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d0b22bb331
This branch fixes a couple of issues which might result in child spans not correctly triggering their parents to close: * subscriber: fix spans closed by their children not being removed The issue here is that the `CloseGuard` removes the span from the registry (dropping the `DataInner`) *before* it decrements CLOSE_COUNT. Dropping the `DataInner` will decrement the parent span's ref count, potentially allowing it to close. When the new close for the parent span starts, CLOSE_COUNT will be 1, not 0, and it will not be decremented until after the try_close call completes. This means that although the close is processed and all the layers see `on_close` calls for that span, the span's data is never removed from the registry, effectively leaking it. This commit fixes the problem by decrementing CLOSE_COUNT *before* we trigger the parent to close. Fixes #511 * subscriber: fix child spans not closing grandparents Currently, in situations where multiple parent spans are kept open by a child, only the first parent will be successfully closed. This is because calling `dispatcher::get_default` unsets the default dispatcher temporarily, so that nested `get_default` calls will receive a no-op subscriber. This was intended to prevent infinite dispatch loops when a subscriber calls into code that emits its own traces. Unfortunately, this means that if dropping the parent span would then trigger an additional span to drop, the dispatcher is now unset. This commit fixes this by cloning the dispatcher out of the `get_default` closure _before_ trying to close the parent span. This means that the `get_default` calls are no longer nested. This does have the disadvantage of introducing an additional `Arc` increment/decrement to the span-closing path. The impact of that shouldn't be too big, but if necessary we can try to optimize this in the future. I've also added tests for these issues. Signed-off-by: Eliza Weisman <eliza@buoyant.io>
tracing-subscriber
Utilities for implementing and composing tracing subscribers.
License
This project is licensed under the MIT license.
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Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Tracing by you, shall be licensed as MIT, without any additional terms or conditions.