Nested Sync IPC?

[Mike Pinkerton]

I think I know the answer to this question already, but wanted to ask
just to be sure.

If I'm calling a synchronous IPC call, say from the renderer to a
plug-in, can the recipient turn around and send a synchronous IPC call
right back (for instance if the plug-in needs information to complete
the request from the renderer)? I'm betting it can't, but I've been
surprised about these things before :-)

If not, how do folks generally work around this kind of thing? Do we
have a preferred pattern?

Thanks!

--
Mike Pinkerton
Mac Weenie
pink...@google.com

[John Abd-El-Malek]

Hi, yes nested sync IPC calls are needed and supported.  When a caller is making a synchronous call, they dispatch any incoming sync calls. 

To be very precise, they dispatch any incoming IPC message with the "unblock" flag set.  Usually sync calls have that set, but to avoid reentrancy in some situations (when webkit is painting, and at the nearly the same time, the plugin asks it to do layout it gets very confused), the plugin process only sets that flag if there's a sync IPC lower in the callstack.

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