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[Qemu-devel] [PATCH v2 00/16] Introduce I/O channels framework
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From: |
Daniel P. Berrange |
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Subject: |
[Qemu-devel] [PATCH v2 00/16] Introduce I/O channels framework |
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Date: |
Mon, 12 Oct 2015 12:14:53 +0100 |
This series of patches is a followup submission for review of another
chunk of my large series supporting TLS across chardevs, VNC and
migration, previously shown here:
RFC: https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg00829.html
v1: https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg04853.html
In this series, I have provided only the general I/O channels
framework, which will ultimately be used by VNC, chardev and
migration code, whicih currently work as follows:
- VNC: uses raw sockets APIs directly, layering in TLS, SASL
and websockets where needed. This has resulted in what should
be fairly generic code for TLS and websockets being entangled
with the rest of the VNC server code.
- Chardevs: uses GLib's GIOChannel framework. This only provides
implementations for sockets and files. Its API lacks support for
using struct iovec for read/writes, file descriptor passing,
misc sockets ioctls/fcntls. While you can work around these
problems by accessing the underling file descriptor directly,
this breaks the encapsulation, requiring callers to know about
specific implementations. It also does not have integration
with QEMU Error reporting framework. So while the GIOChannel
is extensible, extending it would result in throwing away
pretty much the entire of the existing implementations
- Migration: uses QEMUFile framework. The provides an abstract
interface for I/O channels used during migration. It has
impls for sockets, files, memory buffers & commands. While
it has struct iovec support for writes, it does not have
the same for reads. It also doesn't support file descriptor
passing or control of the sockets ioctls/fcntls. It also
does not have any explicit event loop integration, expecting
the callers to directly access the underling file desctriptor
and setup events on that. This limits its utility in cases
where you need channels which are not backed by file
descriptors. It has no integration with QEMU Error object
for error reporting, has fixed semantics wrt writes
ie must always do a full write, no partial writes, and
most strangely forces either input or output mode, but
refuses to allow both, so no bi-directional channels!
Out of all of these, the migration code is probably closest
to what is needed, but is still a good way off from being a
generic framework that be can reused outside of the migration
code.
There is also the GLib GIO library which provides a generic
framework, but we can't depend on that due to the minimum
GLib requirement. It also has various missing pieces such as
file descriptor passing, and no support for struct iovec
either.
Hence, this series was born, which tries to take the best of
the designs for the GIOChannel, QIO and QEMUFile code to
provide QIOChannel. Right from the start this new framework
is explicitly isolated from any other QEMU subsystem, so its
implementation will not get mixed up with specific use cases.
The QIOChannel abstract base class defines the overall API
contract
- qio_channel_{write,writev,write_full} for writing data. The
underling impl always uses struct iovec, but non-iov
APIs are provided as simple wrappers for convenience
- qio_channel_{read,readv,read_full} for reading data. The
underling impl always uses struct iovec, but non-iov
APIs are provided as simple wrappers for convenience
- qio_channel_has_feature to determine which optional
features the channel supports - eg file descriptor
passing, nagle, etc
- qio_channel_set_{blocking,delay,cork} for various fcntl
and ioctl controls
- qio_channel_{close,shutdown} for closing the I/O stream
or individual channels
- qio_channel_seek for random access channels
- qio_channel_{add,create}_watch for integration into the
main loop for event notifications
- qio_channel_wait for blocking of execution pending an
event notification
- qio_channel_yield for switching coroutine until an
event notification
All the APIs support Error ** object arguments where needed.
The object is built using QOM, in order to get reference
counting and sub-classing with type checking. They are *not*
user creatable/visible objects though - these are internal
infrastructure, so we will be free to adapt APIs/objects at
will over time.
In this series there are a variety of implementations. Some
of them provide an actual base layer data transport, while
others provide a data translation layer:
In this series there are a variety of implementations. Some
of them provide an actual base layer data transport, while
others provide a data translation layer:
- QIOChannelSocket - for socket based I/O, IPv4, IPV6 & UNIX,
both stream and datagram.
- QIOChannelFile - any non-socket file, plain file, char dev,
fifo, pipe, etc
- QIOChannelTLS - data translation layer to apply TLS protocol
- QIOChannelWebsock - data translation layer to apply the
websockets server protocol
- QIOChannelCommand - spawn & communicate with a command via
pipes
- QIOChannelBuffer - a simple in-memory buffer
These 6 implementations are sufficient to support the current
needs of the VNC server, chardev network backends, and all
the various migration protocols, except RDMA (which is part
of the larger RFC series I've posted previously).
