Platform/Memory Reporting: Difference between revisions

Platform/Memory Reporting (view source)

714 bytes added , 13 December 2011

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 Sometimes you may need variations on the above forms.  For example, if you have a function that just measures one member <tt>Foo</tt> of an object, it might be called <tt>SizeOfFoo</tt>.  Try to make the names descriptive enough that it's clear what's being measured.
+Sometimes you might want to split the measurements of an object into two or more numbers, e.g. because you want to show them separately in about:memory.  In which case just return the multiple values by reference, like this:
+  void FooBar::SizeOfExcludingThis(nsMallocSizeOfFun aMallocSizeOf,
+                                   size_t *foo, size_t* bar) const;
+Alternatively, you could create a struct:
+  struct FooBarStats {
+      size_t foo;
+      size_t bar;
+  }
+  void FooBar::SizeOfExcludingThis(nsMallocSizeOfFun aMallocSizeOf,
+                                   FooBarStats *stats) const;
+You could even put the <tt>nsMallocSizeOfFun</tt> in <code>FooBarStats</code> to reduce the number of arguments.
 Sometimes it's difficult and/or not worth measuring every member of an object of in a <tt>Foo::SizeOfExcludingThis</tt> method.  This is ok, but it's worth adding a comment explaining this to the method.