cloud-hypervisor/vmm/src/api/mod.rs
Samuel Ortiz 46cde1a38e vmm: Rename the VM start and stop operations to boot and shutdown
To match the OpenAPI description. And also to map the real life
terminology.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
2019-10-04 09:36:33 +02:00

114 lines
3.6 KiB
Rust

// Copyright © 2019 Intel Corporation
//
// SPDX-License-Identifier: Apache-2.0
//
//! The internal VMM API for Cloud Hypervisor.
//!
//! This API is a synchronous, [mpsc](https://doc.rust-lang.org/std/sync/mpsc/)
//! based IPC for sending commands to the VMM thread, from other
//! Cloud Hypervisor threads. The IPC follows a command-response protocol, i.e.
//! each command will receive a response back.
//!
//! The main Cloud Hypervisor thread creates an API event file descriptor
//! to notify the VMM thread about pending API commands, together with an
//! API mpsc channel. The former is the IPC control plane, the latter is the
//! IPC data plane.
//! In order to use the IPC, a Cloud Hypervisor thread needs to have a clone
//! of both the API event file descriptor and the channel Sender. Then it must
//! go through the following steps:
//!
//! 1. The thread creates an mpsc channel for receiving the command response.
//! 2. The thread sends an ApiRequest to the Sender endpoint. The ApiRequest
//! contains the response channel Sender, for the VMM API server to be able
//! to send the response back.
//! 3. The thread writes to the API event file descriptor to notify the VMM
//! API server about a pending command.
//! 4. The thread reads the response back from the VMM API server, from the
//! response channel Receiver.
//! 5. The thread handles the response and forwards potential errors.
extern crate micro_http;
extern crate vmm_sys_util;
pub use self::http::start_http_thread;
pub mod http;
use crate::config::VmConfig;
use crate::vm::Error as VmError;
use crate::{Error, Result};
use std::sync::mpsc::{channel, Sender};
use std::sync::Arc;
use vmm_sys_util::eventfd::EventFd;
/// API errors are sent back from the VMM API server through the ApiResponse.
#[derive(Debug)]
pub enum ApiError {
/// The VM could not be created.
VmCreate(VmError),
/// The VM could not boot.
VmBoot(VmError),
}
pub enum ApiResponsePayload {
/// No data is sent on the channel.
Empty,
}
/// This is the response sent by the VMM API server through the mpsc channel.
pub type ApiResponse = std::result::Result<ApiResponsePayload, ApiError>;
#[allow(clippy::large_enum_variant)]
pub enum ApiRequest {
/// Create the virtual machine. This request payload is a VM configuration
/// (VmConfig).
/// If the VMM API server could not create the VM, it will send a VmCreate
/// error back.
VmCreate(Arc<VmConfig>, Sender<ApiResponse>),
/// Boot the previously created virtual machine.
/// If the VM was not previously created, the VMM API server will send a
/// VmBoot error back.
VmBoot(Sender<ApiResponse>),
}
pub fn vm_create(
api_evt: EventFd,
api_sender: Sender<ApiRequest>,
config: Arc<VmConfig>,
) -> Result<()> {
let (response_sender, response_receiver) = channel();
// Send the VM creation request.
api_sender
.send(ApiRequest::VmCreate(config, response_sender))
.map_err(Error::ApiRequestSend)?;
api_evt.write(1).map_err(Error::EventFdWrite)?;
response_receiver
.recv()
.map_err(Error::ApiResponseRecv)?
.map_err(Error::ApiVmCreate)?;
Ok(())
}
pub fn vm_boot(api_evt: EventFd, api_sender: Sender<ApiRequest>) -> Result<()> {
let (response_sender, response_receiver) = channel();
// Send the VM boot request.
api_sender
.send(ApiRequest::VmBoot(response_sender))
.map_err(Error::ApiRequestSend)?;
api_evt.write(1).map_err(Error::EventFdWrite)?;
response_receiver
.recv()
.map_err(Error::ApiResponseRecv)?
.map_err(Error::ApiVmBoot)?;
Ok(())
}