I am seeing an issue where the block given to dispatch_source_set_event_handler appear not to be released when a new handler is set.
If I build and run the code below:
xcrun clang++ -std=c++11 -stdlib=libc++ test.cc
It outputs the ‘create’ line, but never any ‘destroy’.
If I don’t call dispatch_source_set_event_handler then I see the expected ‘destroy’. Alternatively I can call an extra Block_release(), which also results in the shared pointer being destroyed.
This is on Mac OS X 10.8.2 Build 12C60 using Apple LLVM version 4.2 (clang-425.0.24) (based on LLVM 3.2svn).
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#include <dispatch/dispatch.h>
#include <Block.h>
#include <stdio.h>
#include <memory>
void setup_dispatch_source ()
{
struct record_t
{
record_t () { fprintf(stderr, "%p: create\n", this); }
~record_t () { fprintf(stderr, "%p: destroy\n", this); }
};
std::shared_ptr<record_t> record(new record_t);
auto block = Block_copy(^(){ fprintf(stderr, "%p\n", record.get()); });
dispatch_source_t source = dispatch_source_create(DISPATCH_SOURCE_TYPE_VNODE, open("/tmp", O_EVTONLY, 0), DISPATCH_VNODE_REVOKE, dispatch_get_main_queue());
dispatch_source_set_event_handler(source, block);
dispatch_source_set_event_handler_f(source, NULL);
Block_release(block);
}
int main (int argc, char const* argv[])
{
setup_dispatch_source();
return 0;
}