or(variable, 0);
+#endif
 }
 
 int64_t atomic_load_int64(int64_t *variable)
 {
+#ifdef MXS_USE_ATOMIC_BUILTINS
     return __atomic_load_n(variable, __ATOMIC_SEQ_CST);
+#else
+    return __sync_fetch_and_or(variable, 0);
+#endif
 }
 
 uint64_t atomic_load_uint64(uint64_t *variable)
 {
+#ifdef MXS_USE_ATOMIC_BUILTINS
     return __atomic_load_n(variable, __ATOMIC_SEQ_CST);
+#else
+    return __sync_fetch_and_or(variable, 0);
+#endif
 }
 
 void atomic_store_int32(int *variable, int value)
 {
-    return __atomic_store_n(variable, value, __ATOMIC_SEQ_CST);
+#ifdef MXS_USE_ATOMIC_BUILTINS
+    __atomic_store_n(variable, value, __ATOMIC_SEQ_CST);
+#else
+    __sync_lock_test_and_set(variable, value);
+#endif
 }
 
 void atomic_store_int64(int64_t *variable, int64_t value)
 {
-    return __atomic_store_n(variable, value, __ATOMIC_SEQ_CST);
+#ifdef MXS_USE_ATOMIC_BUILTINS
+    __atomic_store_n(variable, value, __ATOMIC_SEQ_CST);
+#else
+    __sync_lock_test_and_set(variable, value);
+#endif
 }
 
 void atomic_store_uint64(uint64_t *variable, uint64_t value)
 {
-    return __atomic_store_n(variable, value, __ATOMIC_SEQ_CST);
+#ifdef MXS_USE_ATOMIC_BUILTINS
+    __atomic_store_n(variable, value, __ATOMIC_SEQ_CST);
+#else
+    __sync_lock_test_and_set(variable, value);
+#endif
 }

server/core/dcb.cc

@@ -3491,11 +3491,15 @@ int poll_add_dcb(DCB *dcb)
     }
     else if (dcb->dcb_role == DCB_ROLE_BACKEND_HANDLER)
     {
+        ss_dassert(Worker::get_current_id() != -1);
+
         worker_id = dcb->session->client_dcb->poll.thread.id;
         ss_dassert(worker_id == Worker::get_current_id());
     }
     else
     {
+        ss_dassert(Worker::get_current_id() != -1);
+
         worker_id = Worker::get_current_id();
     }