The sockets implementation in particular solves a long standing
limitation of the qemu-sockets.c API by providing a truely
asynchronous API for establishing listener sockets / connections.
The current code is only async for the socket establishment,
but still blocks the caller for DNS resolution.
I have not attempted to make the socket implementation support
multiple listener sockets in a single object. I looked at this
but it would significantly complicate the QIOChannelSocket
implementation. I intend to suggest an alternative approach
for that problem at a later date, whereby we define a
QIONetworkService object, which provides the infrastructure
for managing multiple QIOChannelSocket listeners, and clients,
which was resuable for any QEMU network service.
There are unit tests for the socket, file, tls, and command
channel implementations. I didn't create unit test for the
websock impl, as it needs a websock client to usefully test
it which doesn't exist in QEMU yet. The memory buffer impl
also lacks unit tests for now, simply due to not getting
around to it yet.
This series merely introduces all the new framework. To keep
it an acceptable length for review, it doesn't include any of
the patches which actually use the new APIs. If reviewers want
to see real world usage of these APIs, they can refer to my
previous RFC series.
https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg00829.html
In particular
- VNC conversion to QIOChannelSocket
https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg00851.html
- VNC conversion to QIOChannelTLS
https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg00845.html
- VNC conversion to QIOChannelWebsock
https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg00842.html
- Chardev conversion to QIOChannelSocket
https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg00849.html
- Chardev addition of TLS support
https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg00848.html
- All the migration ones, but most interesting addition of TLS
https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg00871.html
Finally I've listed myself as maintainer for the new io/ and
include/io/ directory prefixes.
Changed in v2:
- Put the Buffer APIs extracted from VNC code into util/ instead
of io/ directories (Paolo)
- Added Kevin & Stefan to MAINTAINERS for coroutine code (Paolo)
- Remove feature checks for TCP_NODELAY and TCP_CORK and
treat them as hints which cannot fail (Paolo)
- Push feature checking for FD passing up into QIOChannel
base class (Paolo)
- Use more constants in websockets code instead of magic
values (David Gilbert)
Daniel P. Berrange (16):
sockets: add helpers for creating SocketAddress from a socket
sockets: move qapi_copy_SocketAddress into qemu-sockets.c
sockets: allow port to be NULL when listening on IP address
ui: convert VNC startup code to use SocketAddress
osdep: add qemu_fork() wrapper for safely handling signals
coroutine: move into libqemuutil.a library
util: pull Buffer code out of VNC module
io: add abstract QIOChannel classes
io: add helper module for creating watches on FDs
io: add QIOTask class for async operations
io: add QIOChannelSocket class
io: add QIOChannelFile class
io: add QIOChannelTLS class
io: add QIOChannelWebsock class
io: add QIOChannelCommand class
io: add QIOChannelBuffer class
MAINTAINERS | 20 +
Makefile | 2 +
Makefile.objs | 9 +-
Makefile.target | 2 +
block.c | 2 +-
block/qcow2.h | 2 +-
block/vdi.c | 2 +-
block/write-threshold.c | 2 +-
blockjob.c | 2 +-
configure | 11 +
hw/9pfs/codir.c | 2 +-
hw/9pfs/cofile.c | 2 +-
hw/9pfs/cofs.c | 2 +-
hw/9pfs/coxattr.c | 2 +-
hw/9pfs/virtio-9p-coth.c | 2 +-
hw/9pfs/virtio-9p-coth.h | 2 +-
hw/9pfs/virtio-9p.h | 2 +-
include/block/block.h | 2 +-
include/block/block_int.h | 2 +-
include/io/channel-buffer.h | 59 ++
