Refactor exec server status to handle init failure

src/exec/src/bin/occlum_exec_client.rs

@@ -116,6 +116,7 @@ fn exec_command(
 /// Starts the server if the server is not running
 fn start_server(client: &OcclumExecClient, server_name: &str) -> Result<u32, String> {
     let mut server_launched = false;
+    let mut child = None;
 
     loop {
         let resp = executor::block_on(
@@ -149,15 +150,18 @@ fn start_server(client: &OcclumExecClient, server_name: &str) -> Result<u32, Str
                         Err(_r) => {
                             return Err("Failed to launch server".to_string());
                         }
-                        Ok(_r) => {
+                        Ok(ret_child) => {
                             server_launched = true;
-
+                            child = Some(ret_child);
                             //wait server 10 millis
                             thread::sleep(time::Duration::from_millis(100));
                             continue;
                         }
                     };
                 } else {
+                    if let Some(mut child) = child {
+                        let _ = child.wait();
+                    }
                     return Err("Failed to launch server".to_string());
                 }
             }

src/exec/src/bin/occlum_exec_server.rs

@@ -11,7 +11,7 @@ use grpc::prelude::*;
 use grpc::ClientConf;
 use occlum_exec::occlum_exec::HealthCheckRequest;
 use occlum_exec::occlum_exec_grpc::{OcclumExecClient, OcclumExecServer};
-use occlum_exec::server::OcclumExecImpl;
+use occlum_exec::server::{OcclumExecImpl, ServerStatus};
 use occlum_exec::DEFAULT_SOCK_FILE;
 use std::env;
 use std::ffi::{CStr, OsString};
@@ -20,7 +20,7 @@ use std::path::Path;
 use std::sync::{Arc, Condvar, Mutex};
 
 //Checks the server status, if the server is running return true, else recover the socket file and return false.
-fn check_server_status(sock_file: &str) -> bool {
+fn is_server_running(sock_file: &str) -> bool {
     if let Err(e) = std::fs::File::open(sock_file) {
         debug!("failed to open the sock_file {:?}", e);
 
@@ -53,7 +53,7 @@ fn check_server_status(sock_file: &str) -> bool {
     }
 }
 
-fn main() {
+fn main() -> Result<(), i32> {
     let matches = App::new("Occlum_server")
         .version("0.1.0")
         .arg(
@@ -71,15 +71,15 @@ fn main() {
     assert!(env::set_current_dir(&instance_dir).is_ok());
 
     //If the server already startted, then return
-    if check_server_status(DEFAULT_SOCK_FILE) {
+    if is_server_running(DEFAULT_SOCK_FILE) {
         println!("server stared");
-        return;
+        return Ok(());
     }
 
-    let server_stopped = Arc::new((Mutex::new(true), Condvar::new()));
+    let server_status = Arc::new((Mutex::new(ServerStatus::default()), Condvar::new()));
 
     let service_def = OcclumExecServer::new_service_def(
-        OcclumExecImpl::new_and_save_execution_lock(server_stopped.clone()),
+        OcclumExecImpl::new_and_save_execution_lock(server_status.clone()),
     );
     let mut server_builder = grpc::ServerBuilder::new_plain();
     server_builder.add_service(service_def);
@@ -87,23 +87,33 @@ fn main() {
         Ok(_) => {}
         Err(e) => {
             debug!("{:?}", e);
-            return;
+            return Err(-1);
         }
     };
 
     if let Ok(server) = server_builder.build() {
-        rust_occlum_pal_init().expect("Occlum image initialization failed");
+        if let Err(_) = rust_occlum_pal_init() {
+            let (status, _) = &*server_status;
+            status.lock().unwrap().set_error();
+            return Err(-1);
+        }
         //server is running
         println!("server stared on addr {}", server.local_addr());
-        let (lock, cvar) = &*server_stopped;
-        let mut server_stopped = lock.lock().unwrap();
-        *server_stopped = false;
-        while !*server_stopped {
-            server_stopped = cvar.wait(server_stopped).unwrap();
+        let (lock, cvar) = &*server_status;
+        let mut status = lock.lock().unwrap();
+        // *server_stopped = false;
+        status.set_running();
+        while status.is_running() {
+            status = cvar.wait(status).unwrap();
         }
-        rust_occlum_pal_destroy().expect("Destory occlum image failed");
+        rust_occlum_pal_destroy()?;
         println!("server stopped");
+    } else {
+        println!("server build failed");
+        return Err(-1);
     }
+
+    Ok(())
 }
 
 extern "C" {

src/exec/src/server.rs

@@ -22,16 +22,56 @@ use std::sync::{Arc, Condvar, Mutex};
 use std::thread;
 use timer::{Guard, Timer};
 
+pub enum ServerStatus {
+    Stopped,
+    Running,
+    Error,
+}
+
+impl Default for ServerStatus {
+    fn default() -> Self {
+        Self::Stopped
+    }
+}
+
+impl ServerStatus {
+    pub fn set_error(&mut self) {
+        *self = Self::Error
+    }
+
+    pub fn set_running(&mut self) {
+        *self = Self::Running
+    }
+
+    fn set_stopped(&mut self) {
+        *self = Self::Stopped
+    }
+
+    pub fn is_running(&self) -> bool {
+        matches!(self, Self::Running)
+    }
+
+    fn is_error(&self) -> bool {
+        matches!(self, Self::Error)
+    }
+
+    fn is_stopped(&self) -> bool {
+        matches!(self, Self::Stopped)
+    }
+}
+
 #[derive(Default)]
 pub struct OcclumExecImpl {
     //process_id, return value, execution status
     commands: Arc<Mutex<HashMap<i32, (Option<i32>, bool)>>>,
-    execution_lock: Arc<(Mutex<bool>, Condvar)>,
+    execution_lock: Arc<(Mutex<ServerStatus>, Condvar)>,
     stop_timer: Arc<Mutex<Option<(Timer, Guard)>>>,
 }
 
 impl OcclumExecImpl {
-    pub fn new_and_save_execution_lock(lock: Arc<(Mutex<bool>, Condvar)>) -> OcclumExecImpl {
+    pub fn new_and_save_execution_lock(
+        lock: Arc<(Mutex<ServerStatus>, Condvar)>,
+    ) -> OcclumExecImpl {
         OcclumExecImpl {
             commands: Default::default(),
             execution_lock: lock,
@@ -111,8 +151,7 @@ impl OcclumExec for OcclumExecImpl {
                 warn!("SIGKILL failed.")
             }
             let (execution_lock, cvar) = &*lock;
-            let mut server_stopped = execution_lock.lock().unwrap();
-            *server_stopped = true;
+            execution_lock.lock().unwrap().set_stopped();
             cvar.notify_one();
         });
 
@@ -132,13 +171,18 @@ impl OcclumExec for OcclumExecImpl {
         *self.stop_timer.lock().unwrap() = None;
 
         //Waits for the Occlum loaded
-        let (lock, _) = &*self.execution_lock.clone();
+        let (status, _) = &*self.execution_lock.clone();
         loop {
-            let server_stopped = lock.lock().unwrap();
-            if *server_stopped {
-                drop(server_stopped);
+            let server_status = status.lock().unwrap();
+            if server_status.is_stopped() {
+                drop(server_status);
                 continue;
             }
+
+            if server_status.is_error() {
+                return Err(grpc::Error::Other("server error"));
+            }
+
             break;
         }