src: cherry-pick from downstream, worker prep#15707

Closed

jasnell wants to merge 9 commits intonodejs:masterfrom jasnell:ayo-sync

+478-129

Commits on Oct 1, 2017

async_wrap: update utility methods for flexibility

addaleax
authored and
jasnell
committed
src: fix fs_stats_field_array memory leak

addaleax
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jasnell
committed
src: protect global state with mutexes

addaleax
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jasnell
committed
src: add environment cleanup hooks

addaleax
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jasnell
committed
src: add can_call_into_js flag

addaleax
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jasnell
committed
src: use lock for c-ares library init/cleanup

addaleax
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jasnell
committed
src: make CleanupHandles() tear down handles/reqs

addaleax
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jasnell
committed
src: unify ReqWrap libuv calling

addaleax
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jasnell
committed
src: keep track of open requests

addaleax
authored and
jasnell
committed