include/io/channel-command.h | 91 ++
include/io/channel-file.h | 93 ++
include/io/channel-socket.h | 244 ++++++
include/io/channel-tls.h | 142 +++
include/io/channel-watch.h | 72 ++
include/io/channel-websock.h | 108 +++
include/io/channel.h | 506 +++++++++++
include/io/task.h | 256 ++++++
include/qemu/buffer.h | 118 +++
include/{block => qemu}/coroutine.h | 0
include/{block => qemu}/coroutine_int.h | 2 +-
include/qemu/osdep.h | 16 +
include/qemu/sockets.h | 34 +
io/Makefile.objs | 9 +
io/channel-buffer.c | 255 ++++++
io/channel-command.c | 369 ++++++++
io/channel-file.c | 237 +++++
io/channel-socket.c | 737 ++++++++++++++++
io/channel-tls.c | 405 +++++++++
io/channel-watch.c | 200 +++++
io/channel-websock.c | 975 +++++++++++++++++++++
io/channel.c | 283 ++++++
io/task.c | 159 ++++
migration/qemu-file-buf.c | 2 +-
migration/qemu-file-stdio.c | 2 +-
migration/qemu-file-unix.c | 2 +-
migration/qemu-file.c | 2 +-
migration/rdma.c | 2 +-
nbd.c | 2 +-
qemu-char.c | 25 -
scripts/create_config | 9 +
tests/.gitignore | 7 +
tests/Makefile | 16 +
tests/io-channel-helpers.c | 247 ++++++
tests/io-channel-helpers.h | 33 +
tests/test-coroutine.c | 4 +-
tests/test-io-channel-command.c | 122 +++
tests/test-io-channel-file.c | 91 ++
tests/test-io-channel-socket.c | 367 ++++++++
tests/test-io-channel-tls.c | 335 +++++++
tests/test-io-task.c | 276 ++++++
tests/test-vmstate.c | 2 +-
thread-pool.c | 2 +-
trace-events | 56 ++
ui/vnc.c | 204 ++---
ui/vnc.h | 16 +-
util/Makefile.objs | 4 +
util/buffer.c | 65 ++
coroutine-gthread.c => util/coroutine-gthread.c | 2 +-
.../coroutine-sigaltstack.c | 2 +-
coroutine-ucontext.c => util/coroutine-ucontext.c | 2 +-
coroutine-win32.c => util/coroutine-win32.c | 2 +-
util/oslib-posix.c | 71 ++
util/oslib-win32.c | 9 +
qemu-coroutine-io.c => util/qemu-coroutine-io.c | 2 +-
.../qemu-coroutine-lock.c | 4 +-
.../qemu-coroutine-sleep.c | 2 +-
qemu-coroutine.c => util/qemu-coroutine.c | 4 +-
util/qemu-sockets.c | 158 +++-
79 files changed, 7396 insertions(+), 197 deletions(-)
create mode 100644 include/io/channel-buffer.h
create mode 100644 include/io/channel-command.h
create mode 100644 include/io/channel-file.h
create mode 100644 include/io/channel-socket.h
create mode 100644 include/io/channel-tls.h
create mode 100644 include/io/channel-watch.h
create mode 100644 include/io/channel-websock.h
create mode 100644 include/io/channel.h
create mode 100644 include/io/task.h
create mode 100644 include/qemu/buffer.h
rename include/{block => qemu}/coroutine.h (100%)
rename include/{block => qemu}/coroutine_int.h (98%)
create mode 100644 io/Makefile.objs
create mode 100644 io/channel-buffer.c
create mode 100644 io/channel-command.c
create mode 100644 io/channel-file.c
create mode 100644 io/channel-socket.c
create mode 100644 io/channel-tls.c
create mode 100644 io/channel-watch.c
create mode 100644 io/channel-websock.c
create mode 100644 io/channel.c
create mode 100644 io/task.c
create mode 100644 tests/io-channel-helpers.c
create mode 100644 tests/io-channel-helpers.h
create mode 100644 tests/test-io-channel-command.c
create mode 100644 tests/test-io-channel-file.c
create mode 100644 tests/test-io-channel-socket.c
create mode 100644 tests/test-io-channel-tls.c
create mode 100644 tests/test-io-task.c
create mode 100644 util/buffer.c
rename coroutine-gthread.c => util/coroutine-gthread.c (99%)
rename coroutine-sigaltstack.c => util/coroutine-sigaltstack.c (99%)
rename coroutine-ucontext.c => util/coroutine-ucontext.c (99%)
rename coroutine-win32.c => util/coroutine-win32.c (98%)
rename qemu-coroutine-io.c => util/qemu-coroutine-io.c (99%)
rename qemu-coroutine-lock.c => util/qemu-coroutine-lock.c (98%)
rename qemu-coroutine-sleep.c => util/qemu-coroutine-sleep.c (96%)
rename qemu-coroutine.c => util/qemu-coroutine.c (98%)
--
2.4.3