This commit builds on top of the `Monitor::subscribe` function and
makes it possible to broadcast events published from `event-monitor`
over D-Bus.
The broadcasting functionality is enabled if the D-Bus API is enabled
and users who wish to also enable the file based `event-monitor` can do
so with the CLI arg `--event-monitor`.
Signed-off-by: Omer Faruk Bayram <omer.faruk@sartura.hr>
This patch modifies `event_monitor` to ensure that concurrent access to
`event_log` from multiple threads is safe. Previously, the `event_log`
function would acquire a reference to the event log file and write
to it without doing any synchronization, which made it prone to
data races. This issue likely went under the radar because the
relevant `SAFETY` comment on the unsafe block was incomplete.
The new implementation spawns a dedicated thread named `event-monitor`
solely for writing to the file. It uses the MPMC channel exposed by
`flume` to pass messages to the `event-monitor` thread. Since
`flume::Sender<T>` implements `Sync`, it is safe for multiple threads
to share it and send messages to the `event-monitor` thread.
This is not possible with `std::sync::mpsc::Sender<T>` since it's
`!Sync`, meaning it is not safe for it to be shared between different
threads.
The `event_monitor::set_monitor` function now only initializes
the required global state and returns an instance of the
`Monitor` struct. This decouples the actual logging logic from the
`event_monitor` crate. The `event-monitor` thread is then spawned by
the `vmm` crate.
Signed-off-by: Omer Faruk Bayram <omer.faruk@sartura.hr>
There is no need to include serde_derive separately,
as it can be specified as serde feature instead.
Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>
This crate exposes the abililty for the VMM to set a file that events
should be written to. The event!() macro provides an interface to report
those events allowing the specification of an event source, an event
type and optional extra data. This will be written to the provided file
descriptor as JSON data.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
