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Clarification and tidy up.

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Christopher Kohlhoff
2017-12-06 09:19:35 +11:00
parent 31e5496b32
commit 6814d260d0
1 changed files with 13 additions and 12 deletions
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25
doc/overview/concurrency_hint.qbk
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@@ -7,12 +7,12 @@
[section:concurrency_hint Concurrency Hints]
The [link boost_asio.reference.io_context.io_context `io_context` constructor] allows
programs to specify a concurrency hint. This is a suggestion to the
implementation as to the number of active threads that should be used for
running completion handlers.
The [link boost_asio.reference.io_context.io_context `io_context` constructor]
allows programs to specify a concurrency hint. This is a suggestion to the
`io_context` implementation as to the number of active threads that should be
used for running completion handlers.
When the Windows I/O completion port backend is in used, this value is passed
When the Windows I/O completion port backend is in use, this value is passed
to [^CreateIoCompletionPort].
When a reactor-based backend is used, the implementation recognises the
@@ -23,13 +23,14 @@ following special concurrency hint values:
[
[`1`]
[
The implementation assumes that the `io_context` will be run from a
single thread, and applies several optimisations based on this
assumption.
For example, when a handler is posted from within another handler, the
new handler is held back until the currently executing handler finishes.
new handler is added to a fast thread-local queue (with the consequence
that the new handler is held back until the currently executing handler
finishes).
]
]
[
@@ -38,14 +39,14 @@ following special concurrency hint values:
This special concurrency hint disables locking in both the scheduler and
reactor I/O. This hint has the following restrictions:
[mdash] Care must be taken to ensure that all operations on the io_context
and any of its associated I/O objects (such as sockets and timers) occur
in only one thread at a time.
[mdash] Care must be taken to ensure that all operations on the
`io_context` and any of its associated I/O objects (such as sockets and
timers) occur in only one thread at a time.
[mdash] Asynchronous resolve operations fail with `operation_not_supported`.
[mdash] If a `signal_set` is used with the `io_context`, `signal_set` objects
cannot be used with any other io_context in the program.
[mdash] If a `signal_set` is used with the `io_context`, `signal_set`
objects cannot be used with any other io_context in the program.
]
]
[