Changeset 174660 in webkit

Timestamp:

Oct 13, 2014 3:30:20 PM (10 years ago)

Author:

Antti Koivisto

Message:

Add StringCapture helper for thread-safe lambda capture
​https://bugs.webkit.org/show_bug.cgi?id=137664

Reviewed by Anders Carlsson.

There is currently no clean way to capture a String in a thread-safe manner. This will now work:

StringCapture stringCapture(string);
auto lambdaThatRunsInAnotherThread = [stringCapture] { String string = stringCapture.string(); ... }

This type won't be necessary with C++14 initialized lambda capture: [string = string.isolatedCopy()].

• wtf/text/WTFString.h:

(WTF::StringCapture::StringCapture): Create isolated copy in copy-constructor.
(WTF::StringCapture::string):

Location:

trunk/Source/WTF

Files:

• ChangeLog (modified) (1 diff)
• wtf/text/WTFString.h (modified) (2 diffs)

trunk/Source/WTF/ChangeLog

@@ +1 @@
+2014-10-13  Antti Koivisto  <antti@apple.com>
+
+        Add StringCapture helper for thread-safe lambda capture
+        https://bugs.webkit.org/show_bug.cgi?id=137664
+
+        Reviewed by Anders Carlsson.
+
+        There is currently no clean way to capture a String in a thread-safe manner. This will now work:
+
+        StringCapture stringCapture(string);
+        auto lambdaThatRunsInAnotherThread = [stringCapture] { String string = stringCapture.string(); ... }
+
+        This type won't be necessary with C++14 initialized lambda capture: [string = string.isolatedCopy()].
+
+        * wtf/text/WTFString.h:
+        (WTF::StringCapture::StringCapture): Create isolated copy in copy-constructor.
+        (WTF::StringCapture::string):
+
 2014-10-11  KwangHyuk Kim  <hyuki.kim@samsung.com>
 

trunk/Source/WTF/wtf/text/WTFString.h

@@ -633 +633 @@
 private:
     const char* m_characters;
+};
+
+// For thread-safe lambda capture:
+// StringCapture stringCapture(string);
+// auto lambdaThatRunsInOtherThread = [stringCapture] { String string = stringCapture.string(); ... }
+// FIXME: Remove when we can use C++14 initialized lambda capture: [string = string.isolatedCopy()].
+class StringCapture {
+public:
+    explicit StringCapture(const String& string) : m_string(string) { }
+    explicit StringCapture(String&& string) : m_string(string) { }
+    StringCapture(const StringCapture& other) : m_string(other.m_string.isolatedCopy()) { }
+    const String& string() const { return m_string; }
+    String releaseString() { return WTF::move(m_string); }
+
+private:
+    void operator=(const StringCapture&) = delete;
+    String m_string;
 };
 
@@ -665 +682 @@
 using WTF::reverseFind;
 using WTF::ASCIILiteral;
+using WTF::StringCapture;
 
 #include <wtf/text/AtomicString.h>