Get thread activity from the OS

Rather than use a heuristic to figure out if a thread is active, query the OS
to see if the thread is running. This should provide a more accurate view on
what's actually happening.

The tricky part here is matching the OS thread id to the python thread id,
which we were already doing for the native code unwinding. This refactors to
allow getting the native thread id even when not getting the native stack.

#92

remoteprocess/src/dylib.rs

@@ -43,7 +43,7 @@ macro_rules! dlsym {
         static $name: self::dylib::Symbol<unsafe extern fn($($t),*) -> $ret> =
             self::dylib::Symbol {
                 name: concat!(stringify!($name), "\0"),
-                addr: ::std::sync::atomic::ATOMIC_USIZE_INIT,
+                addr: ::std::sync::atomic::AtomicUsize::new(0),
                 _marker: ::std::marker::PhantomData,
             };
     )*)

remoteprocess/src/linux/mod.rs

@@ -11,7 +11,6 @@ use std::io::Read;
 use std::os::unix::io::AsRawFd;
 use std::fs::File;
 
-#[cfg(unwind)]
 use crate::dwarf_unwind::Registers;
 use super::Error;
 
@@ -25,6 +24,7 @@ pub use self::libunwind::{LibUnwind};
 use read_process_memory::{CopyAddress};
 
 pub type Pid = pid_t;
+pub type Tid = pid_t;
 
 pub struct Process {
     pub pid: Pid,
@@ -106,7 +106,7 @@ impl super::ProcessMemory for Process {
 }
 
 impl Thread {
-    pub fn new(threadid: i32) -> Thread{
+    pub fn new(threadid: i32) -> Thread {
         Thread{tid: nix::unistd::Pid::from_raw(threadid)}
     }
 
@@ -128,8 +128,8 @@ impl Thread {
         }
     }
 
-    pub fn id(&self) -> Result<u64, Error> {
-        Ok(self.tid.as_raw() as u64)
+    pub fn id(&self) -> Result<Tid, Error> {
+        Ok(self.tid.as_raw())
     }
 
     pub fn active(&self) -> Result<bool, Error> {

remoteprocess/src/osx/mod.rs

@@ -27,6 +27,7 @@ pub use self::unwinder::Unwinder;
 use libproc::libproc::proc_pid::{pidpath, pidinfo, PIDInfo, PidInfoFlavor};
 
 pub type Pid = pid_t;
+pub type Tid = u32;
 
 pub struct Process {
     pub pid: Pid,
@@ -35,7 +36,7 @@ pub struct Process {
 
 #[derive(Eq, PartialEq, Hash, Copy, Clone)]
 pub struct Thread {
-    pub tid: u32
+    pub tid: Tid
 }
 
 impl Process {
@@ -95,7 +96,15 @@ use self::mach_thread_bindings::{thread_info, thread_basic_info, thread_identifi
 
 
 impl Thread {
-    pub fn id(&self) -> Result<u64, Error> {
+    pub fn new(tid: Tid) -> Thread {
+        Thread{tid}
+    }
+
+    pub fn id(&self) -> Result<Tid, Error> {
+        Ok(self.tid)
+    }
+
+    pub fn thread_handle(&self) -> Result<u64, Error> {
         let thread_id = self.get_thread_identifier_info()?;
         Ok(thread_id.thread_handle)
     }

src/main.rs

@@ -283,6 +283,8 @@ fn pyspy_main() -> Result<(), Error> {
 }
 
 fn main() {
+    env_logger::init();
+
     if let Err(err) = pyspy_main() {
         #[cfg(unix)]
         {