Add API for monitoring exited tasks (#11)

To be compliant with the taskstats docs,
also added methods to adjust the RX socket buffer

Co-authored-by: Ilya Byckevich <ilya.byckevich@accenture.com>

Cargo.toml

@@ -22,7 +22,7 @@ required-features = ["executable"]
 
 [dependencies]
 libc = "0.2.139"
-netlink-sys = "0.8.3"
+netlink-sys = "0.8.6"
 thiserror = "1.0.38"
 log = "0.4.17"
 env_logger = { version = "0.10.0", optional = true }

src/lib.rs

@@ -12,15 +12,15 @@ pub use model::*;
 
 pub use c_headers::taskstats as __bindgen_taskstats;
 use c_headers::{
-    __u16, __u32, __u64, __u8, TASKSTATS_CMD_ATTR_PID, TASKSTATS_CMD_ATTR_TGID, TASKSTATS_CMD_GET,
+    __u16, __u32, __u64, __u8, TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK, TASKSTATS_CMD_ATTR_PID,
+    TASKSTATS_CMD_ATTR_REGISTER_CPUMASK, TASKSTATS_CMD_ATTR_TGID, TASKSTATS_CMD_GET,
     TASKSTATS_GENL_NAME, TASKSTATS_TYPE_AGGR_PID, TASKSTATS_TYPE_AGGR_TGID, TASKSTATS_TYPE_NULL,
     TASKSTATS_TYPE_PID, TASKSTATS_TYPE_STATS, TASKSTATS_TYPE_TGID,
 };
 use log::{debug, warn};
 use netlink::Netlink;
 use netlink::NlPayload;
-use std::mem;
-use std::slice;
+use std::{mem, slice};
 use thiserror::Error;
 
 /// Errors possibly returned by `Client`
@@ -93,12 +93,7 @@ impl Client {
     /// * when kernel responded error
     /// * when the returned data couldn't be interpreted
     pub fn pid_stats(&self, tid: u32) -> Result<TaskStats> {
-        self.netlink.send_cmd(
-            self.ts_family_id,
-            TASKSTATS_CMD_GET as u8,
-            TASKSTATS_CMD_ATTR_PID as u16,
-            tid.as_buf(),
-        )?;
+        self.send(TASKSTATS_CMD_ATTR_PID as u16, tid.as_buf())?;
 
         let resp = self.netlink.recv_response()?;
         for na in resp.payload_as_nlattrs() {
@@ -138,12 +133,7 @@ impl Client {
     /// * when kernel responded error
     /// * when the returned data couldn't be interpreted
     pub fn tgid_stats(&self, tgid: u32) -> Result<TaskStats> {
-        self.netlink.send_cmd(
-            self.ts_family_id,
-            TASKSTATS_CMD_GET as u8,
-            TASKSTATS_CMD_ATTR_TGID as u16,
-            tgid.as_buf(),
-        )?;
+        self.send(TASKSTATS_CMD_ATTR_TGID as u16, tgid.as_buf())?;
 
