cloud-hypervisor/vmm/src/migration.rs
Yi Wang a69d8c63b3 vmm: speed up JSON load when reading snap files
We found that it's slow to load JSON when reading snap files. As
described in [1], using from_slice instead of from_reader can fix
this.

Also, fix the error type being returned.

1. https://github.com/serde-rs/json/issues/160

Signed-off-by: Yi Wang <foxywang@tencent.com>
2023-11-16 14:56:04 -08:00

87 lines
2.8 KiB
Rust

// Copyright © 2020 Intel Corporation
//
// SPDX-License-Identifier: Apache-2.0
#[cfg(all(target_arch = "x86_64", feature = "guest_debug"))]
use crate::coredump::GuestDebuggableError;
use crate::{config::VmConfig, vm::VmSnapshot};
use anyhow::anyhow;
use std::fs::File;
use std::io::Read;
use std::path::PathBuf;
use vm_migration::{MigratableError, Snapshot};
pub const SNAPSHOT_STATE_FILE: &str = "state.json";
pub const SNAPSHOT_CONFIG_FILE: &str = "config.json";
pub fn url_to_path(url: &str) -> std::result::Result<PathBuf, MigratableError> {
let path: PathBuf = url
.strip_prefix("file://")
.ok_or_else(|| {
MigratableError::MigrateSend(anyhow!("Could not extract path from URL: {}", url))
})
.map(|s| s.into())?;
if !path.is_dir() {
return Err(MigratableError::MigrateSend(anyhow!(
"Destination is not a directory"
)));
}
Ok(path)
}
#[cfg(all(target_arch = "x86_64", feature = "guest_debug"))]
pub fn url_to_file(url: &str) -> std::result::Result<PathBuf, GuestDebuggableError> {
let file: PathBuf = url
.strip_prefix("file://")
.ok_or_else(|| {
GuestDebuggableError::Coredump(anyhow!("Could not extract file from URL: {}", url))
})
.map(|s| s.into())?;
Ok(file)
}
pub fn recv_vm_config(source_url: &str) -> std::result::Result<VmConfig, MigratableError> {
let mut vm_config_path = url_to_path(source_url)?;
vm_config_path.push(SNAPSHOT_CONFIG_FILE);
// Try opening the snapshot file
let mut vm_config_file =
File::open(vm_config_path).map_err(|e| MigratableError::MigrateReceive(e.into()))?;
let mut bytes = Vec::new();
vm_config_file
.read_to_end(&mut bytes)
.map_err(|e| MigratableError::MigrateReceive(e.into()))?;
serde_json::from_slice(&bytes).map_err(|e| MigratableError::MigrateReceive(e.into()))
}
pub fn recv_vm_state(source_url: &str) -> std::result::Result<Snapshot, MigratableError> {
let mut vm_state_path = url_to_path(source_url)?;
vm_state_path.push(SNAPSHOT_STATE_FILE);
// Try opening the snapshot file
let mut vm_state_file =
File::open(vm_state_path).map_err(|e| MigratableError::MigrateReceive(e.into()))?;
let mut bytes = Vec::new();
vm_state_file
.read_to_end(&mut bytes)
.map_err(|e| MigratableError::MigrateReceive(e.into()))?;
serde_json::from_slice(&bytes).map_err(|e| MigratableError::MigrateReceive(e.into()))
}
pub fn get_vm_snapshot(snapshot: &Snapshot) -> std::result::Result<VmSnapshot, MigratableError> {
if let Some(snapshot_data) = snapshot.snapshot_data.as_ref() {
return snapshot_data.to_state();
}
Err(MigratableError::Restore(anyhow!(
"Could not find VM config snapshot section"
)))
}