virtio-devices: Move the 'rate_limiter' module to its own crate

To support I/O throttling on virt-net devices, we need to use the
'rate_limiter' module from the 'net_utils' crate. Given the
'virtio-devices' crate has dependency on the 'net_utils', we will need
to move the 'rate_limiter' module out of the 'virtio-devices' crate to
avoid circular dependency issue. Considering the 'rate_limiter' is not
virtio specific and could be reused for non virtio devices, we move it
to its own crate.

Signed-off-by: Bo Chen <chen.bo@intel.com>

Cargo.lock

@@ -831,6 +831,15 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "rate_limiter"
+version = "0.1.0"
+dependencies = [
+ "libc",
+ "log 0.4.14",
+ "vmm-sys-util",
+]
+
 [[package]]
 name = "redox_syscall"
 version = "0.1.57"
@@ -1274,6 +1283,7 @@ dependencies = [
  "net_gen",
  "net_util",
  "pci",
+ "rate_limiter",
  "seccomp",
  "serde",
  "serde_derive",

Cargo.toml

@@ -76,6 +76,7 @@ members = [
     "option_parser",
     "pci",
     "qcow",
+    "rate_limiter",
     "vhost_user_backend",
     "vhost_user_block",
     "vhost_user_net",

rate_limiter/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "rate_limiter"
+version = "0.1.0"
+edition = "2018"
+
+[dependencies]
+libc = "0.2.91"
+log = "0.4.14"
+vmm-sys-util = "0.8.0"

rate_limiter/src/lib.rs

@@ -43,6 +43,9 @@
 //! It is meant to be used in an external event loop and thus implements the `AsRawFd`
 //! trait and provides an *event-handler* as part of its API. This *event-handler*
 //! needs to be called by the user on every event on the rate limiter's `AsRawFd` FD.
+#[macro_use]
+extern crate log;
+
 use std::os::unix::io::{AsRawFd, RawFd};
 use std::time::{Duration, Instant};
 use std::{fmt, io};

virtio-devices/Cargo.toml

@@ -21,6 +21,7 @@ log = "0.4.14"
 net_gen = { path = "../net_gen" }
 net_util = { path = "../net_util" }
 pci = { path = "../pci" }
+rate_limiter = { path = "../rate_limiter" }
 seccomp = { git = "https://github.com/firecracker-microvm/firecracker", tag = "v0.22.0" }
 serde = ">=1.0.27"
 serde_derive = ">=1.0.27"

virtio-devices/src/block.rs

@@ -14,7 +14,6 @@ use super::{
     RateLimiterConfig, VirtioCommon, VirtioDevice, VirtioDeviceType, VirtioInterruptType,
     EPOLL_HELPER_EVENT_LAST,
 };
-use crate::rate_limiter::{RateLimiter, TokenType};
 use crate::seccomp_filters::{get_seccomp_filter, Thread};
 use crate::VirtioInterrupt;
 use anyhow::anyhow;
@@ -22,6 +21,7 @@ use block_util::{
     async_io::AsyncIo, async_io::AsyncIoError, async_io::DiskFile, build_disk_image_id, Request,
     RequestType, VirtioBlockConfig,
 };
+use rate_limiter::{RateLimiter, TokenType};
 use seccomp::{SeccompAction, SeccompFilter};
 use std::io;
 use std::num::Wrapping;

virtio-devices/src/lib.rs

@@ -40,7 +40,6 @@ pub mod mem;
 pub mod net;
 pub mod net_util;
 mod pmem;
-mod rate_limiter;
 mod rng;
 pub mod seccomp_filters;
 pub mod transport;