         let resp = self.netlink.recv_response()?;
         for na in resp.payload_as_nlattrs() {
@@ -168,6 +158,107 @@ impl Client {
             "no TASKSTATS_TYPE_STATS found in response".to_string(),
         ))
     }
+
+    /// Register listener with the specific cpumask
+    ///
+    /// # Arguments
+    /// * `cpu_mask` - cpumask is specified as an ascii string of comma-separated cpu ranges e.g.
+    ///   to listen to exit data from cpus 1,2,3,5,7,8 the cpumask would be "1-3,5,7-8".
+    pub fn register_cpumask(&self, cpu_mask: &str) -> Result<()> {
+        self.send(
+            TASKSTATS_CMD_ATTR_REGISTER_CPUMASK as u16,
+            cpu_mask.as_bytes(),
+        )?;
+        Ok(())
+    }
+
+    /// Deregister listener with the specific cpumask
+    /// If userspace forgets to deregister interest in cpus before closing the listening socket,
+    /// the kernel cleans up its interest set over time. However, for the sake of efficiency,
+    /// an explicit deregistration is advisable.
+    ///
+    /// # Arguments
+    /// * `cpu_mask` - cpumask is specified as an ascii string of comma-separated cpu ranges e.g.
+    ///   to listen to exit data from cpus 1,2,3,5,7,8 the cpumask would be "1-3,5,7-8".
+    pub fn deregister_cpumask(&self, cpu_mask: &str) -> Result<()> {
+        self.send(
+            TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK as u16,
+            cpu_mask.as_bytes(),
+        )?;
+        Ok(())
+    }
+
+    /// Listen registered cpumask's.
+    /// If no messages are available at the socket, the receive call
+    /// wait for a message to arrive, unless the socket is nonblocking.
+    ///
+    /// # Return
+    /// * `Ok(Vec<TaskStats>)`: vector with stats messages. If the current task is NOT the last
+    ///   one in its thread group, only one message is returned in the vector.
+    ///   However, if it is the last task, an additional element containing the per-thread
+    ///   group ID (tgid) statistics is also included. This additional element sums up
+    ///   the statistics for all threads within the thread group, both past and present
+    pub fn listen_registered(&self) -> Result<Vec<TaskStats>> {
+        let resp = self.netlink.recv_response()?;
+        let mut stats_vec = Vec::new();
+
+        for na in resp.payload_as_nlattrs() {
+            match na.header.nla_type as u32 {
+                TASKSTATS_TYPE_NULL => break,
+                TASKSTATS_TYPE_AGGR_PID | TASKSTATS_TYPE_AGGR_TGID => {
+                    for inner in na.payload_as_nlattrs() {
+                        match inner.header.nla_type as u32 {
+                            TASKSTATS_TYPE_PID => debug!("Received TASKSTATS_TYPE_PID"),
+                            TASKSTATS_TYPE_TGID => debug!("Received TASKSTATS_TYPE_TGID"),
+                            TASKSTATS_TYPE_STATS => {
+                                stats_vec.push(TaskStats::from(inner.payload()));
+                            }
+                            unknown => println!("Skipping unknown nla_type: {}", unknown),
+                        }
+                    }
+                }
+                unknown => println!("Skipping unknown nla_type: {}", unknown),
+            }
+        }
+        if !stats_vec.is_empty() {
+            return Ok(stats_vec);
+        }
+        Err(Error::Unknown(
+            "no TASKSTATS_TYPE_STATS found in response".to_string(),
+        ))
+    }
+
+    /// Set receiver buffer size in bytes (SO_RCVBUF socket option, see socket(7))
+    ///
+    /// # Arguments
+    /// * `payload` - buffer size in bytes. The kernel doubles this value
+    ///   (to allow space for bookkeeping overhead). The default value is set by the
+    ///   /proc/sys/net/core/rmem_default file, and the maximum allowed value is set by the
+    ///   /proc/sys/net/core/rmem_max file. The minimum (doubled) value for this option is 256.
+    pub fn set_rx_buf_sz<T>(&self, payload: T) -> Result<()> {
+        self.netlink
+            .set_rx_buf_sz(payload)
+            .map_err(|err| err.into())
+    }
+
+    /// Get receiver buffer size in bytes (SO_RCVBUF socket option, see socket(7))
+    ///
+    /// # Return
+    /// * `usize` buffer size in bytes.
+    ///   Kernel returns doubled value, that have been set using [set_rx_buf_sz]
+    pub fn get_rx_buf_sz(&self) -> Result<usize> {
+        self.netlink.get_rx_buf_sz().map_err(|err| err.into())
+    }
+
+    pub fn send(&self, taskstats_cmd: u16, data: &[u8]) -> Result<()> {
+        self.netlink.send_cmd(
+            self.ts_family_id,
+            TASKSTATS_CMD_GET as u8,
+            taskstats_cmd,
+            data,
+        )?;
+        Ok(())
+    }
 }
 
 trait AsBuf<T> {

src/netlink.rs

@@ -105,6 +105,14 @@ impl Netlink<nl::Socket> {
             mypid: process::id(),
         })
     }
+
+    pub fn set_rx_buf_sz<T>(&self, payload: T) -> Result<()> {
+        self.sock.set_rx_buf_sz(payload).map_err(|err| err.into())
+    }
+
+    pub fn get_rx_buf_sz(&self) -> Result<usize> {
+        self.sock.get_rx_buf_sz().map_err(|err| err.into())
+    }
 }
 
 impl<S: NlSocket> Netlink<S> {