Revision 8fa74099 doc/design-2.1.rst
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acquires and no current holders. The caller can have the lock |
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immediately. |
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.. graphviz:: design-2.1-lock-acquire.dot
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.. digraph:: "design-2.1-lock-acquire"
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graph[fontsize=8, fontname="Helvetica"] |
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node[fontsize=8, fontname="Helvetica", width="0", height="0"] |
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edge[fontsize=8, fontname="Helvetica"] |
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/* Actions */ |
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abort[label="Abort\n(couldn't acquire)"] |
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acquire[label="Acquire lock"] |
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add_to_queue[label="Add condition to queue"] |
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wait[label="Wait for notification"] |
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remove_from_queue[label="Remove from queue"] |
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/* Conditions */ |
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alone[label="Empty queue\nand can acquire?", shape=diamond] |
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have_timeout[label="Do I have\ntimeout?", shape=diamond] |
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top_of_queue_and_can_acquire[ |
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label="On top of queue and\ncan acquire lock?", |
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shape=diamond, |
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] |
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/* Lines */ |
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alone->acquire[label="Yes"] |
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alone->add_to_queue[label="No"] |
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have_timeout->abort[label="Yes"] |
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have_timeout->wait[label="No"] |
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top_of_queue_and_can_acquire->acquire[label="Yes"] |
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top_of_queue_and_can_acquire->have_timeout[label="No"] |
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add_to_queue->wait |
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wait->top_of_queue_and_can_acquire |
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acquire->remove_from_queue |
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Release |
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******* |
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exclusive locks by forcing consecutive shared acquires to wait in the |
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queue. |
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.. graphviz:: design-2.1-lock-release.dot |
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.. digraph:: "design-2.1-lock-release" |
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graph[fontsize=8, fontname="Helvetica"] |
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node[fontsize=8, fontname="Helvetica", width="0", height="0"] |
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edge[fontsize=8, fontname="Helvetica"] |
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/* Actions */ |
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remove_from_owners[label="Remove from owner list"] |
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notify[label="Notify topmost"] |
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swap_shared[label="Swap shared conditions"] |
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success[label="Success"] |
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/* Conditions */ |
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have_pending[label="Any pending\nacquires?", shape=diamond] |
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was_active_queue[ |
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label="Was active condition\nfor shared acquires?", |
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shape=diamond, |
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] |
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/* Lines */ |
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remove_from_owners->have_pending |
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have_pending->notify[label="Yes"] |
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have_pending->success[label="No"] |
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notify->was_active_queue |
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was_active_queue->swap_shared[label="Yes"] |
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was_active_queue->success[label="No"] |
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swap_shared->success |
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Delete |
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