Changeset 295740 in webkit

Timestamp:

Jun 22, 2022, 11:35:44 AM (4 years ago)

Author:

achristensen@apple.com

Message:

Make sure return value of dispatch_source_create is memory managed correctly
​https://bugs.webkit.org/show_bug.cgi?id=241836
rdar://95625990

Reviewed by Chris Dumez.

• Source/WTF/wtf/cocoa/MemoryPressureHandlerCocoa.mm:

(WTF::memoryPressureEventSource):
(WTF::timerEventSource):
(WTF::MemoryPressureHandler::install):
(WTF::MemoryPressureHandler::uninstall):
(WTF::MemoryPressureHandler::holdOff):

• Source/WTF/wtf/threads/Signals.cpp:

(WTF::startMachExceptionHandlerThread):

• Source/WebKit/Shared/EntryPointUtilities/Cocoa/XPCService/XPCServiceEntryPoint.mm:

(WebKit::setOSTransaction):

Canonical link: ​https://commits.webkit.org/251745@main

Location:

trunk/Source

Files:

• WTF/wtf/cocoa/MemoryPressureHandlerCocoa.mm (modified) (5 diffs)
• WebKit/Shared/EntryPointUtilities/Cocoa/XPCService/XPCServiceEntryPoint.mm (modified) (2 diffs)

trunk/Source/WTF/wtf/cocoa/MemoryPressureHandlerCocoa.mm

@@ -50 +50 @@
 }
 
-static dispatch_source_t memoryPressureEventSource = nullptr;
-static dispatch_source_t timerEventSource = nullptr;
+static OSObjectPtr<dispatch_source_t>& memoryPressureEventSource()
+{
+    static NeverDestroyed<OSObjectPtr<dispatch_source_t>> source;
+    return source.get();
+}
+
+static OSObjectPtr<dispatch_source_t>& timerEventSource()
+{
+    static NeverDestroyed<OSObjectPtr<dispatch_source_t>> source;
+    return source.get();
+}
+
 static int notifyTokens[3];
 
@@ -67 +77 @@
 void MemoryPressureHandler::install()
 {
-    if (m_installed || timerEventSource)
+    if (m_installed || timerEventSource())
         return;
 
     dispatch_async(m_dispatchQueue.get(), ^{
         auto memoryStatusFlags = DISPATCH_MEMORYPRESSURE_NORMAL | DISPATCH_MEMORYPRESSURE_WARN | DISPATCH_MEMORYPRESSURE_CRITICAL | DISPATCH_MEMORYPRESSURE_PROC_LIMIT_WARN | DISPATCH_MEMORYPRESSURE_PROC_LIMIT_CRITICAL;
-        memoryPressureEventSource = dispatch_source_create(DISPATCH_SOURCE_TYPE_MEMORYPRESSURE, 0, memoryStatusFlags, m_dispatchQueue.get());
-
-        dispatch_source_set_event_handler(memoryPressureEventSource, ^{
-            auto status = dispatch_source_get_data(memoryPressureEventSource);
+        memoryPressureEventSource() = adoptOSObject(dispatch_source_create(DISPATCH_SOURCE_TYPE_MEMORYPRESSURE, 0, memoryStatusFlags, m_dispatchQueue.get()));
+
+        dispatch_source_set_event_handler(memoryPressureEventSource().get(), ^{
+            auto status = dispatch_source_get_data(memoryPressureEventSource().get());
             switch (status) {
             // VM pressure events.
@@ -102 +112 @@
                 RELEASE_LOG(MemoryPressure, "Received memory pressure event %lu vm pressure %d", status, isUnderMemoryPressure());
         });
-        dispatch_resume(memoryPressureEventSource);
+        dispatch_resume(memoryPressureEventSource().get());
     });
 
@@ -141 +151 @@
 
     dispatch_async(m_dispatchQueue.get(), ^{
-        if (memoryPressureEventSource) {
-            dispatch_source_cancel(memoryPressureEventSource);
-            memoryPressureEventSource = nullptr;
+        if (memoryPressureEventSource()) {
+            dispatch_source_cancel(memoryPressureEventSource().get());
+            memoryPressureEventSource() = nullptr;
         }
 
-        if (timerEventSource) {
-            dispatch_source_cancel(timerEventSource);
-            timerEventSource = nullptr;
+        if (timerEventSource()) {
+            dispatch_source_cancel(timerEventSource().get());
+            timerEventSource() = nullptr;
         }
     });
@@ -161 +171 @@
 {
     dispatch_async(m_dispatchQueue.get(), ^{
-        timerEventSource = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, m_dispatchQueue.get());
-        if (timerEventSource) {
-            dispatch_set_context(timerEventSource, this);
+        timerEventSource() = adoptOSObject(dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, m_dispatchQueue.get()));
+        if (timerEventSource()) {
+            dispatch_set_context(timerEventSource().get(), this);
             // FIXME: The final argument `s_minimumHoldOffTime.seconds()` seems wrong.
             // https://bugs.webkit.org/show_bug.cgi?id=183277
-            dispatch_source_set_timer(timerEventSource, dispatch_time(DISPATCH_TIME_NOW, seconds.seconds() * NSEC_PER_SEC), DISPATCH_TIME_FOREVER, s_minimumHoldOffTime.seconds());
-            dispatch_source_set_event_handler(timerEventSource, ^{
-                if (timerEventSource) {
-                    dispatch_source_cancel(timerEventSource);
-                    timerEventSource = nullptr;
+            dispatch_source_set_timer(timerEventSource().get(), dispatch_time(DISPATCH_TIME_NOW, seconds.seconds() * NSEC_PER_SEC), DISPATCH_TIME_FOREVER, s_minimumHoldOffTime.seconds());
+            dispatch_source_set_event_handler(timerEventSource().get(), ^{
+                if (timerEventSource().get()) {
+                    dispatch_source_cancel(timerEventSource().get());
+                    timerEventSource() = nullptr;
                 }
                 MemoryPressureHandler::singleton().install();
             });
-            dispatch_resume(timerEventSource);
+            dispatch_resume(timerEventSource().get());
         }
     });

trunk/Source/WebKit/Shared/EntryPointUtilities/Cocoa/XPCService/XPCServiceEntryPoint.mm

@@ -159 +159 @@
 {
     static NeverDestroyed<OSObjectPtr<os_transaction_t>> globalTransaction;
+    static NeverDestroyed<OSObjectPtr<dispatch_source_t>> globalSource;
 
     // Because we don't use RunningBoard on macOS, we leak an OS transaction to control the lifetime of our XPC
@@ -168 +169 @@
     static dispatch_once_t flag;
     dispatch_once(&flag, ^{
-        auto sigTermSource = dispatch_source_create(DISPATCH_SOURCE_TYPE_SIGNAL, SIGTERM, 0, dispatch_get_main_queue());
-        dispatch_source_set_event_handler(sigTermSource, ^{
+        globalSource.get() = adoptOSObject(dispatch_source_create(DISPATCH_SOURCE_TYPE_SIGNAL, SIGTERM, 0, dispatch_get_main_queue()));
+        dispatch_source_set_event_handler(globalSource.get().get(), ^{
             exit(0);
         });
-        dispatch_resume(sigTermSource);
+        dispatch_resume(globalSource.get().get());
     });