Remove the use of QMutexPool in QHostInfo and QDnsLookup

Q_GLOBAL_STATIC does the thread-safe protection for us. And who said we
could only use non-POD types? We can just use a boolean!

Change-Id: Ifea6e497f11a461db432ffff1449b0a88d75d194
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

src/network/kernel/qdnslookup_unix.cpp

@@ -36,7 +36,6 @@
 #include <qlibrary.h>
 #include <qscopedpointer.h>
 #include <qurl.h>
-#include <private/qmutexpool_p.h>
 
 #include <sys/types.h>
 #include <netinet/in.h>
@@ -71,7 +70,7 @@ struct QDnsLookupStateDeleter
     }
 };
 
-static void resolveLibrary()
+static bool resolveLibraryInternal()
 {
     QLibrary lib;
 #ifdef LIBRESOLV_SO
@@ -81,7 +80,7 @@ static void resolveLibrary()
     {
         lib.setFileName(QLatin1String("resolv"));
         if (!lib.load())
-            return;
+            return false;
     }
 
     local_dn_expand = dn_expand_proto(lib.resolve("__dn_expand"));
@@ -105,19 +104,15 @@ static void resolveLibrary()
         local_res_nquery = res_nquery_proto(lib.resolve("res_9_nquery"));
     if (!local_res_nquery)
         local_res_nquery = res_nquery_proto(lib.resolve("res_nquery"));
+
+    return true;
 }
+Q_GLOBAL_STATIC_WITH_ARGS(bool, resolveLibrary, (resolveLibraryInternal()))
 
 void QDnsLookupRunnable::query(const int requestType, const QByteArray &requestName, const QHostAddress &nameserver, QDnsLookupReply *reply)
 {
     // Load dn_expand, res_ninit and res_nquery on demand.
-    static QBasicAtomicInt triedResolve = Q_BASIC_ATOMIC_INITIALIZER(false);
+    resolveLibrary();
-    if (!triedResolve.loadAcquire()) {
-        QMutexLocker locker(QMutexPool::globalInstanceGet(&local_res_ninit));
-        if (!triedResolve.load()) {
-            resolveLibrary();
-            triedResolve.storeRelease(true);
-        }
-    }
 
     // If dn_expand, res_ninit or res_nquery is missing, fail.
     if (!local_dn_expand || !local_res_nclose || !local_res_ninit || !local_res_nquery) {

src/network/kernel/qhostinfo_unix.cpp

@@ -43,7 +43,6 @@
 #include <qbasicatomic.h>
 #include <qurl.h>
 #include <qfile.h>
-#include <private/qmutexpool_p.h>
 #include <private/qnet_unix_p.h>
 
 #include <sys/types.h>
@@ -86,7 +85,7 @@ typedef void (*res_nclose_proto)(res_state_ptr);
 static res_nclose_proto local_res_nclose = 0;
 static res_state_ptr local_res = 0;
 
-static void resolveLibrary()
+static bool resolveLibraryInternal()
 {
 #if !defined(QT_NO_LIBRARY) && !defined(Q_OS_QNX)
     QLibrary lib;
@@ -97,7 +96,7 @@ static void resolveLibrary()
     {
         lib.setFileName(QLatin1String("resolv"));
         if (!lib.load())
-            return;
+            return false;
     }
 
     local_res_init = res_init_proto(lib.resolve("__res_init"));
@@ -119,7 +118,10 @@ static void resolveLibrary()
             local_res_ninit = 0;
     }
 #endif
+
+    return true;
 }
+Q_GLOBAL_STATIC_WITH_ARGS(bool, resolveLibrary, (resolveLibraryInternal()))
 
 QHostInfo QHostInfoAgent::fromName(const QString &hostName)
 {
@@ -131,14 +133,7 @@ QHostInfo QHostInfoAgent::fromName(const QString &hostName)
 #endif
 
     // Load res_init on demand.
-    static QBasicAtomicInt triedResolve = Q_BASIC_ATOMIC_INITIALIZER(false);
+    resolveLibrary();
-    if (!triedResolve.loadAcquire()) {
-        QMutexLocker locker(QMutexPool::globalInstanceGet(&local_res_init));
-        if (!triedResolve.load()) {
-            resolveLibrary();
-            triedResolve.storeRelease(true);
-        }
-    }
 
     // If res_init is available, poll it.
     if (local_res_init)

src/network/kernel/qhostinfo_win.cpp

@@ -39,7 +39,6 @@
 #include <qmutex.h>
 #include <qbasicatomic.h>
 #include <qurl.h>
-#include <private/qmutexpool_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -72,7 +71,7 @@ static getnameinfoProto local_getnameinfo = 0;
 static getaddrinfoProto local_getaddrinfo = 0;
 static freeaddrinfoProto local_freeaddrinfo = 0;
 
-static void resolveLibrary()
+static bool resolveLibraryInternal()
 {
     // Attempt to resolve getaddrinfo(); without it we'll have to fall
     // back to gethostbyname(), which has no IPv6 support.
@@ -89,7 +88,9 @@ static void resolveLibrary()
     local_freeaddrinfo = (freeaddrinfoProto) QSystemLibrary::resolve(QLatin1String("ws2_32"), "freeaddrinfo");
     local_getnameinfo = (getnameinfoProto) QSystemLibrary::resolve(QLatin1String("ws2_32"), "getnameinfo");
 #endif
+    return true;
 }
+Q_GLOBAL_STATIC_WITH_ARGS(bool, resolveLibrary, (resolveLibraryInternal()))
 
 static void translateWSAError(int error, QHostInfo *results)
 {
@@ -117,14 +118,7 @@ QHostInfo QHostInfoAgent::fromName(const QString &hostName)
     QSysInfo::machineHostName();        // this initializes ws2_32.dll
 
     // Load res_init on demand.
-    static QBasicAtomicInt triedResolve = Q_BASIC_ATOMIC_INITIALIZER(false);
+    resolveLibrary();
-    if (!triedResolve.loadAcquire()) {
-        QMutexLocker locker(QMutexPool::globalInstanceGet(&local_getaddrinfo));
-        if (!triedResolve.load()) {
-            resolveLibrary();
-            triedResolve.storeRelease(true);
-        }
-    }
 
     QHostInfo results;